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Sharathkumar A, Carr J, Claassen D, Syrbu S, Bhagavathi S, Al-Huniti A, Modi A, Bates M, Mott SL. Romiplostim for Treatment of Children and Young Adults With Severe Aplastic Anemia and Myelodysplastic Syndrome. J Pediatr Hematol Oncol 2024:00043426-990000000-00424. [PMID: 38787686 DOI: 10.1097/mph.0000000000002891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/23/2024] [Indexed: 05/26/2024]
Abstract
Thrombopoietin receptor agonists (TPO-RAs) induce trilineage hematopoiesis under conditions with acquired hematopoietic failure. We evaluated safety, tolerability, and preliminary efficacy of a TPO-RA, romiplostim (Nplate), with or without standard-of-care immunosuppressive therapy (±IST) for children (ages <21 y) with newly diagnosed and relapsed/refractory severe aplastic anemia (SAA) and myelodysplastic syndrome (MDS). Data were collected from an observational study and a single arm interventional pilot study. The safety outcome was treatment-related adverse events (AEs). Efficacy was evaluated by complete hematopoietic response (CHR) at week 24. Romiplostim was commenced at 5 µg/kg/week, with dose escalation of 2.5 µg/kg/week (maximum, 20 µg/kg/dose) based on platelet response. Romiplostim was continued until CHR was observed. Ten subjects (SAA, 9 [IST, 4; without IST, 5]; MDS, 1) completed the study (median age: 9.2 y). Median romiplostim dose was 10 µg/kg/week (range: 5 to 17.5 µg/kg/week). The cumulative incidence of CHR was 70.4% (95% CI, 20.2%-92.6%). Among 21 AEs (Grade 1 to 3), 3 were attributed to romiplostim. At a median posttherapy follow-up of 10.9 months (range: 0.7 to 77.5), no clonal evolution, bone marrow fibrosis or mortality was reported. This proof-of-concept study provides data about short-term safety, tolerability, and preliminary efficacy of romiplostim (±IST) for treatment of pediatric SAA/MDS.
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Affiliation(s)
- Anjali Sharathkumar
- Stead Family Department of Pediatrics, Carver College of Medicine
- Holden Comprehensive Cancer Center
| | - Jamie Carr
- Institute for Clinical and Translational Science
| | - David Claassen
- Stead Family Department of Pediatrics, Carver College of Medicine
| | - Sergei Syrbu
- Department of Pathology, University of Iowa, Iowa City, IA
| | | | - Ahmad Al-Huniti
- Department of Pediatrics, Mayo Clinic, Hematology, Rochester, MN
| | - Arunkumar Modi
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Melissa Bates
- Holden Comprehensive Cancer Center
- Department of Health and Human Physiology
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA
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2
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Lee S, Zhan H. Deciphering the differential impact of thrombopoietin/MPL signaling on hematopoietic stem/progenitor cell function in bone marrow and spleen. Stem Cell Reports 2024; 19:211-223. [PMID: 38215758 PMCID: PMC10874852 DOI: 10.1016/j.stemcr.2023.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 01/14/2024] Open
Abstract
Thrombopoietin (TPO) and its receptor MPL play crucial roles in hematopoietic stem cell (HSC) function and platelet production. However, the precise effects of TPO/MPL signaling on HSC regulation in different hematopoietic niches remain unclear. Here, we investigated the effects of TPO/MPL ablation on marrow and splenic hematopoiesis in TPO-/- and MPL-/- mice during aging. Despite severe thrombocytopenia, TPO-/- and MPL-/- mice did not develop marrow failure during a 2-year follow-up. Marrow and splenic HSCs exhibited different responses to TPO/MPL ablation and exogenous TPO treatment. Splenic niche cells compensated for marrow HSC loss in TPO-/- and MPL-/- mice by upregulating CXCL12 levels. These findings provide new insights into the complex regulation of HSCs by TPO/MPL and reveal a previously unknown link between TPO and CXCL12, two key growth factors for HSC maintenance. Understanding the distinct regulatory mechanisms between marrow and spleen hematopoiesis will help to develop novel therapeutic approaches for hematopoietic disorders.
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Affiliation(s)
- Sandy Lee
- Graduate Program in Molecular & Cellular Pharmacology, Stony Brook University, Stony Brook, NY, USA
| | - Huichun Zhan
- Department of Medicine, Stony Brook School of Medicine, Stony Brook, NY, USA; Medical Service, Northport VA Medical Center, Northport, NY, USA.
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3
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Sarson-Lawrence KTG, Hardy JM, Iaria J, Stockwell D, Behrens K, Saiyed T, Tan C, Jebeli L, Scott NE, Dite TA, Nicola NA, Leis AP, Babon JJ, Kershaw NJ. Cryo-EM structure of the extracellular domain of murine Thrombopoietin Receptor in complex with Thrombopoietin. Nat Commun 2024; 15:1135. [PMID: 38326297 PMCID: PMC10850085 DOI: 10.1038/s41467-024-45356-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 01/19/2024] [Indexed: 02/09/2024] Open
Abstract
Thrombopoietin (Tpo) is the primary regulator of megakaryocyte and platelet numbers and is required for haematopoetic stem cell maintenance. Tpo functions by binding its receptor (TpoR, a homodimeric Class I cytokine receptor) and initiating cell proliferation or differentiation. Here we characterise the murine Tpo:TpoR signalling complex biochemically and structurally, using cryo-electron microscopy. Tpo uses opposing surfaces to recruit two copies of receptor, forming a 1:2 complex. Although it binds to the same, membrane-distal site on both receptor chains, it does so with significantly different affinities and its highly glycosylated C-terminal domain is not required. In one receptor chain, a large insertion, unique to TpoR, forms a partially structured loop that contacts cytokine. Tpo binding induces the juxtaposition of the two receptor chains adjacent to the cell membrane. The therapeutic agent romiplostim also targets the cytokine-binding site and the characterisation presented here supports the future development of improved TpoR agonists.
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Affiliation(s)
- Kaiseal T G Sarson-Lawrence
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia
| | - Joshua M Hardy
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
| | - Josephine Iaria
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia
| | - Dina Stockwell
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia
| | - Kira Behrens
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia
| | - Tamanna Saiyed
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia
| | - Cyrus Tan
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia
| | - Leila Jebeli
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, 3000, Victoria, Australia
| | - Nichollas E Scott
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, 3000, Victoria, Australia
| | - Toby A Dite
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia
| | - Nicos A Nicola
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia
| | - Andrew P Leis
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia
| | - Jeffrey J Babon
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia.
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia.
| | - Nadia J Kershaw
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, 3052, Victoria, Australia.
- Department of Medical Biology, The University of Melbourne, Royal Parade, Parkville, 3052, Victoria, Australia.
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Ammeti D, Marzollo A, Gabelli M, Zanchetta ME, Tretti-Parenzan C, Bottega R, Capaci V, Biffi A, Savoia A, Bresolin S, Faleschini M. A novel mutation in MECOM affects MPL regulation in vitro and results in thrombocytopenia and bone marrow failure. Br J Haematol 2023; 203:852-859. [PMID: 37610030 DOI: 10.1111/bjh.19023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/21/2023] [Accepted: 07/21/2023] [Indexed: 08/24/2023]
Abstract
MECOM-associated syndrome (MECOM-AS) is a rare disease characterized by amegakaryocytic thrombocytopenia, progressive bone marrow failure, pancytopenia and radioulnar synostosis with high penetrance. The clinical phenotype may also include finger malformations, cardiac and renal alterations, hearing loss, B-cell deficiency and predisposition to infections. The syndrome, usually diagnosed in the neonatal period because of severe thrombocytopenia, is caused by mutations in the MECOM gene, encoding for the transcription factor EVI1. The mechanism linking the alteration of EVI1 function and thrombocytopenia is poorly understood. In a paediatric patient affected by severe thrombocytopenia, we identified a novel variant of the MECOM gene (p.P634L), whose effect was tested on pAP-1 enhancer element and promoters of targeted genes showing that the mutation impairs the repressive activity of the transcription factor. Moreover, we demonstrated that EVI1 controls the transcriptional regulation of MPL, a gene whose mutations are responsible for congenital amegakaryocytic thrombocytopenia (CAMT), potentially explaining the partial overlap between MECOM-AS and CAMT.
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Affiliation(s)
- Daniele Ammeti
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
| | - Antonio Marzollo
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
| | - Maria Gabelli
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
- Maternal and Child Health Department, Padua University, Padua, Italy
| | | | - Caterina Tretti-Parenzan
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
- Maternal and Child Health Department, Padua University, Padua, Italy
| | - Roberta Bottega
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
| | - Valeria Capaci
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
| | - Alessandra Biffi
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
- Maternal and Child Health Department, Padua University, Padua, Italy
| | - Anna Savoia
- Department of Engineering for Innovation Medicine, University of Verona, Verona, Italy
| | - Silvia Bresolin
- Pediatric Hematology, Oncology and Stem Cell Transplant Division, Padua University Hospital, Padua, Italy
- Maternal and Child Health Department, Padua University, Padua, Italy
| | - Michela Faleschini
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
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5
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Vissers LTW, van der Burg M, Lankester AC, Smiers FJW, Bartels M, Mohseny AB. Pediatric Bone Marrow Failure: A Broad Landscape in Need of Personalized Management. J Clin Med 2023; 12:7185. [PMID: 38002797 PMCID: PMC10672506 DOI: 10.3390/jcm12227185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 11/10/2023] [Accepted: 11/16/2023] [Indexed: 11/26/2023] Open
Abstract
Irreversible severe bone marrow failure (BMF) is a life-threatening condition in pediatric patients. Most important causes are inherited bone marrow failure syndromes (IBMFSs) and (pre)malignant diseases, such as myelodysplastic syndrome (MDS) and (idiopathic) aplastic anemia (AA). Timely treatment is essential to prevent infections and bleeding complications and increase overall survival (OS). Allogeneic hematopoietic stem cell transplantation (HSCT) provides a cure for most types of BMF but cannot restore non-hematological defects. When using a matched sibling donor (MSD) or a matched unrelated donor (MUD), the OS after HSCT ranges between 60 and 90%. Due to the introduction of post-transplantation cyclophosphamide (PT-Cy) to prevent graft versus host disease (GVHD), alternative donor HSCT can reach similar survival rates. Although HSCT can restore ineffective hematopoiesis, it is not always used as a first-line therapy due to the severe risks associated with HSCT. Therefore, depending on the underlying cause, other treatment options might be preferred. Finally, for IBMFSs with an identified genetic etiology, gene therapy might provide a novel treatment strategy as it could bypass certain limitations of HSCT. However, gene therapy for most IBMFSs is still in its infancy. This review summarizes current clinical practices for pediatric BMF, including HSCT as well as other disease-specific treatment options.
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Affiliation(s)
- Lotte T. W. Vissers
- Laboratory for Pediatric Immunology, Department of Pediatrics, Willem-Alexander Children’s Hospital, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands; (L.T.W.V.); (M.v.d.B.)
| | - Mirjam van der Burg
- Laboratory for Pediatric Immunology, Department of Pediatrics, Willem-Alexander Children’s Hospital, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands; (L.T.W.V.); (M.v.d.B.)
| | - Arjan C. Lankester
- Department of Pediatrics, Hematology and Stem Cell Transplantation, Willem-Alexander Children’s Hospital, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands; (A.C.L.); (F.J.W.S.)
| | - Frans J. W. Smiers
- Department of Pediatrics, Hematology and Stem Cell Transplantation, Willem-Alexander Children’s Hospital, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands; (A.C.L.); (F.J.W.S.)
| | - Marije Bartels
- Department of Pediatric Hematology, Wilhelmina Children’s Hospital, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands;
| | - Alexander B. Mohseny
- Department of Pediatrics, Hematology and Stem Cell Transplantation, Willem-Alexander Children’s Hospital, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands; (A.C.L.); (F.J.W.S.)
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6
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Ludhiadch A, Sulena, Singh S, Chakraborty S, Sharma D, Kulharia M, Singh P, Munshi A. Genomic Variation Affecting MPV and PLT Count in Association with Development of Ischemic Stroke and Its Subtypes. Mol Neurobiol 2023; 60:6424-6440. [PMID: 37453995 DOI: 10.1007/s12035-023-03460-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 06/22/2023] [Indexed: 07/18/2023]
Abstract
Platelets play a significant role in the pathophysiology of ischemic stroke since they are involved in the formation of intravascular thrombus after erosion or rupture of the atherosclerotic plaques. Platelet (PLT) count and mean platelet volume (MPV) are the two significant parameters that affect the functions of platelets. In the current study, MPV and PLT count was evaluated using flow cytometry and a cell counter. SonoClot analysis was carried out to evaluate activated clot timing (ACT), clot rate (CR), and platelet function (PF). Genotyping was carried out using GSA and Sanger sequencing, and expression analysis was performed using RT-PCR. In silico analysis was carried out using the GROMACS tool and UNAFold. The interaction of significant proteins with other proteins was predicted using the STRING database. Ninety-six genes were analyzed, and a significant association of THPO (rs6141) and ARHGEF3 (rs1354034) was observed with the disease and its subtypes. Altered genotypes were associated significantly with increased MPV, decreased PLT count, and CR. Expression analysis revealed a higher expression in patients bearing the variant genotypes of both genes. In silico analysis revealed that mutation in the THPO gene leads to the reduced compactness of protein structure. mRNA encoded by mutated ARHGEF3 gene increases the half-life of mRNA. The two significant proteins interact with many other proteins, especially the ones involved in platelet activation, aggregation, erythropoiesis, megakaryocyte maturation, and cytoskeleton rearrangements, suggesting that they could be important players in the determination of MPV values. In conclusion, the current study demonstrated the role of higher MPV affected by genetic variation in the development of IS and its subtypes. The results of the current study also indicate that higher MPV can be used as a biomarker for the disease and altered genotypes, and higher MPV can be targeted for better therapeutic outcomes.
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Affiliation(s)
- Abhilash Ludhiadch
- Complex Disease Genomics and Precision Medicine Laboratory, Department of Human Genetics and Molecular Medicine, Central University of Punjab, Ghudda, Bathinda, Punjab, 151401, India
| | - Sulena
- Department of Neurology, Guru Gobind Singh Medical College and Hospital, Sadiq Road, Faridkot, Punjab, 151203, India
| | | | - Sudip Chakraborty
- Department of Computational Sciences, School of Basic and Applied Sciences, Central University of Punjab, Ghudda, Bathinda, Punjab, 151401, India
| | - Dixit Sharma
- Department of Animal Sciences, School of Life Sciences, Central University of Himachal Pradesh, Kangra, Himachal Pradesh, 176206, India
| | - Mahesh Kulharia
- Centre for Computational Biology and Bioinformatics, School of Life Sciences, Central University of Himachal Pradesh, Kangra, Himachal Pradesh, 176206, India
| | - Paramdeep Singh
- Department of Radiodiagnosis, All India Institute of Medical Sciences, Bathinda, Punjab, 151001, India
| | - Anjana Munshi
- Complex Disease Genomics and Precision Medicine Laboratory, Department of Human Genetics and Molecular Medicine, Central University of Punjab, Ghudda, Bathinda, Punjab, 151401, India.
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7
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Tsutsumi N, Masoumi Z, James SC, Tucker JA, Winkelmann H, Grey W, Picton LK, Moss L, Wilson SC, Caveney NA, Jude KM, Gati C, Piehler J, Hitchcock IS, Garcia KC. Structure of the thrombopoietin-MPL receptor complex is a blueprint for biasing hematopoiesis. Cell 2023; 186:4189-4203.e22. [PMID: 37633268 PMCID: PMC10528194 DOI: 10.1016/j.cell.2023.07.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 06/26/2023] [Accepted: 07/28/2023] [Indexed: 08/28/2023]
Abstract
Thrombopoietin (THPO or TPO) is an essential cytokine for hematopoietic stem cell (HSC) maintenance and megakaryocyte differentiation. Here, we report the 3.4 Å resolution cryoelectron microscopy structure of the extracellular TPO-TPO receptor (TpoR or MPL) signaling complex, revealing the basis for homodimeric MPL activation and providing a structural rationalization for genetic loss-of-function thrombocytopenia mutations. The structure guided the engineering of TPO variants (TPOmod) with a spectrum of signaling activities, from neutral antagonists to partial- and super-agonists. Partial agonist TPOmod decoupled JAK/STAT from ERK/AKT/CREB activation, driving a bias for megakaryopoiesis and platelet production without causing significant HSC expansion in mice and showing superior maintenance of human HSCs in vitro. These data demonstrate the functional uncoupling of the two primary roles of TPO, highlighting the potential utility of TPOmod in hematology research and clinical HSC transplantation.
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Affiliation(s)
- Naotaka Tsutsumi
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan.
| | - Zahra Masoumi
- York Biomedical Research Institute, Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Sophie C James
- York Biomedical Research Institute, Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Julie A Tucker
- York Biomedical Research Institute, Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Hauke Winkelmann
- Department of Biology/Chemistry and Center of Cellular Nanoanalytics, Osnabrück University, 49076 Osnabrück, Germany
| | - William Grey
- York Biomedical Research Institute, Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Lora K Picton
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lucie Moss
- York Biomedical Research Institute, Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Steven C Wilson
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Nathanael A Caveney
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kevin M Jude
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Cornelius Gati
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Jacob Piehler
- Department of Biology/Chemistry and Center of Cellular Nanoanalytics, Osnabrück University, 49076 Osnabrück, Germany
| | - Ian S Hitchcock
- York Biomedical Research Institute, Department of Biology, University of York, Heslington, York YO10 5DD, UK.
| | - K Christopher Garcia
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
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8
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Novel THPO variant in hereditary thrombocytopenia: A potential candidate variant for predisposition to myeloid neoplasm. PLoS One 2022; 17:e0271624. [PMID: 36534659 PMCID: PMC9762605 DOI: 10.1371/journal.pone.0271624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 07/05/2022] [Indexed: 12/23/2022] Open
Abstract
Hereditary thrombocytopenia is a heterogeneous group of congenital disorders with a wide range of symptoms depending on the severity of platelet dysfunction or thrombocytopenia. Because of its clinical phenotypes and the bone marrow morphology associated with this condition, hereditary thrombocytopenia can be misdiagnosed as primary immune thrombocytopenia and myelodysplastic syndrome. Therefore, genetic evidence is necessary for the accurate diagnosis of hereditary thrombocytopenia. Refractory cytopenia of childhood is a subgroup of myelodysplastic syndrome that was added to the World Health Organization classification in 2008. To investigate the germline and somatic variants associated with refractory cytopenia of childhood, we performed targeted multigene sequencing in three patients with refractory cytopenia of childhood. Of the three patients, one progressed from megakaryocytic hypoplasia with thrombocytopenia, and targeted multigene sequencing revealed THPO variants in this patient and his sister. We propose that the monoallelic deletion of THPO is a potential candidate for germline predisposition to myeloid malignancy.
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Yang L, Wu L, Meng P, Zhang X, Zhao D, Lin Q, Zhang Y. Generation of a thrombopoietin-deficient thrombocytopenia model in zebrafish. J Thromb Haemost 2022; 20:1900-1909. [PMID: 35622056 DOI: 10.1111/jth.15772] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/17/2022] [Accepted: 05/21/2022] [Indexed: 11/28/2022]
Abstract
BACKGROUND The production of platelets is tightly regulated by thrombopoietin (THPO). Mutations in the THPO gene cause thrombocytopenia. Although mice lacking Thpo present with thrombocytopenia, predicting phenotypes and pathogenicity of novel THPO mutations in mice is limited. Zebrafish can be a powerful tool for fast validation and study of candidate genes of human hematological diseases and have already been used as a model of human thrombocytopenia. OBJECTIVES We aim to investigate the role of Thpo in zebrafish thrombopoiesis and to establish a Thpo-deficient zebrafish model. The model could be applied for illustrating the clinically discovered human THPO variants of which the clinical significance is not known and to evaluate the effect of THPO receptor agonists (THPO-Ras), as well as a screening platform for new drugs. METHODS We generated a thpo loss-of-function zebrafish model using CRISPR/Cas9. After disruption of zebrafish thpo, thposzy6 zebrafish presented with a significant reduction of thpo expression and developed thrombocytopenia. Furthermore, we performed in vivo studies with zebrafish with the thposzy6 mutation and found two human clinical point mutations (c.091C > T and c.112C > T) that were responsible for the thrombocytopenia phenotype. In addition, effects of THPO-RAs used as therapeutics against thrombocytopenia were evaluated in the Tg(mpl:eGFP);thposzy6 line. RESULTS AND CONCLUSIONS Zebrafish with the mutation thposzy6 presented with a significant reduction of thpo expression and developed thrombocytopenia. Thpo loss-of-function zebrafish model can serve as a valuable preclinical model for thrombocytopenia caused by thpo-deficiency, as well as a tool to study human clinical THPO variants and evaluate the effect of THPO-RAs.
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Affiliation(s)
- Lian Yang
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
| | - Liangliang Wu
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
- Department of Hematology, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, China
| | - Panpan Meng
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
| | - Xuebing Zhang
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
| | - Dejian Zhao
- Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, China
| | - Qing Lin
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
| | - Yiyue Zhang
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, Guangzhou, China
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10
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Abstract
The new techniques of genetic analysis have made it possible to identify many new forms of inherited thrombocytopenias (IT) and study large series of patients. In recent years, this has changed the view of IT, highlighting the fact that, in contrast to previous belief, most patients have a modest bleeding diathesis. On the other hand, it has become evident that some of the mutations responsible for platelet deficiency predispose the patient to serious, potentially life-threatening diseases. Today's vision of IT is, therefore, very different from that of the past and the therapeutic approach must take these changes into account while also making use of the new therapies that have become available in the meantime. This review, the first devoted entirely to IT therapy, discusses how to prevent bleeding in those patients who are exposed to this risk, how to treat it if it occurs, and how to manage the serious illnesses to which patients with IT may be predisposed.
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11
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Bourguignon A, Tasneem S, Hayward CP. Screening and diagnosis of inherited platelet disorders. Crit Rev Clin Lab Sci 2022; 59:405-444. [PMID: 35341454 DOI: 10.1080/10408363.2022.2049199] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Inherited platelet disorders are important conditions that often manifest with bleeding. These disorders have heterogeneous underlying pathologies. Some are syndromic disorders with non-blood phenotypic features, and others are associated with an increased predisposition to developing myelodysplasia and leukemia. Platelet disorders can present with thrombocytopenia, defects in platelet function, or both. As the underlying pathogenesis of inherited thrombocytopenias and platelet function disorders are quite diverse, their evaluation requires a thorough clinical assessment and specialized diagnostic tests, that often challenge diagnostic laboratories. At present, many of the commonly encountered, non-syndromic platelet disorders do not have a defined molecular cause. Nonetheless, significant progress has been made over the past few decades to improve the diagnostic evaluation of inherited platelet disorders, from the assessment of the bleeding history to improved standardization of light transmission aggregometry, which remains a "gold standard" test of platelet function. Some platelet disorder test findings are highly predictive of a bleeding disorder and some show association to symptoms of prolonged bleeding, surgical bleeding, and wound healing problems. Multiple assays can be required to diagnose common and rare platelet disorders, each requiring control of preanalytical, analytical, and post-analytical variables. The laboratory investigations of platelet disorders include evaluations of platelet counts, size, and morphology by light microscopy; assessments for aggregation defects; tests for dense granule deficiency; analyses of granule constituents and their release; platelet protein analysis by immunofluorescent staining or flow cytometry; tests of platelet procoagulant function; evaluations of platelet ultrastructure; high-throughput sequencing and other molecular diagnostic tests. The focus of this article is to review current methods for the diagnostic assessment of platelet function, with a focus on contemporary, best diagnostic laboratory practices, and relationships between clinical and laboratory findings.
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Affiliation(s)
- Alex Bourguignon
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
| | - Subia Tasneem
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
| | - Catherine P Hayward
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada.,Department of Medicine, McMaster University, Hamilton, Canada
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12
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Khatib-Massalha E, Méndez-Ferrer S. Megakaryocyte Diversity in Ontogeny, Functions and Cell-Cell Interactions. Front Oncol 2022; 12:840044. [PMID: 35186768 PMCID: PMC8854253 DOI: 10.3389/fonc.2022.840044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 01/17/2022] [Indexed: 12/12/2022] Open
Abstract
Hematopoietic stem cells (HSCs) rely on local interactions in the bone marrow (BM) microenvironment with stromal cells and other hematopoietic cells that facilitate their survival and proliferation, and also regulate their functions. HSCs and multipotent progenitor cells differentiate into lineage-specific progenitors that generate all blood and immune cells. Megakaryocytes (Mks) are hematopoietic cells responsible for producing blood platelets, which are essential for normal hemostasis and blood coagulation. Although the most prominent function of Mks is platelet production (thrombopoiesis), other increasingly recognized functions include HSC maintenance and host immune response. However, whether and how these diverse programs are executed by different Mk subpopulations remains poorly understood. This Perspective summarizes our current understanding of diversity in ontogeny, functions and cell-cell interactions. Cumulative evidence suggests that BM microenvironment dysfunction, partly caused by mutated Mks, can induce or alter the progression of a variety of hematologic malignancies, including myeloproliferative neoplasms (MPNs) and other disorders associated with tissue scarring (fibrosis). Therefore, as an example of the heterogeneous functions of Mks in malignant hematopoiesis, we will discuss the role of Mks in the onset and progression of BM fibrosis. In this regard, abnormal interactions between of Mks and other immune cells might directly contribute to fibrotic diseases. Overall, further understanding of megakaryopoiesis and how Mks interact with HSCs and immune cells has potential clinical implications for stem cell transplantation and other therapies for hematologic malignancies, as well as for treatments to stimulate platelet production and prevent thrombocytopenia.
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Affiliation(s)
- Eman Khatib-Massalha
- Wellcome-Medical Research Council (MRC) Cambridge Stem Cell Institute, University of Cambridge, Cambridge, United Kingdom
- Department of Hematology, University of Cambridge, Cambridge, United Kingdom
- National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Simón Méndez-Ferrer
- Wellcome-Medical Research Council (MRC) Cambridge Stem Cell Institute, University of Cambridge, Cambridge, United Kingdom
- Department of Hematology, University of Cambridge, Cambridge, United Kingdom
- National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge, United Kingdom
- Instituto de Biomedicina de Sevilla-IBiS, Hospitales Universitarios Virgen del Rocío y Macarena/Spanish National Research Council (CSIC)/Universidad de Sevilla, Seville, Spain
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Seville, Spain
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Cancio M, Hebert K, Kim S, Aljurf M, Olson T, Anderson E, Burroughs L, Vatsayan A, Myers K, Hashem H, Hanna R, Horn B, Prestidge T, Boelens JJ, Boulad F, Eapen M. Outcomes in Hematopoietic Stem Cell Transplantation for Congenital Amegakaryocytic Thrombocytopenia. Transplant Cell Ther 2022; 28:101.e1-101.e6. [PMID: 34670170 PMCID: PMC8816844 DOI: 10.1016/j.jtct.2021.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 10/05/2021] [Accepted: 10/10/2021] [Indexed: 02/03/2023]
Abstract
Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare, inherited bone marrow failure syndrome. Hematopoietic stem cell transplantation (HSCT) is considered a curative treatment option, but existing descriptions of patient and transplant characteristics and outcomes after related and unrelated donor HSCT are sparse. We describe outcomes after HSCT for congenital amegakaryocytic thrombocytopenia (CAMT; n = 86) from 2000 to 2018. We conducted an analysis of data collected by the Center for International Blood and Marrow Transplant Research on patients with CAMT receiving therapeutic allogeneic HSCT. The predominant donor type was HLA-matched or mismatched unrelated donors (n = 58, 67%). The remaining included HLA-matched sibling (n = 23, 27%) and HLA-mismatched relative (n = 5, 6%). The predominant graft types were bone marrow (n = 53, 62%) and cord blood (n = 25, 29%). The median age at transplantation was 3 years, with 82 of 86 patients being transplanted aged ≤10 years. The 5-year graft failure-free and overall survival were 83% (95% confidence interval [CI], 74-90) and 86% (95% CI, 78-93), respectively. An examination for risk factors confirmed mortality was higher after HLA-mismatched relative and mismatched unrelated donor HSCT compared to HLA-matched sibling and matched unrelated donor HSCT (hazard ratio 3.52, P = .04; 75% versus 93%). The 1-year incidence of graft failure was 19% after HLA-mismatched HSCT (n = 32) compared to 7% after HLA-matched HSCT (n = 54, P = .15). Day-100 grade II-IV acute graft-versus-host disease was 13%, 26%, and 30% after HLA-matched sibling, HLA-matched and mismatched unrelated donor HSCT. The 5-year incidence of chronic graft-versus-host disease was 33% with 24 of 28 patients having received grafts from HLA-matched (n = 13) and mismatched unrelated (n = 11) donors. Although HLA-matched donors are preferred, HLA-mismatched donors also extend survival for CAMT.
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Affiliation(s)
- Maria Cancio
- MSK Kids, Stem Cell Transplantation and Cellular Therapy, Memorial Sloan Kettering Cancer Center, New York, NY,Correspondence: Maria Cancio, MD; Memorial Sloan Kettering Cancer Center, 1275 York Ave. New York, NY 10065,
| | - Kyle Hebert
- Center for International Blood and Marrow Transplant Research, Division of Hematology/Oncology, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI
| | - Soyoung Kim
- Department of Biostatistics, Medical College of Wisconsin, Milwaukee, WI
| | - Mahmoud Aljurf
- Oncology Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Timothy Olson
- Comprehensive Bone Marrow Failure Center, Children’s Hospital of Philadelphia, Philadelphia, PA
| | | | - Lauri Burroughs
- Department of Pediatrics, University of Washington-Seattle Children’s Hospital, Seattle, WA
| | - Anant Vatsayan
- Division of Blood and Marrow Transplantation, Children’s National Health System, Washington, DC
| | - Kasiani Myers
- Division of Bone Marrow Transplantation and Immune Deficiency, Cincinnati Children’s Hospital Medical Center
| | - Hasan Hashem
- Department of Pediatrics, Division of Pediatric Hematology Oncology and Bone Marrow Transplantation, King Hussein Cancer Center, Amman, Jordan
| | - Rabi Hanna
- Department of Pediatric Hematology Oncology and BMT, Cleveland Clinic Children’s, Cleveland, OH
| | - Biljana Horn
- Pediatric Hematology/Oncology, University of Florida, Gainesville, FL
| | - Tim Prestidge
- Blood and Cancer Centre, Starship Children’s Hospital, Auckland, New Zealand
| | - Jaap-Jan Boelens
- MSK Kids, Stem Cell Transplantation and Cellular Therapy, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Farid Boulad
- MSK Kids, Stem Cell Transplantation and Cellular Therapy, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Mary Eapen
- Center for International Blood and Marrow Transplant Research, Division of Hematology/Oncology, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI
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14
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Oved JH, Shah YB, Venella K, Paessler ME, Olson TS. Non-myeloablative conditioning is sufficient to achieve complete donor myeloid chimerism following matched sibling donor bone marrow transplant for myeloproliferative leukemia virus oncogene ( MPL) mutation-driven congenital amegakaryocytic thrombocytopenia: Case report. Front Pediatr 2022; 10:903872. [PMID: 35967582 PMCID: PMC9366100 DOI: 10.3389/fped.2022.903872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 06/29/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare platelet production disorder caused mainly by loss of function biallelic mutations in myeloproliferative leukemia virus oncogene (MPL), the gene encoding the thrombopoietin receptor (TPOR). Patients with MPL-mutant CAMT are not only at risk for life-threatening bleeding events, but many affected individuals will also ultimately develop bone marrow aplasia owing to the absence of thrombopoietin/TPOR signaling required for maintenance of hematopoietic stem cells. Curative allogeneic stem cell transplant for patients with CAMT has historically used myeloablative conditioning; however, given the inherent stem cell defect in MPL-mutant CAMT, a less intensive regimen may prove equally effective with reduced morbidity, particularly in patients with evolving aplasia. METHODS We report the case of a 2-year-old boy with MPL-mutant CAMT and bone marrow hypocellularity who underwent matched sibling donor bone marrow transplant (MSD-BMT) using a non-myeloablative regimen consisting of fludarabine, cyclophosphamide, and antithymocyte globulin (ATG). RESULTS The patient achieved rapid trilinear engraftment and resolution of thrombocytopenia. While initial myeloid donor chimerism was mixed (88% donor), due to the competitive advantage of donor hematopoietic cells, myeloid chimerism increased to 100% by 4 months post-transplant. Donor chimerism and blood counts remained stable through 1-year post-transplant. CONCLUSION This experience suggests that non-myeloablative conditioning is a suitable approach for patients with MPL-mutant CAMT undergoing MSD-BMT and is associated with reduced risks of conditioning-related toxicity compared to traditional myeloablative regimens.
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Affiliation(s)
- Joseph Hai Oved
- Pediatric Transplantation and Cell Therapy, MSK Kids, New York, NY, United States
| | - Yash B Shah
- Cell Therapy and Transplant Section, Division of Pediatric Oncology, Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Kimberly Venella
- Cell Therapy and Transplant Section, Division of Pediatric Oncology, Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Michele E Paessler
- Department of Pathology, Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Timothy S Olson
- Cell Therapy and Transplant Section, Division of Pediatric Oncology, Children's Hospital of Philadelphia, Philadelphia, PA, United States
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15
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Germeshausen M, Ballmaier M. CAMT-MPL: congenital amegakaryocytic thrombocytopenia caused by MPL mutations - heterogeneity of a monogenic disorder - a comprehensive analysis of 56 patients. Haematologica 2021; 106:2439-2448. [PMID: 32703794 PMCID: PMC8409039 DOI: 10.3324/haematol.2020.257972] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Indexed: 11/17/2022] Open
Abstract
Congenital amegakaryocytic thrombocytopenia caused by deleterious homozygous or compound heterozygous mutations in MPL (CAMT-MPL) is a rare inherited bone marrow failure syndrome presenting as an isolated thrombocytopenia at birth progressing to pancytopenia due to exhaustion of hematopoietic progenitors. The analysis of samples and clinical data from a large cohort of 56 patients with CAMT-MPL resulted in a detailed description of the clinical picture and reliable genotype-phenotype correlations for this rare disease. We extended the spectrum of CAMT causing MPL mutations regarding number (17 novel mutations) and impact. Clinical courses showed great variability with respect to the severity of thrombocytopenia, the development of pancytopenia and the consequences from bleedings. The most severe clinical problems were (i) intracranial bleedings pre- and perinatally and the resulting long-term consequences, and (ii) the development of aplastic anemia in the later course of the disease. An important and new finding was that thrombocytopenia was not detected at birth in a quarter of the patients. The rate of non-hematological abnormalities in CAMT-MPL was higher than described so far. Most of the anomalies were related to the head region (brain anomalies, ocular and orbital anomalies) and consequences of intracranial bleedings. The present study demonstrates a higher variability of clinical courses than described so far and has important implications on diagnosis and therapy. The diagnosis CAMT-MPL has to be considered even for those patients who are inconspicuous in the first months of life or show somatic anomalies typical for other inherited bone marrow failure syndromes.
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Affiliation(s)
- Manuela Germeshausen
- Central Research Facility Cell Sorting, Hannover Medical School, Hannover, Germany.
| | - Matthias Ballmaier
- Central Research Facility Cell Sorting, Hannover Medical School, Hannover, Germany.
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16
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Kapoor S, Champion G, Olnes MJ. Thrombopoietin receptor agonists for marrow failure: A concise clinical review. Best Pract Res Clin Haematol 2021; 34:101274. [PMID: 34404526 DOI: 10.1016/j.beha.2021.101274] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/20/2021] [Accepted: 05/22/2021] [Indexed: 11/29/2022]
Abstract
Bone marrow failure is characterized by a disruption of hematopoietic stem cell (HSC) homeostasis and function, which causes decreased blood counts. Germline and somatic mutations within HSCs and immune dysregulation contribute to the pathogenesis of marrow failure. Allogeneic HSC transplant is a potentially curative therapy for marrow failure, although not all patients are candidates for this procedure. Immune suppressive therapy (IST) is an effective treatment for patients with aplastic anemia (AA) and select patients with myelodysplastic syndromes, but some patients fail to respond or relapse after IST. Over the past decade, the oral thrombopoietin receptor agonist eltrombopag has become a therapeutic option for AA in combination with frontline IST, and as a single agent for relapsed and refractory patients after IST. In this review, we highlight current knowledge of thrombopoietin receptor agonist mechanisms of action, and clinical indications and toxicities in patients with marrow failure, including the risk of clonal evolution.
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Affiliation(s)
- Sargam Kapoor
- Hematology and Medical Oncology, Alaska Native Tribal Health Consortium, 3900 Ambassador Dr, Anchorage, AK, 99508, USA
| | - Grace Champion
- University of Washington School of Medicine, 1959 NE Pacific St, Seattle, WA, 98195, USA
| | - Matthew J Olnes
- Hematology and Medical Oncology, Alaska Native Tribal Health Consortium, 3900 Ambassador Dr, Anchorage, AK, 99508, USA; University of Washington School of Medicine, 1959 NE Pacific St, Seattle, WA, 98195, USA; WWAMI School of Medical Education, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, AK, 99508, USA.
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17
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Congenital amegakaryocytic thrombocytopenia - Not a single disease. Best Pract Res Clin Haematol 2021; 34:101286. [PMID: 34404532 DOI: 10.1016/j.beha.2021.101286] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 07/09/2021] [Accepted: 07/12/2021] [Indexed: 01/05/2023]
Abstract
Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare inherited bone marrow failure syndrome (IBMFS) that is characterized by severe thrombocytopenia at birth due to ineffective megakaryopoiesis and development towards aplastic anemia during the first years of life. CAMT is not a single monogenetic disorder; rather, many descriptions of CAMT include different entities with different etiologies. CAMT in a narrow sense, which is primarily restricted to the hematopoietic system, is caused mainly by mutations in the gene for the thrombopoietin receptor (MPL), sometimes in the gene for its ligand (THPO). CAMT in association with radio-ulnar synostosis, which is not always clinically apparent, is mostly caused by mutations in MECOM, rarely in HOXA11. Patients affected by other IBMFS - especially Fanconi anemia or dyskeratosis congenita - may be misdiagnosed as having CAMT when they lack typical disease features of these syndromes or have only mild symptoms. This article reviews scientific and clinical aspects of the various disorders associated with the term "CAMT" with a main focus on the disease caused by mutations in the MPL gene.
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18
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Hitchcock IS, Hafer M, Sangkhae V, Tucker JA. The thrombopoietin receptor: revisiting the master regulator of platelet production. Platelets 2021; 32:770-778. [PMID: 34097561 PMCID: PMC8292222 DOI: 10.1080/09537104.2021.1925102] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 12/25/2022]
Abstract
Thrombopoietin (TPO) and its receptor, MPL, are the primary regulators of platelet production and critical for hematopoietic stem cell (HSC) maintenance. Since TPO was first cloned in 1994, the physiological and pathological roles of TPO and MPL have been well characterized, culminating in the first MPL agonists being approved for the treatment of chronic immune thrombocytopenia in 2008. Dysregulation of the TPO-MPL signaling axis contributes to the pathogenesis of hematological disorders: decreased expression or function results in severe thrombocytopenia progressing to bone marrow failure, while hyperactivation of MPL signaling, either by mutations in the receptor or associated Janus kinase 2 (JAK2), results in pathological myeloproliferation. Despite its importance, it was only recently that the long-running debate over the mechanism by which TPO binding activates MPL has been resolved. This review will cover key aspects of TPO and MPL structure and function and their importance in receptor activation, discuss how these are altered in hematological disorders and consider how a greater understanding could lead to the development of better-targeted and more efficacious therapies.
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Affiliation(s)
- Ian S. Hitchcock
- York Biomedical Research Institute, Department of Biology, University of York, York, UK
| | - Maximillian Hafer
- Department of Biology and Center of Cellular Nanoanalytics, University of Osnabrück, Osnabrück, Germany
| | - Veena Sangkhae
- Center for Iron Disorders, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Julie A. Tucker
- York Biomedical Research Institute, Department of Biology, University of York, York, UK
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19
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Bussel JB, Soff G, Balduzzi A, Cooper N, Lawrence T, Semple JW. A Review of Romiplostim Mechanism of Action and Clinical Applicability. Drug Des Devel Ther 2021; 15:2243-2268. [PMID: 34079225 PMCID: PMC8165097 DOI: 10.2147/dddt.s299591] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 05/06/2021] [Indexed: 12/17/2022] Open
Abstract
Thrombocytopenia results from a variety of conditions, including radiation, chemotherapy, autoimmune disease, bone marrow disorders, pathologic conditions associated with surgical procedures, hematopoietic stem cell transplant (HSCT), and hematologic disorders associated with severe aplastic anemia. Immune thrombocytopenia (ITP) is caused by immune reactions that accelerate destruction and reduce production of platelets. Thrombopoietin (TPO) is a critical component of platelet production pathways, and TPO receptor agonists (TPO-RAs) are important for the management of ITP by increasing platelet production and reducing the need for other treatments. Romiplostim is a TPO-RA approved for use in patients with ITP in the United States, European Union, Australia, and several countries in Africa and Asia, as well as for use in patients with refractory aplastic anemia in Japan and Korea. Romiplostim binds to and activates the TPO receptor on megakaryocyte precursors, thus promoting cell proliferation and viability, resulting in increased platelet production. Through this mechanism, romiplostim reduces the need for other treatments and decreases bleeding events in patients with thrombocytopenia. In addition to its efficacy in ITP, studies have shown that romiplostim is effective in improving platelet counts in various settings, thereby highlighting the versatility of romiplostim. The efficacy of romiplostim in such disorders is currently under investigation. Here, we review the structure, mechanism, pharmacokinetics, and pharmacodynamics of romiplostim. We also summarize the clinical evidence supporting its use in ITP and other disorders that involve thrombocytopenia, including chemotherapy-induced thrombocytopenia, aplastic anemia, acute radiation syndrome, perisurgical thrombocytopenia, post-HSCT thrombocytopenia, and liver disease.
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Affiliation(s)
- James B Bussel
- Department of Pediatrics, Division of Hematology, Weill Cornell Medicine, New York, NY, USA
| | - Gerald Soff
- Department of Medicine, Hematology Service, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Adriana Balduzzi
- Clinica Pediatrica Università degli Studi di Milano Bicocca, Ospedale San Gerardo, Monza, Italy
| | | | | | - John W Semple
- Division of Hematology and Transfusion Medicine, Lund University, Lund, Sweden
- Department of Pharmacology, University of Toronto, Toronto, ON, Canada
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20
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Monoallelic loss-of-function THPO variants cause heritable thrombocytopenia. Blood Adv 2021; 4:920-924. [PMID: 32150607 DOI: 10.1182/bloodadvances.2019001293] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 12/23/2019] [Indexed: 12/26/2022] Open
Abstract
Key Points
We report rare monoallelic variants of THPO that alter intracellular trafficking and diminish thrombopoietin secretion. Affected cases have autosomal-dominant thrombocytopenia but no other hematological features.
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21
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Inherited Platelet Disorders: An Updated Overview. Int J Mol Sci 2021; 22:ijms22094521. [PMID: 33926054 PMCID: PMC8123627 DOI: 10.3390/ijms22094521] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/17/2021] [Accepted: 04/21/2021] [Indexed: 02/06/2023] Open
Abstract
Platelets play a major role in hemostasis as ppwell as in many other physiological and pathological processes. Accordingly, production of about 1011 platelet per day as well as appropriate survival and functions are life essential events. Inherited platelet disorders (IPDs), affecting either platelet count or platelet functions, comprise a heterogenous group of about sixty rare diseases caused by molecular anomalies in many culprit genes. Their clinical relevance is highly variable according to the specific disease and even within the same type, ranging from almost negligible to life-threatening. Mucocutaneous bleeding diathesis (epistaxis, gum bleeding, purpura, menorrhagia), but also multisystemic disorders and/or malignancy comprise the clinical spectrum of IPDs. The early and accurate diagnosis of IPDs and a close patient medical follow-up is of great importance. A genotype-phenotype relationship in many IPDs makes a molecular diagnosis especially relevant to proper clinical management. Genetic diagnosis of IPDs has been greatly facilitated by the introduction of high throughput sequencing (HTS) techniques into mainstream investigation practice in these diseases. However, there are still unsolved ethical concerns on general genetic investigations. Patients should be informed and comprehend the potential implications of their genetic analysis. Unlike the progress in diagnosis, there have been no major advances in the clinical management of IPDs. Educational and preventive measures, few hemostatic drugs, platelet transfusions, thrombopoietin receptor agonists, and in life-threatening IPDs, allogeneic hematopoietic stem cell transplantation are therapeutic possibilities. Gene therapy may be a future option. Regular follow-up by a specialized hematology service with multidisciplinary support especially for syndromic IPDs is mandatory.
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22
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Bastida JM, Gonzalez-Porras JR, Rivera J, Lozano ML. Role of Thrombopoietin Receptor Agonists in Inherited Thrombocytopenia. Int J Mol Sci 2021; 22:ijms22094330. [PMID: 33919295 PMCID: PMC8122256 DOI: 10.3390/ijms22094330] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/16/2021] [Accepted: 04/17/2021] [Indexed: 01/05/2023] Open
Abstract
In the last decade, improvements in genetic testing have revolutionized the molecular diagnosis of inherited thrombocytopenias (ITs), increasing the spectrum of knowledge of these rare, complex and heterogeneous disorders. In contrast, the therapeutic management of ITs has not evolved in the same way. Platelet transfusions have been the gold standard treatment for a long time. Thrombopoietin receptor agonists (TPO-RA) were approved for immune thrombocytopenia (ITP) ten years ago and there is evidence for the use of TPO-RA not only in other forms of ITP, but also in ITs. We have reviewed in the literature the existing evidence on the role of TPO-RAs in ITs from 2010 to February 2021. A total of 24 articles have been included, 4 clinical trials, 3 case series and 17 case reports. A total of 126 patients with ITs have received TPO-RA. The main diagnoses were Wiskott–Aldrich syndrome, MYH9-related disorder and ANKRD26-related thrombocytopenia. Most patients were enrolled in clinical trials and were treated for short periods of time with TPO-RA as bridging therapies towards surgical interventions, or other specific approaches, such as hematopoietic stem cell transplantation. Here, we have carried out an updated and comprehensive review about the efficacy and safety of TPO-RA in ITs.
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Affiliation(s)
- José María Bastida
- Department of Hematology, Instituto de Investigación Biomédica de Salamanca (IBSAL), Complejo Asistencial Universitario de Salamanca (CAUSA), Universidad de Salamanca (USAL), 37007 Salamanca, Spain;
- Correspondence:
| | - José Ramón Gonzalez-Porras
- Department of Hematology, Instituto de Investigación Biomédica de Salamanca (IBSAL), Complejo Asistencial Universitario de Salamanca (CAUSA), Universidad de Salamanca (USAL), 37007 Salamanca, Spain;
| | - José Rivera
- Department of Hematology and Oncology, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CIBERER-U765, 30008 Murcia, Spain; (J.R.); (M.L.L.)
| | - María Luisa Lozano
- Department of Hematology and Oncology, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CIBERER-U765, 30008 Murcia, Spain; (J.R.); (M.L.L.)
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Up-front Treatment With Romiplostim in Children With Acquired Bone Marrow Failure: A Single Institutional Pediatric Case Series. J Pediatr Hematol Oncol 2021; 43:e431-e435. [PMID: 32341259 DOI: 10.1097/mph.0000000000001810] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 03/23/2020] [Indexed: 10/24/2022]
Abstract
BACKGROUND Thrombopoietin receptor agonists are emerging as a therapeutic option for patients with aplastic anemia (AA) and myelodysplastic syndrome (MDS). We report our experience of treating children with AA/MDS with romiplostim, thrombopoietin receptor agonist. OBSERVATIONS Three children (AA, 2; MDS, 1) received romiplostim treatment at a median dose of 10 μg/kg/week (starting dose: 5 μg/kg/wk; 2.5 μg/kg/wk increment). Trilineage hematopoietic recovery occurred at a median of 13 weeks (range: 13 to 16 wk) without adverse events. Hematopoiesis continued to improve after therapy discontinuation (median follow-up: 2.8 y; range: 0.5 to 3.0). CONCLUSION Our experience supports the short-term safety and efficacy of romiplostim in children with AA/MDS.
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Ejaz A, Ozcan A, Unal E, Karakukcu M, Sankaran VG. Long-Term Patient-Customized Therapy for a Pathogenic EPO Mutation. MED 2021; 2:33-37.e1. [PMID: 33521754 DOI: 10.1016/j.medj.2020.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Background Recent advances in genomics have enabled the successful identification of a number of rare pathogenic mutations. Uncovering these mutations is essential as the first step towards devising a cure for the often debilitating and life-limiting diseases arising from them. For many of these mutations targeted agents do not yet exist. Here, we describe the case of a patient who has a novel pathogenic mutation in the erythropoietin (EPO) gene, which is essential for normal erythropoiesis, and who presented with a profound hypoplastic anemia. Methods The patient aged 5 months, was started on recombinant erythropoietin, at a standard dose of 500 units (50 U/kg) and subsequently 800 units three time weekly and her blood counts were monitored over 4 years. Findings A prompt response to the recombinant erythropoietin was found with an increase in hemoglobin levels to 12.8 g/dL and increase in red cell count to 4.89×106/uL. The patient became transfusion independent. The therapy enabled the patient to maintain a hemoglobin level in the normal range without any adverse effects and with no requirement for further blood transfusions. Conclusions Patient-customized therapies can be highly effective in the treatment of rare genetic disorders and for many of these disorders effective treatment may already exist in the clinical domain, as described for the patient in this report. Funding This work was supported by the New York Stem Cell Foundation (V.G.S.), a gift from the Lodish Family to Boston Children's Hospital (V.G.S.), and National Institutes of Health Grants R01 DK103794 and R01 HL146500 (V.G.S.).
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Affiliation(s)
- Ayesha Ejaz
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA USA.,Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA USA.,Broad Institute of MIT and Harvard, Cambridge, MA USA.,Department of Hematology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Alper Ozcan
- Department of Pediatrics, Division of Pediatric Hematology and Oncology, Faculty of Medicine, Erciyes University, Kayseri, Turkey
| | - Ekrem Unal
- Department of Pediatrics, Division of Pediatric Hematology and Oncology, Faculty of Medicine, Erciyes University, Kayseri, Turkey.,Department of Molecular Biology and Genetics, Erciyes University Faculty of Medicine, Betül-Ziya Eren Genome and Stem Cell Center (GENKOK), Kayseri, Turkey
| | - Musa Karakukcu
- Department of Pediatrics, Division of Pediatric Hematology and Oncology, Faculty of Medicine, Erciyes University, Kayseri, Turkey
| | - Vijay G Sankaran
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA USA.,Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA USA.,Broad Institute of MIT and Harvard, Cambridge, MA USA
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25
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Cui L, Moraga I, Lerbs T, Van Neste C, Wilmes S, Tsutsumi N, Trotman-Grant AC, Gakovic M, Andrews S, Gotlib J, Darmanis S, Enge M, Quake S, Hitchcock IS, Piehler J, Garcia KC, Wernig G. Tuning MPL signaling to influence hematopoietic stem cell differentiation and inhibit essential thrombocythemia progenitors. Proc Natl Acad Sci U S A 2021; 118:e2017849118. [PMID: 33384332 PMCID: PMC7812794 DOI: 10.1073/pnas.2017849118] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Thrombopoietin (TPO) and the TPO-receptor (TPO-R, or c-MPL) are essential for hematopoietic stem cell (HSC) maintenance and megakaryocyte differentiation. Agents that can modulate TPO-R signaling are highly desirable for both basic research and clinical utility. We developed a series of surrogate protein ligands for TPO-R, in the form of diabodies (DBs), that homodimerize TPO-R on the cell surface in geometries that are dictated by the DB receptor binding epitope, in effect "tuning" downstream signaling responses. These surrogate ligands exhibit diverse pharmacological properties, inducing graded signaling outputs, from full to partial TPO agonism, thus decoupling the dual functions of TPO/TPO-R. Using single-cell RNA sequencing and HSC self-renewal assays we find that partial agonistic diabodies preserved the stem-like properties of cultured HSCs, but also blocked oncogenic colony formation in essential thrombocythemia (ET) through inverse agonism. Our data suggest that dampening downstream TPO signaling is a powerful approach not only for HSC preservation in culture, but also for inhibiting oncogenic signaling through the TPO-R.
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Affiliation(s)
- Lu Cui
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305
| | - Ignacio Moraga
- HHMI, Stanford University School of Medicine, Stanford, CA 94305
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
- School of Life Sciences, University of Dundee, Dundee DD15EH, United Kingdom
| | - Tristan Lerbs
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305
| | - Camille Van Neste
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305
| | - Stephan Wilmes
- School of Life Sciences, University of Dundee, Dundee DD15EH, United Kingdom
| | - Naotaka Tsutsumi
- HHMI, Stanford University School of Medicine, Stanford, CA 94305
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Aaron Claudius Trotman-Grant
- HHMI, Stanford University School of Medicine, Stanford, CA 94305
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Milica Gakovic
- HHMI, Stanford University School of Medicine, Stanford, CA 94305
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
- School of Life Sciences, University of Dundee, Dundee DD15EH, United Kingdom
| | - Sarah Andrews
- York Biomedical Research Institute, Department of Biology, University of York, Heslington, YO10 5DD York, United Kingdom
| | - Jason Gotlib
- Department of Medicine, Division of Hematology, Stanford University School of Medicine, Stanford, CA 94305
| | - Spyros Darmanis
- Department of Bioengineering, School of Bioengineering and Medicine, Stanford University, Stanford, CA 94305
- Microchemistry, Proteomics, Lipidomics and NGS Department Genentech Inc., South San Francisco, CA, 94080
| | - Martin Enge
- Department of Bioengineering, School of Bioengineering and Medicine, Stanford University, Stanford, CA 94305
- Department of Oncology-Pathology Karolinska Institutet, 171 64 Stockholm, Sweden
| | - Stephen Quake
- Department of Bioengineering, School of Bioengineering and Medicine, Stanford University, Stanford, CA 94305
| | - Ian S Hitchcock
- York Biomedical Research Institute, Department of Biology, University of York, Heslington, YO10 5DD York, United Kingdom
| | - Jacob Piehler
- Department of Biology and Center for Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - K Christopher Garcia
- HHMI, Stanford University School of Medicine, Stanford, CA 94305;
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Gerlinde Wernig
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305;
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305
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26
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Al-Samkari H. New therapeutic horizons in Wiskott-Aldriech syndrome. Br J Haematol 2020; 192:231-232. [PMID: 33280084 DOI: 10.1111/bjh.17171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 09/15/2020] [Indexed: 11/30/2022]
Affiliation(s)
- Hanny Al-Samkari
- Division of Hematology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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27
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Pecci A, Balduini CL. Inherited thrombocytopenias: an updated guide for clinicians. Blood Rev 2020; 48:100784. [PMID: 33317862 DOI: 10.1016/j.blre.2020.100784] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/05/2020] [Accepted: 10/28/2020] [Indexed: 02/06/2023]
Abstract
The great advances in the knowledge of inherited thrombocytopenias (ITs) made since the turn of the century have significantly changed our view of these conditions. To date, ITs encompass 45 disorders with different degrees of complexity of the clinical picture and very wide variability in the prognosis. They include forms characterized by thrombocytopenia alone, forms that present with other congenital defects, and conditions that predispose to acquire additional diseases over the course of life. In this review, we recapitulate the clinical features of ITs with emphasis on the forms predisposing to additional diseases. We then discuss the key issues for a rational approach to the diagnosis of ITs in clinical practice. Finally, we aim to provide an updated and comprehensive guide to the treatment of ITs, including the management of hemostatic challenges, the treatment of severe forms, and the approach to the manifestations that add to thrombocytopenia.
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Affiliation(s)
- Alessandro Pecci
- Department of Internal Medicine, IRCCS Policlinico San Matteo Foundation and University of Pavia, Pavia, Italy.
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28
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Beauchemin H, Shooshtharizadeh P, Pinder J, Dellaire G, Möröy T. Dominant negative Gfi1b mutations cause moderate thrombocytopenia and an impaired stress thrombopoiesis associated with mild erythropoietic abnormalities in mice. Haematologica 2020; 105:2457-2470. [PMID: 33054086 PMCID: PMC7556681 DOI: 10.3324/haematol.2019.222596] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 11/21/2019] [Indexed: 11/30/2022] Open
Abstract
GFI1B-related thrombocytopenia (GFI1B-RT) is a rare bleeding disorder mainly caused by the presence of truncated GFI1B proteins with dominant-negative properties. The disease is characterized by low platelet counts, the presence of abnormal platelets, a megakaryocytic expansion and mild erythroid defects. However, no animal models faithfully reproducing the GFI1B-RT phenotype observed in patients exist. We had previously generated mice with floxed Gfi1b alleles that can be eliminated by Cre recombinase, but those animals developed a much more severe phenotype than GFI1B-RT patients and were of limited interest in assessing the disease. Using CRISPR/Cas9 technology, we have now established three independent mouse lines that carry mutated Gfi1b alleles producing proteins lacking DNA binding zinc fingers and thereby acting in a dominant negative (DN) manner. Mice heterozygous for these Gfi1b-DN alleles show reduced platelet counts and an expansion of megakaryocytes similar to features of human GFI1B-RT but lacking the distinctively large agranular platelets. In addition, Gfi1b-DN mice exhibit an expansion of erythroid precursors indicative of a mildly abnormal erythropoiesis but without noticeable red blood cell defects. When associated with megakaryocyte-specific ablation of the remaining allele, the Gfi1b-DN alleles triggered erythroid-specific deleterious defects. Gfi1b-DN mice also showed a delayed recovery from platelet depletion, indicating a defect in stress thrombopoiesis. However, injecting Gfi1b-DN mice with romiplostim, a thrombopoietin receptor super agonist, increased platelet numbers even beyond normal levels. Thus, our data support a causal link between DN mutations in GFI1B and thrombocytopenia and suggest that patients with GFI1B-RT could be treated successfully with thrombopoietin agonists.
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Affiliation(s)
- Hugues Beauchemin
- Institut de Recherches Cliniques de Montréal, IRCM, Montréal, Quebec
| | | | - Jordan Pinder
- Departments of Pathology and Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia
| | - Graham Dellaire
- Departments of Pathology and Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia
| | - Tarik Möröy
- Institut de Recherches Cliniques de Montréal, IRCM, Montréal, Quebec
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montréal, Quebec
- Division of Experimental Medicine, McGill University, Montréal, Quebec, Canada
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29
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Downes K, Borry P, Ericson K, Gomez K, Greinacher A, Lambert M, Leinoe E, Noris P, Van Geet C, Freson K. Clinical management, ethics and informed consent related to multi-gene panel-based high throughput sequencing testing for platelet disorders: Communication from the SSC of the ISTH. J Thromb Haemost 2020; 18:2751-2758. [PMID: 33079472 PMCID: PMC7589386 DOI: 10.1111/jth.14993] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/30/2020] [Accepted: 07/01/2020] [Indexed: 12/22/2022]
Abstract
Molecular diagnostics of inherited platelet disorders (IPD) has been revolutionized by the implementation of high-throughput sequencing (HTS) approaches. A conclusive diagnosis using HTS tests can be obtained quickly and cost-effectively in many, but not all patients. The expanding use of HTS tests has raised concerns regarding complex variant interpretation and the ethical implications of detecting unsolicited findings such as variants in IPD genes RUNX1, ETV6, and ANKRD26, which are associated with increased leukemic risk. This guidance document has been developed and written by a multidisciplinary team of researchers and clinicians, with expertise in hematology, clinical and molecular genetics, and bioethics, alongside a RUNX1 patient advocacy representative. We recommend that for clinical diagnostics, HTS for IPD should use a multigene panel of curated diagnostic-grade genes. Critically, we advise that an HTS test for clinical diagnostics should only be ordered by a clinical expert that is: (a) fully aware of the complexity of genotype-phenotype correlations for IPD; (b) able to discuss these complexities with a patient and family members before the test is initiated; and (c) able to interpret and appropriately communicate the results of a HTS diagnostic report, including the implication of variants of uncertain clinical significance. Each patient should know what an HTS test could mean for his or her clinical management before initiating a test. We hereby propose an exemplified informed consent document that includes information on these ethical concerns and can be used by the community for implementation of HTS of IPD in a clinical diagnostic setting. This paper does not include recommendations for HTS of IPD in a research setting.
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Affiliation(s)
- Kate Downes
- East Genomic Laboratory HubCambridge University Hospitals NHS Foundation TrustCambridgeUK
- Department of HaematologyUniversity of CambridgeCambridge Biomedical CampusCambridgeUK
| | - Pascal Borry
- Department of Public Health and Primary CareKU LeuvenLeuvenBelgium
| | | | - Keith Gomez
- Haemophilia Centre and Thrombosis UnitRoyal Free London NHS Foundation TrustLondonUK
| | - Andreas Greinacher
- Institut für Immunologie und TransfusionsmedizinUniversitätsmedizin GreifswaldGreifswaldGermany
| | - Michele Lambert
- Division of HematologyThe Children’s Hospital of PhiladelphiaPhiladelphiaPAUSA
- Department of PediatricsPerelman School of Medicine at the University of PennsylvaniaPhiladelphiaPAUSA
| | - Eva Leinoe
- Department of HaematologyRigshospitaletNational University HospitalCopenhagenDenmark
| | - Patrizia Noris
- IRCCS Policlinico San Matteo Foundation and University of PaviaPaviaItaly
| | - Chris Van Geet
- Department of Cardiovascular SciencesCenter or Molecular and Vascular BiologyKU LeuvenLeuvenBelgium
| | - Kathleen Freson
- Department of Cardiovascular SciencesCenter or Molecular and Vascular BiologyKU LeuvenLeuvenBelgium
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30
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Abstract
PURPOSE OF REVIEW The increasing use of high throughput sequencing and genomic analysis has facilitated the discovery of new causes of inherited platelet disorders. Studies of these disorders and their respective mouse models have been central to understanding their biology, and also in revealing new aspects of platelet function and production. This review covers recent contributions to the identification of genes, proteins and variants associated with inherited platelet defects, and highlights how these studies have provided insights into platelet development and function. RECENT FINDINGS Novel genes recently implicated in human platelet dysfunction include the galactose metabolism enzyme UDP-galactose-4-epimerase in macrothrombocytopenia, and erythropoietin-producing hepatoma-amplified sequence receptor transmembrane tyrosine kinase EPHB2 in a severe bleeding disorder with deficiencies in platelet agonist response and granule secretion. Recent studies of disease-associated variants established or clarified roles in platelet function and/or production for the membrane receptor G6b-B, the FYN-binding protein FYB1/ADAP, the RAS guanyl-releasing protein RASGRP2/CalDAG-GEFI and the receptor-like protein tyrosine phosphatase PTPRJ/CD148. Studies of genes associated with platelet disorders advanced understanding of the cellular roles of neurobeachin-like 2, as well as several genes influenced by the transcription regulator RUNT-related transcription factor 1 (RUNX1), including NOTCH4. SUMMARY The molecular bases of many hereditary platelet disorders have been elucidated by the application of recent advances in cell imaging and manipulation, genomics and protein function analysis. These techniques have also aided the detection of new disorders, and enabled studies of disease-associated genes and variants to enhance understanding of platelet development and function.
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Abstract
PURPOSE OF REVIEW To provide a comprehensive update on the current available methodologies and techniques for diagnosis of inherited platelet disorders (IPD). RECENT FINDINGS The contributions of many groups have resulted in the significant progress in the molecular diagnosis of IPD including the identification of many genes responsible for the various phenotypes. The widespread use and availability of next-generation sequencing has brought to the forefront ethical challenges associated with nontargeted sequencing as well as provided us with novel variants to functionally validate. These requirements have driven the development of novel tools for functional assessment of platelets, although none of the novel techniques beyond sequencing have yet taken clinical hold. SUMMARY Much work is ongoing on functional and molecular assessment of platelet disorders and the incorporation of combined assessments is likely to yield the highest diagnostic results.
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32
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Romiplostim for the management of pediatric immune thrombocytopenia: drug development and current practice. Blood Adv 2020; 3:1907-1915. [PMID: 31239245 DOI: 10.1182/bloodadvances.2019000279] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 05/29/2019] [Indexed: 12/13/2022] Open
Abstract
Since successful cloning of thrombopoietin (TPO) in 1994, significant advances have been made in the development of recombinant TPO receptor agonists. The US Food and Drug Administration (FDA) has approved 2 agents for use in patients with immune thrombocytopenia (ITP): eltrombopag and romiplostim. Romiplostim is a once-weekly subcutaneous injection that has been shown to increase the platelet count, lessen bleeding, and reduce concurrent medication use in adults with ITP. In December 2018, the US FDA approved romiplostim for use in pediatric patients ≥1 year of age with ITP of >6 months' duration and insufficient response to corticosteroids, immunoglobulins, or splenectomy, based on similarly favorable clinical trial data. In addition, romiplostim is well tolerated, making it an attractive option for the treatment of children. Expansion of off-label romiplostim use is being reported in children for ITP <6 months, neonatal thrombocytopenia, hereditary thrombocytopenias, and chemotherapy- and bone marrow transplant-associated thrombocytopenia. We review here the development of romiplostim with a focus on pediatric use.
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Nurden AT, Nurden P. Inherited thrombocytopenias: history, advances and perspectives. Haematologica 2020; 105:2004-2019. [PMID: 32527953 PMCID: PMC7395261 DOI: 10.3324/haematol.2019.233197] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/08/2020] [Indexed: 12/11/2022] Open
Abstract
Over the last 100 years the role of platelets in hemostatic events and their production by megakaryocytes have gradually been defined. Progressively, thrombocytopenia was recognized as a cause of bleeding, first through an acquired immune disorder; then, since 1948, when Bernard-Soulier syndrome was first described, inherited thrombocytopenia became a fascinating example of Mendelian disease. The platelet count is often severely decreased and platelet size variable; associated platelet function defects frequently aggravate bleeding. Macrothrombocytopenia with variable proportions of enlarged platelets is common. The number of circulating platelets will depend on platelet production, consumption and lifespan. The bulk of macrothrombocytopenias arise from defects in megakaryopoiesis with causal variants in transcription factor genes giving rise to altered stem cell differentiation and changes in early megakaryocyte development and maturation. Genes encoding surface receptors, cytoskeletal and signaling proteins also feature prominently and Sanger sequencing associated with careful phenotyping has allowed their early classification. It quickly became apparent that many inherited thrombocytopenias are syndromic while others are linked to an increased risk of hematologic malignancies. In the last decade, the application of next-generation sequencing, including whole exome sequencing, and the use of gene platforms for rapid testing have greatly accelerated the discovery of causal genes and extended the list of variants in more common disorders. Genes linked to an increased platelet turnover and apoptosis have also been identified. The current challenges are now to use next-generation sequencing in first-step screening and to define bleeding risk and treatment better.
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Affiliation(s)
- Alan T Nurden
- Institut Hospitalo-Universitaire LIRYC, Pessac, France
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34
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Simplifying the diagnosis of inherited platelet disorders? The new tools do not make it any easier. Blood 2019; 133:2478-2483. [PMID: 30858232 DOI: 10.1182/blood-2019-01-852350] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 02/28/2019] [Indexed: 12/25/2022] Open
Abstract
The molecular causes of many inherited platelet disorders are being unraveled. Next-generation sequencing facilitates diagnosis in 30% to 50% of patients. However, interpretation of genetic variants is challenging and requires careful evaluation in the context of a patient's phenotype. Before detailed testing is initiated, the treating physician and patient should establish an understanding of why testing is being performed and discuss potential consequences, especially before testing for variants in genes associated with an increased risk for hematologic malignancies.
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36
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Loss-of-function mutations in PTPRJ cause a new form of inherited thrombocytopenia. Blood 2018; 133:1346-1357. [PMID: 30591527 DOI: 10.1182/blood-2018-07-859496] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 12/19/2018] [Indexed: 12/31/2022] Open
Abstract
Inherited thrombocytopenias (ITs) are a heterogeneous group of disorders characterized by low platelet count that may result in bleeding tendency. Despite progress being made in defining the genetic causes of ITs, nearly 50% of patients with familial thrombocytopenia are affected with forms of unknown origin. Here, through exome sequencing of 2 siblings with autosomal-recessive thrombocytopenia, we identified biallelic loss-of-function variants in PTPRJ . This gene encodes for a receptor-like PTP, PTPRJ (or CD148), which is expressed abundantly in platelets and megakaryocytes. Consistent with the predicted effects of the variants, both probands have an almost complete loss of PTPRJ at the messenger RNA and protein levels. To investigate the pathogenic role of PTPRJ deficiency in hematopoiesis in vivo, we carried out CRISPR/Cas9-mediated ablation of ptprja (the ortholog of human PTPRJ) in zebrafish, which induced a significantly decreased number of CD41+ thrombocytes in vivo. Moreover, megakaryocytes of our patients showed impaired maturation and profound defects in SDF1-driven migration and formation of proplatelets in vitro. Silencing of PTPRJ in a human megakaryocytic cell line reproduced the functional defects observed in patients' megakaryocytes. The disorder caused by PTPRJ mutations presented as a nonsyndromic thrombocytopenia characterized by spontaneous bleeding, small-sized platelets, and impaired platelet responses to the GPVI agonists collagen and convulxin. These platelet functional defects could be attributed to reduced activation of Src family kinases. Taken together, our data identify a new form of IT and highlight a hitherto unknown fundamental role for PTPRJ in platelet biogenesis.
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37
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Rodeghiero F, Pecci A, Balduini CL. Thrombopoietin receptor agonists in hereditary thrombocytopenias. J Thromb Haemost 2018; 16:1700-1710. [PMID: 29956472 DOI: 10.1111/jth.14217] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Indexed: 12/15/2022]
Abstract
Hereditary thrombocytopenias (HTPs) constitute a heterogeneous group of diseases characterized by a reduction in platelet count and a potential bleeding risk. As a result of advances in diagnostic methods, HTPs are increasingly being identified, and appear to be less rare than previously thought. Most HTPs do not have effective treatments, except for platelet transfusion when bleeding occurs and in preparation for procedures associated with a risk of bleeding. Preliminary clinical evidence suggests that thrombopoietin receptor agonists (TPO-RAs) with an established use in the treatment of certain acquired thrombocytopenias are well tolerated and provide clinical benefits in patients with some forms of HTP. These drugs may therefore be considered for the treatment of HTPs in clinical practice. However, caution and close monitoring are recommended, owing to the absence of long-term safety data and the potential risks posed by prolonged bone marrow stimulation in certain HTPs. In this review, we summarize the available clinical data on TPO-RAs in the treatment of HTPs, and discuss their use in patients with these disorders. We believe that TPO-RAs will play a major role in the treatment of HTPs, particularly myosin heavy chain 9-related disease, Wiskott-Aldrich syndrome, X-linked thrombocytopenia, and thrombocytopenia caused by THPO mutations.
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Affiliation(s)
- F Rodeghiero
- Hematology Project Foundation, Affiliated to the Department of Haematology, S. Bortolo Hospital, Vicenza, Italy
| | - A Pecci
- Department of Internal Medicine, IRCCS Policlinico San Matteo Foundation and University of Pavia, Pavia, Italy
| | - C L Balduini
- Department of Internal Medicine, IRCCS Policlinico San Matteo Foundation and University of Pavia, Pavia, Italy
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38
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Abstract
Platelets are anuclear blood cells required for haemostasis and are implicated in other processes including inflammation and metastasis. Platelets are produced by megakaryocytes, specialized cells that are themselves generated by a process of controlled differentiation and maturation of bone-marrow stem and progenitor cells. This process of megakaryopoiesis involves the coordinated interplay of transcription factor-controlled cellular programming with extra-cellular cues produced locally in supporting niches or as circulating factors. This review focuses on these external cues, the cytokines and chemokines, that drive production of megakaryocytes and support the terminal process of platelet release. Emphasis is given to thrombopoietin (Tpo), the major cytokine regulator of steady-state megakaryopoiesis, and its specific cell surface receptor, the Mpl protein, including normal and pathological roles as well as clinical application. The potential for alternative or supplementary regulatory mechanisms for platelet production, particularly in times of acute need, or in states of infection or inflammation are also discussed.
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Affiliation(s)
- Kira Behrens
- a The Walter and Eliza Hall Institute of Medical Research , Parkville , Australia
- b Department of Medical Biology , University of Melbourne , Melbourne , Australia
| | - Warren S Alexander
- a The Walter and Eliza Hall Institute of Medical Research , Parkville , Australia
- b Department of Medical Biology , University of Melbourne , Melbourne , Australia
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39
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Abstract
Thrombopoietin (THPO) has been well characterized as a key regulator of platelet production. THPO also plays an important role in the maintenance and regulation of hematopoietic stem cells (HSCs). In this issue of EMBO Molecular Medicine, Pecci et al (2018) describe a newly identified homozygous mutation in THPO causing congenital amegakaryocytic thrombocytopenia, a disease characterized by a significant impairment in platelet production with rapid onset of aplastic anemia within a few years. The paper nicely investigates the underlying pathogenic mechanisms of this disease. Importantly, this study, in tandem with other recent ones, shows that this rare genetic form of aplastic anemia is treatable with THPO receptor agonists, emphasizing the paramount role of genetic testing in cases of aplastic anemia and other bone marrow failure disorders. This report also refines our understanding of the role of THPO in human HSC function and illustrates the important biological insight that can be gained through studies of such rare genetic disorders.
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Affiliation(s)
- Ah Ram Kim
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Vijay G Sankaran
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
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