Erythropoiesis, EPO, macrophages, and bone

Erythropoietin-Stimulated Macrophage-Derived Extracellular Vesicles in Chitosan Hydrogel Rescue BMSCs Fate by Targeting EGFR to Alleviate Inflammatory Bone Loss in Periodontitis

Loss of periodontal tissue due to persistent inflammation in periodontitis is a major cause of tooth loss in adults. Overcoming osteogenic inhibition in the inflammatory periodontal environment and restoring the regenerative capacity of endogenous bone marrow mesenchymal stem cells (BMSCs) remain critical challenges in current treatment approaches. Macrophage-derived extracellular vesicles (EVs) are key regulators of osteogenesis in recipient cells, yet the role of erythropoietin (EPO) in modifying macrophages and the function of their EVs in bone regeneration remain unclear. In this study, EVs from EPO-stimulated macrophages (EPO-EVs) are isolated, and they are encapsulated in a chitosan/β-sodium glycerophosphate/gelatin (CS/β-GP/gelatin) hydrogel to create a controlled-release EVs delivery system for localized periodontal environment. EPO-EVs restore the osteogenic function of mouse BMSCs (mBMSCs) and mitigate inflammatory bone loss in a periodontitis mouse model. Mechanistically, miR-5107-5p, significantly enriched in EPO-EVs, is delivered to mBMSCs, where it suppresses epidermal growth factor receptor (EGFR) expression and alleviates EGFR's inhibitory effect on RhoA. This process counteracts osteogenic inhibition in inflammatory settings through the EGFR/RhoA axis. Overall, EVs from EPO pretreated macrophages restore the osteogenic capacity of mBMSCs under inflammation by inhibiting EGFR expression, providing new insight into therapeutic mechanisms and offering a promising approach for future periodontitis treatment.

Donkey-Hide Gelatin-Derived Carbon Dots Activate Erythropoiesis and Eliminate Oxidative Stress for Aplastic Anemia Treatment

Aplastic anemia (AA) is a life-threatening hematologic disease with limited therapeutic options. Stalled erythropoiesis and oxidative stress-induced hemocyte apoptosis are the main pathological features of AA, yet therapeutic agents that address these issues remain elusive. In this study, we report distinctive donkey-hide gelatin-derived carbon dots (G-CDs) that enable erythropoiesis activation and oxidative stress elimination to tackle refractory AA. We demonstrate that G-CDs can promote the proliferation and erythroid differentiation of hematopoietic stem cells as well as erythrocyte maturation, activating the whole process of erythropoiesis. Moreover, G-CDs display multienzyme-like activities and dramatically alleviate the oxidative stress of bone marrow and peripheral blood via catalytic scavenging of multiple reactive oxygen species, reconstructing the hematopoietic microenvironment. Intravenously or orally administered to AA mice induced by chemotherapy drugs, G-CDs significantly boost the level of red blood cells and hemoglobin and lead to the complete recovery of hematopoietic function, showing better therapeutic performance than clinically approved erythropoietin (EPO) without adverse effects. By collaboratively addressing the issues of stalled erythropoiesis and oxidative stress, the G-CDs-based intervention strategy may offer a powerful paradigm for clinical AA management.

Advances in the generation of erythrocytes from stem cells in vitro

Red blood cell transfusion is the main treatment to improve anemia caused by many reasons and has important clinical application value. However, the supply of red blood cells at home and abroad is currently very tight. Therefore, the utilization of stem cells to prepare erythrocytes for clinical use is expected to become a new mode of blood supply and security in the future. This review describes the process of erythropoiesis regulation in vivo, summarizes the latest research progress of in vitro erythropoiesis, and points out the current challenges of in vitro erythropoiesis, which is expected to provide a new idea for solving the problem of insufficient clinical erythropoiesis supply.

Type-I Collagen Polypeptide-Based Composite Nanofiber Membranes for Fast and Efficient Bone Regeneration

The clinical treatment of bone defects includes allogeneic bone transplantation and autologous bone transplantation. However, they all have their own limitations, and the scope of application is limited. In recent years, bone tissue engineering scaffolds based on a variety of materials have been well developed and achieved good bone regeneration ability. However, most scaffold materials always face problems such as high biotoxicity, leading to inflammation and poor bioactivity, which limits the bone regeneration effect and prolongs the bone regeneration time. In our work, we prepared hydroxyapatite, erythropoietin (EPO), and osteogenic growth peptide (OGP) codoped type-I collagen (Col I) polypeptide nanofiber membranes (NFMs) by electrostatic spinning. In cell experiments, the composite NFMs had low cytotoxicity and promoted osteogenic differentiation of rat bone marrow mesenchymal stem cells. Quantitative real-time polymerase chain reaction and alkaline phosphatase staining confirmed the high expression of osteogenic genes, and alizarin red S staining directly confirmed the appearance of calcium nodules. In animal experiments, the loaded hydroxyapatite formed multiple independent mineralization centers in the defect center. Under the promotion of Col I, EPO, and OGP, the bone continued to grow along the mineralization centers as well as inward the defect edge, and the bone defect completely regenerated in about two months. The hematological and histological analyses proved the safety of the experiments. This kind of design to promote bone regeneration by simulating bone composition, introducing mineralization center and signal molecules, can shorten repair time, improve repair effect, and has good practical prospects in the future.

The Impact of Sleep on Haematological Parameters in Firefighters

Sleep is a vital process that impacts biological functions such as cell renewal, bone regeneration, and immune system support. Disrupted sleep can interrupt erythropoiesis, leading to fewer red blood cells, reduced haemoglobin concentration, and decreased haematocrit levels, potentially contributing to haematological disorders. This is particularly concerning for shift workers for example firefighters. While previous studies have explored sleep's adverse effects on various professions, research specific to firefighters is limited. This study investigates the relationship between sleep quality and haematological parameters among firefighters in Northeast Portugal. From a sample of 201 firefighters, variations in red blood cells, haemoglobin, and haematocrit values were linked to sleep quality. The study utilised non-parametric tests (Wilcoxon-Mann-Whitney, Spearman's correlation) to explore the connection between sleep quality and haematological profile. The impact of covariates on haematological parameters was assessed using non-parametric ANCOVA (Quade's). A multiple regression analysis was employed to further understand how sleep quality and various confounding variables impact haematological levels. Findings suggest a negative link between sleep quality and haematological levels, meaning that as sleep quality deteriorates, there is a tendency for haematological levels to decrease, as indicated by Spearman's correlation (rRBC = -0.157, pRBC = 0.026; rHb = -0.158, pHb = 0.025; rHCT = -0.175, pHCT = 0.013). As observed in scientific literature, the correlation found suggests a possible inhibition of erythropoiesis, the process responsible for red blood cell production. Despite firefighters presenting a haematological profile within the reference range (RBC: 5.1 × 106/mm3 (SD ± 0.4), Hb: 15.6 g/dL (SD ± 1.3), 47% (SD ± 1.0), there is already an observable trend towards lower levels. The analysis of co-variables did not reveal a significant impact of sleep quality on haematological levels. In conclusion, this study underscores the importance of sleep quality in determining haematological parameters among firefighters. Future research should investigate the underlying mechanisms and long-term implications of poor sleep quality on firefighter health. Exploring interventions to enhance sleep quality is vital for evidence-based strategies promoting firefighter well-being.

Comprehensive analysis of prohibited substances and methods in sports: Unveiling trends, pharmacokinetics, and WADA evolution

This review systematically compiles sports-related drugs, substances, and methodologies based on the most frequently detected findings from prohibited lists published annually by the World Anti-Doping Agency (WADA) between 2003 and 2021. Aligned with structure of the 2023 prohibited list, it covers all proscribed items and details the pharmacokinetics and pharmacodynamics of five representatives from each section. Notably, it explores significant metabolites and metabolic pathways associated with these substances. Adverse analytical findings are summarized in tables for clarity, and the prevalence is visually represented through charts. The review includes a concise historical overview of doping and WADA's role, examining modifications in the prohibited list for an understanding of evolving anti-doping measures.

PI3K/HSCB axis facilitates FOG1 nuclear translocation to promote erythropoiesis and megakaryopoiesis

Erythropoiesis and megakaryopoiesis are stringently regulated by signaling pathways. However, the precise molecular mechanisms through which signaling pathways regulate key transcription factors controlling erythropoiesis and megakaryopoiesis remain partially understood. Herein, we identified heat shock cognate B (HSCB), which is well known for its iron-sulfur cluster delivery function, as an indispensable protein for friend of GATA 1 (FOG1) nuclear translocation during erythropoiesis of K562 human erythroleukemia cells and cord-blood-derived human CD34+CD90+hematopoietic stem cells (HSCs), as well as during megakaryopoiesis of the CD34+CD90+HSCs. Mechanistically, HSCB could be phosphorylated by phosphoinositol-3-kinase (PI3K) to bind with and mediate the proteasomal degradation of transforming acidic coiled-coil containing protein 3 (TACC3), which otherwise detained FOG1 in the cytoplasm, thereby facilitating FOG1 nuclear translocation. Given that PI3K is activated during both erythropoiesis and megakaryopoiesis, and that FOG1 is a key transcription factor for these processes, our findings elucidate an important, previously unrecognized iron-sulfur cluster delivery independent function of HSCB in erythropoiesis and megakaryopoiesis.

CRKL but not CRKII contributes to hemin-induced erythroid differentiation of CML

Destruction of erythropoiesis process leads to various diseases, including thrombocytopenia, anaemia, and leukaemia. miR-429-CT10 regulation of kinase-like (CRKL) axis involved in development, progression and metastasis of cancers. However, the exact role of miR-429-CRKL axis in leukaemic cell differentiation are still unknown. The current work aimed to uncover the effect of miR-429-CRKL axis on erythropoiesis. In the present study, CRKL upregulation was negatively correlated with miR-429 downregulation in both chronic myeloid leukaemia (CML) patient and CR patient samples. Moreover, CRKL expression level was significantly decreased while miR-429 expression level was increased during the erythroid differentiation of K562 cells following hemin treatment. Functional investigations revealed that overexpression and knockdown of CRKL was remarkably effective in suppressing and promoting hemin-induced erythroid differentiation of K562 cells, whereas, miR-429 exhibited opposite effects to CRKL. Mechanistically, miR-429 regulates erythroid differentiation of K562 cells by downregulating CRKL via selectively targeting CRKL-3'-untranslated region (UTR) through Raf/MEK/ERK pathway. Conversely, CRKII had no effect on erythroid differentiation of K562 cells. Taken together, our data demonstrated that CRKL (but not CRKII) and miR-429 contribute to development, progression and erythropoiesis of CML, miR-429-CRKL axis regulates erythropoiesis of K562 cells via Raf/MEK/ERK pathway, providing novel insights into effective diagnosis and therapy for CML patients.

Erythropoietin as promoter of engraftment for treatment of radius/ulnar non-union fracture in a dog: Case report

Background

Fractures with large bone defects and non-unions are a great challenge for veterinary orthopaedists. In small dog breeds, this complication is commonly encountered in fractures of the radius and ulna due to poorer vascularisation of the distal antebrachium region.

Case Description

A case of radius/ulnar non-union in a 1.5-year-old Pinscher occurring after trauma and two successive unsuccessful osteosyntheses is described. During the operative revision, after the removal of existing bone implants, the bone defect was filled with cortical autologous bone graft. Autocancellous bone mixed with erythropoietin was applied proximally and distally to the cortical autograft for stimulation of bone healing. The post-operative period was without complications. As early as the 9th post-operative week, the animal was able to bear weight on the limb, without signs of lameness, pain, and swelling. Radiologically, a very good bridging of the graft was observed. Fifteen weeks after the operative revision, the fracture was completely healed with excellent clinical outcome.

Conclusion

The application of autogenous cortical bone graft and cancellous autograft mixed with erythropoietin demonstrated an excellent therapeutic effect and resulted in complete regeneration of the large bone defect over a 15-week period.

Maximizing longevity: erythropoietin's impact on sickle cell anaemia survival rates

Sickle cell anaemia (SCA) stands as a hereditary blood disorder characterized by mutated haemoglobin, causing red blood cells to adopt a sickle shape, leading to complications like vaso-occlusive crises, anaemia, and organ damage. Despite advancements in treatment, managing SCA remains challenging, with limited options to increase life expectancy and improve quality of life for affected individuals. This paper reviews the potential impact of erythropoietin (EPO) therapy in enhancing life expectancy and ameliorating complications in individuals with SCA. EPO, primarily recognized for its role in stimulating red blood cell production, holds promise in mitigating anaemia, reducing transfusion dependence, and possibly diminishing the frequency and severity of vaso-occlusive crises in SCA patients. Moreover, by stimulating red blood cell production, EPO therapy might alleviate the vaso-occlusive process, thus reducing the frequency of painful crises and associated complications. Additionally, considering the potential side effects and the need for continuous monitoring, the use of EPO in SCA treatment requires cautious consideration. The potential of EPO therapy in SCA offers a glimpse into novel strategies aimed at improving the quality of life and extending the life expectancy of affected individuals. In conclusion, while the application of EPO in SCA treatment holds promise, additional research is indispensable to comprehend its precise role, optimize dosing strategies, and ensure safety, thereby paving the way for enhanced life expectancy and improved outcomes for individuals living with SCA.

EPO regulates the differentiation and homing of bone marrow mesenchymal stem cells through Notch1/Jagged pathway to treat pulmonary hypertension

Purpose

To investigate whether erythropoietin (EPO) can treat pulmonary arterial hypertension (PAH) in rats by regulating the differentiation and homing of bone marrow mesenchymal stem cells (BMSCs) through Notch1/Jagged signaling pathway.

Materials & methods

BMSCs were isolated from the bone marrow of 6-week-old male SD rats by whole bone marrow method and identified. BMSCs were treated with 500 IU/mL EPO, and the proliferation, migration, invasion and differentiation ability, and the expression of MMP-2 and MMP-9 protein of BMSCs were detected in vitro. After the establishment of the pulmonary hypertension model in rats, BMSCs were intervened with different concentrations of EPO and injected into the rats through intravenous injection. The levels of TNF-α, IL-1β and IL-6 in lung tissue, the expression of SRY CXCR4, CCR2, Notch1 and Jagged protein in lung tissue, and the levels of TGF-α, vascular endothelial factor (VEGF), IGF-1 and HGF in serum were detected. Immunofluorescence (IF) staining was used to detect the co-localization of CD34.

Results

EPO promoted the proliferation, migration, and invasion of BMSCs by inhibiting Notch1/Jagged pathway in vitro, and induced BMSCs to differentiate into vascular smooth muscle cells and vascular endothelial cells. EPO inhibited Notch1/Jagged pathway in PAH rats, induced BMSCs homing and differentiation, increased the levels of TGF-α, VEGF, IGF-1 and HGF, and decreased the levels of TNF-α, IL-1β and IL-6.

Discussion & conclusion

EPO can inhibit the Notch1/Jagged pathway and promote the proliferation, migration, invasion, homing and differentiation of BMSCs to treat pulmonary hypertension in rats in vitro and in vivo.

Regulation of erythropoiesis: emerging concepts and therapeutic implications

The process of erythropoiesis is complex and involves the transfer of cells from the yolk sac to the fetal hepar and, ultimately, to the bone marrow during embryonic development. Within the bone marrow, erythroid progenitor cells undergo several stages to generate reticulocytes that enter the bloodstream. Erythropoiesis is regulated by various factors, with erythropoietin (EPO) synthesized by the kidney being the promoting factor and hepcidin synthesized by the hepar inhibiting iron mobilization. Transcription factors, such as GATA and KLF, also play a crucial role in erythropoiesis. Disruption of any of these factors can lead to abnormal erythropoiesis, resulting in red cell excess, red cell deficiency, or abnormal morphological function. This review provides a general description of erythropoiesis, as well as its regulation, highlighting the significance of understanding the process for the diagnosis and treatment of various hematological disorders.

Peripheral inflammation and neurocognitive impairment: correlations, underlying mechanisms, and therapeutic implications

Cognitive impairments, such as learning and memory deficits, may occur in susceptible populations including the elderly and patients who are chronically ill or have experienced stressful events, including surgery, infection, and trauma. Accumulating lines of evidence suggested that peripheral inflammation featured by the recruitment of peripheral immune cells and the release of pro-inflammatory cytokines may be activated during aging and these conditions, participating in peripheral immune system-brain communication. Lots of progress has been achieved in deciphering the core bridging mechanism connecting peripheral inflammation and cognitive impairments, which may be helpful in developing early diagnosis, prognosis evaluation, and prevention methods based on peripheral blood circulation system sampling and intervention. In this review, we summarized the evolving evidence on the prevalence of peripheral inflammation-associated neurocognitive impairments and discussed the research advances in the underlying mechanisms. We also highlighted the prevention and treatment strategies against peripheral inflammation-associated cognitive dysfunction.

Pathogenic Mechanisms in Thalassemia I: Ineffective Erythropoiesis and Hypercoagulability

Erythropoiesis is the physiological process that results in the production of red blood cells (RBCs). In conditions of pathologically altered erythropoiesis or ineffective erythropoiesis, as in the case of β-thalassemia, the reduced ability of erythrocytes to differentiate, survive and deliver oxygen stimulates a state of stress that leads to the ineffective production of RBCs. We herein describe the main features of erythropoiesis and its regulation in addition to the mechanisms behind ineffective erythropoiesis development in β-thalassemia. Finally, we review the pathophysiology of hypercoagulability and vascular disease development in β-thalassemia and the currently available prevention and treatment modalities.

Accumulation of Fat Not Responsible for Femoral Head Necrosis, Revealed by Single-Cell RNA Sequencing: A Preliminary Study

The etiology of osteonecrosis of the femoral head (ONFH) is not yet fully understood. However, ONFH is a common disease with high morbidity, and approximately one-third of cases are caused by glucocorticoids. We performed single-cell RNA sequencing of bone marrow to explore the effect of glucocorticoid on ONFH. Bone marrow samples of the proximal femur were extracted from four participants during total hip arthroplasty, including two participants diagnosed with ONFH for systemic lupus erythematosus (SLE) treated with glucocorticoids (the case group) and two participants with femoral neck fracture (the control group). Unbiased transcriptome-wide single-cell RNA sequencing analysis and computational analyses were performed. Seventeen molecularly defined cell types were identified in the studied samples, including significantly dysregulated neutrophils and B cells in the case group. Additionally, fatty acid synthesis and aerobic oxidation were repressed, while fatty acid beta-oxidation was enhanced. Our results also preliminarily clarified the roles of the inflammatory response, substance metabolism, vascular injury, angiogenesis, cell proliferation, apoptosis, and dysregulated coagulation and fibrinolysis in glucocorticoid-induced ONFH. Notably, we list the pathways that were markedly altered in glucocorticoid-induced ONFH with SLE compared with femoral head fracture, as well as their common genes, which are potential early therapeutic targets. Our results provide new insights into the mechanism of glucocorticoid-induced ONFH and present potential clues for effective and functional manipulation of human glucocorticoid-induced ONFH, which could improve patient outcomes.

Aflatoxin B1 administration induces reactive oxygen species production and apoptosis of erythrocytes in mice

Aflatoxin is a naturally occurring mycotoxin that has various toxic effects to humans and various other animals. In the current study, we have investigated the toxic effects of Aflatoxin B1 (AFB1) on erythrocytes in the blood circulation of mice. Mice were administered orally with repeated doses of AFB1 (0.3 mg/kg of body weight three times a week for four weeks). AFB1 administration resulted in sustained anemia and a significant reduction in blood erythrocyte number as well as hemoglobin level was seen at different time schedules. Body weight, erythrocyte count, and Hb were significantly decreased on days 30 and 45 post-AFB1 administration. The reticulocytes proportion in circulation was analyzed by staining the cells with anti-mouse CD71 monoclonal antibody and flow cytometric analysis. The ROS level and apoptotic cell proportion were determined by staining with CM-H2DCFDA and Annexin V antibody. AFB1 treatment leads to an increment in reticulocytes production. A significant increase in reactive oxygen species (ROS) and apoptotic cells were also observed in erythrocytes.

Strategies of Macrophages to Maintain Bone Homeostasis and Promote Bone Repair: A Narrative Review

Bone homeostasis (a healthy bone mass) is regulated by maintaining a delicate balance between bone resorption and bone formation. The regulation of physiological bone remodeling by a complex system that involves multiple cells in the skeleton is closely related to bone homeostasis. Loss of bone mass or repair of bone is always accompanied by changes in bone homeostasis. However, due to the complexity of bone homeostasis, we are currently unable to identify all the mechanisms that affect bone homeostasis. To date, bone macrophages have been considered a third cellular component in addition to osteogenic spectrum cells and osteoclasts. As confirmed by co-culture models or in vivo experiments, polarized or unpolarized macrophages interact with multiple components within the bone to ensure bone homeostasis. Different macrophage phenotypes are prone to resorption and formation of bone differently. This review comprehensively summarizes the mechanisms by which macrophages regulate bone homeostasis and concludes that macrophages can control bone homeostasis from osteoclasts, mesenchymal cells, osteoblasts, osteocytes, and the blood/vasculature system. The elaboration of these mechanisms in this narrative review facilitates the development of macrophage-based strategies for the treatment of bone metabolic diseases and bone defects.

Erythropoiesis in lower-risk myelodysplastic syndromes and beta-thalassemia

The hematologic disorders myelodysplastic syndromes and beta-thalassemia are characterized by ineffective erythropoiesis and anemia, often managed with regular blood transfusions. Erythropoiesis, the process by which sufficient numbers of functional erythrocytes are produced from hematopoietic stem cells, is highly regulated, and defects can negatively affect the proliferation, differentiation, and survival of erythroid precursors. Treatments that directly target the underlying mechanisms of ineffective erythropoiesis are limited, and management of anemia with regular blood transfusions imposes a significant burden on patients, caregivers, and health care systems. There is therefore a strong unmet need for treatments that can restore effective erythropoiesis. Novel therapies are beginning to address this need by targeting a variety of mechanisms underlying erythropoiesis. Herein, we provide an overview of the role of ineffective erythropoiesis in myelodysplastic syndromes and beta-thalassemia, discuss unmet needs in targeting ineffective erythropoiesis, and describe current management strategies and emerging treatments for these disorders.

Diagnostic Imaging Studies on Local and Systemic Erythropoietin Application for Promoting Bone Regeneration in Rat Calvarial Defects

The purpose of this study was to compare the effects of local and systemic application of recombinant human erythropoietin (rhEPO) on the healing of rat calvarial defects. Twenty-four male skeletally-mature Wistar rats were used. Two bone 5 mm critical size defects were created in calvarial bones of each rat. In rats from experimental group I (n = 12), EPO was applied locally on a collagen cone in left defects, whereas a collagen cone soaked with physiological saline was placed in right defects. The rats from experimental group II were injected once intraperitoneally with 4900 IU/kg EPO; a collagen cone was only placed in left defects, whereas the right defects were left empty. The systemic effect of EPO treatment was monitored by haematological analyses on days 0, 30 and 90. Bone healing was monitored via radiography and computed tomography on the same time intervals. The results demonstrated that local EPO application had no significant effect on haemopoiesis, unlike the systemic application. At the same time, it resulted in new bone formation and therefore, could be successfully used as a means of promoting bone regeneration.

Hypoxia-Inducible Factors Signaling in Osteogenesis and Skeletal Repair

Sufficient oxygen is required to maintain normal cellular and physiological function, such as a creature’s development, breeding, and homeostasis. Lately, some researchers have reported that both pathological hypoxia and environmental hypoxia might affect bone health. Adaptation to hypoxia is a pivotal cellular event in normal cell development and differentiation and in pathological settings such as ischemia. As central mediators of homeostasis, hypoxia-inducible transcription factors (HIFs) can allow cells to survive in a low-oxygen environment and are essential for the regulation of osteogenesis and skeletal repair. From this perspective, we summarized the role of HIF-1 and HIF-2 in signaling pathways implicated in bone development and skeletal repair and outlined the molecular mechanism of regulation of downstream growth factors and protein molecules such as VEGF, EPO, and so on. All of these present an opportunity for developing therapies for bone regeneration.

Macrophages Characterization in an Injured Bone Tissue

Biomaterial use is a promising approach to facilitate wound healing of the bone tissue. Biomaterials induce the formation of membrane capsules and the recruitment of different types of macrophages. Macrophages are immune cells that produce diverse combinations of cytokines playing an important role in bone healing and regeneration, but the exact mechanism remains to be studied. Our work aimed to identify in vivo macrophages in the Masquelet induced membrane in a rat model. Most of the macrophages in the damaged area were M2-like, with smaller numbers of M1-like macrophages. In addition, high expression of IL-1β and IL-6 cytokines were detected in the membrane region by RT-qPCR. Using an innovative combination of two hybridization techniques (in situ hybridization and in situ hybridization chain reaction (in situ HCR)), M2b-like macrophages were identified for the first time in cryosections of non-decalcified bone. Our work has also demonstrated that microspectroscopical analysis is essential for macrophage characterization, as it allows the discrimination of fluorescence and autofluorescence. Finally, this work has revealed the limitations of immunolabelling and the potential of in situ HCR to provide valuable information for in vivo characterization of macrophages.

Molecular Mechanisms Involved in Hypoxia-Induced Alterations in Bone Remodeling

Bone is crucial for the support of muscles and the protection of vital organs, and as a reservoir of calcium and phosphorus. Bone is one of the most metabolically active tissues and is continuously renewed to adapt to the changes required for healthy functioning. To maintain normal cellular and physiological bone functions sufficient oxygen is required, as evidence has shown that hypoxia may influence bone health. In this scenario, this review aimed to analyze the molecular mechanisms involved in hypoxia-induced bone remodeling alterations and their possible clinical consequences. Hypoxia has been associated with reduced bone formation and reduced osteoblast matrix mineralization due to the hypoxia environment inhibiting osteoblast differentiation. A hypoxic environment is involved with increased osteoclastogenesis and increased bone resorptive capacity of the osteoclasts. Clinical studies, although with contradictory results, have shown that hypoxia can modify bone remodeling.

In Situ Gene Expression in Native Cryofixed Bone Tissue

Bone is a very complex tissue that is constantly changing throughout the lifespan. The precise mechanism of bone regeneration remains poorly understood. Large bone defects can be caused by gunshot injury, trauma, accidents, congenital anomalies and tissue resection due to cancer. Therefore, understanding bone homeostasis and regeneration has considerable clinical and scientific importance in the development of bone therapy. Macrophages are well known innate immune cells secreting different combinations of cytokines and their role in bone regeneration during bone healing is essential. Here, we present a method to identify mRNA transcripts in cryosections of non-decalcified rat bone using in situ hybridization and hybridization chain reaction to explore gene expression in situ for better understanding the gene expression of the bone tissues.

Loading of erythropoietin on biphasic calcium phosphate bioceramics promotes osteogenesis and angiogenesis by regulating EphB4/EphrinB2 molecules

Improving osteogenesis and angiogenesis using different cells and drugs is critical in the field of bone tissue engineering. Recent research has found that erythropoietin (EPO) plays an important role in both osteogenesis and angiogenesis. In this study, we grafted polydopamine and EPO onto the surface of biphasic calcium phosphate. The characterization and release property of the modified bioceramics were assessed. Cell proliferation, expression of osteoblastic and endothelial markers, and EphB4/EphrinB2 molecules were investigated while employing co-cultures of two different cells [rat vein endothelial cells (VECs) and rat bone marrow mesenchymal stromal cells (BMSCs)]. The modified bioceramics were finally implanted into the SD rats' femurs and followed by investigating the bone defect repair efficacy and the expression of EphB4/EphrinB2 molecules in vivo. The results indicated that the modified bioceramics could control the release of EPO continuously. The osteogenesis and angiogenesis were improved along with the increased expression of EphB4/EphrinB2 molecules. The expression of EphB4/EphrinB2 molecules was also significantly increased in vivo and the bone defect was repaired effectively. Overall, our findings demonstrated that EPO loading on biphasic calcium phosphate bioceramics could promote both osteogenesis and angiogenesis. The results suggest that EphB4/EphrinB2 may be crucial in the process. Graphical abstract.

ETV6 Regulates Hemin-Induced Erythroid Differentiation of K562 Cells through Mediating the Raf/MEK/ERK Pathway

As a member of transcription factor E-Twenty Six (ETS) family, ETS variant 6 (ETV6) plays significant role in hematopoiesis and embryonic development. ETV6 dysexpression also involved in the occurrence, development and progression of cancers and leukemia. In current work, we hypothesized that ETV6 plays a role in erythroid differentiation of chronic myeloid leukemia (CML). We found the protein expression level of ETV6 was significantly upregulated during hemin-induced erythroid differentiation of K562 cells. Moreover, overexpression of ETV6 inhibited erythroid differentiation in hemin-induced K562 cells with decreased numbers of benzidine-positive cells and decreased expression levels of erythroid differentiation specific markers glycophorin (GPA), CD71, hemoglobin A (HBA), α-globin, γ-globin and ε-globin. Conversely, ETV6 knockdown promoted erythroid differentiation in hemin-induced K562 cells. Furthermore, ETV6 expression level slightly positively with the proliferation capacity of K562 cells treated with hemin. Mechanistically, ETV6 overexpression inhibited fibrosarcoma/mitogen activated extracellular signal-regulated kinase/extracellular regulated protein kinase (Raf/MEK/ERK) pathway, ETV6 knockdown activated the Raf/MEK/ERK pathway. Collectively, the current work demonstrates that ETV6 plays an inhibitory role in the regulation of K562 cell erythroid differentiation via Raf/MEK/ERK pathway, it would be a potentially therapeutic target for dyserythropoiesis.

Cell-based therapeutics for the treatment of hematologic diseases inside the bone marrow

Cell-based therapies could overcome the limitations of traditional drugs for the treatment of refractory diseases. Cell exchange between the bone marrow and blood is bidirectional. Several kinds of cells in the blood have the capability to enter the bone marrow by interacting with sinusoidal cells under specific physiological or pathological conditions. These cells are the potential living therapeutics or delivery vehicles to treat or prevent bone marrow-related hematologic diseases. In this review, we summarized the in vivo molecular mechanisms and kinetics of these cells in entering the bone marrow. The advances in the fabrication of living cell drugs and the strategies to design cell-based carriers into the bone marrow were discussed. The latest studies on how to use blood cells as living drugs or as drug carriers to improve therapeutic outcomes of hematologic diseases inside the bone marrow were highlighted.

Interplay of erythropoietin, fibroblast growth factor 23, and erythroferrone in patients with hereditary hemolytic anemia

Recently, erythropoietin (EPO) was identified as regulator of fibroblast growth factor 23 (FGF23). Proteolytic cleavage of biologically active intact FGF23 (iFGF23) results in the formation of C-terminal fragments (cFGF23). An increase in cFGF23 relative to iFGF23 suppresses FGF receptor signaling by competitive inhibition. EPO lowers the i:cFGF23 ratio, thereby overcoming iFGF23-mediated suppression of erythropoiesis. We investigated EPO-FGF23 signaling and levels of erythroferrone (ERFE) in 90 patients with hereditary hemolytic anemia (www.trialregister.nl [NL5189]). We show, for the first time, the importance of EPO-FGF23 signaling in hereditary hemolytic anemia: there was a clear correlation between total FGF23 and EPO levels (r = +0.64; 95% confidence interval [CI], 0.09-0.89), which persisted after adjustment for iron load, inflammation, and kidney function. There was no correlation between iFGF23 and EPO. Data are consistent with a low i:cFGF23 ratio. Therefore, as expected, we report a correlation between EPO and ERFE in a diverse set of hereditary hemolytic anemias (r = +0.47; 95% CI, 0.14-0.69). There was no association between ERFE and total FGF23 or iFGF23, which suggests that ERFE does not contribute to the connection between FGF23 and EPO. These findings open a new area of research and might provide potentially new druggable targets with the opportunity to ameliorate ineffective erythropoiesis and the development of disease complications in hereditary hemolytic anemias.

The effects of normoxic endurance exercise on erythropoietin (EPO) production and the impact of selective β1 and non-selective β1 + β2 adrenergic receptor blockade

PURPOSE

Habitual endurance exercise results in increased erythropoiesis, which is primarily controlled by erythropoietin (EPO), yet studies demonstrating upregulation of EPO via a single bout of endurance exercise have been equivocal. This study compares the acute EPO response to 30 min of high versus 90 min of moderate-intensity endurance exercise and whether that response can be upregulated via selective adrenergic receptor blockade.

METHODS

Using a counterbalanced, cross-over design, fifteen participants (age 28 ± 8) completed two bouts of running (30-min, high intensity vs 90-min, moderate intensity) matched for overall training stress. A separate cohort of fourteen participants (age 31 ± 6) completed three bouts of 30-min high-intensity cycling after ingesting the preferential β₁-adrenergic receptor (AR) antagonist bisoprolol, the non-preferential β₁ + β₂ antagonist nadolol or placebo. Venous blood was collected before, during, and after exercise, and serum EPO levels were determined by ELISA.

RESULTS

No detectable EPO response was observed during or after high intensity running, however, in the moderate-intensity trial EPO was significantly elevated at both during-exercise timepoints (+ 6.8% ± 2.3% at 15 min and + 8.7% ± 2.2% at 60 min). No significant change in EPO was observed post-cycling or between the trials involving βAR blockade.

CONCLUSION

Neither training mode (running or cycling), nor beta-blockade significantly influenced the EPO response to 30 min of high-intensity exercise, however, 90 min of moderate-intensity running elevated EPO during exercise, returning to baseline immediately post-exercise. Identifying the optimal mode, duration and intensity required to evoke an EPO response to exercise may help tailor exercise prescriptions designed to maximize EPO response for both performance and clinical applications.

Abnormal macrophage polarization impedes the healing of diabetes-associated tooth sockets

Patients with poorly controlled type 2 diabetes mellitus (T2DM) often experience delayed tooth extraction socket (TES) healing. Delayed healing is often associated with an aberrant inflammatory response orchestrated by either M1 pro-inflammatory or M2 anti-inflammatory macrophages. However, the precise mechanism for the attenuated TES healing remains unclear. Here we used diet-induced T2DM mice as a model to study TES. Compared with the control group, the T2DM group showed delayed TES healing and diminished expression of osteogenic and angiogenic genetic profiles. Meanwhile, we detected a more inflammatory profile, with more M1 macrophages and TNF-α expression and less M2 macrophages and PPARγ expression, in TES in the T2DM group when compared to control mice. In vitro co-culture models showed that M1 macrophages inhibited the osteogenic capacity of bone marrow stromal cells and the angiogenic capacity of endothelial cells while M2 macrophages showed an opposite effect. In addition, we constructed a gelatin/β-TCP scaffold with IL-4 to induce macrophage transformation towards M2 polarization. In vitro analyses of the hybrid scaffold revealed sustained release of IL-4 and a phenotype switch to M2 macrophages. Finally, we demonstrated that sustained IL-4 release significantly increased expression of osteogenic and angiogenic genetic profiles and improved TES healing in T2DM mice. Together, we report that increased M1 and decreased M2 macrophage polarization may be responsible for delayed TES healing in T2DM patients through abnormal expression of TNF-α and PPARγ. This imbalance negatively influences osteogenesis and angiogenesis, two of the most important biological factors in bone wound healing. Enhancing M2 macrophage polarization with IL-4 delivery system may represent a potential strategy for promoting the healing of TES in T2DM patients.

Erythropoietin in bone homeostasis-Implications for efficacious anemia therapy

Bone homeostasis and hematopoiesis are irrevocably linked in the hypoxic environment of the bone marrow. Erythropoietin (Epo) regulates erythropoiesis by binding to its receptor, Epor, on erythroid progenitor cells. The continuous process of bone remodeling is achieved by the finely balanced activity of osteoblasts in bone synthesis and osteoclasts in bone resorption. Both osteoblasts and osteoclasts express functional Epors, but the underlying mechanism of Epo‐Epor signaling in bone homeostasis is incompletely understood. Two recent publications have provided new insights into the contribution of endogenous Epo to bone homeostasis. Suresh et al examined Epo‐Epor signaling in osteoblasts in bone formation in mice and Deshet‐Unger et al investigated osteoclastogenesis arising from transdifferentiation of B cells. Both groups also studied bone loss in mice caused by exogenous human recombinant EPO‐stimulated erythropoiesis. They found that either deletion of Epor in osteoblasts or conditional knockdown of Epor in B cells attenuates EPO‐driven bone loss. These findings have direct clinical implications because patients on long‐term treatment for anemia may have an increased risk of bone fractures. Phase 3 trials of small molecule inhibitors of the PHD enzymes (hypoxia inducible factor‐prolyl hydroxylase inhibitors [HIF‐PHIs]), such as Roxadustat, have shown improved iron metabolism and increased circulating Epo levels in a titratable manner, avoiding the supraphysiologic increases that often accompany intravenous EPO therapy. The new evidence presented by Suresh and Deshet‐Unger and their colleagues on the effects of EPO‐stimulated erythropoiesis on bone homeostasis seems likely to stimulate discussion on the relative merits and safety of EPO and HIF‐PHIs.

Stem cell recruitment based on scaffold features for bone tissue engineering

Stem-cell based therapy strategies are promising approaches for the treatment of bone defects. However, extensive cell expansion steps, the low rate of cell survival and uncontrolled differentiation of stem cells transplanted into the body currently remain key challenges in advancing stem cell therapeutics. An alternative strategy is to use specifically designed bone scaffolds to recruit endogenous stem cells upon implantation and to stimulate new bone formation and remodeling. Stem cell recruitment based on scaffold features for bone tissue engineering relies on the development of scaffolds that can effectively mobilize and recruit endogenous stem cells to the implantation site. This article addresses the recent advances in the recruitment of endogenous stem cells in applications of bone scaffolds, particularly focusing on chemical modification and physical characteristic modification of the scaffold for endogenous stem cell homing and recruitment. Finally, the continuing challenges and future directions of scaffold-based stem cell recruitment are discussed.

A Review of the Action of Magnesium on Several Processes Involved in the Modulation of Hematopoiesis

Magnesium (Mg²⁺) is an essential mineral for the functioning and maintenance of the body. Disturbances in Mg²⁺ intracellular homeostasis result in cell-membrane modification, an increase in oxidative stress, alteration in the proliferation mechanism, differentiation, and apoptosis. Mg²⁺ deficiency often results in inflammation, with activation of inflammatory pathways and increased production of proinflammatory cytokines by immune cells. Immune cells and others that make up the blood system are from hematopoietic tissue in the bone marrow. The hematopoietic tissue is a tissue with high indices of renovation, and Mg²⁺ has a pivotal role in the cell replication process, as well as DNA and RNA synthesis. However, the impact of the intra- and extracellular disturbance of Mg²⁺ homeostasis on the hematopoietic tissue is little explored. This review deals specifically with the physiological requirements of Mg²⁺ on hematopoiesis, showing various studies related to the physiological requirements and the effects of deficiency or excess of this mineral on the hematopoiesis regulation, as well as on the specific process of erythropoiesis, granulopoiesis, lymphopoiesis, and thrombopoiesis. The literature selected includes studies in vitro, in animal models, and in humans, giving details about the impact that alterations of Mg²⁺ homeostasis can have on hematopoietic cells and hematopoietic tissue.

Highly increased risk of fracture in patients with myeloproliferative neoplasm

The risk for hip and vertebral fracture was determined in 10,752 patients diagnosed with myeloproliferative neoplasms (MPN) in Sweden 1995-2015. The mean follow-up time were 6.34 years. Five percent developed hip fracture and 1.3% a vertebral fracture. There was a significant increased risk for fracture among the MPN patients compared with the Swedish population. The ratio of observed (obs) and expected (exp) number of hip fracture in all MPN patients, polycythemia vera (PV), essential thrombocythemia and MPN undetermined (MPNu) was 1.20 (95% confidence interval (CI): 1.10-1.31), 1.37 (95% CI: 1.19-1.58), 1.02 (95% CI: 0.87-1.19), and 1.28 (95% CI: 1.07-1.52), respectively. Corresponding figures for vertebral fractures were 1.94 (95% CI: 1.64-2.29), 2.09 (95% CI: 1.56-2.75), 1.50 (95% CI: 1.06-2.07) and 2.47 (95% CI: 1.77-3.35), respectively. Patients with MPN had an increased risk of hip and vertebral fracture, especially patients with PV and MPNu in comparison with the entire Swedish population.

Erythropoietin receptor in B cells plays a role in bone remodeling in mice

Erythropoietin (EPO) is a key regulator of erythropoiesis. However, EPO receptors (EPO-Rs) are also expressed on non-erythroid cell types, including myeloid and bone cells. Immune cells also participate in bone homeostasis. B cells produce receptor activator of nuclear factor kappa-Β ligand (RANKL) and osteoprotegerin (OPG), two pivotal regulators of bone metabolism. Here we explored the ability of B cells to transdifferentiate into functional osteoclasts and examined the role of EPO in this process in a murine model.

Methods: We have combined specifically-designed experimental mouse models and in vitro based osteoclastogenesis assays, as well as PCR analysis of gene expression.

Results: (i) EPO treatment in vivo increased RANKL expression in bone marrow (BM) B cells, suggesting a paracrine effect on osteoclastogenesis; (ii) B cell-derived osteoclastogenesis occured in vivo and in vitro, as demonstrated by B cell lineage tracing in murine models; (iii) B-cell-derived osteoclastogenesis in vitro was restricted to Pro-B cells expressing CD115/CSF1-R and is enhanced by EPO; (iv) EPO treatment increased the number of B-cell-derived preosteoclasts (β3⁺CD115⁺), suggesting a physiological rationale for B cell derived osteoclastogenesis; (v) finally, mice with conditional EPO-R knockdown in the B cell lineage (cKD) displayed a higher cortical and trabecular bone mass. Moreover, cKD displayed attenuated EPO-driven trabecular bone loss, an effect that was observed despite the fact that cKD mice attained higher hemoglobin levels following EPO treatment.

Conclusions: Our work highlights B cells as an important extra-erythropoietic target of EPO-EPO-R signaling and suggests their involvement in the regulation of bone homeostasis and possibly in EPO-stimulated erythropoietic response. Importantly, we present here for the first time, histological evidence for B cell-derived osteoclastogenesis in vivo.

EPO could be regulated by HIF-1 and promote osteogenesis and accelerate bone repair

Bone defects caused by many factors prompt further study of pathological process and restoration methods. This study was aimed to clarify the effect of erythropoietin on the repair of bone defect. We added the designated concentration of rhEPO to endothelial progenitor cells and marrow stromal cells, then detected its osteogenic and angiogenesis effects. The results showed that rhEPO promoted the proliferation of EPC and ST2 by promoting the mitosis without affecting cell apoptosis. The protein and mRNA levels of angiogenesis and osteogenic related factors exhibited higher expressions. Additionally, rhEPO encapsulated in PLGA scaffolds accelerated the new bone formation in rat calvaria bone defect model. Since the centre of bone defect was hypoxia environment, we cultured EPC and ST2 under hypoxia. SiRNA and an inhibitor of HIF-1 were used to interfere HIF-1, then the following changes of VEGF and EPO were detected. The results showed that all the factors were upregulated under the hypoxia environment. The expression of VEGF at protein and mRNA level decreased as HIF-1 was inhibited or interfered from 6 h, while the mRNA expression of EPO from 6 h and changed significantly at protein level from 12 h. Therefore, EPO is a promising factor for further studies.

Injectable thermosensitive chitosan/gelatin-based hydrogel carried erythropoietin to effectively enhance maxillary sinus floor augmentation in vivo

OBJECTIVE

Maxillary sinus floor augmentation (MSFA) is commonly used to increase the alveolar bone height in the posterior maxilla before implant placement. In the present study, we evaluated if the injectable thermosensitive chitosan/β-sodium glycerophosphate disodium salt hydrate/gelatin (CS/GP/GA) hydrogel carried erythropoietin (EPO) could enhance the new bone formation for MSFA in vivo.

METHODS

EPO-CS/GP/GA hydrogel was prepared by ionic crosslinking. Then, characteristics of EPO-CS/GP/GA were evaluated by morphology, injectable property and pH on the gelling time (GT). The release profile of EPO was evaluated by enzyme linked immunosorbent assay (ELISA), and effects of EPO on proliferation and osteoblastic differentiation of bone marrow stromal cells (BMSC) were analyzed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and reverse transcription quantitative real-time PCR (RT-qPCR), respectively. Finally, EPO-CS/GP/GA was injected into the maxillary sinus floor of the rabbit to test the potential application for MSFA.

RESULTS

Results showed that GT was decreased with the increase of pH value. The GT was 110±15s at pH 7.0. SEM images showed that the CS/GP/GA hydrogel had a sponge network structure. Results from ELISA assay revealed that the cumulative release of EPO from the EPO-CS/GP/GA hydrogel reached 67% at 4h, and 94% at 15 days. MTT assay showed that EPO within EPO-CS/GP/GA hydrogel could significantly promote proliferation of BMSCs compared to control group (p<0.001) . Results of RT-qPCR assays demonstrated that the expression of Sp7, Runx2, Col I and Alp were significantly increased from EPO-CS/GP/GA group compared to control group on day 14 (p<0.001). Importantly, EPO-CS/GP/GA hydrogel could significantly induce bone formation (81.98mm³) compared with control group (43.11mm³) after 12 weeks post-implantation in vivo. The calculation of thickness of mesenchymal condensation indicated that thickness of mesenchymal condensation was significantly increased from EPO-CS/GP/GA group (∼121.4μm) compared to control group (∼37μm) resulting in enhancing intramembranous ossification.

SIGNIFICANCE

The EPO-CS/GP/GA hydrogel provides a novel strategy for MSFA with a minimally invasive way.

Gadofullerene nanoparticles for robust treatment of aplastic anemia induced by chemotherapy drugs

Aplastic anemia (AA) is characterized as hypoplasia of bone marrow hematopoietic cells and hematopenia of peripheral blood cells. Though the supplement of exogenous erythropoietin (EPO) has been clinically approved for AA treatment, the side-effects hinder its further application. Here a robust treatment for AA induced by chemotherapy drugs is explored using gadofullerene nanoparticles (GFNPs).

Methods: The gadofullerene were modified with hydrogen peroxide under alkaline conditions to become the water-soluble nanoparticles (GFNPs). The physicochemical properties, in vitro chemical construction, stability, hydroxyl radical scavenging ability, in vitro cytotoxicity, antioxidant activity, in vivo treatment efficacy, therapeutic mechanism and biological distribution, metabolism, toxicity of GFNPs were examined.

Results: GFNPs with great stability and high-efficiency antioxidant activity could observably increase the number of red blood cells (RBC) in the peripheral blood of AA mice and relieve the abnormal pathological state of bone marrow. The erythropoiesis mainly includes hemopoietic stem cells (HSCs) differentiation, erythrocyte development in bone marrow and erythrocyte maturation in peripheral blood. The positive control-EPO promotes erythropoiesis by regulating HSCs differentiation and erythrocyte development in bone marrow. Different from the anti-AA mechanism of EPO, GFNPs have little impact on both the differentiation of HSCs and the myeloid erythrocyte development, but notably improve the erythrocyte maturation. Besides, GFNPs can notably decrease the excessive reactive oxygen species (ROS) and inhibit apoptosis of hemocytes in blood. In addition, GFNPs are mostly excreted from the living body and cause no serious toxicity.

Conclusion: Our work provides an insight into the advanced nanoparticles to powerfully treat AA through ameliorating the erythrocyte maturation during erythropoiesis.

[Characterisation of the protective role of erythropoetin in a murine model of acute lung injury]

In addition to its role in erythropoiesis, erythropoietin (Epo) plays a role in tissue protection, which includes cardioprotective, nephroprotective and neuroprotective effects. The presence of Epo and its receptor (Epo-R) in pulmonary tissue also suggests a cytoprotective effect of Epo in the lung. Our project aims to document this role in a murine model under-expressing Epo. The obtained results will lead to a better understanding of the cytoprotective effects of Epo and will also give an appreciation of its beneficial effects in cases of lung injury.

High Plasma Erythropoietin Predicts Incident Fractures in Elderly Men with Normal Renal Function: The MrOS Sweden Cohort

Preclinical studies on the role of erythropoietin (EPO) in bone metabolism are contradictory. Regeneration models indicate an anabolic effect on bone healing, whereas models on physiologic bone remodeling indicate a catabolic effect on bone mass. No human studies on EPO and fracture risk are available. It is known that fibroblast growth factor 23 (FGF23) affects bone mineralization and that serum concentration of FGF23 is higher in men with decreased estimated glomerular filtration rate (eGFR). Recently, a direct association between EPO and FGF23 has been shown. We have explored the potential association between EPO and bone mineral density (BMD), fracture risk, and FGF23 in humans. Plasma levels of EPO were analyzed in 999 men (aged 69 to 81 years), participating in the Gothenburg part of the population-based Osteoporotic Fractures in Men (MrOS) study, MrOS Sweden. The mean ± SD EPO was 11.5 ± 9.0 IU/L. Results were stratified by eGFR 60 mL/min. For men with eGFR ≥60 mL/min (n = 728), EPO was associated with age (r = 0.13, p < 0.001), total hip BMD (r = 0.14, p < 0.001), intact (i)FGF23 (r = 0.11, p = 0.004), and osteocalcin (r = -0.09, p = 0.022). The association between total hip BMD and EPO was independent of age, body mass index (BMI), iFGF23, and hemoglobin (beta = 0.019, p < 0.001). During the 10-year follow-up, 164 men had an X-ray-verified fracture, including 117 major osteoporotic fractures (MOF), 39 hip fractures, and 64 vertebral fractures. High EPO was associated with higher risk for incident fractures (hazard ratio [HR] = 1.43 per tertile EPO, 95% confidence interval [CI] 1.35-1.63), MOF (HR = 1.40 per tertile EPO, 95% CI 1.08-1.82), and vertebral fractures (HR = 1.42 per tertile EPO, 95% CI 1.00-2.01) in a fully adjusted Cox regression model. In men with eGFR<60 mL/min, no association was found between EPO and BMD or fracture risk. We here demonstrate that high levels of EPO are associated with increased fracture risk and increased BMD in elderly men with normal renal function. © 2019 American Society for Bone and Mineral Research.

Bioinspired surface modification of orthopedic implants for bone tissue engineering

Biomedical implants have been widely used in various orthopedic treatments, including total hip arthroplasty, joint arthrodesis, fracture fixation, non-union, dental repair, etc. The modern research and development of orthopedic implants have gradually shifted from traditional mechanical support to a bioactive graft in order to endow them with better osteoinduction and osteoconduction. Inspired by structural and mechanical properties of natural bone, this review provides a panorama of current biological surface modifications for facilitating the interaction between medical implants and bone tissue and gives a future outlook for fabricating the next-generation multifunctional and smart implants by systematically biomimicking the physiological processes involved in formation and functioning of bones.

Erythrocytosis and fatigue fractures associated with hepatoblastoma in a 3-year-old gelding

Hepatoblastoma was diagnosed in a 3-year-old Thoroughbred gelding presented with forelimb lameness with bilateral fatigue fractures of the proximal third metacarpal bones. An abdominal mass was detected on ultrasound examination of the abdomen. Absolute erythrocytosis was diagnosed after clinical and haematological evaluation. The fractured metacarpal bones were surgically removed but complications after surgery were fatal. The liver mass was diagnosed as a hepatoblastoma based on histology and immunochemical staining. The combination of hepatoblastoma and fatigue fractures has not been described previously in horses. A potential link between the hepatic and orthopaedic pathologies is hypothesised.

The EPO-FGF23 Signaling Pathway in Erythroid Progenitor Cells: Opening a New Area of Research

We provide an overview of the evidence for an erythropoietin-fibroblast growth factor 23 (FGF23) signaling pathway directly influencing erythroid cells in the bone marrow. We outline its importance for red blood cell production, which might add, among others, to the understanding of bone marrow responses to endogenous erythropoietin in rare hereditary anemias. FGF23 is a hormone that is mainly known as the core regulator of phosphate and vitamin D metabolism and it has been recognized as an important regulator of bone mineralization. Osseous tissue has been regarded as the major source of FGF23. Interestingly, erythroid progenitor cells highly express FGF23 protein and carry the FGF receptor. This implies that erythroid progenitor cells could be a prime target in FGF23 biology. FGF23 is formed as an intact, biologically active protein (iFGF23) and proteolytic cleavage results in the formation of the presumed inactive C-terminal tail of FGF23 (cFGF23). FGF23-knockout or injection of an iFGF23 blocking peptide in mice results in increased erythropoiesis, reduced erythroid cell apoptosis and elevated renal and bone marrow erythropoietin mRNA expression with increased levels of circulating erythropoietin. By competitive inhibition, a relative increase in cFGF23 compared to iFGF23 results in reduced FGF23 receptor signaling and mimics the positive effects of FGF23-knockout or iFGF23 blocking peptide. Injection of recombinant erythropoietin increases FGF23 mRNA expression in the bone marrow with a concomitant increase in circulating FGF23 protein. However, erythropoietin also augments iFGF23 cleavage, thereby decreasing the iFGF23 to cFGF23 ratio. Therefore, the net result of erythropoietin is a reduction of iFGF23 to cFGF23 ratio, which inhibits the effects of iFGF23 on erythropoiesis and erythropoietin production. Elucidation of the EPO-FGF23 signaling pathway and its downstream signaling in hereditary anemias with chronic hemolysis or ineffective erythropoiesis adds to the understanding of the pathophysiology of these diseases and its complications; in addition, it provides promising new targets for treatment downstream of erythropoietin in the signaling cascade.

FUSE binding protein 1 (FUBP1) expression is upregulated by T-cell acute lymphocytic leukemia protein 1 (TAL1) and required for efficient erythroid differentiation

During erythropoiesis, haematopoietic stem cells (HSCs) differentiate in successive steps of commitment and specification to mature erythrocytes. This differentiation process is controlled by transcription factors that establish stage- and cell type-specific gene expression. In this study, we demonstrate that FUSE binding protein 1 (FUBP1), a transcriptional regulator important for HSC self-renewal and survival, is regulated by T-cell acute lymphocytic leukaemia 1 (TAL1) in erythroid progenitor cells. TAL1 directly activates the FUBP1 promoter, leading to increased FUBP1 expression during erythroid differentiation. The binding of TAL1 to the FUBP1 promoter is highly dependent on an intact GATA sequence in a combined E-box/GATA motif. We found that FUBP1 expression is required for efficient erythropoiesis, as FUBP1-deficient progenitor cells were limited in their potential of erythroid differentiation. Thus, the finding of an interconnection between GATA1/TAL1 and FUBP1 reveals a molecular mechanism that is part of the switch from progenitor- to erythrocyte-specific gene expression. In summary, we identified a TAL1/FUBP1 transcriptional relationship, whose physiological function in haematopoiesis is connected to proper erythropoiesis.