Cytokines and hematopoietic stem cell mobilization

Identification of cellular retinoic acid binding protein 2 (CRABP2) as downstream target of nuclear factor I/X (NFIX): implications for skeletal dysplasia syndromes

Nuclear factor I/X (NFIX) mutations are associated with 2 skeletal dysplasias, Marshall-Smith (MSS) and Malan (MAL) syndromes. NFIX encodes a transcription factor that regulates expression of genes, including Bobby sox (BBX) and glial fibrillary acidic protein (GFAP) in neural progenitor cells and astrocytes, respectively. To elucidate the role of NFIX mutations in MSS, we studied their effects in fibroblast cell lines obtained from 5 MSS unrelated patients and 3 unaffected individuals. The 5 MSS NFIX frameshift mutations in exons 6-8 comprised 3 deletions (c.819-732_1079-948del, c.819-471_1079-687del, c.819-592_1079-808del), an insertion (c.1037_1038insT), and a duplication (c.1090dupG). Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analyses using MSS and unrelated control fibroblasts and in vitro expression studies in monkey kidney fibroblast (COS-7) cells showed that frameshift mutations in NFIX exons 6-8 generated mutant transcripts that were not cleared by nonsense-mediated-decay mechanisms and encoded truncated NFIX proteins. Moreover, BBX or GFAP expression was unaffected in the majority of MSS fibroblasts. To identify novel NFIX downstream target genes, RNA sequencing and proteomics analyses were performed on mouse embryonic fibroblast (MEF) cells derived from control Nfix+/+, Nfix+/Del2, Nfix+/Del24, NfixDel24/Del24, Nfix+/Del140, and NfixDel140/Del140 mice, compared with NfixDel2/Del2 mice which had developmental, skeletal, and neural abnormalities. This identified 191 transcripts and 815 proteins misregulated in NfixDel2/Del2 MEFs with ≥2-fold-change (P <0 .05). Validation studies using qRT-PCR and western blot analyses confirmed that 2 genes, cellular retinoic acid binding protein 2 (Crabp2) and vascular cell adhesion molecule 1 (Vcam1), were misregulated at the RNA and protein levels in NfixDel2/Del2 MEFs, and that CRABP2 and VCAM1 expressions were altered in 60%-100% of MSS fibroblast cells. Furthermore, in vitro luciferase reporter assays confirmed that NFIX directly regulates CRABP2 promoter activity. Thus, these altered genes and pathways may represent possible targets for drugs as potential treatments and therapies for MSS.

Establishment of human hematopoietic organoids for evaluation of hematopoietic injury and regeneration effect

BACKGROUND

Human hematopoietic organoids have a wide application value for modeling human bone marrow diseases, such as acute hematopoietic radiation injury. However, the manufacturing of human hematopoietic organoids is an unaddressed challenge because of the complexity of hematopoietic tissues.

METHODS

To manufacture hematopoietic organoids, we obtained CD34+ hematopoietic stem and progenitor cells (HSPCs) from human embryonic stem cells (hESCs) using stepwise induction and immunomagnetic bead-sorting. We then mixed these CD34+ HSPCs with niche-related cells in Gelatin-methacryloyl (GelMA) to form a three-dimensional (3D) hematopoietic organoid. Additionally, we investigated the effects of radiation damage and response to granulocyte colony-stimulating factor (G-CSF) in hematopoietic organoids.

RESULTS

The GelMA hydrogel maintained the undifferentiated state of hESCs-derived HSPCs by reducing intracellular reactive oxygen species (ROS) levels. The established hematopoietic organoids in GelMA with niche-related cells were composed of HSPCs and multilineage blood cells and demonstrated the adherence of hematopoietic cells to niche cells. Notably, these hematopoietic organoids exhibited radiation-induced hematopoietic cell injury effect, including increased intracellular ROS levels, γ-H2AX positive cell percentages, and hematopoietic cell apoptosis percentages. Moreover, G-CSF supplementation in the culture medium significantly improved the survival of HSPCs and enhanced myeloid cell regeneration in these hematopoietic organoids after radiation.

CONCLUSIONS

These findings substantiate the successful manufacture of a preliminary 3D hematopoietic organoid from hESCs-derived HSPCs, which was utilized for modeling hematopoietic radiation injury and assessing the radiation-mitigating effects of G-CSF in vitro. Our study provides opportunities to further aid in the standard and scalable production of hematopoietic organoids for disease modeling and drug testing.

Stem cell mobilizating effect of heparin in patients undergoing autologous stem cell transplantation

BACKGROUND

Adequate stem cell collection is essential for successful stem cell transplantation. Heparin enhances stem cell mobilization by competing with heparin sulfate proteoglycans. Heparin is also used as an anticoagulant before leukapheresis. Here, we evaluated the effects of heparin on stem cell mobilization in patients who underwent autologous stem cell transplantation (ASCT).

METHODS

We evaluated patients who underwent ASCT. Patients were divided into two groups: those who received heparin plus citrate (heparinized patients) and those who received citrate only (nonheparinized patients) for anticoagulation. Univariate and multivariate analyses were also performed. The collection efficiency 2 (CE2) for CD34+ cells was calculated and compared between heparinized and nonheparinized patients.

RESULTS

This study included 1017 patients. There were 478 (47%) heparinized and 539 (53%) nonheparinized patients. The number of collected CD34+ cells was significantly higher in heparinized patients (P < .00001). The multivariate analyses showed that using heparin was an independent positive factor for collected CD34+ cells (adj-R2  = 0.744; F = 369.331, P < .00001). CE2 was significantly higher in heparinized patients than in nonheparinized patients (66.8% vs 52.1%; P < .00001). The rate of collecting at least 2 × 106 /kg CD34+ cells was 3.3 times higher for heparinized patients in poor mobilizers (P < .00001). Heparinized patients had significantly higher total nucleated and mononuclear cell counts (P < .00001 and <.00001, respectively).

CONCLUSION

Heparin enhances stem cell collection and increases CE2. The use of heparin may reduce the need for other strategies to increase stem cell mobilization.

Good Cop, Bad Cop: Profiling the Immune Landscape in Multiple Myeloma

Multiple myeloma (MM) is a dyscrasia of plasma cells (PCs) characterized by abnormal immunoglobulin (Ig) production. The disease remains incurable due to a multitude of mutations and structural abnormalities in MM cells, coupled with a favorable microenvironment and immune suppression that eventually contribute to the development of drug resistance. The bone marrow microenvironment (BMME) is composed of a cellular component comprising stromal cells, endothelial cells, osteoclasts, osteoblasts, and immune cells, and a non-cellular component made of the extracellular matrix (ECM) and the liquid milieu, which contains cytokines, growth factors, and chemokines. The bone marrow stromal cells (BMSCs) are involved in the adhesion of MM cells, promote the growth, proliferation, invasion, and drug resistance of MM cells, and are also crucial in angiogenesis and the formation of lytic bone lesions. Classical immunophenotyping in combination with advanced immune profiling using single-cell sequencing technologies has enabled immune cell-specific gene expression analysis in MM to further elucidate the roles of specific immune cell fractions from peripheral blood and bone marrow (BM) in myelomagenesis and progression, immune evasion and exhaustion mechanisms, and development of drug resistance and relapse. The review describes the role of BMME components in MM development and ongoing clinical trials using immunotherapeutic approaches.

Beyond brain injury biomarkers: chemoattractants and circulating progenitor cells as biomarkers of endogenous rehabilitation effort in preterm neonates with encephalopathy

Introduction

Preclinical work and studies in adults have shown that endogenous regeneration efforts that involve mobilization of progenitor cells take place after brain injury. However, kinetics of endogenous circulating progenitor cells (CPCs) in preterm neonates is not well described, particularly their possible role regarding brain injury and regeneration. We aimed to assess the kinetics of CPCs in neonates with encephalopathy of prematurity in relation to brain injury biomarkers, chemoattractants and relevant antenatal and postanal clinical factors, in an effort to outline the related pathophysiology.

Materials and methods

47 preterm neonates (of 28-33 weeks GA) were enrolled: 31 newborns with no or minimal brain injury (grade I IVH) and 16 prematures with encephalopathy (grade III or IV IVH, PVL or infarct). Peripheral blood samples obtained on days 1, 3, 9, 18 and 45 after birth were analyzed using flow cytometry, focusing on EPCs (early and late Endothelial Progenitor Cells), HSCs (Hematopoietic Stem Cells) and VSELs (Very Small Embryonic-Like Stem Cells). At the same time-points serum levels of S100B, Neuron-specific Enolase (NSE), Erythropoietin (EPO), Insulin-like growth factor-1 (IGF-1) and SDF-1 were also measured. Neonates were assessed postnatally with brain MRI, and with Bayley III developmental test at 2 years of corrected age.

Results

Preterms with brain injury proved to have significant increase of S100B and NSE, followed by increase of EPO and enhanced mobilization mainly of HSCs, eEPCs and lEPCs. IGF-1 was rather decreased in this group of neonates. IGF-1 and most CPCs were intense decreased in cases of antenatal or postnatal inflammation. S100B and NSE correlated with neuroimaging and language scale in Bayley III test, providing good prognostic ability.

Conclusion

The observed pattern of CPCs' mobilization and its association with neurotrophic factors following preterm brain injury indicate the existence of an endogenous brain regeneration process. Kinetics of different biomarkers and associations with clinical factors contribute to the understanding of the related pathophysiology and might help to early discriminate neonates with adverse outcome. Timely appropriate enhancement of the endogenous regeneration effort, when it is suppressed and insufficient, using neurotrophic factors and exogenous progenitor cells might be a powerful therapeutic strategy in the future to restore brain damage and improve the neurodevelopmental outcome in premature infants with brain injury.

Bone Marrow Microenvironment as a Source of New Drug Targets for the Treatment of Acute Myeloid Leukaemia

Acute myeloid leukaemia (AML) is a heterogeneous disease with one of the worst survival rates of all cancers. The bone marrow microenvironment is increasingly being recognised as an important mediator of AML chemoresistance and relapse, supporting leukaemia stem cell survival through interactions among stromal, haematopoietic progenitor and leukaemic cells. Traditional therapies targeting leukaemic cells have failed to improve long term survival rates, and as such, the bone marrow niche has become a promising new source of potential therapeutic targets, particularly for relapsed and refractory AML. This review briefly discusses the role of the bone marrow microenvironment in AML development and progression, and as a source of novel therapeutic targets for AML. The main focus of this review is on drugs that modulate/target this bone marrow microenvironment and have been examined in in vivo models or clinically.

Granulocyte Colony-Stimulating Factor Has a Sex-Dependent Positive Effect in the Maternal Immune Activation-Induced Autism Model

OBJECTIVE

The medical intervention for autism spectrum disorder (ASD) is restricted to ameliorating comorbid situations. Granulocyte colony-stimulating factor (G-CSF) is a growth factor that enhances the proliferation, differentiation and survival of hematopoietic progenitor cells. In the present study, we aimed to investigate the effects of G-CSF in a maternal immune activation-induced autism model.

METHODS

Sixteen female and 6 male Wistar adult rats were included in the study. After 21 days, forty-eight littermates (8 male controls, 8 female controls, 16 male lipopolysaccharide (LPS)-exposed rats and 16 female LPS-exposed rats) were divided into groups. Sixteen male LPS-exposed and 16 female LPS-exposed rats were divided into saline and G-CSF treatment groups.

RESULTS

In male rats, the LPS-exposed group was found to have significantly higher levels of TNF-α, IL-2, and IL-17 than the LPS-exposed G-CSF group. Levels of nerve growth factor, brain PSD-95 and brain GAD67 were higher in the LPS-exposed G-CSF group than in the LPS-exposed group in male rats. In female rats, brain NGF levels were similar between groups. There was no difference between groups in terms of brain GAD 67 levels. Brain PSD-95 levels were higher in the control group than in both the LPS-exposed and LPS-exposed G-CSF groups in female rats. Both neuronal CA1 and neuronal CA2 levels were lower, and the GFAP immunostaining index (CA1) and GFAP immunostaining index (CA3) were higher in the LPS-exposed group than in the LPS-exposed G-CSF group in male rats. However, neuronal count CA1 and Neuronal count CA3 values were found to be similar between groups in female rats.

CONCLUSIONS

The present research is the first to demonstrate the beneficial effects of G-CSF on core symptoms of ASD experimentally depending on male sex. G-CSF can be a good candidate for ameliorating the core symptoms of ASD without serious side effects in males.

Mobilization with high-dose granulocyte colony-stimulating factor alone at 12 μg/kg twice a day in high-risk pediatric patients: A retrospective analysis of the experience in a single center

INTRODUCTION

Mobilization regimes in pediatric patients at high risk for poor mobilization are not standardized across different institutions. We present a retrospective analysis of our experience with a high-dose granulocyte colony-stimulating factor (G-CSF) regime of 12 μg/Kg per body weight (BW) twice a day for 4 days used in high-risk patients.

MATERIAL AND METHODS

We report the results of all pediatric patients mobilized with high-dose G-CSF between January 1999 and February 2021 in our center. A successful mobilization was defined as a peripheral blood (PB) CD34⁺ cell count of ≥10 CD34⁺ cells/μl on the fifth day of mobilization immediately before leukapheresis. A minimum cell yield of ≥2 × 10⁶ CD34⁺ cells/Kg of BW was required for a successful collection.

RESULTS

Of the 262 patients included in the analysis, mobilization failure was found in 27 (10.3%). In a univariate analysis, this was associated with age, weight, baseline diagnosis, and having undergone a previous mobilization cycle, the latter being the only factor that remained significantly associated in a multivariate analysis (P = 0.03). The 54 patients (20.6%) did not reach the minimum required CD34⁺ cell yield. 50.4% of the patients reported adverse events (AEs) during the mobilization period, and 23 (9.1%) reported 3 or more concomitant AEs. However, all of them were mild and did not affect the mobilization schedule.

CONCLUSIONS

Although most high-risk pediatric patients are successfully mobilized with the high-dose G-CSF regime, this approach does not salvage all of them and significantly increases the presence of AEs in comparison to standard-dose regimes.

Role of melatonin mediated G-CSF induction in hematopoietic system of gamma-irradiated mice

AIMS

Hematopoietic acute radiation syndrome (H-ARS) can cause lethality, and therefore, the necessity of a safe radioprotector. The present study was focused on investigating the role of melatonin in granulocytes colony-stimulating factor (G-CSF) and related mechanisms underlying the reduction of DNA damage in hematopoietic system of irradiated mice.

MAIN METHODS

C57BL/6 male mice were exposed to 2, 5, and 7.5Gy of whole-body irradiation (WBI), 30 min after intra-peritoneal administration of melatonin with different doses. Mice were sacrificed at different time intervals after WBI, and bone marrow, splenocytes, and peripheral blood lymphocytes were isolated for studying various parameters including micronuclei (MN), cell cycle, comet, γ-H2AX, gene expression, amino acid profiling, and hematology.

KEY FINDINGS

Melatonin100mg/kg ameliorated radiation (7.5Gy and 5Gy) induced MN frequency and cell death in bone marrow without mortality. At 24 h of post-WBI (2Gy), the frequency of micronucleated polychromatic erythrocytes (mnPCE) with different melatonin doses revealed 20 mg/kg as optimal i.p. dose for protecting the hematopoietic system against radiation injury. In comet assay, a significant reduction in radiation-induced % DNA tail (p ≤ 0.05) was observed at this dose. Melatonin reduced γ-H2AX foci/cell and eventually reached to the control level. Melatonin also decreased blood arginine levels in mice after 24 h of WBI. The gene expression of G-CSF, Bcl-2-associated X protein (BAX), and Bcl2 indicated the role of melatonin in G-CSF regulation and downstream pro-survival pathways along with anti-apoptotic activity.

SIGNIFICANCE

The results revealed that melatonin recovers the hematopoietic system of irradiated mice by inducing G-CSF mediated radioprotection.

Outcomes of stem cell mobilization and engraftment in patients with multiple myeloma according to CD56 expression status

BACKGROUND

The molecular mechanism underlying the mobilization and engraftment of CD34+ cells is poorly understood. The most relevant factors in the regulation of stem cell release and engraftment include chemokines, adhesion molecules, and chemokine receptors. Previously, it was suggested that the absence of CD56 expression could be used as a predictive factor for mobilization failure at the time of diagnosis. Here, we investigated the effect of CD56 expression status on both mobilization and engraftment processes. Additionally, other factors affecting mobilization and engraftment efficacy were investigated.

METHODS

Data from 79 multiple myeloma patients undergoing autologous stem cell transplantation between 2015 and 2020 were analyzed for peripheral stem cell mobilization and posttransplant neutrophil and platelet engraftment according to CD56 expression on myeloma cells.

RESULTS

No difference in either the median number of CD34+ cells collected or time to engraftment was found between the CD56+ and CD56- groups. The age of the patients (p = 0.025) and peak number of circulating CD34+ cells in peripheral blood (p = 0.005) were important predictors for a higher number of collected CD34+ cells. The average time to recovery of leukocytes and platelets after transplantation was markedly correlated with the number of transplanted stem cells and peak number of circulating CD34+ cells in peripheral blood, respectively (p = 0.049 and p = 0.003).

CONCLUSIONS

Our results indicated no effect of CD56 expression status on the mobilization and engraftment of PBSCs. Our results also support the notion that the peak number of circulating CD34+ cells in peripheral blood is clinically important for rapid platelet engraftment following HPC transplantation.

Molecular characterization of hematopoietic stem cells after in vitro amplification on biomimetic 3D PDMS cell culture scaffolds

Hematopoietic stem cell (HSC) transplantation is successfully applied since the late 1950s. However, its efficacy can be impaired by insufficient numbers of donor HSCs. A promising strategy to overcome this hurdle is the use of an advanced ex vivo culture system that supports the proliferation and, at the same time, maintains the pluripotency of HSCs. Therefore, we have developed artificial 3D bone marrow-like scaffolds made of polydimethylsiloxane (PDMS) that model the natural HSC niche in vitro. These 3D PDMS scaffolds in combination with an optimized HSC culture medium allow the amplification of high numbers of undifferentiated HSCs. After 14 days in vitro cell culture, we performed transcriptome and proteome analysis. Ingenuity pathway analysis indicated that the 3D PDMS cell culture scaffolds altered PI3K/AKT/mTOR pathways and activated SREBP, HIF1α and FOXO signaling, leading to metabolic adaptations, as judged by ELISA, Western blot and metabolic flux analysis. These molecular signaling pathways can promote the expansion of HSCs and are involved in the maintenance of their pluripotency. Thus, we have shown that the 3D PDMS scaffolds activate key molecular signaling pathways to amplify the numbers of undifferentiated HSCs ex vivo effectively.

Hematopoietic stem cell mobilization strategies to support high-dose chemotherapy: A focus on relapsed/refractory germ cell tumors

High-dose chemotherapy (HDCT) with autologous hematopoietic stem cell transplantation has been explored and has played an important role in the management of patients with high-risk germ cell tumors (GCTs) who failed to be cured by conventional chemotherapy. Hematopoietic stem cells (HSCs) collected from the peripheral blood, after appropriate pharmacologic mobilization, have largely replaced bone marrow as the principal source of HSCs in transplants. As it is currently common practice to perform tandem or multiple sequential cycles of HDCT, it is anticipated that collection of large numbers of HSCs from the peripheral blood is a prerequisite for the success of the procedure. Moreover, the CD34+ cell dose/kg of body weight infused after HDCT has proven to be a major determinant of hematopoietic engraftment, with patients who receive > 2 × 10⁶ CD34+ cells/kg having consistent, rapid, and sustained hematopoietic recovery. However, many patients with relapsed/refractory GCTs have been exposed to multiple cycles of myelosuppressive chemotherapy, which compromises the efficacy of HSC mobilization with granulocyte colony-stimulating factor with or without chemotherapy. Therefore, alternative strategies that use novel agents in combination with traditional mobilizing regimens are required. Herein, after an overview of the mechanisms of HSCs mobilization, we review the existing literature regarding studies reporting various HSC mobilization approaches in patients with relapsed/refractory GCTs, and finally report newer experimental mobilization strategies employing novel agents that have been applied in other hematologic or solid malignancies.

Mechanisms involved in selecting and maintaining neuroblastoma cancer stem cell populations, and perspectives for therapeutic targeting

Pediatric neuroblastomas (NBs) are heterogeneous, aggressive, therapy-resistant embryonal tumours that originate from cells of neural crest (NC) origin and in particular neuroblasts committed to the sympathoadrenal progenitor cell lineage. Therapeutic resistance, post-therapeutic relapse and subsequent metastatic NB progression are driven primarily by cancer stem cell (CSC)-like subpopulations, which through their self-renewing capacity, intermittent and slow cell cycles, drug-resistant and reversibly adaptive plastic phenotypes, represent the most important obstacle to improving therapeutic outcomes in unfavourable NBs. In this review, dedicated to NB CSCs and the prospects for their therapeutic eradication, we initiate with brief descriptions of the unique transient vertebrate embryonic NC structure and salient molecular protagonists involved NC induction, specification, epithelial to mesenchymal transition and migratory behaviour, in order to familiarise the reader with the embryonic cellular and molecular origins and background to NB. We follow this by introducing NB and the potential NC-derived stem/progenitor cell origins of NBs, before providing a comprehensive review of the salient molecules, signalling pathways, mechanisms, tumour microenvironmental and therapeutic conditions involved in promoting, selecting and maintaining NB CSC subpopulations, and that underpin their therapy-resistant, self-renewing metastatic behaviour. Finally, we review potential therapeutic strategies and future prospects for targeting and eradication of these bastions of NB therapeutic resistance, post-therapeutic relapse and metastatic progression.

Alterations in microRNA Expression during Hematopoietic Stem Cell Mobilization

Simple Summary

Lymphoproliferative disorders comprise a heterogeneous group of hematological malignancies characterized by abnormal lymphocyte proliferation. Autologous hematopoietic stem cell transplantation plays a very important role in the treatment of lymphoproliferative diseases. The key element in this process is the effective mobilization of hematopoietic cells from the marrow niche to the peripheral blood. Mobilization of HSC is regulated by many factors, out of which miRNAs present in the hematopoietic niche via targeting cytokines, and signaling pathways may play an important regulatory role. This study investigated the expression of selected miRNAs in patients with multiple myeloma, Hodgkin’s lymphomas, and non-Hodgkin’s lymphomas undergoing mobilization procedures. The aim of the study was to evaluate the expression of hsa-miR-15a-5p, hsa-miR-16-5p, hsa-miR-34a-5p, hsa-miR-126-3p, hsa-miR-146a-5p, hsa-miR-155-5p, and hsa-miR-223-3p during the mobilization procedure, and to assess their role in mobilization efficacy. The level of miRNAs was tested at two time points before the initiation of mobilization and on the day of the first apheresis. Our results suggest that the investigated miRNAs, especially hsa-miR-146a-5p, may influence the efficacy of HSC mobilization.

Abstract

microRNAs play an important role in the regulation of gene expression, cell fate, hematopoiesis, and may influence the efficacy of CD34+ cell mobilization. The present study examines the role of hsa-miR-15a-5p, hsa-miR-16-5p, hsa-miR-34a-5p, hsa-miR-126-3p, hsa-miR-146a-5p, hsa-miR-155-5p, and hsa-miR-223-3p in the course of hematopoietic stem cell mobilization. The numbers of CD34+ cells collected in patients with hematological malignancies (39 multiple myelomas, 11 lymphomas) were determined during mobilization for an autologous hematopoietic stem cell transplantation. The miRNA level was evaluated by RT-PCR. Compared to baseline, a significant decline in hsa-miR-15a-5p, hsa-miR-16-5p, hsa-miR-126-3p, hsa-miR-146a-5p, and hsa-miR-155-5p was observed on the day of the first apheresis (day A). An increase was observed only in the expression of hsa-miR-34a-5p. On day A, a negative correlation was found between hsa-miR-15a-5p and hsa-miR-146a-5p levels and the number of CD34+ cells in peripheral blood. A negative correlation was observed between hsa-miR-146a-5p and the number of collected CD34+ cells after the first apheresis. Good mobilizers, defined according to GITMO criteria, demonstrated a lower hsa-miR-146a-5p level on day A than poor mobilizers. Patients from the hsa-miR-146a-5p “low expressors” collected more CD34+ cells than “high expressors”. Our results suggest that the investigated miRNAs, especially hsa-miR-146a-5p, may influence the efficacy of HSC mobilization.

Long-acting granulocyte colony-stimulating factor pegfilgrastim (lipegfilgrastim) for stem cell mobilization in multiple myeloma patients undergoing autologous stem cell transplantation

Autologous stem cell transplantation (ASCT) is a standard of care in newly-diagnosed multiple myeloma (MM) patients. Several studies before the introduction of novel therapies in MM, demonstrated a pegylated G-CSF to be successful in mobilizing peripheral blood stem cells (PBSCs). Lipegfilgrastim is a novel long-acting G-CSF that is produced by the conjugation of a single 20-kDa polyethelene glycol to the natural O-glycosylation site of G-CSF. Twenty-four MM patients were included for PBSCs mobilization with a single SC injection of 6 mg lipegfilgrastim. PBSC collection was started when the CD34⁺ count was > 10 × 10⁶ cells/L. The target progenitor cells were 6 × 10⁶ cells/kg. The median day of apheresis was + 3 (range 2-5) following lipegfilgrastim. Median peripheral blood CD34⁺ count pre-mobilization was of 22.65 (range 3.36-105) × 10⁶ cells/L. The median number of leukaphaeresis procedures was 2 (range 1-4). The median mobilized CD34⁺ cells/kg were 8.26 (range 0.77-12.42). One patient failed to mobilize and two patients mobilized < 6 × 10⁶ cells/kg. Toxicity was mild and transient. Twenty-three patients underwent ASCT following high dose melphalan. All patients engrafted. As lipegfilgrastim is administered only once, it is conceivable that it improves both compliance and quality-of-life (NCT02488382).

Systemic Administration of G-CSF Accelerates Bone Regeneration and Modulates Mobilization of Progenitor Cells in a Rat Model of Distraction Osteogenesis

Granulocyte colony-stimulating factor (G-CSF) was shown to promote bone regeneration and mobilization of vascular and osteogenic progenitor cells. In this study, we investigated the effects of a systemic low dose of G-CSF on both bone consolidation and mobilization of hematopoietic stem/progenitor cells (HSPCs), endothelial progenitor cells (EPCs) and mesenchymal stromal cells (MSCs) in a rat model of distraction osteogenesis (DO). Neovascularization and mineralization were longitudinally monitored using positron emission tomography and planar scintigraphy. Histological analysis was performed and the number of circulating HSPCs, EPCs and MSCs was studied by flow cytometry. Contrary to control group, in the early phase of consolidation, a bony bridge with lower osteoclast activity and a trend of an increase in osteoblast activity were observed in the distracted callus in the G-CSF group, whereas, at the late phase of consolidation, a significantly lower neovascularization was observed. While no difference was observed in the number of circulating EPCs between control and G-CSF groups, the number of MSCs was significantly lower at the end of the latency phase and that of HSPCs was significantly higher 4 days after the bone lengthening. Our results indicate that G-CSF accelerates bone regeneration and modulates mobilization of progenitor cells during DO.

A novel small molecule CXCR4 antagonist potently mobilizes hematopoietic stem cells in mice and monkeys

Background

Hematopoietic stem cell (HSC) transplantation is an effective treatment strategy for many types of diseases. Peripheral blood (PB) is the most commonly used source of bone marrow (BM)-derived stem cells for current HSC transplantation. However, PB usually contains very few HSCs under normal conditions, as these cells are normally retained within the BM. This retention depends on the interaction between the CXC chemokine receptor 4 (CXCR4) expressed on the HSCs and its natural chemokine ligand, stromal cell-derived factor (SDF)-1α (also named CXCL12) present in the BM stromal microenvironment. In clinical practice, blocking this interaction with a CXCR4 antagonist can induce the rapid mobilization of HSCs from the BM into the PB.

Methods

C3H/HEJ, DBA/2, CD45.1⁺, and CD45.2⁺ mice and monkeys were employed in colony-forming unit (CFU) assays, flow cytometry assays, and competitive/noncompetitive transplantation assays, to assess the short-term mobilization efficacy of HF51116 and the long-term repopulating (LTR) ability of HSCs. Kinetics of different blood cells and the concentration of HF51116 in PB were also explored by blood routine examinations and pharmacokinetic assays.

Results

In this paper, we report that a novel small molecule CXCR4 antagonist, HF51116, which was designed and synthesized by our laboratory, can rapidly and potently mobilize HSCs from BM to PB in mice and monkeys. HF51116 not only mobilized HSCs when used alone but also synergized with the mobilizing effects of granulocyte colony-stimulating factor (G-CSF) after co-administration. Following mobilization by HF51116 and G-CSF, the long-term repopulating (LTR) and self-renewing HSCs were sufficiently engrafted in primary and secondary lethally irradiated mice and were able to rescue and support long-term mouse survival. In monkeys, HF51116 exhibited strong HSC mobilization activity and quickly reached the highest in vivo blood drug concentration.

Conclusions

These results demonstrate that HF51116 is a new promising stem cell mobilizer which specifically targets CXCR4 and merits further preclinical and clinical studies.

Cytokines, Chemokines, and Inflammation in Pulmonary Arterial Hypertension

According to the World Symposium Pulmonary Hypertension (WSPH) classification, pulmonary hypertension (PH) is classified into five categories based on etiology. Among them, Group 1 pulmonary arterial hypertension (PAH) disorders are rare but progressive and often, fatal despite multiple approved treatments. Elevated pulmonary arterial pressure in patients with WSPH Group 1 PAH is mainly caused by increased pulmonary vascular resistance (PVR), due primarily to sustained pulmonary vasoconstriction and excessive obliterative pulmonary vascular remodeling. Growing evidence indicates that inflammation plays a critical role in the development of pulmonary vascular remodeling associated with PAH. While the role of auto-immunity is unclear, infiltration of inflammatory cells in and around vascular lesions, including T- and B-cells, dendritic cells, macrophages, and mast cells have been observed in PAH patients. Serum and plasma levels of chemokines, cytokines, and autoantibodies are also increased in PAH patients; some of these circulating molecules are correlated with disease severity and survival. Preclinical experiments have reported a key role of the inflammation in PAH pathophysiology in vivo. Importantly, anti-inflammatory and immunosuppressive agents have further exhibited therapeutic effects. The present chapter reviews published experimental and clinical evidence highlighting the canonical role of inflammation in the pathogenesis of PAH and as a major target for the development of anti-inflammatory therapies in patients with PAH.

Is absence of CD56 a predictive factor for peripheral blood stem cell mobilization failure in patients with multiple myeloma?

BACKGROUND

CD56 is believed to play a major role in MM pathogenesis with a 70% to 80% expression rate in malignant plasma cells at the time of diagnosis. Our objective in this study was to investigate the relationship between the characteristics of CD56 expression in bone marrow aspiration material at the time of diagnosis and the success of stem cell mobilization in patients diagnosed with MM.

METHODS

This monocenter study included 94 patients who were diagnosed with MM and had a stem cell mobilization procedure for autologous hematopoietic stem cell transplantation. The primary endpoint of the study was to compare the mobilization success between the groups with and without CD56 expression. The secondary endpoint was to identify other factors affecting mobilization failure outside CD56.

RESULTS

At the time of diagnosis, 49 (52.1%) patients had CD56 expression and 45 (47.9%) did not. Mobilization failed in 11 (11.7%) patients. Age, gender, ISS stage and the number of premobilization treatment regimens were not found predictive of mobilization failure. CD56 negativity was 42.2% in the group that had mobilization success and 90.9% in the group that had mobilization failure (P = .001).

CONCLUSIONS

The fact that CD56 residing on the membrane enables interaction between bone marrow cells and ECM and functions as a signal molecule increases sensitivity to the chemotherapy and G-CSF that are used for mobilization. We found that absence of CD56 can be used as a predictive factor for mobilization failure at the time of diagnosis.

Development of Site-Specific PEGylated Granulocyte Colony Stimulating Factor With Prolonged Biological Activity

Currently, amino-terminal PEGylated human granulocyte colony stimulating factor (huG-CSF) is used to prevent and treat neutropenia. Although huG-CSF has been used as a drug for more than 20 years, it has three significant drawbacks: (i) it relies on PEG aldehyde for PEGylation of the alpha-amino group of the first amino acid, and this leads to non-specific PEGylation of the epsilon amino group of lysine residues within the G-CSF; (ii) longer-acting G-CSF variants are desirable to reduce the risk of chemotherapy-associated neutropenia; and (iii) G-CSF cannot be administered on the day of chemotherapy. In an attempt to overcome the above drawbacks, we engineered cysteine variants of G-CSF to facilitate the maleimide PEG-based site-specific PEGylation that leads to a highly homogenous PEGylated product. Importantly, we have demonstrated that 20 kDa thiol-reactive PEG conjugated by maleimide chemistry to the Cys2 G-CSF variant exhibits leukocyte proliferative activity similar to that of the commercially available G-CSF conjugated with aldehyde PEG in a neutropenia mice model. Moreover, we have demonstrated that PEGylation of the cysteine variant of huG-CSF with higher molecular weight PEGs, such as 30 kDa PEG and 40 kDa PEG, leads to significantly prolonged leukocyte proliferation activity compared to the variant conjugated with 20 kDa PEG. Importantly, even a half-dose of the engineered variant conjugated with 40 kDa PEG exhibited significantly longer biological activity than the commercially available 20 kDa PEGylated huG-CSF. Finally, we have demonstrated that administration of the engineered variant conjugated with 40 kDa PEG on the day of administration of cyclophosphamide for inducing neutropenia in mice can alleviate neutropenia through leukocyte proliferation. In summary, this study provides the design of site-specific PEGylated huG-CSF variants with improved therapeutic potential. It opens the possibility of long-acting and same-day prophylactic administration of G-CSF after chemotherapy drug regimens. These results may pave the way for the development of potential G-CSF derivatives possessing longer half-lives and favorable clinical attributes.

Pathologic angiogenesis in the bone marrow of humanized sickle cell mice is reversed by blood transfusion

Sickle cell disease (SCD) is a monogenic red blood cell (RBC) disorder with high morbidity and mortality. Here, we report, for the first time, the impact of SCD on the bone marrow (BM) vascular niche, which is critical for hematopoiesis. In SCD mice, we find a disorganized and structurally abnormal BM vascular network of increased numbers of highly tortuous arterioles occupying the majority of the BM cavity, as well as fragmented sinusoidal vessels filled with aggregates of erythroid and myeloid cells. By in vivo imaging, sickle and control RBCs have significantly slow intravascular flow speeds in sickle cell BM but not in control BM. In sickle cell BM, we find increased reactive oxygen species production in expanded erythroblast populations and elevated levels of HIF-1α. The SCD BM exudate exhibits increased levels of proangiogenic growth factors and soluble vascular cell adhesion molecule-1. Transplantation of SCD mouse BM cells into wild-type mice recapitulates the SCD vascular phenotype. Our data provide a model of SCD BM, in which slow RBC flow and vaso-occlusions further diminish local oxygen availability in the physiologic hypoxic BM cavity. These events trigger a milieu that is conducive to aberrant vessel growth. The distorted neovascular network is completely reversed by a 6-week blood transfusion regimen targeting hemoglobin S to <30%, highlighting the plasticity of the vascular niche. A better insight into the BM microenvironments in SCD might provide opportunities to optimize approaches toward efficient and long-term hematopoietic engraftment in the context of curative therapies.

Combined GM-CSF and G-CSF administration mobilizes CD4+ CD25hi Foxp3hi Treg in leukapheresis products of rhesus monkeys

Early phase clinical trials are evaluating the feasibility, safety, and therapeutic potential of ex vivo expanded regulatory T cells (Treg) in transplantation. A limitation is the paucity of naturally occurring Treg numbers in peripheral blood. Hence, protracted ex vivo expansion is required to obtain sufficient Treg in order to meet target cell doses. Because cytokine administration has been used successfully to mobilize immune cells to the peripheral blood in experimental and clinical studies, we hypothesized that granulocyte macrophage-colony-stimulating factor (GM-CSF) and granulocyte-CSF (G-CSF) administration would enhance Treg percentages in leukapheresis products of rhesus monkeys. Following combined GM-CSF and G-CSF administration, the incidence of Treg in peripheral blood and leukapheresis products was elevated significantly, where approximately 3.7 × 10⁶ /kg CD4⁺ CD25^hi Foxp3^hi or 6.8 × 10⁶ /kg CD4⁺ CD25^hi CD127^lo Treg can be collected from individual products. Mobilized Treg expressed a comparable repertoire of surface markers, chemokine receptors, and transcription factors to naïve monkey peripheral blood Treg. Furthermore, when expanded ex vivo, mobilized leukapheresis product and peripheral blood Treg exhibited similar ability to suppress autologous CD4⁺ and CD8⁺ T cell proliferation. These observations indicate that leukapheresis products from combined GM-CSF- and G-CSF-mobilized individuals are a comparatively rich source of Treg and may circumvent long-term ex vivo expansion required for therapeutic application.

G-CSF (filgrastim) treatment for amyotrophic lateral sclerosis: protocol for a phase II randomised, double-blind, placebo-controlled, parallel group, multicentre clinical study (STEMALS-II trial)

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a fatal progressive neurological disorder characterised by a selective degeneration of motor neurons (MNs). Stem cell transplantation is considered as a promising strategy in neurological disorders therapy and the possibility of inducing bone marrow cells (BMCs) to circulate in the peripheral blood is suggested to investigate stem cells migration in degenerated ALS nerve tissues where potentially repair MN damage. Granulocyte-colony stimulating factor (G-CSF) is a growth factor which stimulates haematopoietic progenitor cells, mobilises BMCs into injured brain and it is itself a neurotrophic factor for MN. G-CSF safety in humans has been demonstrated and many observations suggest that it may affect neural cells. Therefore, we decided to use G-CSF to mobilise BMCs into the peripheral circulation in patients with ALS, planning a clinical trial to evaluate the effect of G-CSF administration in ALS patients compared with placebo.

METHODS AND ANALYSIS

STEMALS-II is a phase II multicentre, randomised double-blind, placebo-controlled, parallel group clinical trial on G-CSF (filgrastim) and mannitol in ALS patients. Specifically, we investigate safety, tolerability and efficacy of four repeated courses of intravenous G-CSF and mannitol administered in 76 ALS patients in comparison with placebo (indistinguishable glucose solution 5%). We determine increase of G-CSF levels in serum and cerebrospinal fluid as CD34⁺ cells and leucocyte count after treatment; reduction in ALS Functional Rating Scale-Revised Score, forced vital capacity, Scale for Testing Muscle Strength Score and quality of life; the adverse events/reactions during the treatment; changes in neuroinflammation biomarkers before and after treatment.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of Azienda Ospedaliera Universitaria 'Città della Salute e della Scienza', Torino, Italy. Results will be presented during scientific symposia or published in scientific journals.

TRIAL REGISTRATION NUMBER

Eudract 2014-002228-28.

Results from a multicenter, noninterventional registry study for multiple myeloma patients who received stem cell mobilization regimens with and without plerixafor

Plerixafor plus granulocyte-colony stimulating factor (G-CSF) enhances the mobilization of hematopoietic stem cells (HSCs) for collection and subsequent autologous hematopoietic stem cell transplantation (HSCT) in patients with multiple myeloma (MM). This international, multicenter, noninterventional registry study (NCT01362972), evaluated long-term outcomes for MM patients who received plerixafor versus other mobilization regimens. The comparisons were: G-CSF + plerixafor (G-CSF + P) versus G-CSF-; G-CSF + P versus G-CSF + chemotherapy (G-CSF + C); and G-CSF + P + C versus G-CSF + C. Propensity score matching was used to balance groups. Primary outcome measures were progression free survival (PFS), overall survival (OS), and cumulative incidence of relapse (CIR) after transplantation. After propensity matching, 77 versus 41 patients in the G-CSF + P versus G-CSF cohorts, 129 versus 129 in the G-CSF + P versus G-CSF + C cohorts, and 117 versus 117 in the G-CSF + P + C versus G-CSF + C cohorts were matched, respectively. Propensity score matching resulted in a smaller sample size and imbalances were not completely overcome. For both PFS and OS, the upper limits of the hazard ratio 95% confidence intervals exceeded prespecified boundaries; noninferiority was not demonstrated. CIR rates were higher in the plerixafor cohorts. G-CSF + P remains an option for the mobilization of HSCs in poor mobilizers with MM with no substantial differences in PFS, OS, and CIR in comparison with other regimens.

Chemokines and Bone

Chemokines are a family of small proteins, subdivided by their conserved cysteine residues and common structural features. Chemokines interact with their cognate G-protein-coupled receptors to elicit downstream signals that result in cell migration, proliferation, and survival. This review presents evidence for how the various CXC and CC subfamily chemokines influence bone hemostasis by acting on osteoclasts, osteoblasts, and progenitor cells. Also discussed are the ways in which chemokines contribute to bone loss as a result of inflammatory diseases such as rheumatoid arthritis, HIV infection, and periodontal infection. Both positive and negative effects of chemokines on bone formation and bone loss are presented. In addition, the role of chemokines in altering the bone microenvironment through effects on angiogenesis and tumor invasion is discussed. Very few therapeutic agents that influence bone formation by targeting chemokines or chemokine receptors are available, although a few are currently being evaluated.

Mobilized peripheral blood: an updated perspective

Enforced egress of hematopoietic stem cells (HSCs) out of the bone marrow (BM) into the peripheral circulation, termed mobilization, has come a long way since its discovery over four decades ago. Mobilization research continues to be driven by the need to optimize the regimen currently available in the clinic with regard to pharmacokinetic and pharmacodynamic profile, costs, and donor convenience. In this review, we describe the most recent findings in the field and how we anticipate them to affect the development of mobilization strategies in the future. Furthermore, the significance of mobilization beyond HSC collection, i.e. for chemosensitization, conditioning, and gene therapy as well as a means to study the interactions between HSCs and their BM microenvironment, is reviewed. Open questions, controversies, and the potential impact of recent technical progress on mobilization research are also highlighted.

Analysis of data collected in the European Society for Blood and Marrow Transplantation (EBMT) Registry on a cohort of lymphoma patients receiving plerixafor

Plerixafor + granulocyte-colony stimulating factor (G-CSF) is administered to patients with lymphoma who are poor mobilizers of hematopoietic stem cells (HSCs) in Europe. This international, multicenter, non-interventional registry study (NCT01362972) evaluated long-term follow-up of patients with lymphoma who received plerixafor for HSC mobilization versus other mobilization methods. Propensity score matching was conducted to balance baseline characteristics between comparison groups. The following mobilization regimens were compared: G-CSF + plerixafor (G + P) versus G-CSF alone; G + P versus G-CSF + chemotherapy (G + C); and G-CSF + plerixafor + chemotherapy (G + P + C) versus G + C. The primary outcomes were progression-free survival (PFS), overall survival (OS), and cumulative incidence of relapse (CIR). Overall, 313/3749 (8.3%) eligible patients were mobilized with plerixafor-containing regimens. After propensity score matching, 70 versus 36 patients were matched in the G + P versus G-CSF alone cohort, 124 versus 124 in the G + P versus G + C cohort, and 130 versus 130 in the G + P + C versus G + C cohort. For both PFS and OS, the upper bound of confidence interval for the hazard ratio was >1.3 for all comparisons, implying that non-inferiority was not demonstrated. No major differences in PFS, OS, and CIR were observed between the plerixafor and comparison groups.

Modest and nonessential roles of the endocannabinoid system in immature hematopoiesis of mice

Endocannabinoids are lipid mediators that signal via several seven-transmembrane domain G protein-coupled receptors. The endocannabinoid receptor CB2 is expressed on blood cells, including stem cells, and mediates the effects of cannabinoids on the immune system. The role of the endocannabinoid system in immature hematopoiesis is largely elusive. Both direct effects of endocannabinoids on stem cells and indirect effects through endocannabinoid-responsive niche cells like macrophages have been reported. Using two different CB2-deficient mouse models, we studied the role of the endocannabinoid system in immature hematopoiesis. Moreover, we utilized both models to assess the specificity of putative CB2 agonists. As heterodimerization of CB2 and CXCR4, which is highly expressed on hematopoietic stem cells, has already been described, we also assessed potential consequences of CB2 loss for CXCR4/CXCL12 signaling. Overall, no differential effects were observed with any of the compounds tested; the compounds barely induced signaling by themselves, whereas they attenuated CXCL12-induced signals in both CB2-competent and CB2-deficient cells. In vivo experiments were therefore by necessity restricted to loss-of-function studies in knockout (CB2-/-) mice: Except for mild lymphocytosis and slightly elevated circulating progenitor cells, homeostatic hematopoiesis in CB2-/- mice appears to be entirely normal. Mobilization in response to pharmacological stimuli, Plerixafor or G-CSF, was equally potent in wild-type and CB2-/- mice. CB2-/- bone marrow cells reconstituted hematopoiesis in lethally irradiated recipients with engraftment kinetics indistinguishable from those of wild-type grafts. In summary, we found the endocannabinoid system to be largely dispensable for normal murine hematopoiesis.

FL/GCSF/AMD3100-mobilized Hematopoietic Stem Cells Induce Mixed Chimerism With Nonmyeloablative Conditioning and Transplantation Tolerance

BACKGROUND

Mobilization of hematopoietic stem cells (HSCs) has become the preferred approach for HSC transplantation. AMD3100, a competitive inhibitor of C-X-C motif chemokine receptor-4, has been found to be a rapid mobilizing agent. The present study evaluated approaches to optimize the product collected.

METHODS

Mobilized peripheral blood mononuclear cells (mPBMCs) from B6 mice were transplanted to recipient BALB/c mice conditioned with ablative or nonmyeloablative approaches.

RESULTS

The optimal dose of AMD3100 was found to be 5.0 mg/kg. Optimal HSC mobilization was observed when AMD3100 (day 10) was coadministered with Flt3 ligand (FL) (days 1-10) and granulocyte colony-stimulating factor (GCSF) (days 4-10). There was a 228.8-fold increase of HSC with FL/GCSF/AMD3100 compared with AMD3100 treatment alone. When unmodified mPBMCs were transplanted into ablated allogeneic recipients, all recipients expired by day 40 from severe acute graft versus host disease (GVHD). When T cells were depleted from mPBMC, long-term survival and engraftment were achieved in majority of the recipients. When PBMC mobilized by FL/GCSF/AMD3100 were transplanted into recipients conditioned nonmyeloablatively with anti-CD154/rapamycin plus 100, 200, and 300 cGy of total body irradiation, 42.9%, 85.7%, and 100% of mice engrafted, respectively. Donor chimerism was durable, multilineage, and stable. Lymphocytes from mixed chimeras showed no response to host or donor antigens, suggesting functional bidirection T-cell tolerance in vitro. Most importantly, none of the engrafted mice exhibited clinical features of GVHD.

CONCLUSIONS

FL/GCSF/AMD3100 is an efficient treatment to maximally mobilize HSC. Durable engraftment and donor-specific tolerance can be achieved with mPBMC in nonmyeloablative conditioning without GVHD.

GM-CSF Enhances Mobilization of Bone Marrow Mesenchymal Stem Cells via a CXCR4-Medicated Mechanism

Background

This study was conducted to investigate the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the mobilization of mesenchymal stem cells (MSCs) from the bone marrow (BM) into the peripheral blood (PB) in rats.

Methods

GM-CSF was administered subcutaneously to rats at 50 μg/kg body weight for 5 consecutive days. The BM and PB of rats were collected at 1, 3, and 5 days during the administration for analysis.

Results

Upon GM-CSF administration, the number of mononuclear cells increased rapidly at day 1 both in the BM and PB. This number decreased gradually over time in the BM to below the initial amount by day 5, but was maintained at a high level in the PB until day 5. The colony-forming unit-fibroblasts were increased in the PB by 10.3-fold at day 5 of GM-CSF administration, but decreased in the BM. Compared to GM-CSF, granulocyte-colony stimulating factor (G-CSF) stimulated lower levels of MSC mobilization from the BM to the PB. Immunohistochemical analysis revealed that GM-CSF induced a hypoxic and proteolytic microenvironment and increased C-X-C chemokine receptor type 4 (CXCR4) expression in the BM. GM-CSF added to BM MSCs in vitro dose-dependently increased CXCR4 expression and cell migration. G-CSF and stromal cell derived factor-1 (SDF-1) showed similar results in these in vitro assays. Know-down of CXCR4 expression with siRNA significantly abolished GM-CSF- and G-CSF-induced MSC migration in vitro, indicating the involvement of the SDF-1-CXCR4 interaction in the mechanism.

Conclusion

These results suggest that GM-CSF is a useful tool for mobilizing BM MSCs into the PB.

Circulating Progenitor Cells and Racial Differences

RATIONALE

Blacks compared with whites have a greater risk of adverse cardiovascular outcomes. Impaired regenerative capacity, measured as lower levels of circulating progenitor cells (CPCs), is a novel determinant of adverse outcomes; however, little is known about racial differences in CPCs.

OBJECTIVE

To investigate the number of CPCs, PC-mobilizing factors, PC mobilization during acute myocardial infarction and the predictive value of CPC counts in blacks compared with whites.

METHODS AND RESULTS

CPCs were enumerated by flow cytometry as CD45med+ blood mononuclear cells expressing CD34+, CD133+, VEGF2R+, and CXCR4+ epitopes in 1747 subjects, mean age 58.4±13, 55% male, and 26% self-reported black. Patients presenting with acute myocardial infarction (n=91) were analyzed separately. Models were adjusted for relevant clinical variables. SDF-1α (stromal cell-derived factor-1α), VEGF (vascular endothelial growth factor), and MMP-9 (matrix metallopeptidase-9) levels were measured (n=561), and 623 patients were followed for median of 2.2 years for survival analysis. Blacks were younger, more often female, with a higher burden of cardiovascular risk, and lower CPC counts. Blacks had fewer CD34+ cells (-17.6%; [95% confidence interval (CI), -23.5% to -11.3%]; P<0.001), CD34+/CD133+ cells (-15.5%; [95% CI, -22.4% to -8.1%]; P<0.001), CD34+/CXCR4+ cells (-17.3%; [95% CI, -23.9% to -10.2%]; P<0.001), and CD34+/VEGF2R+ cells (-27.9%; [95% CI, -46.9% to -2.0%]; P=0.04) compared with whites. The association between lower CPC counts and black race was not affected by risk factors or cardiovascular disease. Results were validated in a separate cohort of 411 patients. Blacks with acute myocardial infarction had significantly fewer CPCs compared with whites ( P=0.02). Blacks had significantly lower plasma MMP-9 levels ( P<0.001) which attenuated the association between low CD34+ and black race by 19% (95% CI, 13%-33%). However, VEGF and SDF-1α levels were not significantly different between the races. Lower CD34+ counts were similarly predictive of mortality in blacks (hazard ratio, 2.83; [95% CI, 1.12-7.20]; P=0.03) and whites (hazard ratio, 1.79; [95% CI, 1.09-2.94]; P=0.02) without significant interaction.

CONCLUSIONS

Black subjects have lower levels of CPCs compared with whites which is partially dependent on lower circulating MMP-9 levels. Impaired regenerative capacity is predictive of adverse outcomes in blacks and may partly account for their increased risk of cardiovascular events.

In vivo somatic cell reprogramming for tissue regeneration: the emerging role of the local microenvironment

The past few years have witnessed an exponential increase of interest in the reprogramming process. This has been motivated by the enthusiasm of unravelling key aspects not only of cell identity and dedifferentiation, but also of the endogenous regenerative capacities of mammalian organs. Here, we present the most recent advances in the field of reprogramming, stressing how they are re-defining the rules of cell fate and plasticity in vivo. Specifically, we focus on the emerging role of the tissue microenvironment, with particular emphasis on tissue damage, inflammation and senescence that can facilitate in vivo reprogramming and regeneration through cell-extrinsic mechanisms.

The march of pluripotent stem cells in cardiovascular regenerative medicine

Cardiovascular disease (CVD) continues to be the leading cause of global morbidity and mortality. Heart failure remains a major contributor to this mortality. Despite major therapeutic advances over the past decades, a better understanding of molecular and cellular mechanisms of CVD as well as improved therapeutic strategies for the management or treatment of heart failure are increasingly needed. Loss of myocardium is a major driver of heart failure. An attractive approach that appears to provide promising results in reducing cardiac degeneration is stem cell therapy (SCT). In this review, we describe different types of stem cells, including embryonic and adult stem cells, and we provide a detailed discussion of the properties of induced pluripotent stem cells (iPSCs). We also present and critically discuss the key methods used for converting somatic cells to pluripotent cells and iPSCs to cardiomyocytes (CMs), along with their advantages and limitations. Integrating and non-integrating reprogramming methods as well as characterization of iPSCs and iPSC-derived CMs are discussed. Furthermore, we critically present various methods of differentiating iPSCs to CMs. The value of iPSC-CMs in regenerative medicine as well as myocardial disease modeling and cardiac regeneration are emphasized.

Tracking embryonic hematopoietic stem cells to the bone marrow: nanoparticle options to evaluate transplantation efficiency

BACKGROUND

As the prevalence of therapeutic approaches involving transplanted cells increases, so does the need to noninvasively track the cells to determine their homing patterns. Of particular interest is the fate of transplanted embryonic stem cell-derived hematopoietic progenitor cells (HPCs) used to restore the bone marrow pool following sublethal myeloablative irradiation. The early homing patterns of cell engraftment are not well understood at this time. Until now, longitudinal studies were hindered by the necessity to sacrifice several mice at various time points of study, with samples of the population of lymphoid compartments subsequently analyzed by flow cytometry or fluorescence microscopy. Thus, long-term study and serial analysis of the transplanted cells within the same animal was cumbersome, making difficult an accurate documentation of engraftment, functionality, and cell reconstitution patterns.

METHODS

Here, we devised a noninvasive, nontoxic modality for tracking early HPC homing patterns in the same mice longitudinally over a period of 9 days using mesoporous silica nanoparticles (MSNs) and magnetic resonance imaging.

RESULTS

This approach of potential translational importance helps to demonstrate efficient uptake of MSNs by the HPCs as well as retention of MSN labeling in vivo as the cells were traced through various organs, such as the spleen, bone marrow, and kidney. Altogether, early detection of the whereabouts and engraftment of transplanted stem cells may be important to the overall outcome. To accomplish this, there is a need for the development of new noninvasive tools.

CONCLUSIONS

Our data suggest that multifunctional MSNs can label viably blood-borne HPCs and may help document the distribution and homing in the host followed by successful reconstitution.

The effects of lower CD34 yields after lowe dose G-CSF induction on long-term autologous stem cell transplantation outcome: A single center study

Peripheral blood stem cell transplantation (PBSCT) is an effective treatment for hematological malignancies. Mobilization of peripheral blood stem cells performs in different ways among transplantation centers. Since the Effects of lower CD34+ cells dose after low dose G-CSF induction on autologous stem cell transplantation outcomes are not studied much, so this study was performed for this purpose. 735 autologous stem cell transplanted patients with diagnoses of multiple myeloma (n = 330), Hodgkin lymphoma (n = 200), non-Hodgkin lymphoma (n = 129), acute myeloid leukemia (n = 54) and solid tumors (n = 22) were retrospectively evaluated. G-CSF was administered at the dose of 5 μg/kg/day during mobilization and all patients except acute myeloid leukemia received 10 μg/kg/day on the last day. Peripheral blood stem cells were harvested in one session for all patients. The amount of injected CD34+ cells/kg for patients were divided and studied in four groups: <0.5 × 10⁶ (n = 36), 0.5-1.0 × 10⁶, (n = 132), 1.0-2.0 × 10⁶ (n = 226) and >2.0 × 10⁶ (n = 305). The median time of follow up was 26.9 months. The amount of CD34+ cells dose were a significant predictor of platelet engraftment, but overall survival, relapse-free survival and also relapse rate was not associated with cells yield. More platelet transfusion (P = 0.003) and antibiotics prescription (P = 0.001) in transplanted patients with lower CD34 cells dose should be balanced with risks of higher G-CSF doses administration and also its side effects. Our results declare that lower CD34 yields after lowe dose G-CSF induction are probably not a troublesome issue affecting transplantation outcomes.

CXCR4 Antagonist AMD3100 Promotes Mesenchymal Stem Cell Mobilization in Rats Preconditioned with the Hypoxia-Mimicking Agent Cobalt Chloride

Mobilization of mesenchymal stem cells (MSCs) is an attractive strategy for cell therapy. Our previous study demonstrated that MSCs can be mobilized in circulating blood by short-term hypoxia, and hypoxia-inducible factor-1α is essential for MSC mobilization. In the present study, the effect of the hypoxia-mimicking agent CoCl₂ was examined on MSC mobilization. The results indicated that the frequency of circulating MSCs increased slightly by administration of CoCl₂. However, the mobilization efficiency was low. Considering the critical role of stromal cell-derived factor-1α (SDF-1)/CXCR4 axis in the regulation of MSC migration, the effects of granulocyte colony-stimulating factor (G-CSF) and the CXCR4 antagonist AMD3100 were investigated on MSC mobilization. The experiments were notably demonstrated in animals preconditioned with CoCl₂. The frequency of colony-forming unit fibroblast and the proportion of CD45^-CD90⁺ cells did not significantly increase in the peripheral blood of rats treated with G-CSF and/or AMD3100 alone. The concomitant administration of G-CSF with CoCl₂ could not stimulate the release of MSCs. However, AMD3100 dramatically increased MSC mobilization efficiency in rats pretreated with CoCl_2. Furthermore, we identified and compared the multilineage differentiation capacities of MSCs derived from bone marrow (BM-MSCs) and mobilized peripheral blood (PB-MSCs). The results indicated that PB-MSCs exhibited higher osteogenic potential and lower adipogenic differentiation as compared with BM-MSCs. The findings may inform studies investigating mechanisms of the regulation of MSC mobilization and can aid in the development of clinically useful therapeutic agents.

Endogenous Mobilization of Bone-Marrow Cells Into the Murine Retina Induces Fusion-Mediated Reprogramming of Müller Glia Cells

Müller glial cells (MGCs) represent the most plastic cell type found in the retina. Following injury, zebrafish and avian MGCs can efficiently re-enter the cell cycle, proliferate and generate new functional neurons. The regenerative potential of mammalian MGCs, however, is very limited. Here, we showed that N-methyl-d-aspartate (NMDA) damage stimulates murine MGCs to re-enter the cell cycle and de-differentiate back to a progenitor-like stage. These events are dependent on the recruitment of endogenous bone marrow cells (BMCs), which, in turn, is regulated by the stromal cell-derived factor 1 (SDF1)-C-X-C motif chemokine receptor type 4 (CXCR4) pathway. BMCs mobilized into the damaged retina can fuse with resident MGCs, and the resulting hybrids undergo reprogramming followed by re-differentiation into cells expressing markers of ganglion and amacrine neurons. Our findings constitute an important proof-of-principle that mammalian MGCs retain their regenerative potential, and that such potential can be activated via cell fusion with recruited BMCs. In this perspective, our study could contribute to the development of therapeutic strategies based on the enhancement of mammalian endogenous repair capabilities.

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Endogenous bone marrow cells migrate into NMDA-damaged murine retinae and fuse with retinal Müller glial cells (MGCs).

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MGCs can be reprogrammed to retinal progenitors to then differentiate into ganglion and amacrine neurons.

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Modulation of the SDF1/CXCR4 pathway regulates BMC migration, BMC-MGC fusion, and MGC reprogramming.

Retinal degeneration is present in a large and heterogeneous group of debilitating diseases, often not curable. Cell therapy represents an interesting approach to regenerate injured retinal tissue. However, it comes with some hurdles in terms of engraftment and differentiation of the transplanted cells. Here, we reported that murine Müller glia cells can be converted into retinal neurons after fusion with endogenous bone marrow cells. The efficiency of this mechanism can be enhanced by perturbation of the SDF1/CXCR4 signaling pathway. Our study provides an important proof-of-principle that the limited endogenous regeneration capability of mammals can be enhanced by modulation of specific signaling pathways.

CD44/CD44v6 a Reliable Companion in Cancer-Initiating Cell Maintenance and Tumor Progression

Metastasis is the leading cause of cancer death, tumor progression proceeding through emigration from the primary tumor, gaining access to the circulation, leaving the circulation, settling in distant organs and growing in the foreign environment. The capacity of a tumor to metastasize relies on a small subpopulation of cells in the primary tumor, so called cancer-initiating cells (CIC). CIC are characterized by sets of markers, mostly membrane anchored adhesion molecules, CD44v6 being the most frequently recovered marker. Knockdown and knockout models accompanied by loss of tumor progression despite unaltered primary tumor growth unraveled that these markers are indispensable for CIC. The unexpected contribution of marker molecules to CIC-related activities prompted research on underlying molecular mechanisms. This review outlines the contribution of CD44, particularly CD44v6 to CIC activities. A first focus is given to the impact of CD44/CD44v6 to inherent CIC features, including the crosstalk with the niche, apoptosis-resistance, and epithelial mesenchymal transition. Following the steps of the metastatic cascade, we report on supporting activities of CD44/CD44v6 in migration and invasion. These CD44/CD44v6 activities rely on the association with membrane-integrated and cytosolic signaling molecules and proteases and transcriptional regulation. They are not restricted to, but most pronounced in CIC and are tightly regulated by feedback loops. Finally, we discuss on the engagement of CD44/CD44v6 in exosome biogenesis, loading and delivery. exosomes being the main acteurs in the long-distance crosstalk of CIC with the host. In brief, by supporting the communication with the niche and promoting apoptosis resistance CD44/CD44v6 plays an important role in CIC maintenance. The multifaceted interplay between CD44/CD44v6, signal transducing molecules and proteases facilitates the metastasizing tumor cell journey through the body. By its engagement in exosome biogenesis CD44/CD44v6 contributes to disseminated tumor cell settlement and growth in distant organs. Thus, CD44/CD44v6 likely is the most central CIC biomarker.

Dormant breast cancer micrometastases reside in specific bone marrow niches that regulate their transit to and from bone

Breast cancer metastatic relapse can occur years after therapy, indicating that disseminated breast cancer cells (BCCs) have a prolonged dormant phase before becoming proliferative. A major site of disease dissemination and relapse is bone, although the critical signals that allow circulating BCCs to identify bone microvasculature, enter tissue, and tether to the microenvironment are poorly understood. Using real-time in vivo microscopy of bone marrow (BM) in a breast cancer xenograft model, we show that dormant and proliferating BCCs occupy distinct areas, with dormant BCCs predominantly found in E-selectin- and stromal cell-derived factor 1 (SDF-1)-rich perisinusoidal vascular regions. We use highly specific inhibitors of E-selectin and C-X-C chemokine receptor type 4 (CXCR4) (SDF-1 receptor) to demonstrate that E-selectin and SDF-1 orchestrate opposing roles in BCC trafficking. Whereas E-selectin interactions are critical for allowing BCC entry into the BM, the SDF-1/CXCR4 interaction anchors BCCs to the microenvironment, and its inhibition induces mobilization of dormant micrometastases into circulation. Homing studies with primary BCCs also demonstrate that E-selectin regulates their entry into bone through the sinusoidal niche, and immunohistochemical staining of patient BMs shows dormant micrometastatic disease adjacent to SDF-1(+) vasculature. These findings shed light on how BCCs traffic within the host, and suggest that simultaneous blockade of CXCR4 and E-selectin in patients could molecularly excise dormant micrometastases from the protective BM environment, preventing their emergence as relapsed disease.

bFGF promotes Sca‑1+ cardiac stem cell migration through activation of the PI3K/Akt pathway

Cardiac stem cells (CSCs) are important for improving cardiac function following myocardial infarction, with CSC migration to infarcted or ischemic myocardium important for cardiac regeneration. Strategies to improve cell migration may improve the efficiency of myocardial regeneration. Basic fibroblast growth factor (bFGF) is an essential molecule in cell migration, but the endogenous bFGF level is too low to be effective. The effect of exogenously delivered bFGF on CSC migration was observed in vitro and in vivo in the present study. The CSC migration index in response to various bFGF concentrations was demonstrated in vitro. In addition, a murine myocardial infarction model was constructed and bFGF protein expression levels and CSC aggregation following myocardial infarction were observed. To study cell migration in vivo, CM-Dil-labeled CSCs or bFGF-CSCs were injected into the peri-infarct myocardium following myocardium infarction and cell migration and maintenance in the peri-infarct/infarct area was observed 1 week later. Protein expression levels of bFGF, CXCR-4 and SDF-1 were assessed, as was myocardium capillary density. The Akt inhibitor deguelin was used to assess the role of the PI3K/Akt pathway in vitro and in vivo. The present study demonstrated that bFGF-promoted Sca-1⁺ CSC migration, with the highest migration rate occurring at a concentration of 45 ng/ml. The PI3K/Akt pathway inhibitor deguelin attenuated this increase. The phospho-Akt/Akt ratio was elevated significantly after 30 min of bFGF exposure. Transplantation of bFGF-treated Sca-1⁺ CSCs led to improved cell maintenance in the peri-infarct area and increased cell migration to the infarct area, as well as improved angiogenesis. Protein expression levels of bFGF, CXCR-4 and SDF-1 were upregulated, and this upregulation was partially attenuated by deguelin. Therefore, bFGF was demonstrated to promote Sca-1⁺ CSC migration both in vitro and in vivo, partially through activation of the PI3K/Akt pathway. This may provide a new method for facilitating CSC therapy for myocardium repair after myocardium injury.

Peripheral blood stem cell mobilization in multiple myeloma: Growth factors or chemotherapy?

High-dose therapy followed by autologous hematopoietic stem cell (HSC) transplant is considered standard of care for eligible patients with multiple myeloma. The optimal collection strategy should be effective in procuring sufficient HSC while maintaining a low toxicity profile. Currently available mobilization strategies include growth factors alone, growth factors in combination with chemotherapy, or growth factors in combination with chemokine receptor antagonists; however, the optimal strategy has yet to be elucidated. Herein, we review the risks and benefits of each approach.

'Waterloo': when normal blood cells meet leukemia

PURPOSE OF REVIEW

Mortality and morbidity associated with leukemia are largely due to frequently occurring cytopenias or the dysfunction of normal blood cells in patients. Our knowledge of how normal blood cells degenerate in response to leukemic cell infiltration has been quite limited. This review summarizes recent findings and discusses both extrinsic and intrinsic mechanisms underlying the suppression of normal hematopoiesis in leukemia.

RECENT FINDINGS

Recent studies have shown that leukemic cells are able to remodel the bone marrow niche by secreting specific cytokines or dampening its hematopoietic-supporting functions. In turn, a suitable microenvironment for leukemic cell proliferation but not for normal hematopoietic cell growth is created. Intrinsically, the leukemic condition impairs the normalcy of hematopoietic stem and progenitor cells and alters their signaling networks; consequently, it exhausts hematopoietic progenitor cells and forces stem cells into a more quiescent state, which would allow a reversible suppression of hematopoietic regeneration. The deepened quiescence of hematopoietic stem cells in leukemic marrow was achieved in part via transcription factor Egr3.

SUMMARY

These findings provide new insights into the mechanisms underlying hematopoietic suppression in response to leukemic cell outgrowth and offer new strategies to further improve current therapies for leukemias, placing more emphasis on the augmentation of normal hematopoietic regeneration when targeting leukemic cells.

Granulocyte–Colony Stimulating Factor plus Plerixafor in Patients with β-thalassemia Major Results in the Effective Mobilization of Primitive CD34+ Cells with Specific Gene Expression Profile

Successful gene therapy for β-thalassemia requires optimal numbers of autologous gene-transduced hematopoietic stem and progenitor cells (HSPCs) with high repopulating capacity. Previous studies suggested superior mobilization in these patients by the combination of granulocyte–colony stimulating factor (G-CSF) plus plerixafor over single agents. We mobilized four adult patients using G-CSF+plerixafor to assess the intra-individual variation of the circulating CD34+ cells number and subtypes preand post-plerixafor administration. The procedure was well-tolerated and the target cell dose of ≥8 × 106 CD34+ cells/kg was achieved in three of them with one apheresis procedure. The addition of plerixafor unanimously increased the number of circulating CD34+ cells, and the frequency of the most primitive CD34+ subtypes: CD34+/38− and CD34+/133+/38− as well as the in vitro clonogenic potency. Microarray analyses of CD34+ cells purified from the leukapheresis of one patient mobilized twice, with G-CSF and with G-CSF+plerixafor, highlighted in G-CSF+plerixafor-mobilized CD34+ cells, higher levels of expression genes involved in HSPC motility, homing, and cell cycles. In conclusion, G-CSF+plerixafor in β-thalassemia patients mobilizes optimal numbers of HSPCs with characteristics that suggest high capacity of engraftment after transplantation.

Biomaterial-enabled delivery of SDF-1α at the ventral side of breast cancer cells reveals a crosstalk between cell receptors to promote the invasive phenotype

The SDF-1α chemokine (CXCL12) is a potent bioactive chemoattractant known to be involved in hematopoietic stem cell homing and cancer progression. The associated SDF-1α/CXCR4 receptor signaling is a hallmark of aggressive tumors, which can metastasize to distant sites such as lymph nodes, lung and bone. Here, we engineered a biomimetic tumoral niche made of a thin and soft polyelectrolyte film that can retain SDF-1α to present it, in a spatially-controlled manner, at the ventral side of the breast cancer cells. Matrix-bound SDF-1α but not soluble SDF-1α induced a striking increase in cell spreading and migration in a serum-containing medium, which was associated with the formation of lamellipodia and filopodia in MDA-MB231 cells and specifically mediated by CXCR4. Other Knockdown and inhibition experiments revealed that CD44, the major hyaluronan receptor, acted in concert, via a spatial coincidence, to drive a specific matrix-bound SDFα-induced cell response associated with ERK signaling. In contrast, the β1 integrin adhesion receptor played only a minor role on cell polarity. The CXCR4/CD44 mediated cellular response to matrix-bound SDF-1α involved the Rac1 RhoGTPase and was sustained solely in the presence of matrix-bound SDFα, in contrast with the transient signaling observed in response to soluble SDF-1α. Our results highlight that a biomimetic tumoral niche enables to reveal potent cellular effects and so far hidden molecular mechanisms underlying the breast cancer response to chemokines. These results open new insights for the design of future innovative therapies in metastatic cancers, by inhibiting CXCR4-mediated signaling in the tumoral niche via dual targeting of receptors (CXCR4 and CD44) or of associated signaling molecules (CXCR4 and Rac1).

Bone Niches, Hematopoietic Stem Cells, and Vessel Formation

Bone marrow (BM) is a source of hematopoietic stem cells (HSCs). HSCs are localized in both the endosteum, in the so-called endosteal niche, and close to thin-walled and fenestrated sinusoidal vessel in the center of BM, in the so-called vascular niche. HSCs give rise to all types of mature blood cells through a process finely controlled by numerous signals emerging from the bone marrow niches where HSCs reside. This review will focus on the description of the role of BM niches in the control of the fate of HSCs and will also highlight the role of the BM niches in the regulation of vasculogenesis and angiogenesis. Moreover, alterations of the signals in niche microenvironment are involved in many aspects of tumor progression and vascularization and further knowledge could provide the basis for the development of new therapeutic strategies.

Pathophysiological aldosterone levels modify the secretory activity of cardiac progenitor cells

Cardiac progenitor cells (CPCs) trigger regenerative processes via paracrine mechanisms in response to changes in their environment. In the present study we explored alterations in the secretory activity of CPCs induced by raised aldosterone levels symptomatic for heart failure. The cytokine profile of the supernatant of CPCs that were treated with the mineralocorticoid showed an induction of interleukin-6 secretion. Mass spectrometric analyses revealed an increase in the abundance of secreted proteins associated with regeneration and cell migration like gelsolin and galectin-1. Differential regulation of proteins associated with the extracellular matrix further points to an activation of cell migration. In response to supernatant, migration and proliferation were induced in CPCs, indicating a potential role of paracrine factors in the activation of CPCs from other regions of the heart or extra-cardiac sources. Changes in the secretory activity of CPCs might aim to compensate for the detrimental actions of aldosterone in heart failure.

Effect of administration timing of postchemotherapy granulocyte colony-stimulating factor on host-immune cell recovery and CD8+ T-cell response

Granulocyte colony-stimulating factor (G-CSF), a hematopoietic growth factor, is a standard supportive therapy given during cancer treatment. It induces acceleration in neutrophil recovery through stimulation of mobilization of hematopoietic progenitors. Given that the latter is also induced by chemotherapy itself, the timing of administration of G-CSF postchemotherapy might impact the resultant overall effects. The present study aimed to determine the optimal timing of G-CSF postchemotherapy to exert its optimal effects on the immune cell recovery and its impact on antigen-specific CD8⁺ T-cell response. B6 mice were treated once with cyclophosphamide (4 mg/mouse; CTX) and then daily with G-CSF (5 g/mouse) from Days 1-5, 2-5 or 5-9 post-CTX treatment. The total numbers of various immune cell types were analyzed on Days 7, 9 and 12 post-CTX treatment. To evaluate effects on CD8⁺ T-cell response, a pmel-1 transgenic mouse model was used in combination with prime boost peptide vaccination therapy. The total number of white blood cells (WBC), neutrophils, monocytes, lymphocytes, granulocytes and dendritic cells (DC) were significantly increased after G-CSF treatment in particular when G-CSF was administered from Days 2-5 post-CTX treatment. Application of this timing of G-CSF and CTX treatment after adoptive transfer of T-cells followed by prime-boost vaccination with antigenic peptide did not block the expansion of the donor pmel-1 CD8⁺ T-cells. In conclusion, adjusting the timing of treatment with G-CSF postchemotherapy can optimize its promoting effects on recovery of myeloid cells without altering the associated antigen-specific immunity.

Systemic Problems: A perspective on stem cell aging and rejuvenation

This review provides balanced analysis of the advances in systemic regulation of young and old tissue stem cells and suggests strategies for accelerating development of therapies to broadly combat age-related tissue degenerative pathologies. Many highlighted recent reports on systemic tissue rejuvenation combine parabiosis with a “silver bullet” putatively responsible for the positive effects. Attempts to unify these papers reflect the excitement about this experimental approach and add value in reproducing previous work. At the same time, defined molecular approaches, which are “beyond parabiosis” for the rejuvenation of multiple old organs represent progress toward attenuating or even reversing human tissue aging.

Absence of CCR2 results in an inflammaging environment in young mice with age-independent impairments in muscle regeneration

Skeletal muscle regeneration requires coordination between dynamic cellular populations and tissue microenvironments. Macrophages, recruited via CCR2, are essential for regeneration; however, the contribution of macrophages and the role of CCR2 on nonhematopoietic cells has not been defined. In addition, aging and sex interactions in regeneration and sarcopenia are unclear. Muscle regeneration was measured in young (3-6 mo), middle (11-15 mo), old (24-32 mo) male and female CCR2^-/- mice. Whereas age-related muscle atrophy/sarcopenia was present, regenerated myofiber cross-sectional area (CSA) in CCR2^-/- mice was comparably impaired across all ages and sexes, with increased adipocyte area compared with wild-type (WT) mice. CCR2^-/- mice myofibers achieved approximately one third of baseline CSA even 84 d after injury. Regenerated CSA and clearance of necrotic tissue were dependent on bone marrow-derived cellular expression of CCR2. Myogenic progenitor cells isolated from WT and CCR2^-/- mice exhibited comparable proliferation and differentiation capacity. The most striking cellular anomaly in injured muscle of CCR2^-/- mice was markedly decreased macrophages, with a predominance of Ly6C^- anti-inflammatory monocytes/macrophages. Ablation of proinflammatory TLR signaling did not affect muscle regeneration or resolution of necrosis. Of interest, many proinflammatory, proangiogenic, and chemotactic cytokines were markedly elevated in injured muscle of CCR2^-/- relative to WT mice despite impairments in macrophage recruitment. Collectively, these results suggest that CCR2 on bone marrow-derived cells, likely macrophages, were essential to muscle regeneration independent of TLR signaling, aging, and sex. Decreased proinflammatory monocytes/macrophages actually promoted a proinflammatory microenvironment, which suggests that inflammaging was present in young CCR2^-/- mice.

Evaluation of circulating haematopoietic progenitor cells in patients with Trauma Haemorrhagic shock and its correlation with outcomes

Background:

Haemorrhagic shock accounts up to 50% of early trauma deaths. Hematopoietic failure has been observed in experimental animals and human following shock and injury. One of the facets of bone marrow failure is multiple organ dysfunction syndrome and is commonly seen in patients recovering from severe trauma and hemorrhagic shock. Bone Marrow (BM) dysfunction is associated with mobilization of hematopoietic progenitor cells (HPCs) into peripheral blood. Present study explored the association of peripheral blood hematopoietic progenitor cells (HPCs) with mortality in trauma haemorrhagic shock patients (T/HS).

Materials and Methods:

Prospective cohort studies of patients presenting within 8 hrs of injury with T/HS to the Department of Emergency Medicine, Jai Prakash Narayan Apex Trauma Center, All India Institute of Medical Sciences were recruited. Peripheral blood samples were collected in each patient for measurement of peripheral blood HPCs. Peripheral blood progenitor cell (PBPC) quantification was performed by measuring HPCs counts using the haematology analyzer (Sysmex XE-2100). Clinical and laboratory data were prospectively collected after consent. Ethical approval was taken and data was analysed by Stata 11.2.

Results:

39 patients with trauma hemorrhagic shock and 30 normal healthy controls were recruited. HPCs were significantly higher (P < 0.001) in the T/HS as compared to control. Among study group, 14 patients died within 24 h. at the hospital admission, and found HPCs concentrations were highly significant (<0.001) in non-survivors (n = 14) when compared with survivors (n = 25) among T/HS patients.

Conclusions:

Our studies suggest the peripheral blood HPCs may be early prognostic marker for mortality among patients who presented with trauma hemorrhagic shock on admission. But the exact molecular mechanism and signalling pathway involved in the change of the behaviour of bone marrow microenvironment is still unclear.