Effects of different concentrations of nicotinamide on hematopoietic stem cells cultured in vitro

BACKGROUND In vitro expansion to increase numbers of hematopoietic stem cells(HSCs)in cord blood could improve clinical efficacy of this vital resource.Nicotinamide(NAM)can promote HSC expansion ex vivo,but its effect on hematopoietic stem and progenitor cells(HSPCs,CD34^(+)CD38)and functional subtypes of HSCs-shortterm repopulating HSCs(ST-HSCs,CD34^(+)CD38CD45RACD49f^(+))and long-term repopulating HSCs(LT-HSCs,CD34^(+)CD38CD45RACD49f^(+)CD90^(+))is not yet known.As a sirtuin 1(SIRT1)inhibitor,NAM participates in regulating cell adhesion,polarity,migration,proliferation,and differentiation.However,SIRT1 exhibits dual effects by promoting or inhibiting differentiation in different tissues or cells.We propose that the concentration of NAM may influence proliferation,differentiation,and SIRT1 signaling of HSCs.AIM To evaluate the effects and underlying mechanisms of action of different concentrations of NAM on HSC proliferation and differentiation.METHODS CD34^(+)cells were purified from umbilical cord blood using MacsCD34 beads,and cultured for 10-12 d in a serum-free medium supplemented with cytokines,with different concentrations of NAM added according to experimental requirements.Flow cytometry was used to detect phenotype,cell cycle distribution,and apoptosis of the cultured cells.Real-time polymerase chain reaction was used to detect the transcription levels of target genes encoding stemness-related factors,che mokines,components of hypoxia pathways,and antioxidant enzymes.Dichloro-dihydro-fluorescein diacetate probes were used to evaluate intracellular production of reactive oxygen species(ROS).Determination of the effect of different culture conditions on the balance of cytokine by cytometric bead array.RESULTS Compared with the control group,the proportion and expansion folds of HSPCs(CD34^(+)CD38)incubated with 5 mmol/L or 10 mmol/L NAM were significantly increased(all P<0.05).The ST-HSCs ratio and fold expansion of the 5 mmol/L NAM group were significantly higher than those of the control and 10 mmol/L NAM groups(all P<0.001),whereas the LT-HSCs ratio and fold expansion of the 10 mmol/L NAM group were significantly higher than those of the other two groups(all P<0.05).When the NAM concentration was>10 mmol/L,cell viability significantly decreased.In addition,compared with the 5 mmol/L NAM group,the proportion of apoptotic cells in the 10 mmol/L NAM group increased and the proportion of cells in S and G2 phase decreased.Compared with the 5 mmol/L NAM group,the HSCs incubated with 10 mmol/L NAM exhibited significantly inhibited SIRT1 expression,increased intracellular ROS content,and downregulated expression of genes encoding antioxidant enzymes(superoxide dismutase 1,peroxiredoxin 1).CONCLUSION Low concentrations(5 mmol/L)of NAM can better regulate the balance between proliferation and differentiation,thereby promoting expansion of HSCs.These findings allow adjustment of NAM concentrations according to expansion needs.

Effect of ginsenoside Rg1 on hematopoietic stem cells in treating aplastic anemia in mice via MAPK pathway

BACKGROUND Aplastic anemia(AA)presents a significant clinical challenge as a life-threatening condition due to failure to produce essential blood cells,with the current the-rapeutic options being notably limited.AIM To assess the therapeutic potential of ginsenoside Rg1 on AA,specifically its protective effects,while elucidating the mechanism at play.METHODS We employed a model of myelosuppression induced by cyclophosphamide(CTX)in C57 mice,followed by administration of ginsenoside Rg1 over 13 d.The invest-igation included examining the bone marrow,thymus and spleen for pathological changes via hematoxylin-eosin staining.Moreover,orbital blood of mice was collected for blood routine examinations.Flow cytometry was employed to identify the impact of ginsenoside Rg1 on cell apoptosis and cycle in the bone marrow of AA mice.Additionally,the study further evaluated cytokine levels with enzyme-linked immunosorbent assay and analyzed the expression of key proteins in the MAPK signaling pathway via western blot.RESULTS Administration of CTX led to significant damage to the bone marrow’s structural integrity and a reduction in hematopoietic cells,establishing a model of AA.Ginsenoside Rg1 successfully reversed hematopoietic dysfunction in AA mice.In comparison to the AA group,ginsenoside Rg1 provided relief by reducing the induction of cell apoptosis and inflammation factors caused by CTX.Furthermore,it helped alleviate the blockade in the cell cycle.Treatment with ginsenoside Rg1 significantly alleviated myelosuppression in mice by inhibiting the MAPK signaling pathway.CONCLUSION This study suggested that ginsenoside Rg1 addresses AA by alleviating myelosuppression,primarily through modulating the MAPK signaling pathway,which paves the way for a novel therapeutic strategy in treating AA,highlighting the potential of ginsenoside Rg1 as a beneficial intervention.

Growing and aging of hematopoietic stem cells

In the hematopoietic system, a small number of stem cells produce a progeny ofseveral distinct lineages. During ontogeny, they arise in the aorta-gonadmesonephrosregion of the embryo and the placenta, afterwards colonise the liverand finally the bone marrow. After this fetal phase of rapid expansion, thenumber of hematopoietic stem cells continues to grow, in order to sustain theincreasing blood volume of the developing newborn, and eventually reaches asteady-state. The kinetics of this growth are mirrored by the rates of telomereshortening in leukocytes. During adulthood, hematopoietic stem cells undergo avery small number of cell divisions. Nonetheless, they are subjected to aging,eventually reducing their potential to produce differentiated progeny. The causalrelationships between telomere shortening, DNA damage, epigenetic changes,and aging have still to be elucidated.

High expression of BCL6 inhibits the differentiation and development of hematopoietic stem cells and affects the growth and development of chickens

Background:B-cell CLL/lymphoma 6(BCL6)is a transcriptional master regulator that represses more than 1200 potential target genes.Our previous study showed that a decline in blood production in runting and stunting syndrome(RSS)affected sex-linked dwarf(SLD)chickens compared to SLD chickens.However,the association between BCL6 gene and hematopoietic function remains unknown in chickens.Methods:In this study,we used RSS affected SLD(RSS-SLD)chickens,SLD chickens and normal chickens as research object and overexpression of BCL6 in hematopoietic stem cells(HSCs),to investigate the effect of the BCL6 on differentiation and development of HSCs.Results:The results showed that comparison of RSS-SLD chickens with SLD chickens,the BCL6 was highly expressed in RSS-SLD chickens bone marrow.The bone marrow of RSS-SLD chickens was exhausted and red bone marrow was largely replaced by yellow bone marrow,bone density was reduced,and the levels of immature erythrocytes in peripheral blood were increased.At the same time,the hematopoietic function of HSCs decreased in RSS-SLD chickens,which was manifested by a decrease in the hematopoietic growth factors(HGFs)EPO,SCF,TPO,and IL-3,as well as hemoglobinα1 and hemoglobinβexpression.Moreover,mitochondrial function in the HSCs of RSS-SLD chickens was damaged,including an increase in ROS production,decrease in ATP concentration,and decrease in mitochondrial membrane potential(ΔΨm).The same results were also observed in SLD chickens compared with normal chickens;however,the symptoms were more serious in RSS-SLD chickens.Additionally,after overexpression of the BCL6 in primary HSCs,the secretion of HGFs(EPO,SCF,TPO and IL-3)was inhibited and the expression of hemoglobinα1 and hemoglobinβwas decreased.However,cell proliferation was accelerated,apoptosis was inhibited,and the HSCs entered a cancerous state.The function of mitochondria was also abnormal,ROS production was decreased,and ATP concentration andΔΨm were increased,which was related to the inhibition of apoptosis of stem cells.Conclusions:Taken together,we conclude that the high expression of BCL6 inhibits the differentiation and development of HSCs by affecting mitochondrial function,resulting in impaired growth and development of chickens.Moreover,the abnormal expression of BCL6 might be a cause of the clinical manifestations of chicken comb,pale skin,stunted growth and development,and the tendency to appear RSS in SLD chickens.

How mesenchymal stem cell cotransplantation with hematopoietic stem cells can improve engraftment in animal models

BACKGROUND Bone marrow transplantation(BMT)can be applied to both hematopoietic and nonhematopoietic diseases;nonetheless,it still comes with a number of challenges and limitations that contribute to treatment failure.Bearing this in mind,a possible way to increase the success rate of BMT would be cotransplantation of mesenchymal stem cells(MSCs)and hematopoietic stem cells(HSCs)to improve the bone marrow niche and secrete molecules that enhance the hematopoietic engraftment.AIM To analyze HSC and MSC characteristics and their interactions through cotransplantation in murine models.METHODS We searched for original articles indexed in PubMed and Scopus during the last decade that used HSC and MSC cotransplantation and in vivo BMT in animal models while evaluating cell engraftment.We excluded in vitro studies or studies that involved graft versus host disease or other hematological diseases and publications in languages other than English.In PubMed,we initially identified 555 articles and after selection,only 12 were chosen.In Scopus,2010 were identified,and six were left after the screening and eligibility process.RESULTS Of the 2565 articles found in the databases,only 18 original studies met the eligibility criteria.HSC distribution by source showed similar ratios,with human umbilical cord blood or animal bone marrow being administered mainly with a dose of 1×10^(7) cells by intravenous or intrabone routes.However,MSCs had a high prevalence of human donors with a variety of sources(umbilical cord blood,bone marrow,tonsil,adipose tissue or fetal lung),using a lower dose,mainly 106 cells and ranging 104 to 1.5×107 cells,utilizing the same routes.MSCs were characterized prior to administration in almost every experiment.The recipient used was mostly immunodeficient mice submitted to low-dose irradiation or chemotherapy.The main technique of engraftment for HSC and MSC cotransplantation evaluation was chimerism,followed by hematopoietic reconstitution and survival analysis.Besides the engraftment,homing and cellularity were also evaluated in some studies.CONCLUSION The preclinical findings validate the potential of MSCs to enable HSC engraftment in vivo in both xenogeneic and allogeneic hematopoietic cell transplantation animal models,in the absence of toxicity.

Identification of key genes responsible for cytokine-induced erythroid and myeloid differentiation and switching of hematopoietic stem cells by RAGE

We utilized a unique culture system to analyze the expression patterns of gene, protein, and cell surface antigen, and the biological process of the related genes in erythroid and myeloid differentiation and switching of hematopoietic stem cells （HSCs） in response to cytokine alterations. Gene-specific fragments （266） identified from five populations of cytokine-stimulated HSCs were categorized into three groups： （1） expressed specifically in a single cell population; （2） expressed in two cell populations, and （3） expressed in three or more populations. Of 145 defined cDNAs, three （2%） were novel genes. Protein two-dimensional gel electrophoresis and flow cytometry analyses showed overlapped and distinguished protein expression profiles in the cell populations studied. Biological process mapping of mRNAs expressed in erythroid and myeloid lineages indicated that mRNAs shared by both lineages attended ＇core processes,＇ whereas genes specifically expressed in either lineage alone were related to specific processes or cellular maturation. Data from this study support the hypothesis that committed HSCs （El4 or G14） cells can still be redirected to develop into myeloid or erythroid cells when erythropoietin （EPO） is replaced with granulocyte-colony stimulating factor （G-CSF） under erythroid-cultured condition or G-CSF with EPO in myeloid-cultured environment, respectively. Our results suggest that genes or proteins co-expressed in erythroid and myeloid lineages may be essential for the lineage maintenance and switching in hematopoiesis.

Isolation and <i>Ex Vivo</i>Expansion of Human Hematopoietic Stem Cells Derived from Umbilical Cord Blood

Umbilical cord blood (UCB) is a current major source of hematopoietic stem cells (HSCs) for cell transplantation therapy. Cell transplantation with HSCs derived from UCB is advantageous over transplantation with HSCs from adult tissues. However, the low number of HSC derived from a single unit of UCB limits its application. Thus, ex vivo expansion is a good option to create more UCB HSCs for clinical application. The strategies for HSC expansion in vitro focus on mimicking the composition and structure of HSC natural niche by enhancing self-renewal and inhibiting lineage differentiation of HSCs. In the past decade, the mechanisms of the interaction between HSC and the natural niche have been deeply investigated. This great progress in basic research has led to advancements in UCB HSC ex vivo expansion. In addition, the biological characteristics of the originally isolated UCB HSCs correlate with outcome of subsequent ex vivo expansion. In this paper, we summarize the late progress achieved in isolation and ex vivo expansion of UCB HSCs. Importantly, we attempt to provide an impact and practicable procedure to expand UCB HSC in vitro from isolation of original HSCs to identification of expanded HSCs.

In vivo anti-tumor activity of murine hematopoietic stem cells expressing a p185HER2-specific chimeric T-cell receptor gene

We have confirmed efficient anti-tumor activities of the peripheral lymphocytes transduced with a p185HEH2-specific chimeric T-cell receptor gene both in murine and in human in our previous studies. To further test the feasibility of chimeric T-cell receptor in a bone marrow transplantation model, we first, made two routine tumor cell lines： MT901 and MCA-205, to express human p185HER2 by retroviral gene transduction. Murine bone marrow cells were retrovirally transduced to express the chimeric T-cell receptor and gene-modified bone marrow cells were transplanted into lethally irradiated mouse. Six months post transplantation, p185HER2-positive tumor ceils： MT-901/HER2 or MCA-205/ HER2 was subcutaneously or intravenously injected to make mouse models simulating primary breast cancer or pulmonary metastasis. The in vivo anti-tumor effects were monitored by the size of the subcutaneous tumor or counting the tumor nodules in the lungs after India ink staining. The size of the subcutaneous tumor was significantly inhibited and the number of pulmonary nodules were significantly decreased in mouse recipients transplanted with chimeric T-cell receptor modified bone marrow cells compared with the control group. Our results suggest the efficient in vivo anti-tumor activities of chimeric T-cell receptor gene modified bone marrow cells.

The related effects of astragalus polysaccharides on the improvement of bone marrow suppression and hematopoietic stem cells during chemotherapy in elderly patients with lung cancer

Objective:To investigate the effects of astragalus polysaccharides(APS)on bone marrow suppression and hematopoietic stem cells during chemotherapy in elderly patients with lung cancer.Methods:120 elderly patients with lung cancer treated in the first hospital of Xingtai city from January 2019 to early December 2019 were divided into the treatment group and the control group by the random number table method,all of whom received pemetrexed+carboplatin chemotherapy,and the treatment group was treated with APS at the same time.The efficacy was evaluated after 2 cycles of chemotherapy,bone marrow suppression was observed,and levels of TCM symptoms score,peripheral blood T lymphocyte subgroup index,L-selectin(CD62L)and macrophage differentiation antigen-1(Mac-1)were measured before and after 2 cycles of chemotherapy.Results:The response rate(RR)was 56.67%in the treatment group and 45.00%in the control group,with no statistically significant difference(P>0.05);The disease control rate(DCR)in the treatment group was 81.67%,which was significantly higher than 65.00%in the control group(P<0.05);The reduction degree of leukopenia in the treatment group was significantly lower than that in the control group(P<0.05);The treatment group had a platelet reduction of grade 1+2 at a rate of 40.00%,and hemoglobin reduction of grade 1+2 at a rate of 28.33%,which were significantly lower than the control group at 65.00%and 58.33%(P<0.05);Compared with those before chemotherapy,the total score of TCM symptoms,serum CD62L and Mac-1 levels in the two groups all decreased significantly after chemotherapy,and they were significantly lower in the treatment group than in the control group(P<0.05);After chemotherapy,CD3+,CD4+and CD4+/CD8+in the treatment group increased significantly and they were all higher in the treatment group than in the control group,while CD8+decreased significantly and was lower in the treatment group than in the control group(P<0.05).There was no statistically significant difference in T lymphocyte subsets before and after chemotherapy in the control group(P>0.05).Conclusion:Astragalus polysaccharide can improve the chemotherapy effect and improve the bone marrow suppression in elderly patients with lung cancer,which may be related to its obvious enhancement of immune function and decrease of CD62L and Mac-1 levels.

Epigenetic regulatory differentiation of hematopoietic stem cells to the red lineage

The differentiation process from hematopoietic stem cells(HSCs)to mature red blood cells(RBCs)is characterized by remarkable precision and is tightly controlled from the initial lineage commitment to eventual terminal differentiation.Erythropoiesis is the dynamic journey of HSCs through various functional and phenotypic stages.The physiological course of erythrogenesis is intricately linked to significant changes in chromatin accessibility,necessitating precise coordination of transcription factors and epigenetic elements.This review presents a comprehensive overview of recent investigations into the molecular-level epigenetic regulatory factors that influence the differentiation of the erythroid lineage.This encompasses the exploration of transcriptional,post-transcriptional,and post-translational regulatory processes.The intricate interplay of epigenetic and transcriptional regulatory networks in erythroid differentiation not only enhances our understanding of this fundamental biological process but also provides valuable insights into the underlying mechanisms contributing to the pathogenesis of disorders associated with abnormal erythroid development.These findings hold significant promise for the development of novel therapeutic strategies to address these diseases and improve patient outcomes.

The DNA damage and regulatory strategy in hematopoietic stem cells after irradiation exposure:Progress and challenges

The hematopoietic system is susceptible to ionizing radiation(IR),which can cause acute hematopoietic failure or long-term myelosuppression.As the most primitive cells of the hematopoietic hierarchy,hematopoietic stem cells(HSCs)maintain lifelong hematopoietic homeostasis and promote hematopoietic regeneration during stress.Numerous studies have shown that nuclear and mitochondrial genomes are the main targets of radiation injury in HSCs.More importantly,the damage of DNA may trigger a series of biological responses that largely determine HSC fate following IR exposure.Although some essential pathways and factors involved in DNA injury and damage in HSCs have been revealed,a comprehensive understanding of the biological effects of radiation on HSCs still needs to be improved.This review focuses on recent insights into the molecular mechanisms underlying DNA damage and repair in HSCs after IR.Then summarize corresponding regulatory measures,which may provide a reference for further research in this field.

Exploring hematopoietic stem cell population in human milk and its benefits for infants:A scoping review

Objective:To comprehensively explore hematopoietic stem cells(HSCs)in human milk,understanding their molecular markers,isolation methods,benefits for infants,and potential medical applications.Methods:We conducted a scoping literature review following the PRISMA-ScR guidelines.This review included studies investigating HSCs in human milk,utilizing molecular markers such as CD34^(+),CD113^(+),and CD117^(+)for characterization.Both in vitro and in vivo studies exploring the morphology,function,and clinical implications of these cells were considered.The diverse range of papers reviewed were indexed in PubMed,Science Direct,Scopus,Sage Journals,and Google Scholar,published between 2010 and 2023.Results:This scoping review explored 577 articles and selected 13 studies based on our inclusion criteria,focusing on HSCs in human milk.Most studies dilute samples prior to HSC isolation,followed by detection using markers such as CD34^(+),CD113^(+),and CD117^(+),with flow cytometry serving as the primary analysis tool,focusing on their isolation and detection methods.While no definitive benefits have been conclusively established,there is a strong belief in the potential of HSCs to positively impact infant immunity,growth,and tissue repair.Conclusions:This review presents significant evidence supporting the presence of HSCs in human milk,identified by markers such as CD34^(+),CD113^(+),and CD117^(+).These cells show considerable potential in enhancing infant health,including immunity,tissue repair,cognitive development,and gastrointestinal health.Despite methodological variations in isolation and detection techniques,the collective findings underscore the potential clinical relevance of HSCs in human milk.Moreover,this review highlights the noninvasive accessibility of human milk as a source of HSCs and emphasizes the need for further research to unlock their therapeutic potential.

Quality-adjusted time without symptoms or toxicity analysis of haploidentical-related donor vs.identical sibling donor hematopoietic stem cell transplantation in acute myeloid leukemia

Objective:We aimed to compare the quality-adjusted time without symptoms or toxicity(Q-TWiST)in acute myeloid leukemia(AML)patients who received haploidentical-related donor(HID)and identical sibling donor(ISD)hematopoietic stem cell transplantation(HSCT).Methods:Five clinical health states were defined:toxicity(TOX),acute graft-versus-host disease(GVHD),chronic GVHD(cGVHD),time without symptoms and toxicity(TWiST)and relapse(REL).The equation used in this study was as follows:Q-TWiST=UTOX×TOX+UTWiST×TWiST+UREL×REL+UaGVHD×aGVHD+UcGVHD×cGVHD.Results:A total of 239 AML patients were enrolled.We established a mathematical model,i.e.,Q-TWiST HID HSCT>Q-TWiST ISD HSCT,to explore the range of utility coefficients satisfying the inequality.Based on the raw data,the utility coefficient is equivalent to the following inequality:10.57067UTOX-46.27733UREL+105.9374+3.388078UaGVHD-210.8198UcGVHD>0.The model showed that when UTOX,UREL,and UaGVHD were within the range of 0-1,as well as when UcGVHD was within the range of 0-0.569,the inequality Q-TWiST HID HSCT>Q-TWiST ISD HSCT was valid.According to the results of the ChiCTR1800016972 study,the median coefficients of TOX,acute GVHD(aGVHD),and cGVHD were 0.56(0.41-0.76),0.56(0.47-0.72),and 0.54(0.37-0.79),respectively.We selected a series of specific examples of the coefficients,i.e.,UTOX=0.5,UREL=0.05,UaGVHD-0.5,and UcGVHD-0.5.The Q-TWiST values of ISD and HID HSCT were 896 and 900 d,respectively(P=0.470).Conclusions:We first observed that Q-TWiST was comparable between AML patients receiving HID HSCT and those receiving ISD HSCT.

COVID-19 impact in Crohn’s disease patients submitted to autologous hematopoietic stem cell transplantation

BACKGROUND Severe acute respiratory syndrome coronavirus 2 is the virus responsible for coronavirus disease 2019(COVID-19),a disease that has been blamed for inducing or exacerbating symptoms in patients with autoimmune diseases.Crohn's disease(CD)is an inflammatory bowel disease that affects genetically susceptible patients who develop an abnormal mucosal immune response to the intestinal microbiota.Patients who underwent hematopoietic stem cell transplantation(HSCT)are considered at risk for COVID-19.AIM To describe for the first time the impact of COVID-19 in CD patients who had undergone autologous,non-myeloablative HSCT.METHODS In this descriptive study a series of 19 patients were diagnosed with positive COVID-19.For two patients there were reports of the occurrence of two infectious episodes.Parameters related to HSCT,such as time elapsed since the procedure,vaccination status,CD status before and after infection,and clinical manifestations resulting from COVID-19,were evaluated.RESULTS Among the patients with COVID-19,three,who underwent Auto HSCT less than six months ago,relapsed and one,in addition to the CD symptoms,started to present thyroid impairment with positive anti-TPO.Only one of the patients required hospitalization for five days to treat COVID-19 and remained in CD clinical remission.Nine patients reported late symptoms that may be related to COVID-19.There were no deaths,and a statistical evaluation of the series of COVID-19 patients compared to those who did not present any infectious episode did not identify significant differences regarding the analyzed parameters.CONCLUSION Despite the change in CD status in three patients and the presence of nine patients with late symptoms,we can conclude that there was no significant adverse impact concerning COVID-19 in the evaluated patients who underwent HSCT to treat CD.

Aged hematopoietic stem cells entrap regulatory T cells to create a prosurvival microenvironment

Although DNA mutation drives stem cell aging,how mutation-accumulated stem cells obtain clonal advantage during aging remains poorly understood.Here,using a mouse model of irradiation-induced premature aging and middle-aged mice,we show that DNA mutation accumulation in hematopoietic stem cells(HSCs)during aging upregulates their surface expression of major histocompatibility complex class II(MHCII).MHCII upregulation increases the chance for recognition by bone marrow(BM)-resident regulatory T cells(Tregs),resulting in their clonal expansion and accumulation in the HSC niche.On the basis of the establishment of connexin 43(Cx43)-mediated gap junctions,BM Tregs transfer cyclic adenosine monophosphate(cAMP)to aged HSCs to diminish apoptotic priming and promote their survival via activation of protein kinase A(PKA)signaling.Importantly,targeting the HSC–Treg interaction or depleting Tregs effectively prevents the premature/physiological aging of HSCs.These findings show that aged HSCs use an active self-protective mechanism by entrapping local Tregs to construct a prosurvival niche and obtain a clonal advantage.

Lymphoid-biased hematopoietic stem cells and myeloid-biased hematopoietic progenitor cells have radioprotection activity

Radioprotection was previously considered as a function of hematopoietic stem cells(HSCs).However,recent studies have reported its activity in hematopoietic progenitor cells(HPCs).To address this issue,we compared the radioprotection activity in 2 subsets of HSCs(nHSC1 and 2 populations)and 4 subsets of HPCs(nHPC1–4 populations)of the mouse bone marrow,in relation to their in vitro and in vivo colony-forming activity.Significant radioprotection activity was detected in the nHSC2 population enriched in lymphoid-biased HSCs.Moderate radioprotection activity was detected in nHPC1 and 2 populations enriched in myeloid-biased HPCs.Low radioprotection activity was detected in the nHSC1 enriched in myeloid-biased HSCs.No radioprotection activity was detected in the nHPC3 and 4 populations that included MPP4(LMPP).Single-cell colony assay combined with flow cytometry analysis showed that the nHSC1,nHSC2,nHPC1,and nHPC2 populations had the neutrophils/macrophages/erythroblasts/megakaryocytes(nmEMk)differentiation potential whereas the nHPC3 and 4 populations had only the nm differentiation potential.Varying day 12 spleen colony-forming units(day 12 CFU-S)were detected in the nHSC1,nHSC2,and nHPC1–3 populations,but very few in the nHPC4 population.These data suggested that nmEMk differentiation potential and day 12 CFU-S activity are partially associated with radioprotection activity.Reconstitution analysis showed that sufficient myeloid reconstitution around 12 to 14 days after transplantation was critical for radioprotection.This study implied that radioprotection is specific to neither HSC nor HPC populations,and that lymphoid-biased HSCs and myeloid-biased HPCs as populations play a major role in radioprotection.

Regulation of hematopoietic stem cells in the niche

Hematopoiesis provides a suitable model for understanding adult stem cells and their niche. Hematopoietic stem cells(HSCs) continuously produce blood cells through orchestrated proliferation, self-renewal, and differentiation in the bone marrow(BM). Within the BM exists a highly organized microenvironment termed "niche" where stem cells reside and are maintained. HSC niche is the first evidence that a microenvironment contributes to protecting stem cell integrity and functionality in mammals. Although multiple models exist, recent progress has principally elucidated the cellular complexity of the HSC niche that maintains and regulates HSCs in BM. Here we introduce the development and summarize the achievements of HSC niche studies.

Optimising gene therapy of hypoparathyroidism with hematopoietic stem cells

Background The treatment of hypoparathyroidism (HPT) is still a difficult clinical problem, which necessitates a new therapy. Gene therapy of HPT has been valuable, but how to improve the gene transfer efficiency and expression stability is a problem. This study was designed to optimize the gene therapy of HPT with hematopoietic stem cells (HSCs) recombined with the parathyroid hormone (PTH) gene. Methods The human PTH gene was amplified by polymerase chain reaction (PCR) from pcDNA3.1-PTH vectors and inserted into murine stem cell virus (MSCV) vectors with double enzyme digestion (EcoRI and XhoI). The recombinant vectors were transfected into PA317 packaging cell lines by the lipofectin method and screened by G418 selective medium. The condensed recombinant retroviruses were extracted and used to infect HSCs, which were injected into mice suffering from HPT. The change of symptoms and serum levels of PTH and calcium in each group of mice were investigated. Results The human PTH gene was inserted into MSCV vectors successfully and the titres were up to 2×107 colony forming unit (CFU)/ml in condensed retroviral solution. The secretion of PTH reached 15 ng·10-6·cell-1 per 48 hours. The wild type viruses were not detected via PCR amplification, so they were safe for use. The mice suffering from HPT recovered quickly and the serum levels of calcium and PTH remained normal for about three months after the HSCs recombined with PTH were injected into them. The therapeutic effect of this method was better than simple recombinant retroviruses injection.Conclusions The recombinant retroviral vectors MSCV-PTH and the high-titre condensed retroviral solution recombined with the PTH gene are obtained. The recombinant retroviral solution could infect HSCs at a high rate of efficiency. The infected HSCs could cure HPT in mice. This method has provided theoretical evidence for the clinical gene therapy of HPT.