Donor Hematopoietic Stem Cells Did No Major Contribution to Hair Follicle Repair Either in Short or in Long Term Allogeneic Hematopoietic Stem Cell Transplants Recipients.

Abstract Several reports suggest that hematopoietic stem cell (HSC) develops unexpected plasticity and can form non-hematopoietic tissue. However the intrinsic plasticity of these cells has been questioned suggesting that such cells might fuse with other cells giving the appearance of differentiation. Most of the controversy over the mechanism arises from the techniques that are used to track and characterize the progenitor cell in different tissues. In the clinical setting there are no prospective quantitative studies in the human being. Objective: we assessed in a prospective study the incidence and extent of donor type chimerism in blood and non-hematopoietic cells tissue in allogeneic HSC transplants irrespective of donor type, stem cell source, conditioning and disease category. We focused on tissues with high need of organ repair: following conditioning and free of blood contamination: hair follicles. In a preliminary report we showed hair chimerism results from 53 long term survivors of allogeneic HSCT. In those recipients donor cells did not contribute to hair follicle repair. We now extend the study by increasing the number of long term patients and including short term survivors after successful engraftment. Methods: all consecutive male and female patients above 18 years old, with a full donor chimerism of hemopoiesis at last control were included. The visit included: anamnesis, clinical examination and chimerism from peripheral blood and hair follicles. Chimerism was analyzed by PCR-based amplification of 9 different short tandem repeat (STR) loci and the amelogenin locus, detecting a minor cell population ≥3%. We minimized the risk of blood contamination by careful hair follicles washing according to the procedure used in forensic medicine. The protocol was approved by the Ethics Committee. Results: between April 2003 and July 2004, 145 patients were invited to participate in this study, 119 patients (82%) accepted, 4 patients were excluded due to insufficient hair DNA; therefore the study included 100 long term (≥ 24 months of follow-up) and 15 short term (1–12 month follow-up) patients. Population demographic characteristics and results Conclusions: we observed a high grade of acceptance for participation in the study. In this population all hair follicles chimerism showed 100% recipient alleles, there was no difference between recipients with short or long term follow-up after HSCT. Hematopoietic stem cells from donor did not make a major contribution to repair hair growth in recipients. Contamination by hematopoietic cells can be excluded in this study due to the fact that we found no donor alleles in the hair analyzed. Follow up after HSCT(months) ≥ 24 1–12 N 100 15 Gender Male/Female 59/41 10/ 5 Median age at HSCT 36 (range 6–63) 40 (range 17–50) Median age at follow up 43 (range 20–66) 40 (range 18–51) Median follow up (months) 96 (range 24–264) 8 (range 2–12) Donor gender Male/Female 58/42 9/6 Diagnosis to transplantation Severe aplastic anemia 6 0 Hematological malignancy 94 15 HLA Type donor identical sibling 85 12 matched related 1 0 mismatched related 3 1 matched unrelated 11 2 Source PB/BM 33/67 15/0 Conditioning High intensity 85 13 Low intensity 15 2 Acute GVHD no/yes 25/75 5/10 Chronic GVHD no/yes 41/59 6/9 Blood chimerism 100% donor alleles 98 15 90–95% donor alleles 2 0 Hair chimerism 100% recipient alleles 100 15

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Short-Term Hematopoietic Stem Cells (ST-HSC) Have Full Long-Term Capacity with Sustained but Reduced Potential Compared with LT-HSC.

Blood ◽

10.1182/blood.v114.22.2550.2550 ◽

2009 ◽

Vol 114 (22) ◽

pp. 2550-2550

Author(s):

Gerald A. Colvin ◽

David Berz ◽

Peter J. Quesenberry ◽

Elaine Papa ◽

Liansheng Liu

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Bone Marrow Cells ◽

Conflicts Of Interest ◽

Cell Number ◽

Large Animal ◽

Short Term ◽

Hematopoietic Stem ◽

One Year

Abstract Abstract 2550 Poster Board II-527 We evaluated the hypothesis that there was a homing defect between long-term (LT) hematopoietic stem cell (HSC) (KLS-Flk2-) and ST-HSC (KLS-Flk2+) that explained differences in engraftment potential and duration. Short-term HSC by definition have limited self-renewal capacity, generally described as giving rise to lymphohematopoiesis for 4–12 weeks before senescence. We performed three large animal engraftment studies into lethally ablated mice (950cGy split dose) looking at engraftment of both ST and LT-HSC cells delivered via intravenous, intraperitoneal and intra-femoral route. Two-hundred or 500 cells derived from B6/SJL mice were administered to each animal along with 300,000 recipient (C57/BLK) whole bone marrow cells for radioprotection following prior published studied [PNAS:98;14541, Stem Cells 24:1087] with optimization of flourochromes for better discrimination with our Cytopeia sorter. The animals were serially transplanted after eight months or one year to secondary recipients. In our hands, the ST-HSC engrafted animals did not lose chimerism over time. Review of the literature revealed that there were not confirmatory studies from those published from the initial one publication describing the ST-HSC. We found the ST-HSC were not short-term and persisted for one year in primary recipients and at least 3 months in secondary recipients. Engraftment kinetics favored LT-HSC over ST-HSC with engraftment examples at one year of 62% compared with 30% respectively when administered intravenously, 10% verses 4% given intra-femoral and 0.5% verse 0.3% given intraperitoneal. Chimerism was on average 50% better for the LT-HSC when compared with the ST-HSC and was irrespective of route proving that the differences seen are not due to homing deficiency but rather intrinsic differences in the two stem cell pools. Prior studies gave a maximum of 100 cells. Cell number was purposely increased for better differentiate of subtle differences in engraftment kinetics for statistical reasons. To avoid contamination of Flk2+ cells in the Flk2- cohort and vise-versa, discrimination of the gates were enhanced from that which was published prior. Double sorting of the cells confirmed that there was no appreciable cross contamination but obviously we cannot totally rule that out as a potentially confounding factor. In conclusion we found that ST-HSC as described have long-term capacity with intrinsic differences in engraftment potential that is not driven by a homing defect. Disclosures: No relevant conflicts of interest to declare.

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Integrin-α3 Is a New Marker of Long-Term Hematopoietic Stem Cells in Ex Vivo Expanded Cells

Blood ◽

10.1182/blood-2018-99-111963 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 1267-1267

Author(s):

Elisa Tomellini ◽

Iman Fares ◽

Bernhard Lehnertz ◽

Jalila Chagraoui ◽

Nadine Mayotte ◽

...

Keyword(s):

Gene Expression ◽

Stem Cells ◽

Stem Cell ◽

Hematopoietic Stem Cells ◽

Ex Vivo ◽

Stem Cell Markers ◽

Short Term ◽

Differentiation Potential ◽

Hematopoietic Stem

Abstract Hematopoietic stem cell (HSC) transplantation constitutes one of the most effective therapeutic strategies to treat numerous hematological diseases. Cord blood (CB) is one of the most attractive donor sources of stem cells for this procedure due to its rapid availability, HLA mismatches tolerance and low associated risk of chronic graft-versus-host disease. However, these advantages are offset by the limited cell dose in CB units, which can contribute to delayed hematopoietic engraftment following transplantation. Mastering ex vivo HSC expansion is therefore of great interest for clinical purposes and for genetic manipulation. HSCs can be functionally defined as either long-term (LT-HSC), providing life-long hematopoiesis and characterized by delayed engraftment pattern, or short-term repopulating stem cells (ST-HSC), providing early and transient hematopoietic recovery. Major hurdles hindering the study of these cell populations is the current inability to evaluate their content in cultured samples and the lack of understanding of the molecular mechanisms regulating stem cell self-renewal ex vivo. Those issues highly benefited from the discovery by our laboratory of the small molecule UM171, which promote HSC expansion ex vivo, as well as from the identification of EPCR as one of the most reliable surface markers for cultured HSCs. We now describe the identification of Integrin-α3 (ITGA3) as a novel marker for cultured HSCs. ITGA3 expression was found to be sufficient to split the primitive EPCR+CD90+CD133+CD34+CD45RA- HSC population in two functionally distinct fractions presenting only short-term (ITGA3-) and both short-term and long-term (ITGA3+) repopulating potential. ITGA3+ cells, as opposed to the ITGA3- fraction, exhibited robust multilineage differentiation potential and serial reconstitution ability in immunocompromised mice. This combination of markers identifies repopulating HSCs in culture by FACS beyond what is currently possible with other approaches, with a frequency of LT-HSC found in the ITGA3+ population estimated at 1:38 in day 7 UM171 expanded CB-cells. Moreover, lentiviral-mediated ITGA3 knockdown was shown to compromise the LT repopulating activity of cultured HSC in vivo. Gene expression profiling revealed striking molecular similarity between ITGA3+ and ITGA3- cells, showing overrepresentation of genes involved in fundamental hematopoietic programs known to govern HSC specification and function in both of these populations. However, ITGA3+ and ITGA3- subsets clearly clustered separately by principle component analysis, indicating broad differences in gene expression. Concordantly with their primitive phenotype, stem cell markers and cell quiescence are gene sets enriched in ITGA3+ cells, while progenitor markers, DNA replication, M/G1 and G2/M checkpoints, mRNA processing, reduction of hypoxia and Myc targets were significantly downregulated in these cells. Altogether, our results indicate that ITGA3 is a reliable marker for cultured HSCs, improving the accuracy of prospective HSC identification in culture. Deciphering the function of genes upregulated in primitive ITGA3+ HSCs will represent an invaluable resource for dissecting the genetic programs that govern hematopoietic stem cells biology. Disclosures Sauvageau: ExCellThera: Employment, Equity Ownership.

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A Monocentric Clinical Observation of Haploidientical Transplantation in 27 Patients with Acute Megakaryocytic Leukemia

Blood ◽

10.1182/blood-2020-137374 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 15-16

Author(s):

Zhijie Wei ◽

Fei Pan ◽

Rong Yang ◽

Shuquan Ji ◽

Yue Guanlan ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Down Syndrome ◽

Stem Cell ◽

Hematopoietic Stem Cell Transplantation ◽

Clinical Observation ◽

Hematopoietic Stem ◽

Acute Megakaryocytic Leukemia

Background Acute Megakaryocytic Leukemia (AMKL) accounts for approximately 10% of childhood AML and 1% of adult AML cases. Although AMKL with Down syndrome has a good prognosis, the prognosis for non-DS-AMKL is quite poor with a 3-years survival rate of less than 40%. At present, only allogeneic HSCT is curative. In our study, we followed 27 patients with AMKL who received a modified Bu/Cy/Mel protocol and underwent hematopoietic stem cell transplantation. The patients were then followed up with monocentric clinical observation. Methods From August 2015 to July 2020, 27 AMKL patients (14 males, 13 females, all non-Down-AMKL) with a median age of 2 years (range: 1-9 years) were continuously treated in our hospital (Hebei Yanda Lu Daopei Hospital) including 18 cases of chromosome abnormality including 3 cases of CBFA2T3/GLIS2 gene fusion (11.1%). Gene mutation included WT1(8), EVI1(5), JAK2(5): 18.51%, TET2(4), ASXL1(4), PTPN11(4): 14.81%, GATA1(2), GATA2(2): 7.4%. Bone marrow status before transplantation: 19 complete remission (CR) cases, 3 partial response (PR) cases, and 5 no response (NR) cases. There were 24 haploidentical transplants (including one patient going through 3 transplants), one transplant from a HLA-identical sibling donor and two from matched unrelated donors. Source of donor stem cells: parents in 23 cases, brothers in 2 cases, non-blood relationship in 2 cases, and none from offspring. HLA matching between the donor and recipient: 21 cases with HLA 5/10, 6 cases with ≥HLA 6/10. Haplo stem cells all came from BM+PBSC, with a median MNC input of 20.32x108/kg (10.1-26.7), CD34+ 11.68106/kg (4.05-22.44), and CD3+ 4.66x108/kg (2.11-11.29). Pre-treatment protocol: 27 patients received a modified Bu/Cy/Mel and were treated with graft-versus-host disease (GVHD) to prevent CsA+MMF+sMTX. Results During a median follow-up period of 10 months (range: 2-48 months), the 27 patients remained alive, with a median of +13 days (range: 9-21 days) to leukocyte transplantation and a median of +9 days (range: 4-38 days) to platelet transplantation. One month following transplantation, the bone marrow of all patients was 100% donor type. The overall survival (OS) rate was 63.0%, event-free survival (EFS) was 59.3%. OS was 84.2%, 33.3%, and 0% in the CR, PR, and NR groups, respectively (P<0.001). There were 7 cases of relapse and 10 deaths, among which 4 were caused by GVHD and 5 due to relapse. Incidence of acute GVHD (aGVHD) was 59.25% Grade I-IV and 18.51% Grade III-IV. Incidence of chronic GVHD (cGVHD) was 56%, with cystitis accounting for 14.81% of cases, 29.62% cytomegalovirus (CMV), 3.7% EBV, 0% thrombotic microangiopathy (TMA) and 18.51% infection. Conclusion For high-risk AMKL patients with poor long-term prognosis, the application of a modified Bu/Cy/Mel pretreatment significantly improves the efficacy of haploid transplantation without increasing pretreat-related death. For non-Down syndrome AMKL, we conclude that it is feasible to perform hematopoietic stem cell transplantation in CR status patients. Additional studies and multicenter and large-scale clinical studies with long-term follow-up are still needed to confirm these results. Disclosures No relevant conflicts of interest to declare.

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ETO2 Controls Hematopoietic Stem Cell Expansion.

Blood ◽

10.1182/blood.v114.22.396.396 ◽

2009 ◽

Vol 114 (22) ◽

pp. 396-396

Author(s):

Stephane Barakat ◽

Julie Lambert ◽

Guy Sauvageau ◽

Trang Hoang

Keyword(s):

Stem Cells ◽

Transcription Factor ◽

Stem Cell ◽

Hematopoietic Stem Cells ◽

Short Term ◽

Self Renewal ◽

Hematopoietic Stem

Abstract Abstract 396 Hematopoietic stem cells that provide short term reconstitution (ST-HSCs) as well as hematopoietic progenitors expand from a small population of long term hematopoietic stem cells (LT-HSCs) that are mostly dormant cells. The mechanisms underlying this expansion remain to be clarified. SCL (stem cell leukemia), is a bHLH transcription factor that controls HSC quiescence and long term competence. Using a proteomics approach to identify components of the SCL complex in erythroid cells, we and others recently showed that the ETO2 co-repressor limits the activity of the SCL complex via direct interaction with the E2A transcription factor. ETO2/CBF2T3 is highly homologous to ETO/CBFA2T1 and both are translocation partners for AML1. We took several approaches to identify ETO2 function in HSCs. We initially found by Q-PCR that ETO2 is highly expressed in populations of cells enriched in short-term HSC (CD34+Flt3-Kit+Sca+Lin-) and lympho-myeloid progenitors (CD34+Flt3+Kit+Sca+Lin-) and at lower levels in LT-HSCs (CD34-Kit+Sca+Lin- or CD150+CD48-Kit+Sca+Lin-). Next, the role of ETO2 was studied by overexpression or downregulation combined with transplantation in mice. Ectopic ETO2 expression induces a 100 fold expansion of LT-HSCs in vivo in transplanted mice associated with differentiation blockade in all lineages, suggesting that ETO2 overexpression overcomes the mechanisms that limit HSC expansion in vivo. We are currently testing the role of the NHR1 domain of ETO2 in this expansion. Conversely, shRNAs directed against ETO2 knock down ET02 levels in Kit+Sca+Lin- cells, causing a ten-fold decrease in this population after transplantation, associated with reduced short-term reconstitution in mice. Finally, proliferation assays using Hoechst and CFSE indicate that ETO2 downregulation affects cell division (CFSE) and leads to an accumulation of Kit+Sca+Lin-cells in G0/G1 state (Hoescht). In conclusion, we show that ETO2 is highly expressed in ST-HSCs and lymphoid progenitors, and controls their expansion by regulating cell cycle entry at the G1-S checkpoint. In addition, ETO2 overexpression converts the self-renewal of maintenance into self-renewal of expansion in LT-HSCs. Disclosures: No relevant conflicts of interest to declare.

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Safety of Peripheral Hematopoietic Stem Cell Mobilization with Lenograstim in Allogeneic Healthy Donors ≥ 50 Years Old: A Single-Centre Experience

Blood ◽

10.1182/blood.v124.21.3844.3844 ◽

2014 ◽

Vol 124 (21) ◽

pp. 3844-3844

Author(s):

Massimo Martino ◽

Antonella Dattola ◽

Roberta Fedele ◽

Antonella Pontari ◽

Tiziana Moscato ◽

...

Keyword(s):

Stem Cell ◽

Hematopoietic Stem Cell ◽

Age Groups ◽

Stem Cell Mobilization ◽

Short Term ◽

Hematopoietic Stem ◽

Healthy Donors ◽

Cell Mobilization

Abstract Background and Objectives The use of allogenic hematopoietic stem cell transplantation (HSCT) is increasing in older patients because of reduced ablative regimens and improved supportive care. An old patient usually has a old sibling healthy donors (HDs). The safety of G-CSF for mobilization in elderly HDs has not been provided. In our institution a long-term active follow-up study of G-CSF-mobilized healthy volunteer donors has been implemented. Patients and Methods After a median follow up of 94 months (7.8 years) we reviewed and analyzed safety data of our HDs database according to HDs age: HDs-1 (162), patients younger than 50 years old, HDs-2 (62), patients 50-59 years old and HDs-3 (23), patients 60 or more years old. Long-term follow-up included monitoring of neoplastic, cardiac or autoimmune diseases. Results Two hundred and forty-seven successive donors were evaluated and their characteristics are well balanced among age-groups and no statistical differences have been detected: most of them were male (55.9% ), sibling (97.2%) and HLA matching (93.1%). Mobilization failure rate has been 4.3% (7/162), 1.6% (1/62) and 13% (3/23) in HDs-1, HDs-2 and HDs-3, respectively (p=0.075). Short- and long-term safety was not different among age-groups. Bone pain was reported as the most frequent short-term adverse event (76.5%). Other commonly observed short-term symptoms included headache (31.6%), fatigue (28.7%), insomnia (21.5%), nausea (13.0%) and fever (6.1%). For long-term safety surveillance no haematological malignancies were observed. The observed rate of solid tumors, cardiovascular and autoimmune events, was the expected incidence for these diseases in the western countries. Conclusion In our study, mobilization with lenograstim in elderly HDs seems to be as safe as for young HDs safe. This data contribute to the growing body of evidence of the long-term safety of G-CSF for allogenic donor stem cell mobilization also for elderly HDs. Disclosures No relevant conflicts of interest to declare.

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The hematopoietic stem compartment consists of a limited number of discrete stem cell subsets

Blood ◽

10.1182/blood-2005-07-2970 ◽

2006 ◽

Vol 107 (6) ◽

pp. 2311-2316 ◽

Cited By ~ 151

Author(s):

Hans B. Sieburg ◽

Rebecca H. Cho ◽

Brad Dykstra ◽

Naoyuki Uchida ◽

Connie J. Eaves ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Stem Cell ◽

Steady State ◽

Hematopoietic Stem ◽

Homogeneous Population ◽

Donor Type ◽

External Stimuli ◽

Limiting Dilution

AbstractHematopoietic stem cells (HSCs) display extensive heterogeneity in their behavior even when isolated as phenotypically homogeneous populations. It is not clear whether this heterogeneity reflects inherently diverse subsets of HSCs or a homogeneous population of HSCs diversified by their response to different external stimuli. To address this, we analyzed 97 individual HSCs in long-term transplantation assays. HSC clones were obtained from unseparated bone marrow (BM) through limiting dilution approaches. Following transplantation into individual hosts, donor-type cells in blood were measured bimonthly and the resulting repopulation kinetics were grouped according to overall shape. Only 16 types of repopulation kinetics were found among the HSC clones even though combinatorially 54 groups were possible. All HSC clones, regardless of their origin, could be assigned to this subset of groups, and the probability of finding new patterns is negligible. Thus, the full repertoire of repopulating HSCs was covered. These data indicate that the HSC compartment consists of a limited number of distinct HSC subsets, each with predictable behavior. Enrichment of HSCs (Lin–Rho–SP) changes the representation of HSC types by selecting for distinct subsets of HSCs. These data from the steady-state HSC repertoire could provide a basis for the diagnosis of perturbed patterns of HSCs potentially caused by disease or aging.

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EPCR/PAR1 Signaling Navigates Long-Term Repopulating Hematopoietic Stem Cell Bone Marrow Homing to Thrombomodulin-Enriched Blood Vessels

Blood ◽

10.1182/blood.v126.23.33.33 ◽

2015 ◽

Vol 126 (23) ◽

pp. 33-33 ◽

Cited By ~ 2

Author(s):

Shiri Gur Cohen ◽

Tomer Itkin ◽

Sagarika Chakrabarty ◽

Claudine Graf ◽

Orit Kollet ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Stem Cell ◽

Stem Cell Transplantation ◽

Protein C ◽

No Production ◽

Short Term ◽

Hematopoietic Stem ◽

Epcr Shedding

Abstract Bone marrow (BM) homing and lodgment of long-term repopulating hematopoietic stem cells (LT-HSCs) is an active and essential first step in clinical stem cell transplantation. EPCR is expressed by murine BM LT-HSCs endowed with the highest repopulation potential and its ligand, activated protein C (aPC), has anticoagulant and anti-sepsis effects in EPCR+/PAR1+ endothelial cells. We recently found that signaling cascades, traditionally viewed as coagulation and inflammation related, also independently control EPCR+ LT-HSC BM retention and recruitment to the blood via distinct PAR1 mediated pathways. EPCR/PAR1 signaling retains LT-HSCs in the BM by restricting nitric oxide (NO) production and Cdc42 activity, promoting VLA4 affinity and adhesion. Conversely, thrombin/PAR1 signaling overcome EPCR+ LT-HSC BM retention by initiating NO production, leading to TACE-‎mediated EPCR shedding, CXCR4 and PAR1 upregulation and parallel CXCL12 secretion by PAR1+ BM stromal cells, enhancing stem cell migration and mobilization. Since EPCR shedding is essential for BM LT-HSC recruitment, we tested EPCR role in LT-HSC BM homing. EPCR+ LT-HSC exhibited reduced in vitro migration towards CXCL12 and enhanced CXCL12-dependent adhesion to fibronectin. Unexpectedly, transplanted EPCR+ LT-HSCs preferentially homed ‎to the host BM, while immature progenitors were equally distributed between the BM and spleen. Specificity of BM homing was further confirmed by EPCR neutralizing antibody treatment, which blocks binding to aPC, leading to attenuated EPCR+ LT-HSC homing to the BM but not to the spleen. Importantly, short term aPC pretreatment inhibited NO production and dramatically increased EPCR+ LT-HSC BM homing. Since EPCR navigates LT-HSC to the BM, we studied the role of EPCR signaling in LT-HSC BM repopulation. Mimicking EPCR signaling by in vivo NO inhibition induced preferential expansion of blood and bone-forming stem cells and gave rise to higher donor type EPCR+ LT-HSCs in competitive repopulation assays. Similarly, repeated treatment with aPC expanded BM EPCR+ stem cells and increased competitive LT-repopulation. Importantly, loss of EPCR function reduced HSC long-term repopulation ability while maintaining their short-term repopulation activity. BM HSCs obtained from Procrlow mice, expressing markedly reduced surface EPCR, failed to compete with normal stem cells in competitive long-term repopulation assays. Consistent with inferior HSC BM repopulation, Procrlow mice exhibited reduced numbers of BM LT-HSC with reduced adhesion capacity. Additionally, these mice displayed increased HSC frequencies in the blood circulation and the spleen, which were pharmacologically corrected by inhibiting NO generation with L-NAME treatment. BM retention is essential for quiescent HSC protection from chemotherapy. Mice treated with NO donor SNAP, or with blocking EPCR antibody as well as Fr2-/-mice lacking PAR1 expression, were more susceptible to hematological failure and mortality induced by 5-FU treatment compared to control mice. Together, these results indicate a functional aPC/EPCR/PAR1 signaling pathway, regulating EPCR+ LT-HSC BM homing, adhesion and long-term repopulation potential. The thrombin-thrombomodulin (TM) complex converts protein C to its activated form aPC, facilitating high affinity binding to its receptor EPCR. To further address the preferential homing of EPCR+ LT-HSCs to the BM, we found that TM is exclusively expressed by a unique BM endothelial cell (BMEC) subpopulation, but not in the spleen. Moreover, EPCR+ LT-HSCs were found adjacent to TM+/aPC+ BMECs, imposing their adhesion and retention. Interestingly, similar to BMECs, BM EPCR+ LT-HSC also express surface TM, implying the possibility of autocrine aPC generation. Herein we define EPCR as a guidance molecule, navigating slow migrating LT-HSC in the blood flow specifically to TM+ BMEC supporting niches, maintaining NOlow stem cell retention, long-term blood production and protection from myelotoxic insult. Conversely, thrombin/PAR1 signaling oppositely increase NO generation and EPCR shedding allowing increased CXCR4-dependent LT-HSC migration and mobilization. Harnessing EPCR signaling may improve clinical stem cell transplantation, increasing LT-HSC specific BM homing and repopulation by aPC pretreatment, as well as potentially to overcome malignant stem cell chemotherapy resistance. Disclosures No relevant conflicts of interest to declare.

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A Mouse Model for Studying Stem Cell Effects on Regeneration of Hair Follicle Outer Root Sheaths

Open Life Sciences ◽

10.1515/biol-2020-0005 ◽

2020 ◽

Vol 15 (1) ◽

pp. 41-50

Author(s):

Jingxu Guo ◽

Shuwei Li ◽

Hongyang Wang ◽

Tinghui Wu ◽

Zhenhui Wu ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Mouse Model ◽

Hair Follicle ◽

Smooth Muscle Actin ◽

Hair Follicles ◽

Alpha Smooth Muscle Actin ◽

Papillary Structure ◽

Glass Membrane

AbstractObjectiveStem cells hold promise for treating hair loss. Here an in vitro mouse model was developed using outer root sheaths (ORSs) isolated from hair follicles for studying stem cell-mediated dermal papillary regeneration.MethodsUnder sterile conditions, structurally intact ORSs were isolated from hair follicles of 3-day-old Kunming mice and incubated in growth medium. Samples were collected daily for 5 days. Stem cell distribution, proliferation, differentiation, and migration were monitored during regeneration.ResultsCell proliferation began at the glass membrane periphery then spread gradually toward the membrane center, with the presence of CD34 and CD200 positive stem cells involved in repair initiation. Next, CD34 positive stem cells migrated down the glass membrane, where some participated in ORS formation, while other CD34 cells and CD200 positive cells migrated to hair follicle centers. Within the hair follicle matrix, stem cells divided, grew, differentiated and caused outward expansion of the glass membrane to form a dermal papillary structure containing alpha-smooth muscle actin. Neutrophils attracted to the wound site phagocytosed bacterial and cell debris to protect regenerating tissue from infection.ConclusionIsolated hair follicle ORSs can regenerate new dermal papillary structures in vitro. Stem cells and neutrophils play important roles in the regeneration process.

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Therapeutic Potential of Stem Cells in Follicle Regeneration

Stem Cells International ◽

10.1155/2018/1049641 ◽

2018 ◽

Vol 2018 ◽

pp. 1-16 ◽

Cited By ~ 14

Author(s):

Agnieszka Owczarczyk-Saczonek ◽

Magdalena Krajewska-Włodarczyk ◽

Anna Kruszewska ◽

Łukasz Banasiak ◽

Waldemar Placek ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Hair Follicle ◽

Therapeutic Potential ◽

Cell Activity ◽

Hair Follicles ◽

Treatment Technique ◽

Androgenic Alopecia ◽

The Metabolic Syndrome ◽

Increased Risk

Alopecia is caused by a variety of factors which affect the hair cycle and decrease stem cell activity and hair follicle regeneration capability. This process causes lower self-acceptance, which may result in depression and anxiety. However, an early onset of androgenic alopecia is associated with an increased incidence of the metabolic syndrome and an increased risk of the cardiac ischaemic disease. The ubiquity of alopecia provides an encouragement to seek new, more effective therapies aimed at hair follicle regeneration and neoregeneration. We know that stem cells can be used to regenerate hair in several therapeutic strategies: reversing the pathological mechanisms which contribute to hair loss, regeneration of complete hair follicles from their parts, and neogenesis of hair follicles from a stem cell culture with isolated cells or tissue engineering. Hair transplant has become a conventional treatment technique in androgenic alopecia (micrografts). Although an autologous transplant is regarded as the gold standard, its usability is limited, because of both a limited amount of material and a reduced viability of cells obtained in this way. The new therapeutic options are adipose-derived stem cells and stem cells from Wharton’s jelly. They seem an ideal cell population for use in regenerative medicine because of the absence of immunogenic properties and their ease of obtainment, multipotential character, ease of differentiating into various cell lines, and considerable potential for angiogenesis. In this article, we presented advantages and limitations of using these types of cells in alopecia treatment.

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