Ex Vivo Expansion of Human Mobilized Peripheral Blood Stem Cells Using Epigenetic Modifiers

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1920-1920
Author(s):  
Santosh Saraf ◽  
Hiroto Araki ◽  
Benjamin Petro ◽  
Kazumi G Yoshinaga ◽  
Simona Taioli ◽  
...  
Keyword(s):  
Peripheral Blood ◽  
Ex Vivo ◽  
Ex Vivo Expansion ◽  
Self Renewal ◽  
Transcript Levels ◽  
Epigenetic Modifiers ◽  
Cd34 Cells ◽  
Mobilized Peripheral Blood

Abstract Abstract 1920 Currently, a significant percentage of hematopoietic stem cell (HSC) transplantations are being performed using growth factor mobilized peripheral blood (MPB) grafts. Unfortunately, about 5 to 40% of patients are unable to benefit from HSC transplantation due to failure to mobilize and harvest an adequate graft (> 2 × 106 CD34+ cells/kg). Epigenetic modifications are thought to be important in determining the fate of HSC including self renewal and differentiation. We have previously demonstrated that sequential addition of chromatin modifying agents (CMA), 5-aza-2'-deoxyctidine (5azaD) and trichostatin A (TSA), is capable of expanding transplantable HSC 7-fold from human cord blood (CB), likely by preventing the silencing of genes which promote HSC self renewal divisions (Araki et al. Blood 2007). Using the same protocol we have also previously shown that 5azaD/TSA can expand CD34+CD90+ cells containing in vivo repopulating capacity from human bone marrow (BM) 2.5-fold (Milhem et al. Blood 2004). The objectives of our current studies were to assess whether CMA can also expand HSCs present in MPB. In order to test this hypothesis, CD34+ cells were isolated from MPB products from three healthy donors and were expanded ex vivo using 5azaD/TSA for 9 days as described previously (Araki et al. Blood 2007). Following culture, expansion of primitive CD34+CD90+ cells, colony forming unit mixed lineages (CFU-mix), and long term (5 weeks) cobblestone area forming cells (CAFC) were assessed. A 3.74 ± 0.77 fold expansion of CD34+CD90+ cells was observed in 5azaD/TSA expanded MPB cells while only a 0.93 ± 0.23 fold expansion was observed in control cultures (p = 0.025). The 5azaD/TSA expanded MPB cells had a 10.1-fold increase in the number of CFU-mix in comparison to no expansion in the control cultures (p = 0.0055). A 2.26-fold expansion of CAFC numbers was observed in 5azaD/TSA expanded MPB cells in comparison to 0.19-fold expansion in control cultures. Taken together, our data indicate that 5azaD/TSA can expand MPB CD34+CD90+ cells 3.74-fold which also possess the functional capacity to generate primitive CFU-mix and long term CAFCs. This expansion of primitive MPB CD34+CD90+ cells appears to be at an intermediate level (3.74 fold) in comparison to BM and CB which had 2.5-fold and 10.5-fold expansion, respectively. We have previously demonstrated that CD34+CD90+ expanded CB cells are exclusively responsible for reconstituting blood cells following transplantation (Araki et al. Exp Hematol 2006). Currently, the frequency of in vivo repopulating units for CMA expanded MPB is being determined in contrast to expanded BM and CB cells. However, it remains to be investigated what determines the limit for ex vivo expansion of HSC by epigenetic modifiers based on their ontogeny. Towards this goal we analyzed transcription levels of several genes implicated for HSC self renewal/expansion including HoxB4, GATA 2, and Ezh2, which were compared between MPB cells prior to and following expansion in 5azaD/TSA or control cultures. Significantly higher transcript levels were detected for HoxB4 (p = 0.003), GATA 2 (p = 0.0002), and Ezh2 (p = 0.0001) by real time quantitative RT PCR in the 5azaD/TSA expanded MPB graft in comparison to control cultures. Interestingly the transcript levels of HoxB4 and GATA 2 but not Ezh2 were significantly lower in expanded cells in contrast to unmanipulated primary MPB cells. This is in sharp contrast to our earlier results from CB in which 5azaD/TSA expanded cells displayed much higher transcript levels of HoxB4 and GATA 2 compared to primary unmanipulated CB cells. Previously we have demonstrated that environmental conditions can influence the degree of expansion of transplantable HSC from CB (Araki et al. Exp Hematol 2009). Using the same protocol we expanded MPB cells in the presence or absence of CMA using either optimal (SCF, TPO, FLT3L) or suboptimal cytokine cocktails (SCF, TPO, FLT3L with IL-3 and IL-6). Interestingly, unlike CB cells no significant difference in expansion between the two cytokine groups with or without CMA was observed (4.5 versus 4.3-fold expansion of CD34+CD90+ cells, respectively). Corresponding to this, transcript levels of HoxB4 and Ezh2 did not vary between MPB cells expanded with 5azaD/TSA in the two different cytokine environments. Our studies have the potential to be used to expand HSC from poor mobilizers in order to optimize MPB grafts for transplantation. Disclosures: No relevant conflicts of interest to declare.

scholarly journals SALL4 Is a Key Factor in HDAC Inhibitor Mediated Ex Vivo Expansion of Human Peripheral Blood Mobilized Stem/Progenitor CD34+CD90+ Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1566-1566 ◽  
Author(s):  
Hiro Tatetsu ◽  
Fei Wang ◽  
Chong Gao ◽  
Shikiko Ueno ◽  
Xi Tian ◽  
...  
Keyword(s):  
Cord Blood ◽  
Peripheral Blood ◽  
Cell Expansion ◽  
Ex Vivo ◽  
Ex Vivo Expansion ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Cell Numbers ◽  
Cd34 Cells

Abstract Hematopoietic stem cells (HSCs) possess the unique capacity to self-renew and give rise to all types of mature cells within the blood and immune systems. Despite our progress in understanding the molecular factors that support the self-renewal and differentiation of the hematopoietic system in vivo, less is known on how to modulate the factors that govern the self-renewal of hematopoietic stem/progenitor cells (HSPCs) ex vivo. Unlike in the case of embryonic stem (ES) cells, expansion of CD34+ HSPC in culture in general is at the expense of loss of “stemness”. HSPCs can be collected from cord blood (CB), mobilized peripheral blood (PBSC), and rarely bone marrow (BM) at the present practice. Due to the limited CD34+ cell number in one single cord blood unit, much of the current efforts on developing technology of ex vivo expansion of HSPC uses cord blood as a source and is clinically applied to cord blood HSPC transplants. However, there are growing needs for expanding PBSCs for transplant-related practices such as HSPC expansion from poor autologous mobilizations, gene therapy or genome-editing via TALENs or CRISPR/Cas9. Developing a technology that would allow HSPC ex vivo expansion from both CB and PBSC sources is a key step towards this goal. Several groups have reported that ex vivo culture of CB CD34+ cells with HDAC inhibitors (HDACi) can lead to expansion of a CD34+CD90+ population, which is responsible for enhanced marrow-repopulating potential. In this study, we ask whether HDACi can have a similar effect on PBSC CD34+ cells. Furthermore, we have explored the mechanism(s) mediated by HDACi in CD34+CD90+ cell expansion. First we assessed a panel of HDACi to identify the most potent molecule for CD34+CD90+ cell expansion and selected trichostatin A (TSA) for future study. Next, TSA was added to the cytokines (SCF, Flt3 ligand, IL-3 and IL-6) to further characterize its potential in PBSC CD34+CD90+ cell expansion. We observed TSA treated CD34+ cultures with cytokines yielded 4.8 times greater numbers of CD34+CD90+ cells as compared to the cultures containing cytokines with DMSO solvent control. We next examined SCID repopulating ability (SRA) to evaluate the cultured CD34+CD90+ cells in vivo. We observed that mice transplanted with 3 million CD34+ cells treated with TSA had higher degree of human cell chimerism than those treated with DMSO at 8 weeks bone marrow and peripheral blood (32% vs 18%; p < 0.05), which was further confirmed by secondary transplantation. Furthermore, these cells were capable of differentiating into cells belonging to multiple hematopoietic lineages. To investigate the molecular mechanisms responsible for the expansion of functional HSCs and progenitors that were observed following TSA treatment, we analyzed the expression levels of several HSPC related genes, which were compared between CD34+ cells treated with TSA and DMSO. Significantly higher transcript levels were detected for GATA 2 (p < 0.05), HOXB4 (p < 0.05), HOXA9 (p < 0.05), and SALL4 (p < 0.05) by real time quantitative RT-PCR in TSA expanded cells as compared with controls. To evaluate whether these transcription factors can contribute to the expansion of CD34+CD90+ cells, GATA2, HOXB4 or SALL4 shRNAs were transfected into PBSC CD34+ cells, followed by culture with TSA. Among these transcription factors, knocking down SALL4 expression led to the most significant reduction of CD34+CD90+ cell numbers (33% of reduction). In addition, overexpression of SALL4 in PBSC CD34+ cells led to an increase of CD34+CD90+ cell numbers when compared to controls (p < 0.05). Overall, our study demonstrated a novel HDACi mediated ex vivo PBSC culture technology that leads to the expansion of CD34+CD90+ cells and an increase of the marrow repopulating potential of these cells. Both gain-of-function and loss-of-function studies support that SALL4 is a key transcription factor responsible for the process. Future study on the use of HDACi or other methods to increase SALL4 expression/function will be highly beneficial to ex vivo HSPC (CB and PBSC) expansion technology. Disclosures No relevant conflicts of interest to declare.

Ex Vivo Expansion of Genetically Marked Rhesus Peripheral Blood Progenitor Cells Results in Diminished Long-Term Repopulating Ability

Blood ◽  
1998 ◽  
Vol 92 (4) ◽  
pp. 1131-1141 ◽  
Author(s):  
J.F. Tisdale ◽  
Y. Hanazono ◽  
S.E. Sellers ◽  
B.A. Agricola ◽  
M.E. Metzger ◽  
...  
Keyword(s):  
Peripheral Blood ◽  
Ex Vivo ◽  
Retroviral Vectors ◽  
Ex Vivo Expansion ◽  
Us Government ◽  
Government Work ◽  
Stromal Support ◽  
Short And Long Term

Abstract The possibility of primitive hematopoietic cell ex vivo expansion is of interest for both gene therapy and transplantation applications. The engraftment of autologous rhesus peripheral blood (PB) progenitors expanded 10 to 14 days were tracked in vivo using genetic marking. Stem cell factor (SCF)/granulocyte colony-stimulating factor (G-CSF)–mobilized and CD34-enriched PB cells were divided into two equal aliquots and transduced with one of two retroviral vectors carrying the neomycin-resistance gene (neo) for 4 days in the presence of interleukin-3 (IL-3), IL-6, and SCF in the first 5 animals, IL-3/IL-6/SCF/Flt-3 ligand (FLT) in 2 subsequent animals, or IL-3/IL-6/SCF/FLT plus an autologous stromal monolayer (STR) in the final 2. At the end of transduction period, one aliquot (nonexpanded) from each animal was frozen, whereas the other was expanded under the same conditions but without vector for a total of 14 days before freezing. After total body irradiation, both the nonexpanded and expanded transduced cells were reinfused. Despite 5- to 13-fold higher cell and colony-forming unit (CFU) doses from the expanded fraction of marked cells, there was greater short- and long-term marking from the nonexpanded cells in all animals. In animals receiving cells transduced and expanded in the presence of IL-3/IL-6/SCF/FLT, engraftment by the marked expanded cells was further diminished. This discrepancy was even more pronounced in the animals who received cells transduced and expanded in the presence of FLT and autologous stroma, with no marking detectable from the expanded cells. Despite lack of evidence for expansion of engrafting cells, we found that the addition of FLT and especially STR during the initial brief transduction period increased engraftment with marked cells into a clinically relevant range. Levels of marked progeny cells originating from the nonexpanded aliqouts were significantly higher than that seen in previous 4 animals receiving cells transduced in the presence of IL-3/IL-6/SCF, with levels of 10% to 20% confirmed by Southern blotting from the nonexpanded IL-3/IL-6/SCF/FLT/STR graft compared with 0.01% in the original IL-3/IL-6/SCF cohort. These results suggest that, although expansion of PB progenitors is feasible ex vivo, their contribution towards both short- and long-term engraftment is markedly impaired. However, a brief transduction in the presence of specific cytokines and stromal support allows engraftment with an encouraging number of retrovirally modified cells. This is a US government work. There are no restrictions on its use.

scholarly journals Ex vivo expansion of human mobilized peripheral blood stem cells using epigenetic modifiers

Transfusion ◽  
2014 ◽  
Vol 55 (4) ◽  
pp. 864-874 ◽  
Author(s):  
Santosh Saraf ◽  
Hiroto Araki ◽  
Benjamin Petro ◽  
Youngmin Park ◽  
Simona Taioli ◽  
...  
Keyword(s):  
Stem Cells ◽  
Peripheral Blood ◽  
Ex Vivo ◽  
Ex Vivo Expansion ◽  
Peripheral Blood Stem Cells ◽  
Epigenetic Modifiers ◽  
Blood Stem Cells ◽  
Mobilized Peripheral Blood

Ex Vivo Expansion of Genetically Marked Rhesus Peripheral Blood Progenitor Cells Results in Diminished Long-Term Repopulating Ability

Blood ◽  
1998 ◽  
Vol 92 (4) ◽  
pp. 1131-1141 ◽  
Author(s):  
J.F. Tisdale ◽  
Y. Hanazono ◽  
S.E. Sellers ◽  
B.A. Agricola ◽  
M.E. Metzger ◽  
...  
Keyword(s):  
Peripheral Blood ◽  
Ex Vivo ◽  
Retroviral Vectors ◽  
Ex Vivo Expansion ◽  
Us Government ◽  
Government Work ◽  
Stromal Support ◽  
Short And Long Term

The possibility of primitive hematopoietic cell ex vivo expansion is of interest for both gene therapy and transplantation applications. The engraftment of autologous rhesus peripheral blood (PB) progenitors expanded 10 to 14 days were tracked in vivo using genetic marking. Stem cell factor (SCF)/granulocyte colony-stimulating factor (G-CSF)–mobilized and CD34-enriched PB cells were divided into two equal aliquots and transduced with one of two retroviral vectors carrying the neomycin-resistance gene (neo) for 4 days in the presence of interleukin-3 (IL-3), IL-6, and SCF in the first 5 animals, IL-3/IL-6/SCF/Flt-3 ligand (FLT) in 2 subsequent animals, or IL-3/IL-6/SCF/FLT plus an autologous stromal monolayer (STR) in the final 2. At the end of transduction period, one aliquot (nonexpanded) from each animal was frozen, whereas the other was expanded under the same conditions but without vector for a total of 14 days before freezing. After total body irradiation, both the nonexpanded and expanded transduced cells were reinfused. Despite 5- to 13-fold higher cell and colony-forming unit (CFU) doses from the expanded fraction of marked cells, there was greater short- and long-term marking from the nonexpanded cells in all animals. In animals receiving cells transduced and expanded in the presence of IL-3/IL-6/SCF/FLT, engraftment by the marked expanded cells was further diminished. This discrepancy was even more pronounced in the animals who received cells transduced and expanded in the presence of FLT and autologous stroma, with no marking detectable from the expanded cells. Despite lack of evidence for expansion of engrafting cells, we found that the addition of FLT and especially STR during the initial brief transduction period increased engraftment with marked cells into a clinically relevant range. Levels of marked progeny cells originating from the nonexpanded aliqouts were significantly higher than that seen in previous 4 animals receiving cells transduced in the presence of IL-3/IL-6/SCF, with levels of 10% to 20% confirmed by Southern blotting from the nonexpanded IL-3/IL-6/SCF/FLT/STR graft compared with 0.01% in the original IL-3/IL-6/SCF cohort. These results suggest that, although expansion of PB progenitors is feasible ex vivo, their contribution towards both short- and long-term engraftment is markedly impaired. However, a brief transduction in the presence of specific cytokines and stromal support allows engraftment with an encouraging number of retrovirally modified cells. This is a US government work. There are no restrictions on its use.

Ex Vivo Expansion of CD34+ Cells From Cord Blood, Bone Marrow, and Mobilized Peripheral Blood Using NANEX Nanofiber Scaffold

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4816-4816
Author(s):  
Stephen L Fischer ◽  
Jacqueline M Fonseca ◽  
Yukang Zhao ◽  
Linda L. Kelley ◽  
Ramasamy Sakthivel
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Peripheral Blood ◽  
Ex Vivo ◽  
Ex Vivo Expansion ◽  
Cell Phenotype ◽  
Cd34 Cells ◽  
Ex Vivo Culture ◽  
Mobilized Peripheral Blood ◽  
Stem Cell Phenotype

Abstract Abstract 4816 Hematopoietic stem cell (HSC) transplantation has become the standard of care for patients with hematologic cancers, anemia, and a variety of other malignant and non-malignant disorders, with greater than 50,000 such procedures being performed globally each year, according to the Worldwide Network for Blood and Marrow Transplantation. Although mobilized peripheral blood (MPB) has become a preferred source of HSCs for transplants, bone marrow (BM) and umbilical cord blood (UCB) are also frequently utilized. Regardless of source, several groups have reported that grafts containing lower total nucleated cell (TNC) and CD34+ cell doses contribute to delayed engraftment and higher graft failure rate. Therefore, methods to increase the total cell number while maintaining the progenitor phenotype, especially the CD34+ progenitor cells, from individual grafts would have a significant clinical impact. Ex vivo expansion of HSCs prior to transplantation is one approach that offers tremendous promise for increasing cell doses and improving clinical outcomes. In many ex vivo culture systems, HSCs are cultured as a suspension cells and cultured in the presence of various media additives that act to enhance cell proliferation while reducing differentiation. An often-overlooked factor influencing fate decisions is the interaction of HSCs with a substrate. In the natural bone marrow microenvironment, HSCs maintain close contact with a complex network of stromal cells and extracellular matrix, likely indicating that cell-cell and cell-matrix interactions play an important role in maintaining their stem cell phenotype. With the goal of mimicking the bone marrow stem cell niche, Arteriocyte, Inc. has developed a 3-D NANEX nanofiber based cell culture substrate. The functionalized NANEX substrate is designed to provide topographical and substrate-immobilized biochemical cues that act in synergy with media additives to enhance HSC proliferation while maintain the progenitors stem cell phenotype. Here, we present our recent work with the NANEX platform towards comparing and achieving a high yield ex vivo expansion of CD34+ cells from MPB, BM, and UCB. Additionally, through the use of flow cytometry and CFU assays, we quantify and characterize NANEX-expanded cells from each source. Furthermore, we compared NANEX to a variety of commercially available products and demonstrate that NANEX significantly improves expansion and reduces phenotype loss during ex vivo culture. Our data indicates that NANEX technology provides a robust ex vivo expansion of HSCs and, with further GMP and clinical development, offers great potential for clinical applications. Disclosures: No relevant conflicts of interest to declare.

Cell Cycle-Related Changes in Repopulating Capacity of Human Mobilized Peripheral Blood CD34+ Cells in Non-Obese Diabetic/Severe Combined Immune-Deficient Mice

Blood ◽  
1998 ◽  
Vol 92 (8) ◽  
pp. 2641-2649 ◽  
Author(s):  
André Gothot ◽  
Johannes C.M. van der Loo ◽  
D. Wade Clapp ◽  
Edward F. Srour
Keyword(s):  
Cell Cycle ◽  
Incubation Period ◽  
Peripheral Blood ◽  
Cell Cycle Progression ◽  
Ex Vivo ◽  
Scid Mice ◽  
Cd34 Cells ◽  
Mobilized Peripheral Blood

Abstract Most primitive hematopoietic progenitor cells reside in vivo within the G0/G1 phase of the cell cycle. By simultaneous DNA/RNA staining it is possible to distinguish G0 and G1 states and to isolate cells in defined phases of the cell cycle. We report here the use of cell cycle fractionation to separate human mobilized peripheral blood (MPB) CD34+ cells capable of repopulating the bone marrow (BM) of non-obese diabetic/severe combined immune-deficient (NOD/SCID) mice. In freshly isolated MPB, repopulating cells were predominant within the G0 phase, because transplantation of CD34+cells residing in G0 (G0CD34+) resulted on average in a 16.6- ± 3.2-fold higher BM chimerism than infusion of equal numbers of CD34+ cells isolated in G1. We then investigated the effect of ex vivo cell cycle progression, in the absence of cell division, on engraftment capacity. Freshly isolated G0CD34+ cells were activated by interleukin-3 (IL-3), stem cell factor (SCF), and flt3-ligand (FL) for a 36-hour incubation period during which a fraction of cells progressed from G0 into G1 but did not complete a cell cycle. The repopulating capacity of stimulated cells was markedly diminished compared with that of unmanipulated G0CD34+ cells. Cells that remained in G0 during the 36-hour incubation period and those that traversed into G1 were sorted and assayed separately in NOD/SCID recipients. The repopulating ability of cells remaining in G0 was insignificantly reduced compared with that of unstimulated G0CD34+ cells. On the contrary, CD34+ cells traversing from G0 into G1 were largely depleted of repopulating capacity. Similar results were obtained when G0CD34+ cells were activated by the combination of thrombopoietin-SCF-FL. These studies provide direct evidence of the quiescent nature of cells capable of repopulating the BM of NOD/SCID mice. Furthermore, these data also demonstrate that G0-G1 progression in vitro is associated with a decrease in engraftment capacity. © 1998 by The American Society of Hematology.

Self-Renewal of Hematopoietic Stem Cells by a Small Molecule

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 210-210
Author(s):  
Anthony E Boitano ◽  
Peter G Schultz ◽  
Michael Cooke
Keyword(s):  
Cord Blood ◽  
Small Molecule ◽  
High Throughput ◽  
Peripheral Blood ◽  
Ex Vivo ◽  
Fold Increase ◽  
Ex Vivo Expansion ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Cd34 Cells

Abstract Hematopoietic stem cell (HSC) transplantation has been effectively used to manage hematopoietic malignancies and immunodeficiency. Despite the successful use several challenges remain. For autologous transplants, HSCs are routinely isolated from the peripheral blood following mobilization with G-CSF, however many patients that have been treated with chemotherapy are refractory to mobilization. In the allogeneic transplant setting, treatment related toxicity including graft vs. host disease, delayed or failed engraftment, and lack of suitable HLA-matched donors represent major challenges. Umbilical cord blood (CB) cells have great potential as an alternative source of HSCs for individuals who lack a HLA-matched donor, but at present have limited utility because of low HSC numbers per graft leading to delayed recovery. Ex-vivo expansion of HSCs is an attractive strategy to optimize autologous and allogeneic transplantation as engraftment speed (absolute neutrophil count &gt;500/μl) and success correlates positively with HSC dose. For this reason ex-vivo HSC expansion has been a subject of intense research for the past 20 years; however, identification of culture conditions that allow HSC expansion and long-term hematopoietic reconstitution have remained elusive. Recently, several groups have reported that signals other than hematopoietic growth factors, including ligands for G protein-coupled receptors and signaling molecules sensing neighboring cells such as notch may be required for optimal HSC expansion. Manipulation of signaling pathways using low molecular weight (LMW) compounds represents an alternative approach that can be exploited to regulate ex-vivo HSC expansion. To identify such compounds, we developed and performed an unbiased high-throughput screen for small molecules that regulate HSC self-renewal. The assay took advantage of advances in screening technology developed at GNF that permit low volume (10uL) screens to be conducted in massively parallel fashion using advanced automation and imaging technologies. These advances allow screens to be conducted on purified human CD34+ HSCs isolated from normal donors and circumvent a major limitation of the field- a lack of a suitable cell line model for human HSCs. From this screen we identified a small molecule (SR1) that regulates HSC self-renewal. Mobilized peripheral blood (mPB) CD34+ HSCs cultured with SR1 for 14 days had a ten-fold increase in the number of CD34+ cells compared to cultures without compound. The expansion of mPB CD34+ cells with SR1 for 1 week was associated with increased numbers of mixed (GM and GEMM) colony forming cells (CFC) and a 9-fold increase in the number of 4 week cobblestone area forming cells (CAFC). In the NOD-SCID repopulation assay, mPB CD34+ cells expanded with SR1 for 4 days displayed &gt;2-fold higher levels of engraftment compared to control cultures and uncultured cells. These data suggest that SR1 promotes the net expansion of NOD-SCID repopulating cells. To explore the utility of SR1 for expansion of CB HSC, CD34+ cells were isolated from CB and cultured in the presence or absence of SR1 for up to five weeks. Remarkably, SR1 supported the sustained growth of CB HSCs with &gt;100-fold increased numbers of CD34+ cells and CD34+CD133+CD38− cells compared to control cultures (Figure 1). In vitro assays of cord blood CD34+ cells expanded for 5 weeks with SR1 showed a 65-fold increase in total CFC and &gt;1000-fold increase in the number of GEMM CFC compared to control cultures. NOD-SCID repopulating experiments of expanded cord blood HSC are in progress. These results demonstrate that high throughput screening of LMW compound libraries is a viable approach to find novel regulators of HSC self-renewal and identify a compound class that greatly facilitates ex-vivo expansion of HSCs. Fig. 1 SR promotes sustained expansion of CB CD34 133+ CD38− cells Fig. 1. SR promotes sustained expansion of CB CD34 133+ CD38− cells

Cell Cycle-Related Changes in Repopulating Capacity of Human Mobilized Peripheral Blood CD34+ Cells in Non-Obese Diabetic/Severe Combined Immune-Deficient Mice

Blood ◽  
1998 ◽  
Vol 92 (8) ◽  
pp. 2641-2649 ◽  
Author(s):  
André Gothot ◽  
Johannes C.M. van der Loo ◽  
D. Wade Clapp ◽  
Edward F. Srour
Keyword(s):  
Cell Cycle ◽  
Incubation Period ◽  
Peripheral Blood ◽  
Cell Cycle Progression ◽  
Ex Vivo ◽  
Scid Mice ◽  
Cd34 Cells ◽  
Mobilized Peripheral Blood

Most primitive hematopoietic progenitor cells reside in vivo within the G0/G1 phase of the cell cycle. By simultaneous DNA/RNA staining it is possible to distinguish G0 and G1 states and to isolate cells in defined phases of the cell cycle. We report here the use of cell cycle fractionation to separate human mobilized peripheral blood (MPB) CD34+ cells capable of repopulating the bone marrow (BM) of non-obese diabetic/severe combined immune-deficient (NOD/SCID) mice. In freshly isolated MPB, repopulating cells were predominant within the G0 phase, because transplantation of CD34+cells residing in G0 (G0CD34+) resulted on average in a 16.6- ± 3.2-fold higher BM chimerism than infusion of equal numbers of CD34+ cells isolated in G1. We then investigated the effect of ex vivo cell cycle progression, in the absence of cell division, on engraftment capacity. Freshly isolated G0CD34+ cells were activated by interleukin-3 (IL-3), stem cell factor (SCF), and flt3-ligand (FL) for a 36-hour incubation period during which a fraction of cells progressed from G0 into G1 but did not complete a cell cycle. The repopulating capacity of stimulated cells was markedly diminished compared with that of unmanipulated G0CD34+ cells. Cells that remained in G0 during the 36-hour incubation period and those that traversed into G1 were sorted and assayed separately in NOD/SCID recipients. The repopulating ability of cells remaining in G0 was insignificantly reduced compared with that of unstimulated G0CD34+ cells. On the contrary, CD34+ cells traversing from G0 into G1 were largely depleted of repopulating capacity. Similar results were obtained when G0CD34+ cells were activated by the combination of thrombopoietin-SCF-FL. These studies provide direct evidence of the quiescent nature of cells capable of repopulating the BM of NOD/SCID mice. Furthermore, these data also demonstrate that G0-G1 progression in vitro is associated with a decrease in engraftment capacity. © 1998 by The American Society of Hematology.

Sign in / Sign up

Export Citation Format

Share Document