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

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Self-Renewal of Hematopoietic Stem Cells by a Small Molecule

Blood ◽

10.1182/blood.v112.11.210.210 ◽

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 >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 >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 >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 >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

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Ex-Vivo Expansion of Human Cord Blood CD34+ Cells by Overexpression of Bmi-1.

Blood ◽

10.1182/blood.v108.11.1329.1329 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1329-1329

Author(s):

Aleksandra Rizo ◽

Edo Vellenga ◽

Gerald de Haan ◽

Jan Jacob Schuringa

Keyword(s):

Cord Blood ◽

Cell Expansion ◽

Cultured Cells ◽

Ex Vivo ◽

Human Cord Blood ◽

Self Renewal ◽

Hematopoietic Stem ◽

Cd34 Cells ◽

Cord Blood Cd34

Abstract Hematopoietic stem cells (HSCs) are able to self-renew and differentiate into cells of all hematopoietic lineages. Because of this unique property, they are used for HSC transplantations and could serve as a potential source of cells for future gene therapy. However, the difficulty to expand or even maintain HSCs ex vivo has been a major limitation for their clinical applications. Here, we report that overexpression of the Polycomb group gene Bmi-1 in human cord blood-derived HSCs can potentially overcome this limitation as stem/progenitor cells could be maintained in liquid culture conditions for over 16 weeks. In mouse studies, it has been reported that increased expression of Bmi-1 promotes HSC self-renewal, while loss-of-function analysis revealed that Bmi-1 is implicated in maintenance of the hematopoietic stem cells (HSC). In a clinically more relevant model, using human cord blood CD34+ cells, we have established a long-term ex-vivo expansion method by stable overexpression of the Bmi-1 gene. Bmi-1-transduced cells proliferated in liquid cultures supplemented with 20% serum, SCF, TPO, Flt3 ligand, IL3 and IL6 for more than 4 months, with a cumulative cell expansion of more then 2×105-fold. The cells remained cytokine-dependent, while about 4% continued to express CD34 for over 20 weeks of culture. The cultured cells retained their progenitor activity throughout the long-term expansion protocol. The colony-forming units (CFUs) were present at a frequency of ~ 30 colonies per 10 000 cells 16 weeks after culture and consisted of CFU-GM, BFU-E and high numbers of CFU-GEMM type progenitors. After plating the transduced cells in co-cultures with the stromal cell line MS5, Bmi-1 cells showed a proliferative advantage as compared to control cells, with a cumulative cell expansion of 44,9 fold. The non-adherent cells from the co-cultures gave rise to higher numbers of colonies of all types (~70 colonies/10.000 cells) after 4 weeks of co-culture. The LTC-IC frequencies were 5-fold higher in the Bmi-1-transduced cells compared to control cells (1/361 v.s. 1/2077, respectively). Further studies will be focused on in-vivo transplantation of the long-term cultured cells in NOD/SCID mice to test their repopulating capacity. In conclusion, our data implicate Bmi-1 as an important modulator of human HSC self-renewal and suggest that it can be a potential target for therapeutic manipulation of human HSCs.

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

Blood ◽

10.1182/blood.v118.21.1920.1920 ◽

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.

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Small Molecule Screens for Stem Cell Expansion

Blood ◽

10.1182/blood.v118.21.sci-42.sci-42 ◽

2011 ◽

Vol 118 (21) ◽

pp. SCI-42-SCI-42

Author(s):

Michael P. Cooke ◽

Anthony E. Boitano

Keyword(s):

Cord Blood ◽

Cell Expansion ◽

Ex Vivo ◽

Fold Increase ◽

Hematopoietic Stem ◽

Cell Numbers ◽

Human Cd34 ◽

Cd34 Cells ◽

Ex Vivo Culture ◽

Cd34 Expression

Abstract SCI-42 The identification of safe and effective methods to expand human hematopoietic stem cells (HSC) would have a major impact on the use of HSC in clinical medicine. Several features of human HSC, including the lack of a suitable cell line model and cumbersome methods for quantification, have made the identification of conditions for human HSC expansion challenging. Current culture methods using cytokine cocktails in serum-free media support the robust proliferation of CD34 positive (CD34+) cells but this is accompanied by rapid differentiation such that after 1 week of culture fewer than 20% of cells continue to express CD34. To overcome these limitations we developed a high throughput screen that uses primary human CD34+ cells and multiparameter flow cytometry to identify compounds capable of expanding human CD34 positive cells. By screening >100,000 LMW compounds we identified a molecule (SR1) that enhanced CD34 expression during ex vivo culture. Culture of CD34+ cells with cytokines and SR1 for 3 weeks leads to a >600-fold increase in the number of CD34+ cells, and a >2000-fold increase in the number of CFU compared to starting cell numbers. Importantly, cells expanded in the presence of SR1contain a 17-fold increase in the number of NOD-SCID repopulating cells compared to starting cell numbers. Mechanistic studies reveal that SR1 binds to and antagonizes the aryl hydrocarbon receptor (AHR). Knockdown of the AHR in CD34+ cells using lentiviral transduction also maintains CD34 expression. These findings suggest that AHR normally promotes HSC differentiation during ex vivo culture and that AHR antagonists can be used to promote CD34 cell expansion. To determine the clinical utility of these findings, we have begun to explore the use of SR1 to expand CD34+ cells isolated from umbilical cord blood for clinical transplantation. To this end, we have developed a GMP compatible process to manufacture CD34 positive cells expanded with SR1 for use in cord blood transplantation. In addition, we have also explored the use of SR1 to prevent HSC differentiation during HSC transduction and enable manufacturing of differentiated blood cells. These data reveal AHR antagonism and SR1 treatment as a promising method to promote HSC expansion for clinical use. Disclosures: Cooke: Novartis: Employment. Boitano:Novartis: Employment.

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Study of the Mechanisms by Which Angptl5 and IGFBP2 Support Ex Vivo Expansion of Human Cord Blood Hematopoietic Stem Cells.

Blood ◽

10.1182/blood.v112.11.2308.2308 ◽

2008 ◽

Vol 112 (11) ◽

pp. 2308-2308

Author(s):

Junke Zheng ◽

Chengcheng Zhang

Keyword(s):

Stem Cells ◽

Transcription Factors ◽

Cord Blood ◽

Ex Vivo ◽

Ex Vivo Expansion ◽

Human Cord Blood ◽

Self Renewal ◽

Hematopoietic Stem ◽

Cd34 Cells ◽

Cord Blood Cd34

Abstract We previously showed that angiopoietin-like protein 5 (Angptl5) and IGF Binding Protein 2 (IGFBP2) support dramatic ex vivo expansion of human hematopoietic stem cells (HSCs). To understand the mechanisms of their action, here we studied the effects of Angptl5 and IGFBP2 on the surface phenotype, signaling activation, self-renewal, apoptosis, differentiation, and homing of human cord blood CD34+ cells. Using immunofluorescence staining, we showed that Angptl5 and IGFBP2 activate certain signaling pathways such as MAPK and Stat5 in human cord blood CD34+ cells. IGFBP2 and Angptl5 increased the expression of transcription factors HoxB4, Bmi-1, EZH2, and survivin, measured by intracellular staining flow cytometry analysis and real-time RT-PCR. IGFBP2 and Angptl5 also inhibit expression of certain transcription factors important for differentiation of myeloid, erythroid, and lymphoid lineages. To test whether IGFBP2 and Angptl5 affect the homing of HSCs, we cultured human cord blood CD34+ cells in serum-free medium supplemented with SCF, TPO, Flt3-L, IGFBP2 or Angptl5, and transplanted them into sublethally irradiated NOD/SCID mice intraveneously or intrafemorally. Both IGFBP2 and Angptl5 support ex vivo expansion of SRCs in intrafemorally injected mice, suggesting the expansion-stimulating effects elicited by both factors are not caused by modulation of HSC homing. Interestingly, when we used intrafemoral injection, we found that Angptl5 treated HSCs have enhanced engraftment in non-injected bone marrow. This suggests Angptl5 treated HSCs further facilitate the mobilization of HSCs in vivo. We conclude that IGFBP2 and Angptl5 support self-renewal and inhibit differentiation of human cord blood HSCs. Our data also suggest that a combination of expression of transcription factors important for self-renewal, survival, and differentiation of HSCs can be used as a “stemness index” that predicts the activity of cultured human HSCs.

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Pyrimido-Indole Derivatives Are Novel Agonists of Human Cord Blood Hematopoietic Stem Cell Self-Renewal

Blood ◽

10.1182/blood.v124.21.650.650 ◽

2014 ◽

Vol 124 (21) ◽

pp. 650-650

Author(s):

Iman Fares ◽

Jalila Chagaroui ◽

Yves Gareau ◽

Stéphane Gingras ◽

Nadine Mayotte ◽

...

Keyword(s):

Stem Cells ◽

Cord Blood ◽

Conflicts Of Interest ◽

Ex Vivo ◽

Ex Vivo Expansion ◽

Fed Batch ◽

Self Renewal ◽

Hematopoietic Stem

Abstract The widespread use of cord blood (CB) unit in transplantation is limited with low number of long-term hematopoietic stem cells (LT-HSCs) and progenitors. Several approaches have been developed to expand HSC ex vivo such as automated and continuous medium delivery (fed-batch), notch delta ligand and SR1 (antagonist of aryl hydrocarbon receptor (AhR)). Concurrent with these studies, we hypothesized that small molecule with potent LT-HSC stimulating activity might be identified and potentiated in fed-batch culture system. Accordingly, we tested a library of more than 5000 small molecules for their in vitro expansion of CD34+CD45RA- cells. Most of the identified hits, except one (UM729) synthesized in our institute, suppress AhR pathway. Structure activity relationship was performed on UM729 to generate a more potent analog named UM171. This optimized molecule was 10-20 times more potent with an effective concentration of 15-20 nM when tested for its ability to expand CD34+CD45RA- cells. When compared to SR1, UM171 delivered in a fed-batch system for 12 and 16 days showed a better expansion of HSC phenotypes and lower apoptotic cell number compared to SR1 or DMSO controls. Also, UM171-expaned cultures showed higher number in multipotent progenitors (CFU-GEMM) and long term initiating cells (LTC-IC) compared to DMSO controls. Further studies showed the UM171 did not affect division rate, and its effect in expanding HSC phenotype was reversible. When combined with SR1, UM171 showed a better suppression of differentiation and led to a higher CFU-GEMM expansion compared to the single treatment of the compounds or DMOS controls. These observations suggest that UM171+SR1 cooperate to enhance ex vivo expansion of progenitor cells and suppress differentiation. To determine the in vivo activity of the expanded CD34+ CB cells, we transplanted fresh (un-manipulated) and 12-day cultured cells in NSG mice and monitored the human hematopoietic reconstitution after 20 and 30 weeks post-transplantation. Frequencies of day0 equivalent LT-HSCs were 13-fold higher in UM171 expanded cultures compared to fresh or fed-batch cultures supplemented with DMSO or SR1. Secondary experiments indicated that UM171 ex vivo treatment did not appear to affect the capability of LT-HSC to expand in primary recipients and hence similarly reconstituted secondary animals for at least 18 more weeks. This suggests that UM171 expands LT-HSC ex vivo without losing their engraftment potential. To further investigate UM171 mechanism of action, RNA- Seq expression profiling was performed. Unlike SR1 or DMSO controls, UM171 treatment was accompanied by a marked suppression of transcripts associated with erythroid and megakaryocytic differentiation and up-regulation of membrane protein transcripts such as EPCR and TEMEM 183a. In summery, UM171 is the first molecule identified so far that enables a robust ex vivo expansion of human CD34+ CB cells that sustain their in vivo activity independent of AhR suppression. Conversely, AhR suppression was limited to expand cells with less durable self-renewal potential. This study could enhance the use of small yet well HLA-matched CB units to become a prioritized source for stem cells transplantation. Disclosures No relevant conflicts of interest to declare.

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Directed Differentiation of Mobilized Hematopoietic Stem and Progenitor Cells into Functional NK Cells with Enhanced Antitumor Activity

Cells ◽

10.3390/cells9040811 ◽

2020 ◽

Vol 9 (4) ◽

pp. 811

Author(s):

Pranav Oberoi ◽

Kathrina Kamenjarin ◽

Jose Francisco Villena Ossa ◽

Barbara Uherek ◽

Halvard Bönig ◽

...

Keyword(s):

Nk Cells ◽

Progenitor Cells ◽

Peripheral Blood ◽

Cell Expansion ◽

Nk Cell ◽

Ex Vivo ◽

Feeder Cells ◽

Hematopoietic Stem ◽

Cd34 Cells ◽

Stem And Progenitor Cells

Obtaining sufficient numbers of functional natural killer (NK) cells is crucial for the success of NK-cell-based adoptive immunotherapies. While expansion from peripheral blood (PB) is the current method of choice, ex vivo generation of NK cells from hematopoietic stem and progenitor cells (HSCs) may constitute an attractive alternative. Thereby, HSCs mobilized into peripheral blood (PB-CD34+) represent a valuable starting material, but the rather poor and donor-dependent differentiation of isolated PB-CD34+ cells into NK cells observed in earlier studies still represents a major hurdle. Here, we report a refined approach based on ex vivo culture of PB-CD34+ cells with optimized cytokine cocktails that reliably generates functionally mature NK cells, as assessed by analyzing NK-cell-associated surface markers and cytotoxicity. To further enhance NK cell expansion, we generated K562 feeder cells co-expressing 4-1BB ligand and membrane-anchored IL-15 and IL-21. Co-culture of PB-derived NK cells and NK cells that were ex-vivo-differentiated from HSCs with these feeder cells dramatically improved NK cell expansion, and fully compensated for donor-to-donor variability observed during only cytokine-based propagation. Our findings suggest mobilized PB-CD34+ cells expanded and differentiated according to this two-step protocol as a promising source for the generation of allogeneic NK cells for adoptive cancer immunotherapy.

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Ex Vivo Expansion of Frozen Cord Blood Products without Selection.

Blood ◽

10.1182/blood.v104.11.2844.2844 ◽

2004 ◽

Vol 104 (11) ◽

pp. 2844-2844

Author(s):

Ian K. McNiece ◽

Jenny Harrington ◽

Joshua Kellner ◽

Jennifer Turney ◽

Elizabeth J. Shpall

Keyword(s):

Cord Blood ◽

Mononuclear Cells ◽

Ex Vivo ◽

Ex Vivo Expansion ◽

In Vivo Studies ◽

Adherent Cells ◽

Blood Products ◽

Cd34 Cells ◽

Duke University

Abstract Ex vivo expansion of cord blood products (CB) has been proposed as an approach to increase the number of cells available from a single CB unit. We and others have reported the requirement of CD34 selection for optimal expansion of CB products, however, the selection of frozen CB products results in significant losses of CD34+ cells with a median recovery of 43% (range 6 to 203%, N=40) and low purities resulting in decreased expansion. Therefore we explored approaches to expand CB without prior selection and have described the use of co-culture of CB mononuclear cells (MNC) on mesenchymal stem cells (MSC). In the present study we have evaluated the expansion of clinical CB products (provided by Duke University CB Bank CB). MNC were obtained after ficol separation of RBCs and 10% of the CB product was cultured on preformed layers of MSC in T150 flasks containing 50ml of defined media (Sigma Aldrich) plus 100 ng/ml each of rhSCF, rhG-CSF and rhTpo. After 6 days of culture, the non adherent cells were transferred to a Teflon bag and a further 50 ml of media and GFs added to the flask. Again at day 10, non adherent cells were transferred to the Teflon bag and media and growth factors replaced. At day 12 to 13 of incubation the cells were harvested, washed and total nucleated cell (TNC) counts and progenitor assays performed. In three separate experiments we have achieved greater than 20 fold expansion of TNC with a median of 22, and a median expansion of GM-CFC of 37 fold. Morphologic analysis demonstrated the expanded cells contained high levels of mature neutrophils and neutrophil precursors. In vivo studies in NOD/SCID mice also demonstrated that the expanded cells maintained in vivo engraftment potential. Clinical studies are being designed to evaluate the in vivo potential of CB MNC products expanded on MSC.

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Use of Chromatin Modifying Agents for Ex Vivo Expansion of Human Umbilical Cord Blood Stem Cells.

Blood ◽

10.1182/blood.v106.11.4208.4208 ◽

2005 ◽

Vol 106 (11) ◽

pp. 4208-4208

Author(s):

Hiroto Araki ◽

Nadim Mahmud ◽

Mohammed Milhem ◽

Mingjiang Xu ◽

Ronald Hoffman

Keyword(s):

Stem Cells ◽

Cord Blood ◽

Functional Properties ◽

Ex Vivo ◽

Fold Increase ◽

Scid Mice ◽

Human Umbilical Cord ◽

Self Renewal ◽

Hematopoietic Stem ◽

Cd34 Cells

Abstract The fixed number of hematopoietic stem cells (HSCs) within a single cord blood (CB) unit has limited the use of CB grafts for allogeneic transplantation in adults. Efforts to promote self-renewal and expansion of HSCs have been met with limited success. Using presently available ex-vivo culture techniques HSCs lose their functional properties in proportion to the number of cellular divisions they have undergone. We hypothesized that chromatin modifying agents, 5-aza-2′-deoxycytidine (5azaD) and histone deacetylase inhibitor, trichostatin A (TSA) could reactivate pivotal genes required for retaining the functional properties of dividing HSC. We have demonstrated previously that the fate of human bone marrow CD34+ cells could be altered by the addition of 5azaD/TSA (Milhem et al. Blood.2004;103:4102). In our current studies we hypothesized that in vitro exposure of CB CD34+ cells to chromatin modifying agents might lead to optimal HSC expansion to permit transplantation of adults. A 12.5-fold expansion was observed in the 5azaD/TSA treated CD34+CD90+ cell cultures containing SCF, thrombopoietin and FLT3 ligand (cytokines) in comparison to the input cell number. Despite 9 days of culture, 35.4% ± 5.8% (n = 10) of the total cells in the cultures exposed to chromatin modifying agents were CD34+CD90+ as compared to 1.40 % ± 0.32% in the culture containing cytokines alone. The 12.5-fold expansion of CD34+CD90+ cells was associated with a 9.8-fold increase in the numbers of CFU-mix and 11.5-fold expansion of cobblestone area-forming cells (CAFC). The frequency of SCID repopulating cells (SRC) was 1 in 26,537 in primary CB CD34+CD90+ cells but was increased to 1 in 2,745 CD34+CD90+ cells following 9 days of culture in the presence of 5azaD/TSA resulting in a 9.6-fold expansion of the absolute number of SRC. In contrast, the cultures lacking 5azaD/TSA had a net loss of both CFC/CAFC as well as SRC. The expansion of cells maintaining CD34+CD90+ phenotype was not due to the retention of a quiescent population of cells since all of the CD34+CD90+ cells in the culture had undergone cellular division as demonstrated by labeling with a cytoplasmic dye. CD34+CD90+ cells that had undergone 5–10 cellular divisions in the presence of 5azaD/TSA but not in the absence still retained the ability to repopulate NOD/SCID mice. 5azaD/TSA treated CD34+CD90+ cells, but not CD34+CD90- cells were responsible for in vivo hematopoietic repopulation of NOD/SCID assay, suggesting a strong association between CD34+CD90+ phenotype and their ability to repopulate NOD/SCID mice. We next assessed the effect of 5azaD/TSA treatment on the expression of HOXB4, a transcription factor which has been implicated in HSC self-renewal. A significantly higher level of HOXB4 protein was detected by western blot analysis after 9 days of culture in the cells treated with 5azaD/TSA as compared to cells exposed to cytokines alone. The almost 10-fold increase in SRC achieved using the chromatin modifying agents should be sufficient to increase the numbers of engraftable HSC within a single human CB unit so as to permit these expanded grafts to be routinely used for transplanting adult recipients.

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Kinetics of Engraftment and Graft Versus Host Disease After Cotransplantation of Ex Vivo Expanded and Unexpanded Cord Blood Units In Immunodeficient Mice.

Blood ◽

10.1182/blood.v116.21.3722.3722 ◽

2010 ◽

Vol 116 (21) ◽

pp. 3722-3722

Author(s):

Li Ming Ong ◽

Xiubo Fan ◽

Pak Yan Chu ◽

Florence Gay ◽

Justina Ang ◽

...

Keyword(s):

Cord Blood ◽

Conflicts Of Interest ◽

Ex Vivo ◽

Ex Vivo Expansion ◽

Hematopoietic Stem ◽

Immunodeficient Mice ◽

Insulin Growth Factor ◽

Nsg Mice ◽

Nonobese Diabetic ◽

Cd34 Cells

Abstract Abstract 3722 Ex vivo expansion of cord blood (CB) hematopoietic stem cells (HSCs) and cotransplantation of two CB units can enhance applicability of CB transplants to adult patients. This is the first study on cotransplantation of ex vivo expanded and unexpanded human CB units in immunodeficient mice, simulating conditions for ex vivo CB expansion clinical trials. CB units were cultured in serum-free medium supplemented with Stem Cell Factor, Flt-3 ligand, Thrombopoietin and Insulin Growth Factor Binding Protein-2 with mesenchymal stromal co-culture. Cotransplantation of unexpanded and expanded CB cells was achieved by tail vein injection into forty-five sublethally irradiated nonobese diabetic SCID-IL2γ−/− (NSG) mice. Submandibular bleeding was performed monthly and mice were sacrificed 4 months following transplantation to analyze for human hematopoietic engraftment. CB expansion yielded 40-fold expansion of CD34+ cells and 18-fold expansion of HSCs based on limiting dilution analysis of NSG engraftment. Mice receiving expanded grafts had 4.30% human cell repopulation, compared to 0.92% in mice receiving only unexpanded grafts at equivalent starting cell doses (p = 0.07). Ex vivo expanded grafts with lower initiating cell doses also had equivalent engraftment to unexpanded grafts with higher cell dose (8.0% vs 7.9%, p= 0.93). However, the unexpanded graft, richer in T-cells, predominated in final donor chimerism. Ex vivo expansion resulted in enhanced CB engraftment at equivalent starting cell doses, even though the unexpanded graft predominated in long-term hematopoiesis. The expanded graft with increased stem/progenitor cells enhanced initial engraftment despite eventual rejection by the unexpanded graft. Disclosures: No relevant conflicts of interest to declare.

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