Russell, Athena

Mesenchymal stem cells (MSCs) are becoming an increasingly popular therapeutic option among patients with a broad range of ailments to modulate immunity and induce regeneration. The majority of patients receiving these MSC therapies are on concurrent medication or have ongoing infection. In the present study, we examined the effect of immunosuppressive drugs and lipopolysaccharides (LPS)/endotoxins on the secretory profile, migration towards site of injury, and suppression of lymphocyte proliferation of bone marrow-derived MSCs (BMSCs). Generally, LPS coculture augmented the secretory capacity of BMSCs while exposure to immunosuppressive drugs resulted primarily in no change or attenuated secretion, with some cases of increased secretion, dependent on the cytokine assayed. Among the immunosuppressants evaluated, Hydrocortisone had the most widespread inhibitory effect, while LPS from E. coli O111:B4 had the most potent stimulatory effect. In addition, we also showed that Hydrocortisone or LPS from E. coli O111:B4 affected the migratory and immunosuppressive capacity of BMSCs. Following simulation with Hydrocortisone, BMSC migration was attenuated, and immunosuppressive capacity against T cell proliferation was enhanced, however, the opposite effects were seen with LPS from E. coli O111:B4. Our data suggests that the clinical outcomes of MSC-based therapy are affected by the use of immunosuppressive medication or the presence of endotoxemia in patients.

BACKGROUND Expanding quantities of mesenchymal stem cells (MSCs) sufficient to treat large numbers of patients in cellular therapy and regenerative medicine clinical trials is an ongoing challenge for cell manufacturing facilities. STUDY DESIGN AND METHODS We evaluated options for scaling up large quantities of bone marrow–derived MSCs (BM‐MSCs) using methods that can be performed in compliance with Good Manufacturing Practices (GMP). We expanded BM‐MSCs from fresh marrow aspirate in αMEM supplemented with 5% human platelet lysate using both an automated cell expansion system (Quantum, Terumo BCT) and a manual flask‐based method using multilayer flasks. We compared MSCs expanded using both methods and assessed their differentiation to adipogenic and osteogenic tissue, capacity to suppress T‐cell proliferation, cytokines, and growth factor secretion profile and cost‐effectiveness of manufacturing enough BM‐MSCs to administer a single dose of 100 × 10 6 cells per subject in a clinical trial of 100 subjects. RESULTS We have established that large quantities of clinical‐grade BM‐MSCs manufactured with an automated hollow‐fiber bioreactor were phenotypically (CD73, CD90, CD105) and functionally (adipogenic and osteogenic differentiation and cytokine and growth factor secretion) similar to manually expanded BM‐MSCs. In addition, MSC manufacturing costs significantly less and required less time and effort when using the Quantum automated cell expansion system over the manual multilayer flasks method. CONCLUSION MSCs manufactured by an automated bioreactor are physically and functionally equivalent to the MSCs manufactured by the manual flask method and have met the standards required for clinical application.

BACKGROUNDClinical trials involving mesenchymal stem cell (MSC) therapy have variable outcomes. We hypothesize this is largely attributed to donor‐to‐donor variability and tissue of origin.STUDY DESIGN AND METHODSWe examined proliferation rates, cytokine secretion profiles, and differentiation capability of seven bone marrow–derived MSCs (BM‐MSCs) and 16 adipose tissue–derived MSCs (AD‐MSCs) from 23 donors.RESULTSAD‐MSCs had the capacity to undergo more than 40 population doublings, while the BM‐MSC proliferation rate was found to be considerably slower. We observed more donor‐to‐donor variability in proliferation rates of BM‐MSCs than with AD‐MSCs. Cytokine analysis revealed that secretion of eight cytokines was significantly increased by AD‐MSCs at Passage (P)3 compared with P1, while for BM‐MSCs at P3 relative to P1, only interleukin‐8 and RANTES secretion was significantly increased. By P5, secretion of all cytokines by AD‐MSCs was either decreased or unchanged relative to P1. In contrast, cytokine secretion by BM‐MSCs at P5 was mostly unchanged, although secretion of six cytokines was significantly increased relative to P1. When we compared cytokine secretion between AD‐MSCs and BM‐MSCs at P3, AD‐MSCs significantly secreted higher concentrations of cytokines than BM‐MSCs while the opposite was observed at P5. This suggests that BM‐MSCs are relatively more potent at P5 while AD‐MSCs are relatively more potent at P3. AD‐MSCs and BM‐MSCs exhibited the capacity for chondrogenic differentiation. AD‐MSCs and BM‐MSCs appeared to display a more enhanced inclination toward adipogenic and osteogenic differentiation, respectively.CONCLUSIONMSC physiology is significantly influenced by donor variability and tissue of origin and this should be considered when designing clinical trials.

BACKGROUNDPoor marrow cellularity alone cannot explain poor hematopoietic progenitor cell (HPC) mobilization. This study assessed the role of CD8+ T cells in HPC cell mobilization and engraftment.STUDY DESIGN AND METHODSMobilization and engraftment were assessed in 192 autologous HPC donors. CD34+, CD4+, and CD8+ T‐cell contents in apheresis products were evaluated. Using a chemotaxis assay, we assessed the effect of purified autologous CD8+ T cells from low and high mobilizers on HPC migration from high to low stromal cell–derived factor (SDF‐1α) concentration gradients. We also assessed CD8+ T‐cell content association with days to neutrophil engraftment.RESULTSThe median number of CD34+ cells/kg was 4.7 × 106. Patients were categorized according to their total CD34+ cell collection quartile distribution into low, moderate, and high mobilizers. We found that HPC products from low mobilizers contained more CD8+ T cells than HPC products from moderate and high mobilizers. Chemotaxis assays showed depletion of CD8+ T cells enhances HPC mobilization independent of SDF‐1α concentration. Neutrophil engraftment analysis showed that the higher the CD8+ T‐cell content per unit CD34+ cell, the faster the rate of engraftment.CONCLUSIONOur findings suggest CD8+ T cells inhibit HPC mobilization and facilitate homing and engraftment.