(157q) Cycling Aggregation and Planar Culture Extends in Vitro Expansion Potential of Human Mesenchymal Stem Cells

Mesenchymal stem cell (MSC) treatment has shown great promise in in vitro and small animal models. However, this has not been seen when applied to human clinical trials. This is due to both the availability of MSCs at the time of need and lack of viable expansion method. MSCs are very susceptible to culture adaptation-induced in vitro aging which results in loss of MSC functionality and clinical relevance. To combat this effect, this work assessed cyclical aggregation as a means of expanding MSCs while still maintaining functionality. Cyclical aggregation consists of an aggregation phase followed by dissociation and replating onto planar tissue culture plastic as a means to expand the cells. The results indicate that cyclical aggregation maintains proliferative capability, stem cell proteins, and clonogenicity, and prevents the acquisition of senescence. To determine why aggregation was responsible for this phenomenon, the integrated stress response pathway was probed with salubrial and GSK-2606414. Treatment with salubrial had no significant effect, while GSK-2606414 mitigated the effects of aggregation leading to in vitro aging. This method holds the potential to increase the clinical relevance of MSC therapeutic effects from small model systems (such as rats and mice) to humans, and may open the potential of patient-derived MSCs for treatment thereby removing the need for immunosuppression.