(234d) Shear Stress Effects on Energy Metabolism and Exosome Secretion of Human Mesenchymal Stem Cells in a Novel Pbs Vertical Wheel Bioreactor

The number of publications and clinical trials for human mesenchymal stem cells (hMSCs) and their secreted extracellular vesicles (EVs) have been growing exponentially over the last two decades as their potential for facilitating tissue repair and treating autoimmune disorders has been realized. As a direct result, the demand for therapeutically potent hMSCs and derived EVs has risen dramatically highlighting the need for xeno-free bioreactor culture systems that are capable of delivering high cell densities without compromising inherent hMSC properties underpinned by energy metabolism. However, hMSCs are highly sensitive to microenvironment conditions, including shear stress caused by dynamic bioreactor systems. In this study, we cultured hMSCs on Synthemax II microcarriers in the PBS mini 0.1L vertical wheel bioreactor system under variable shear stress by varying the wheel agitation (25 rpm, 40 rpm, and 64 rpm). Our bioreactor culture results show up to a 20-fold increase in cell densities over 5 days of culture with glucose consumption decreasing roughly tenfold on a per cell basis when compared to the planar control. We demonstrate the scalability of the PBS vertical wheel system showing no change in growth kinetics between the 0.1L and 0.5L models. Furthermore, with a growing body of evidence that hMSC secretome is responsible for the therapeutic benefits post-transplantation, we isolate and characterize exosomes generated by hMSCs that are exposed to variable shear stress as well as in the 0.5L bioreactor and planar control. This study should advance the bio-manufacturing for stem cell-based therapy towards treating neurological disorders such as stroke, Alzheimer’s disease, and multiple sclerosis.

This study is supported by National Science Foundation (NSF 1743426). CBET: Advanced Biomanufacturing program.