Hypoxia priming improves in vitro angiogenic properties of umbilical cord derived-mesenchymal stromal cells expanded in stirred-tank bioreactor

Abstract

Mesenchymal stromal cells (MSC) have been investigated for their remarkable regenerative and immunomodulatory therapeutic potential. However, clinical trials have revealed limited results, which have led to the search for priming/preconditioning strategies to improve efficacy of these cells. MSC cultured under hypoxia exhibit increased migration, angiogenesis and release of trophic factors, decreased senescence and apoptosis, as well as high therapeutic potential in several preclinical models. Clinical applications of MSC require the implementation of scalable expansion process compliant with Good Manufacturing Practice (GMP) standards. Bioreactor systems present advantages such as reduced costs and greater process control, reproducibility and cell product standardization. Here, we describe the establishment of a scalable xenogeneic-free process for hypoxia-primed umbilical cord-MSC expansion. Efficient UC-MSC expansion was achieved after 5 days of culture in stirred-tank bioreactor under hypoxia conditions using human collagen-coated microcarriers and human serum (HS) as culture medium supplement. Cells retained their immunophenotype, multilineage differentiation and immunosuppressive potential. The association of hypoxia and 3D xenogeneic-free culture priming enhanced in vitro angiogenic properties of UC-MSC, when compared to non-primed cells. These results indicate that the fine-tuning of culture conditions, combined with expansion in a controllable, robust and closed system, could enhance functional properties and ultimately improve clinical efficacy.