Comparative analysis of the effects of different hypoxia mimetic agents on the secretome contents of conditioned medium obtained from mesenchymal stem/stromal cells cultured in 2 or 3-dimensional cell culture systems.

Paracrine factors secreted by mesenchymal stem/stromal cells (MSCs) have been demonstrated to have significant therapeutic potential. The secretome profiles of MSCs variate depending on culture conditions. Generally, the effects of a single preconditioning strategy on secretome profiles of MSCs were investigated. However, until now, there has been no study examining the combinatory effects of different preconditioning strategies in a comparative manner. This study aimed to evaluate the secretome contents of conditioned media obtained from human umbilical cord-derived MSCs cultured in 2- or 3-dimensional (D) culture systems preconditioned with deferoxamine (DFS) or dimethyloxalylglycine (DMOG). Immunocytochemical analysis showed that MSCs preconditioned with DFS or DMOG have increased nuclear hypoxia-inducible factor-1α expression. Transmission electron microscopic analysis showed that cells preconditioned with DFS or DMOG have increased autophagic vesicles, which could be attributed to altered energy metabolism under hypoxic conditions. It was revealed that hypoxia-mimetic agents added to the 2D-, or 3D-culture environment raised total protein concentrations per cell along with vascular endothelial growth factor. The concentrations of glial cell-derived neurotrophic factor (GDNF) and nerve growth factor (NGF) were differentially regulated in 2D-, and 3D-culture system, that the secretions of GDNF and NGF per cell were more prominent in 3D- and 2D-culture systems, respectively. These findings indicate that hypoxic conditions alone significantly elevate total protein concentrations, while the contribution of the 3D environment is more modest than initially anticipated. However, concentrations of secreted growth factors may be affected differently depending on the topography of the culture condition and the types of hypoxia mimetic agents.