Production of osteogenic and angiogenic factors by microencapsulated adipose stem cells varies with culture conditions

Growth factors produced by stem cells aid in the bone repair process. We investigated the ability of encapsulated rat adipose-derived stem cells (rASCs) treated with osteogenic media (OM) to produce growth factors, and determined the optimal combination of OM components that will lead to the production of both osteogenic and angiogenic factors. Our results demonstrate that microencapsulated stem cells were able to produce vascular endothelial growth factor (VEGF), fibroblast growth factor-2, and bone morphogenetic protein-2 (BMP2) necessary for bone regeneration. OM led to the reduction of angiogenic factors; however, the removal of dexamethasone restored angiogenic factor production. Additionally, we determined whether the effect of dexamethasone on VEGF and BMP2 varied among rat, rabbit, mouse, and humans. Dexamethasone led to a reduction in VEGF levels in ASCs derived from rats, mice, and humans, while this reduction was absent in rabbit ASCs (rbASCs). Human ASCs (hASCs) from donors of different race and sex showed a similar response to dexamethasone with secreted VEGF levels. BMP2 levels secreted by rbASCs, mouse ASCs (mASCs), and hASCs were independent of the media treatments, while rASCs responded differently in the surrounding media and within the microbeads. In conclusion, microencapsulated ASCs can be treated to produce osteogenic and angiogenic factors for tissue regeneration applications, but outcomes may vary with culture conditions.