Spheroids of adipose derived stem cells show their potential in differentiating towards the angiogenic lineage

Introduction: Adipose derived stem cells (ASCs) are a mesenchymal stem cell population of great scientific interest due to their abundance and easiness in obtaining them from adipose tissue. Recently, several techniques for three dimensional (3D) ASCs cultivation have been developed to obtain spheroids of adipose stem cells (SASCs). It was already proved that ASCs are able to differentiate towards the endothelial lineage thus, for the first time, we investigated the ability of our 3D SASCs to differentiate endothelially and the effects of not differentiated SASC secreted factors on specific cultured cells. Materials and methods: SASCs were differentiated with a specific medium towards endothelial lineage. Cell viability, gene and protein expression of typical endothelial markers were analysed. Moreover, tube formation, wound healing and migration assays were performed to investigate the ability in migration and angiogenic networks formation of endothelially differentiated cells. SASCs secretome were also tested. Results: We showed the ability of SASCs to differentiate towards the endothelial lineage with an increase in cell viability of 15-fold and 8-fold at 14 and 21 days of differentiation respectively. Moreover, we showed the upregulation of VEGF-A and CD31 mRNAs of 9-fold and 1300-fold in SASCs endothelially differentiated cells, whilst protein expression was different. VEGF-A protein expression was upregulated whilst CD31 protein wasn't translated. In addition, ICAM1, VCAM1, ANGPT1, CD62E protein levels remain unchanged. SASCs were also able to organize themselves into angiogenic networks after 7 days of culturing themon ECMatrix. Secreted factors from undifferentiated 3D SASCs acted in a paracrine way on HUVECs and endothelially differentiated ASCs seeded on ECMatrix to promote angiogenic events. Conclusions: SASCs, thanks to their multilineage differentiation potential, also possess the ability to differentiate towards endothelial lineage and to organize themselves into angiogenic networks. Moreover, they are able to promote angiogenesis through their secreted factors.