Induction of angiogenesis. Angiogenesis assay with incubation of HUVEC cells with conditioned media from mono-cultured ADSCs (a, e), A431-SCCs (b), pSCCs (f), co-cultured ADSC-A431-SCCs (c), and co-cultured ADSCs-pSCCs (g). Controls (d, h) were induced with PMA. Tube formation could be detected with conditioned media from co-cultured ADSC-A431-SCCs, slightly from co-cultured ADSCs-pSCCs, and mono-cultured ADSCs or A431-SCCs. No significant angiogenesis could be detected when conditioned media from pSCC- or A431-SCC-mono-culture was added to the system. ADSC, adipose tissue derived stem cells; HUVEC, human umbilical vein endothelial cells; PMA, phorbol 12-myristate 13-acetate; pSCCs, primary squamous cell carcinoma cells; SCCs, squamous cell carcinoma cells.