Adherence of human adipose-derived stem cells (hASCs) variably increases a prompt osteogenic differentiation

Human adipose derived stem cells have been extensively studied for their ability to differentiate into multilineage cell types such as adipocytes, osteoblasts, chondrocytes, myocytes and endothelial cells. We have previously compared hASCs derived from young and elderly females evaluating their cell number, their proliferation rate, their CFU-F ability and their adipogenic and osteogenic potential. These differentiated cells have potential clinical applications in regenerative medicine and in the field of tissue engineering. The purpose of this study is to examine the effect of the adherence of either undifferentiated or differentiated hASCs to several biomaterials to establish better conditions for preparing ideal cells for clinical applications in the orthopaedic field. We assessed that undifferentiated hASCs are able to properly colonize scaffolds, such as hydroxyapatite granules, silicium carbide (SiC-PECVD), chemically-modified titanium disks and polyurethane sponges, when cultured for just 2 weeks on them. They tightly adhere to the surfaces without the appearance of any toxicity and they show a significant increase of ALP-activity and extracellular calcified matrix formation compared to hASCs grown on monolayer. These data clearly show the osteo-inductive effect of these specific biomaterials. Furthermore, hASCs, either pre-differentiated or directly osteogenic-induced on scaffolds, do not show any difference in their cellular differentiation capacity, suggesting that the pre-differentiation step is not required, and it may be avoided in (pre-)clinical future applications. In addition, the synergistic effect produced by the scaffolds and the chemical stimuli has been shown with the expression of both early and late differentiation markers.