Human adipose stem cells can differentiate in an osteoblastic-like phenotype on trabecular titanium scaffolds without osteogenic medium

Introduction Pluripotent human adipose tissue-derived stem cells (hASCs) can differentiate into multiple mesenchymal cell lineages Previous studies demonstrated that the material, the geometry and the porosity of scaffolds affect cell binding and migration depth of cellular ingrowth, and that hASCs can differentiate in an osteoblasticlike phenotype when seeded on trabecular titanium scaffolds with osteogenic medium. Aim of this study was to demonstrate that trabecular titanium scaffolds could induce osteogenic differentiation of hASCs also without osteogenic medium. Materials and methods hASCs were isolated from subcutaneous adipose tissue, seeded on monolayer and on trabecular titanium scaffolds (Ti6Al 4 V, LimaCorporate, Villanova di San Daniele del Friuli, Italy; average porosity, 65%, average diameter of cell pores, 640 lm) and incubated at 37 C in 5% CO(2) with osteogenic and proliferation medium in static conditions. Cells before seeding corresponded to reference group. After seeding on scaffolds, hASCs were cultured for 7 days in the presence of proliferation medium before the osteogenic medium was added (Time 0). The osteogenic differentiation was detected with real-time PCR to analyze the expression of ALP and RUNX-2 genes, at time 0 and after 3, 7 and 21 days from differentiation. Alkaline phosphatase activity on cell lysates was also measured after 7 days from differentiation. Results Monolayer: both ALP and RUNX-2 gene expression and alkaline phosphatase activity were higher in hASCs grown in presence of osteogenic medium. Trabecular titanium scaffolds: in hASCs grown in proliferation medium, ALP gene expression was higher than reference group still at time 0, and remained 2.5 fold higher at time 3 and 7. Similar results were found with osteogenic medium. RUNX-2 gene expression was higher in hASCs grown in osteogenic medium, and increased also in the presence of proliferation medium respect to reference group. At time 7, there were no difference in alkaline phosphatase activity of hASCs grown with proliferation and osteogenic medium. Conclusions hASCs on trabecular titanium expressed higher amount of ALP and RUNX-2 gene expression in proliferation medium with respect to cells on monolayer in the same condition. The expression of osteogenic genes similar in cells grown on scaffold with both medium, leads to the conclusion that trabecular titanium scaffold seems to have not only osteoconductive but also osteoinductive properties.