Promoting osteogenic differentiation of BMSCs via mineralization of polylactide/gelatin composite fibers in cell culture medium.

Mineralization capability is an important issue in developing bone repairing biomaterials, while it is not quite clear how this feature would act in the presence of cells and influence cell osteogenic differentiation without adding extra osteoinductive factors such as β‑sodium glycerophosphate and dexamethasone. Poly(l‑lactide) (PLLA) and gelatin composite fibers (PG, 1:1 in weight) were electrospun, treated with CaCl ₂ solution (PG-Ca), and used for mineralization studies by using cell culture media (αMEM, and αMEM + serum). Bone mesenchymal stromal cells (BMSCs) were then seeded and cultured on both PG and PG-Ca fibrous mats for 28 days by only using αMEM + serum. Interestingly, mineral depositions on both PG and PG-Ca fibers were detected in the environment of αMEM or αMEM + serum, in which, PG-Ca fibers demonstrated stronger ability in inducing hydroxyapatite formation than PG fibers, especially in the presence of fetal bovine serum. When BMSCs were cultured on the two kinds of fibrous mats, apatite depositions were still clearly detected, while the depositing amounts decreased in comparison with corresponding cell-free cases. It was ascribed to the consumption of ions by the continuously proliferating BMSCs, whose osteogenic differentiation was significantly promoted even without extra osteoinductive factors, especially on PG-Ca fibrous mats, in comparison with the control group. Therefore, it was confirmed the capability of scaffolding materials in enriching ions like calcium and phosphate around cells was an efficient way to promote bone regeneration.
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