Improved efficacy of bio-mineralization of human mesenchymal stem cells on modified PLLA nanofibers coated with bioactive materials via enhanced expression of integrin α2β1

Current therapeutic interventions in bone defects are mainly focused on finding the best bioactive materials for inducing bone regeneration via activating the related intracellular signaling pathways. Integrins are trans-membrane receptors that facilitate cell-extracellular matrix (ECM) interactions and activate signal transduction. To develop a suitable platform for supporting human bone marrow mesenchymal stem cells (hBM-MSCs) differentiation into bone tissue, electrospun poly L-lactide (PLLA) nanofiber scaffolds were coated with nano-hydroxyapatite (PLLA/nHa group), gelatin nanoparticles (PLLA/Gel group), and nHa/Gel nanoparticles (PLLA/nHa/Gel group) and their impacts on cell proliferation, expression of osteoblastic biomarkers, and bone differentiation were examined and compared. MTT data showed that proliferation of hBM-MSCs on PLLA/nHa/Gel scaffolds was significantly higher than other groups (P < .05). Alkaline phosphatase activity was also more increased in hBM-MSCs cultured under osteogenic media on PLLA/nHa/Gel scaffolds compared to others. Gene expression evaluation confirmed up-regulation of integrin alpha 2 beta 1 as well as the osteogenic genes BGLAP, COL1A1, and RUNX2. Following use of integrin alpha 2 beta 1 blocker antibody, the protein level of integrin alpha 2 beta 1 in cells seeded on PLLA/nHa/Gel scaffolds was decreased compared to control, which confirmed that most of the integrin receptors were bound to gelatin molecules on scaffolds and could activate the integrin alpha 2 beta 1/ERK axis. Collectively, PLLA/nHa/Gel scaffold is a suitable platform for hBM-MSCs adhesion, proliferation, and osteogenic differentiation in less time via activating integrin alpha 2 beta 1/ERK axis, and thus it might be applicable in bone tissue engineering.