Osteogenic and osteoclastogenic differentiation of co-cultured cells in polylactic acid–nanohydroxyapatite fiber scaffolds

• PLA and composite PLA-nHA fiber scaffolds with 20 and 50 wt.% of nHA were realized.
• Comparison of osteogenic and osteoclastogenic markers in homotypic and co-culture systems on PLA and PLA–nHA scaffolds.
• Differentiation of hMSCs into osteoblasts and the osteoclastogenesis.
• Cross-talk of osteoblasts and osteoclasts enhanced their differentiation in PLA–nHA scaffolds.

The design of bone substitutes involves the creation of a microenvironment supporting molecular cross-talk between cells and scaffolds during tissue formation and remodelling. Bone remodelling process includes the cooperation of bone-building cells and bone-resorbing cells.In this paper we developed polylactic acid (PLA) and composite PLA-nanohydroxyapatite (nHA) scaffolds with 20 and 50 wt.% of nHA by electrospinning technique to be used in bone tissue engineering. The developed scaffolds have different fiber diameter, porosity with interconnected pores and mechanical properties. Taking cues from the bone environment features we investigated the differentiation of human mesenchymal stem cells (hMSCs) from bone marrow in osteoblasts and the osteoclastogenesis in the developed scaffolds in homotypic and in co-culture up to 46 days.PLA and composite PLA–nHA scaffolds induced osteogenic and osteoclastogenic differentiation. Both osteoblasts and osteoclasts displayed high expression of specific markers (osteopontin, osteocalcin, RANK, RANKL) and functions such as secretion of ALP, cathepsin K and TRAP activity on composite scaffolds especially on PLA–nHA containing 20 wt.% of nHA. The heterotypic interactions between osteoblasts and osteoclasts co-cultured in the developed scaffolds triggered their functional differentiation and activation.