Metabolic diseases or injuries damage bone structure and self-renewal capacity. Trace elements and hydroxyapatite crystals are important in the development of biomaterials to support the renewal of bone extracellular matrix. In this study, it was assumed that the boron-loaded nanometer-sized hydroxyapatite composite supports the construction of extracellular matrix by controlled boron release in order to prevent its toxic effect. In this context, boron release from nanometer-sized hydroxyapatite was calculated by ICP-MS as in large proportion within 1 h and continuing release was provided at a constant low dose. The effect of the boron-containing nanometer-sized hydroxyapatite composite on the proliferation of SaOS-2 osteoblasts and human bone marrow-derived mesenchymal stem cells was evaluated by WST-1 and compared with the effects of nano-hydroxyapatite and boric acid. Boron increased proliferation of mesenchymal stem cells at high doses and exhibited different effects on osteoblastic cell proliferation. Boron-containing nano-hydroxyapatite composites increased osteogenic differentiation of mesenchymal stem cells by increasing alkaline phosphatase activity, when compared to nano-hydroxyapatite composite and boric acid. The molecular mechanism of effective dose of boron-containing hydroxyapatite has been assessed by transcriptomic analysis and shown to affect genes involved in Wnt, TGF-β, and response to stress signaling pathways when compared to nano-hydroxyapatite composite and boric acid. Finally, a safe osteoconductive dose range of boron-containing nano-hydroxyapatite composites for local repair of bone injuries and the molecular effect profile in the effective dose should be determined by further studies to validation of the regenerative therapeutic effect window.
Keywords: Bone; Boron; Mesenchymal stem cell; Nano-hydroxyapatite; SaOS-2; Transcriptome.