Cissus quadrangularis stem derived fiber: a natural osteoinductive substrate for regenerative bone tissue engineering

Natural biomaterials with intrinsic biomineralization potential are of utmost interest in bone tissue engineering (BTE) applications. Here, we report the biomimetic mineralization potential of a natural fiber derived from Cissus quadrangularis (CQ) stem, CQF, with inherent biomineralization and osteoinductive potential and is proposed for regenerative BTE. CQF has an organized microstructure characterized by an array of submicron size fibrils (SEM analysis) saturated with –OH groups of cellulose on the surface (FTIR spectrum), which provides a better platform for cell adhesion/proliferation and play a key role in the early nucleation of calcium phosphate, the inorganic phase of bone. A single unit of CQF has a tensile strength of 89.75 ± 5.25 MPa, which is in line with the mechanical property requirement of bone. CQF depicts signs of surface erosion (SEM analysis) with a weight loss of 11% after 30 days incubation in physiological conditions, supporting its intended stability required during the bone regeneration phase. CQF demonstrated excellent cytocompatibility (MTT assay and cell adhesion) and elicited primary nucleation and growth of apatite crystals (Ca/P 1.30; day 7), progressed further to secondary growth (Ca/P 1.51; day 14) upon incubation in simulated body fluid (SBF; 1.5X). Biomineralization of CQF was further confirmed by Alizarin Red S staining (day 14) in MG-63 cells. The osteoinductive potential of CQF was validated by quantifying early osteoblast differentiation marker alkaline phosphatase activity in Rat Bone marrow Mesenchymal Cells (BMC). The results, therefore, confer that CQF could be proposed for regenerative BTE.