Injectable GSK3 inhibitor (Tideglusib) hydrogel versus enhanced β-tricalcium phosphate in tibial bone healing (in vitro and in vivo study)

This study was carried out to assess the potential effect of a glycogen synthase kinase-3 inhibitor tideglusib hydrogel formulation on bone regeneration and to compare it with Ethoss a beta tricalcium phosphate alloplastic bone substitute mixed with calcium sulphate in vitro and in vivo. Bone marrow mesenchymal stem cells (BMMSCs) were isolated from New Zealand white rabbit tibias and characterized by flowcytometric analysis. Sodium alginate hydrogel loaded with tideglusib was formulated and underwent characterization by scanning electron microscopy, the fourier transform infrared and zeta potential. Extraction media from both tideglusib hydrogel and Ethoss were prepared then MTT, alizarin red (ARS) and scratch wound assays were performed. Two bone defects were trephined in tibias of eighteen adult healthy rabbits, which were classified into three groups: group 1, bone defects were left untreated; group 2, each defect was filled with tideglusib hydrogel; group 3, each defect was filled with Ethoss. Animals were sacrificed after three and six weeks. Histological and immunohistochemical analyses using alkaline phosphatase (ALP) and osteopontin (OPN) were performed to assess bone regeneration. The tideglusib hydrogel group expressed higher mineral deposition than Ethoss group using ARS but without significant difference, stronger stimulatory effect on the migration of BMMSCs was also evident with significant narrowing of the wound area. New bone tissue was progressively seen bridging and filling the defects with significantly higher ALP and OPN expression in hydrogel group. Tideglusib hydrogel formulation exhibited superior bone regenerative potential in comparison to beta tricalcium phosphate alloplastic bone substitute.