Bovine hydroxyapatite and low-oxygen tension bone marrow mesenchymal stem cell-derived metabolite improve bone formation in critical-sized bone defect

Abstract

The treatment of massive bone defects remains a substantial challenge in orthopedic practice due to the limited regenerative capacity of autographs and metal implants. Tissue engineering approaches that integrate Mesenchymal Stem Cell (MSCs), scaffold, dan bioactive metabolites have shown great potential in promoting osteogenesis, particularly through secretome-mediated mechanisms under hypoxic conditions. The objective of this study to examine the effectiveness of metabolites derived from MSCs cultured under normoxic and hypoxic conditions, in combination with hydroxyapatite scaffolds, on bone regeneration in critical-size bone defects at the fourth and eighth weeks. This research is true experimental research which use post-test only control group design. The samples were 42 male New Zealand White rabbits, which were classified into three groups namely, BHA, BHA + normoxic metabolites, and BHA + hypoxic metabolites. These groups were observed at the fourth and eighth weeks. The parameters assessed included microvascularization (MV), woven bone (WB), COL 1, and radiological scores. Data were analyzed using One-Way ANOVA, Brown-Forsythe, Kruskal-Wallis, Mann-Whitney, Post Hoc LSD, and Games-Howell tests to determine significant differences among groups. In addition, statistical analyses were carried out with SPSS, using a significance level of 5% (p < 0.05). The results of the study demonstrated that the implantation of BHA, BHA + normoxic metabolites, and BHA + hypoxic metabolites in the rabbit radius bone produced significant differences in several parameters of bone regeneration. In the 4th week, significant differences were observed in the microvascular and woven bone parameters (p < 0.05), whereas the radiological scores exhibited no significant differences (p > 0.05). At the 8th week, almost all parameters showed significant differences among groups, except for COL 1 (p > 0.05), with notable increases in microvascularization, woven bone formation, and radiological scores compared to the other groups. Normoxic metabolite supplementation with BHA demonstrated superior bone recovery compared to BHA. However, the hypoxic metabolite + BHA composite exhibited the most promising bone regeneration across groups, suggesting its potential as an alternative treatment for critical-sized defects.