Rabbit mesenchymal stem cells cultured in a dynamic culture system displayed superior cell proliferation and osteogenetic induction

Objective: We evaluated the effect of three-dimensional static and dynamic culture on the proliferation, distribution, and differentiation of rabbit mesenchymal stem cells (MSCs) in a porous scaffold via autograft for bone regeneration. Methods: Rabbit MSCs were seeded in a porous hydroxyapatite scaffold (MSCs/scaffold), and then cultured in petri dishes and a bidirectional flow reactor for 4 weeks for osteogenetic induction invitro. Metabolic assay of the culture medium was carried out every 2 days; glucose, lactic acid, and calcium concentrations in the medium were also examined. Cell distribution in the scaffold was examined histologically. Cultured MSCs/scaffolds were implanted in rabbit condyles for the evaluation of bone regeneration invivo. Results: Histological sections showed that cells cultured in petri dishes grew only around the scaffolds and seldom in the inner part. However, the scaffolds cultured with MSCs in a bioreactor were almost fully occupied by cells. Metabolic results revealed that the average concentration of glucose in the medium was decreased as cells propagated. Glucose consumption was observed in both static and dynamic cultures, but higher lactic acid production was found in the static culture. Calcium ion concentration was reduced significantly in the dynamic culture after the addition of an osteogenetic induction medium, indicating progression of mineralization. The invivo results showed that about 80% of the defect in the condyles with dynamically cultured MSCs/scaffold implants was filled with new bone tissue, a proportion much higher than that in the petri dish-cultured MSCs/scaffolds, in which only half of the bone regeneration occurred in the cavity. Conclusion: This study provides evidence of the effectiveness of dynamic invitro MSC culture for robust osteogenesis and indicates that it may impart superior potential for bone regeneration invivo.