Effect of Dose-Delivery Strategies on BMP-2 Mediated Osteogenesis of GMCSCs

Objectives: Biomaterials-mediated delivery of bioactive agents including growth factors and stem cells emerged as a promising strategy to promote bone regeneration. Bone morphogenetic protein-2 (BMP-2), is widely used growth factor as bone graft substitute. The objective of the study was to compare BMP2 delivery strategies and its effect on the osteogenic differentiation of human gingiva derived mesenchymal stem cells.
Methods: GMSCs isolated from the human gingiva tissue were cultured under standard culture conditions. Three types of delivery methods were utilized to deliver BMP2, 1) BMP2 was added to the culture medium on GMSCs monolayer cultures (2D culture), 2) BMP2 was administered in the culture medium to the hydrogel encapsulated GMSCSc (3-D culture) 3) The GMSCs and BMP2 were encapsulated together in the hydrogel (3-D culture). The cells were treated with 50,100, 200ng/ml BMP2 for all groups. The osteogenic marker gene expressions was measured at day 7 and mineralization deposition was compared at 3 week and 4 weeks culture.
Results: The ALP gene expression were significantly upregulated in dose dependent manner in 2-D cultures as well as 3-cultures. Nevertheless, there was a 2-fold increase in ALP expression in 3-D cultures compared to 2-D cultures. Furthermore, the expression of collagen type I and RUNX2 genes expressed significantly high compared to control in 3-D cultures while in 2-D culture there was no significant difference between control group and BMP2 group. There was an enhanced mineral deposition in-Group 2 and 3 compared to Group 1. Our overall results indicated that BMP2 enhanced HGMSCs osteogenic differentiation ability in all culture conditions. However, the effect was significantly higher in the cells cultured in 3-D environment compared to 2-D cultures.
Conclusions: Our results demonstrated that dose and delivery strategies of growth factor are crucial in bone tissue engineering.