Effect of In-Situ Synthesized Nano-Hydroxyapatite/Collagen Composite Hydrogel on Osteoblasts Growth In Vitro

Composites of collagen and hydroxyapatite (HA) were widely used in bone tissue engineering due to their biological resemblance and favorable biocompatibility. However, the composites were often prepared as porous scaffolds, such as sponges or blocks, with the final step of freeze-drying. This may prevent cell growth and disfavor filling into specific bone defect. In this study, we prepared nano-scaled HA and collagen composite hydrogels (nHC) and investigated osteoblasts growth in the hydrogels by detecting cell proliferation, the expression of osteogenic specific genes and proteins. Comparison with micro-HA/collagen hydrogel (HC) by blending and pure collagen hydrogel was also performed. The results showed that cell survival, growth and osteogenic specific markers such as alkaline phosphatase (ALP), type I collagen (COL I), osteocalcin (OCN) and bone nnorphogenetic protein 2 (BMP2) were significantly enhanced in nHC group compared with HC and collagen hydrogels. The results indicated that in-situ synthesized nHC hydrogel can better facilitate osetoblasts proliferation and osteogenic differentiation. Nano-HA particles in hydrogel may provide adhesive sites for cell anchorage and proliferation, which benefit further differentiation. In conclusion, nHC hydrogel is promising scaffold for bone tissue engineering.