Poly-l-lysine-coated PLGA/poly(amino acid)-modified hydroxyapatite porous scaffolds as efficient tissue engineering scaffolds for cell adhesion, proliferation, and differentiation

Abstract

Ideal bone tissue engineering scaffolds should be biocompatible, biodegradable, and mechanically robust and have the ability to regulate cell function. Porous poly(lactide-co-glycolide) (PLGA)/hydroxyapatite (HA) scaffolds have attracted extensive attention recently, which can transfer nutrients and waste products from the cells in the pores and well support the cell attachment and growth. Herein, we demonstrated a simple and low-cost method for modifying porous PLGA/HA scaffolds with poly(γ-benzyl-L-glutamate) (PBLG) and poly-L-lysine (PLL) to promote cell growth and osteogenic differentiation. The morphology and physico-chemical properties of all porous scaffolds were compared by SEM, materials testing machine and water contact angle measurements. Subsequently, the influence of PLL@PLGA/PBLG-g-HA porous scaffolds on cell proliferation was assessed by the MTT assay, whereas cell osteogenic differentiation was determined via the Alizarin Red staining, alkaline phosphatase activity and expression of osteogenic marker genes. The results indicated that the dispersion of PBLG-modified HA (PBLG-g-HA) nanoparticles was more uniform than that of n-HA in chloroform and nanocomposite scaffolds. The mechanical strength was much higher in the PLL@PLGA/PBLG-g-HA scaffolds than that in the other groups. The MC3T3-E1 cell culture showed that the osteogenic differentiation and proliferation of cells were enhanced by PBLG-g-HA and PLL, respectively. The PLL@PLGA/PBLG-g-HA porous scaffolds were more favorable for cells to proliferate and for osteogenic differentiation due to their increased initial cell attachment numbers and enhanced osteogenesis capacity. In vivo, digital radiograph evaluation demonstrated that the most rapid healing was in the bone defects treated with the PLL@PLGA/PBLG-g-HA porous scaffolds when compared with the other groups eight weeks after implantation. Based on the results, the PLL@PLGA/PBLG-g-HA porous scaffold is a promising candidate for bone defect repair.