Three‐dimensional, bioactive, biodegradable, polymer–bioactive glass composite scaffolds with improved mechanical properties support collagen synthesis and mineralization of human osteoblast‐like cells <i>in vitro</i>

TLDR

Tissue‑engineering bone grafts have become a viable alternative, but the biomaterial used is critical to graft success. The study aimed to develop a PLAGA‑BG composite scaffold that is biodegradable, bioactive, and mechanically superior, and to test its effects on osteoblast adhesion, growth, differentiation, and calcium‑phosphate deposition in vitro. The composite’s structure, mechanical strength, and surface calcium‑phosphate formation were characterized, and human osteoblast‑like cell growth and differentiation on the scaffold were assessed. The PLAGA‑BG composite exhibited a higher compressive modulus, formed surface calcium‑phosphate deposits, promoted osteoblast‑like morphology, alkaline phosphatase activity, and collagen I production, and overall showed improved mechanical properties and osteointegrative potential compared to PLAGA alone.

Abstract

In the past decade, tissue engineering-based bone grafting has emerged as a viable alternative to biological and synthetic grafts. The biomaterial component is a critical determinant of the ultimate success of the tissue-engineered graft. Because no single existing material possesses all the necessary properties required in an ideal bone graft, our approach has been to develop a three dimensional (3-D), porous composite of polylactide-co-glycolide (PLAGA) and 45S5 bioactive glass (BG) that is biodegradable, bioactive, and suitable as a scaffold for bone tissue engineering (PLAGA-BG composite). The objectives of this study were to examine the mechanical properties of a PLAGA-BG matrix, to evaluate the response of human osteoblast-like cells to the PLAGA-BG composite, and to evaluate the ability of the composite to form a surface calcium phosphate layer in vitro. Structural and mechanical properties of PLAGA-BG were measured, and the formation of a surface calcium phosphate layer was evaluated by surface analysis methods. The growth and differentiation of human osteoblast-like cells on PLAGA-BG were also examined. A hypothesis was that the combination of PLAGA with BG would result in a biocompatible and bioactive composite, capable of supporting osteoblast adhesion, growth and differentiation, with mechanical properties superior to PLAGA alone. The addition of bioactive glass granules to the PLAGA matrix resulted in a structure with higher compressive modulus than PLAGA alone. Moreover, the PLAGA-BA composite was found to be a bioactive material, as it formed surface calcium phosphate deposits in a simulated body fluid (SBF), and in the presence of cells and serum proteins. The composite supported osteoblast-like morphology, stained positively for alkaline phosphatase, and supported higher levels of Type I collagen synthesis than tissue culture polystyrene controls. We have successfully developed a degradable, porous, polymer bioactive glass composite possessing improved mechanical properties and osteointegrative potential compared to degradable polymers of poly(lactic acid-glycolic acid) alone. Future work will focus on the optimization of the composite scaffold for bone tissue-engineering applications and the evaluation of the 3-D composite in an in vivo model.