Scaffold degradation in bone tissue engineering: An overview

Successful bone tissue engineering strategies require 3D scaffolds with controllable properties tailored to the intended clinical applications. The scaffold as a temporary substrate for cells to live and grow, must be degraded over time and replaced with the host tissue gradually. However, despite remarkable advances in bone tissue engineering, adjusting the rate of scaffold degradation with the ability of host tissue to regenerate, is still one of the main challenges. To date, most studies on bone tissue engineering have addressed the role of scaffold properties in cell differentiation and bone regeneration, and scaffold degradation has received less attention. For this reason, an understanding of bone tissue engineering materials and their degradation process is valuable if we are to exploit their potential for the regeneration of bone defects. In this review, we specifically have focused on the bone scaffold materials. Bone scaffold materials can be degraded through hydrolytic, oxidative, enzymatic, stimuli-assisted, and cell-mediated reactions. In various studies, chemical composition, structure, surface modification and fabrication method of scaffolds have been introduced as influencing factors in the degradation of scaffolds. Herein, not only the degradation mechanisms of materials used in bone scaffolds has been discussed, but also the approaches used by researchers to control the rate of degradation are pointed out.