The degradation behavior of 3D-printed polyurethane composite scaffolds regulates bone regeneration.

Abstract

Biodegradable scaffolds offer a promising platform for<i>in situ</i>bone regeneration, yet the regulatory mechanism underlying how the degradation behavior of the scaffold influences bone regeneration is still unclear. Herein, by harnessing<i>β</i>-tricalcium phosphate (<i>β</i>-TCP) as a dual regulator for degradation and osteogenesis, a series of degradation-tunable polyurethane biodegradable polyurethane/<i>β</i>-TCP composite scaffolds (PT scaffolds) was developed as the ideal foundation to explore the regulatory role of degradation behavior in bone regeneration. The PT scaffolds fabricated via a low-temperature deposition three-dimensional printing, presented a porous structure with interconnected macro-pores and abundant micro-pores, superior mechanical properties, and excellent osteogenic capability. Both<i>in vitro</i>and<i>in vivo</i>degradation-tunable behaviors of these PT scaffolds were comprehensively investigated. By adjusting<i>β</i>-TCP contents, their degradation half-life could be tuned from 10.5 to 16.7 weeks<i>in vitro</i>and from 11.2 to 17.7 weeks<i>in vivo</i>, with their average degradation rates ranging from 9.9%/week to 5.3%/week<i>in vitro</i>and 9.5%/week to 3.8%/week<i>in vivo</i>. By implantation into two different bone defect models, the PT scaffold, whose degradation behavior is synchronous with the bone regeneration process, was observed to yield better bone formation, suggesting that the degradation behavior of scaffolds itself is of great importance in determining the bone regeneration.