Regulating Bone Formation <i>via</i> Controlled Scaffold Degradation

TLDR

Coupling polymer degradation rate to tissue growth is assumed to enhance bone formation quality and quantity. The authors created gamma‑irradiated alginate hydrogels with a spectrum of degradation rates to test this hypothesis. These hydrogels, modified with RGD peptides, were implanted in vivo to evaluate how degradation speed influences bone tissue development. Rapidly degrading gels produced markedly greater and higher‑quality bone formation, showing that biomaterial degradability is a critical design criterion for optimal regeneration.

Abstract

It is widely assumed that coupling the degradation rate of polymers used as cell transplantation carriers to the growth rate of the developing tissue will improve its quantity or quality. To test this hypothesis, we developed alginate hydrogels with a range of degradation rates by gamma-irradiating high-molecular-weight alginate to yield polymers of various molecular weights and structures. Decreasing the size of the polymer chains increased the degradation rate in vivo, as measured by implant retrieval rates, masses, and elastic moduli. Rapidly and slowly degrading alginates, covalently modified with RGD-containing peptides to control cell behavior, were then used to investigate the effect of biodegradation rate on bone tissue development in vivo. The more rapidly degrading gels led to dramatic increases in the extent and quality of bone formation. These results indicate that biomaterial degradability is a critical design criterion for achieving optimal tissue regeneration with cell transplantation.