Controlled Release of Anti-inflammatory and Pro-angiogenic Factors from Macroporous Scaffolds

Abstract

The simultaneous local delivery of anti-inflammatory and pro-angiogenic agents via biomaterial scaffolds presents a promising method for improving the engraftment of tissue-engineered implants while avoiding potentially detrimental systemic delivery. In this study, PDMS microbeads were loaded with either anti-inflammatory dexamethasone (Dex) or pro-angiogenic 17{beta}-estradiol (E2) and subsequently integrated into a single macroporous scaffold to create a controlled, dual drug-delivery platform. Compared to a standard monolithic drug dispersion scaffold, macroporous scaffolds containing drug-loaded microbeads exhibited reduced initial burst release and increased the durability of drug release for both agents. Incubation of scaffolds with LPS-stimulated M1 macrophages found that Dex suppressed the production of pro-inflammatory and pro-angiogenic factors, when compared to drug-free control scaffolds; however, the co-incubation of macrophages with Dex and E2 scaffolds restored their pro-angiogenic features. Following implantation, Dex-loaded microbead scaffolds (Dex-{micro}BS) suppressed host cell infiltration and integration, when compared to controls. In contrast, the co-delivery of dexamethasone with estrogen from the microbead scaffold (Dex/E2-{micro}BS) dampened overall host cell infiltration but restored graft vascularization. These results demonstrate the utility of a microbead scaffold approach for the controlled, tailored, and local release of multiple drugs from an open framework implant. It further highlights the complementary impacts of local Dex and E2 delivery to direct the healthy integration of implants, which has broad applications to the field of tissue engineering and regenerative medicine.