In situ sequestration of endogenous PDGF-BB with an ECM-mimetic sponge for accelerated wound healing.

Recapitulating the typical features of extracellular matrix (ECM) in engineered biomaterials is crucial for preparing a suitable niche to activate endogenous tissue repair. Here, we report the design and evaluation of an ECM-mimetic scaffold that successfully accelerated wound healing through enriching endogenous platelet-derived growth factor-BB (PDGF-BB). Specifically, we prepared a electrospun hydrogel sponge (EGS) comprising a PDGF-BB-binding polysaccharide (EUP3) and gelatin. The two polymers in concert exerted a 'retention-and-release' function: upon the application of EGS in vivo, EUP3 started to bind and sequester endogenous PDGF-BB at the wound site; gradually, gelatin was degraded to free the PDGF-BB/EUP3 complex that acted on the cells in situ. Our serial in vitro and in vivo tests validated the efficacy of EGS in retaining PDGF-BB, releasing PDGF-BB/EUP3 in response to collagenase, and promoting various PDGF-BB-mediated regenerative activities. Particularly, EGS accelerated the repair of a full-thickness skin wound in mice and induced optimal neo-tissue formation, without the addition of any exogenous GFs, cells or genes. Collectively, our results suggest that, by mimicking the distinctive GF-affinitive feature of ECM, EGS as an engineered biomaterial can effectively harness the endogenous regenerative power of the native tissue. Our investigation may inspire the design of new, effective and safer approaches for tissue regeneration.