"ludwigia sedioides" inspired substance-exchangeable spacer facilitating revascularization for skin repair.

Schematic diagram of "Ludwigia sedioides" inspired substance-exchangeable spacer PTMS@P with PRP incorporated and its therapeutic effects for skin flap repair. [Display omitted] • A "Ludwigia sedioides" inspired ultra-thin microporous spacer is developed. • Slow-released growth factors from PRP strengthen revascularization and ECM synthesis. The spacer facilitates vascular shuttling and substance exchange. Extended vascular networks promoted skin flap survival and regeneration. Adequate substance exchange is an important prerequisite for tissue repair, and how to efficiently establish mature vascular networks to enhance the graft-host substance exchange is a challenge. Herein, inspired by the special structure of the aquatic plant "Ludwigia sedioides", ultra-thin microporous scaffolds (TMS) of bovine Achilles tendon derived collagen were fabricated as "floating leaves" via pyridine reaction, and cleverly combined with platelet-rich plasma (PRP) after the Schiff base and Michael additions reactions of polydopamine to construct a biomimetic "Ludwigia sedioides" spacer (PTMS@P), allowing blood vessels (as a "rhizome") freely shuttling and substance exchange. In this spacer, growth factors were efficiently released to peak concentrations in the first 12 h, thereby facilitating rapid blood vessel growth. In the subsequent 96 h, these slow-released growth factors retained at 11.6 % to 45.8 % of the peak concentrations, sustainedly promoting vascular networks shuttling through the spacer, graft-host substance exchange and extracellular matrix synthesis in fibroblasts. In vitro, the spacer significantly fostered fibroblasts and endothelial cells' proliferation, adhesion and migration, which were fundamental for revascularization and substance exchange. Immunohistochemical staining of CD31 and Ki67 in vivo demonstrated that abundant vascular networks shuttled through PTMS@P and extended from flap base to the farther flap body, promoting more robust substance exchange and cellular metabolism, which significantly enhanced the survival of ischemic flaps in nude mice. Altogether, this "Ludwigia sedioides" inspired spacer PTMS@P with strengthened revascularization and substance-exchange functionality holds promising applications for tissue repair and regeneration. [ABSTRACT FROM AUTHOR]