Engineering a multilayered micro-vascularized soft tissue graft: Integrating polyurethane composite nanofibres with...

Soft tissue defects and injuries, such as gingival recession, those requiring dermal tissue filling, and other indications, affect millions worldwide, yet autologous grafting remains the standard of care in most instances, despite donor site morbidity and limited tissue availability. Tissue-engineered alternatives have strong potential to overcome these limitations. We evaluated an 8 mm-diameter, 1 mm-thick layered electrospun composite formed from polar/hydrophobic/ionic polyurethane with methacrylated gelatin (FD-PHI) and polycarbonate urethane (PCNU), seeded with a co-culture of human adipose-derived stem cells (ASCs) and microvascular endothelial cells (HAMVECs). A 1:2 HAMVEC:ASC ratio supported interconnected CD31⁺ network formation and upregulated key proangiogenic factors (e.g., artemin, IL-1β, CXCL16, Serpin B5, leptin) after 7 days in vitro. Constructs were implanted subcutaneously into immunocompromised rats. Both cellular and acellular layered grafts integrated with the host tissue, aided by interlayer spacing facilitating tissue infiltration; however, cellular constructs exhibited significantly greater vessel density and diameter at 90 days. Pro-angiogenic proteins such as TGFBI, ITGAV, THY1, and PARVA were upregulated at early timepoints, which subsided over time, suggesting that a temporary upregulation may be sufficient to induce long-term outcomes for vascular function. Further proteomic analysis of the explants revealed an upregulation of laminin and collagen VI expression in cellular grafts, suggesting enhanced support for the development of the basement membrane. The work successfully shows the fabrication of a fully autologous EC and fibroblast-like co-culture, from a single adipose sample. This work holds promise as an alternative to current autologous grafting techniques, while overcoming challenges in preparing clinically applicable co-cultures.