Rapid intraoperative construction of autologous EpiSCs-loaded scaffold + split-thickness skin graft （one-step or two-step procedure）

Autologous split-thickness skin (0.15-0.2 mm) is harvested from the donor site at a donor-to-wound area ratio of 1:20-30. The harvested skin is processed using a specialized cell sorter to isolate autologous epidermal stem cells (EpiSCs) with >93% viability within 30 minutes. The cell suspension is adjusted to a concentration of ≥1×10⁶ cells/mL and loaded onto a tissue-engineered scaffold via spraying or immersion (3-5 minutes). The cell-seeded scaffold is then applied to the wound bed. Depending on wound condition: (1) One-step procedure: scaffold and a split-thickness skin graft (0.15-0.2 mm) are applied simultaneously; (2) Two-step procedure: scaffold is implanted first, followed by split-thickness skin graft at 14±3 days post-primary surgery. Negative pressure wound therapy (-100 to -125 mmHg) is applied as needed.

The percentage of participants achieving complete wound epithelialization （defined as 100% re-epithelialization without drainage or dressing requirements）

Incidence of wound recurrence at the healed site

Scar quality is assessed using the Vancouver Scar Scale (VSS) and the Patient and Observer Scar Assessment Scale (POSAS) at 4 weeks, 3, 6, and 12 months post-surgery. The VSS total score ranges from 0 to 13, with higher scores indicating worse scar outcome (assessing vascularity, pigmentation, pliability, and height). The POSAS includes two separate subscales: the Observer Scale (6 items, each scored 1 to 10, total range 6-60) and the Patient Scale (6 items, each scored 1 to 10, total range 6-60). For both POSAS subscales, higher scores represent worse scar outcome.