Autologous Meshed Graft Healing Within the Interstice versus Surrounding Adhered Split Thickness Skin Sites: Where Should Tissue Biopsies be Taken to Assess Tissue-Level Histoarchitecture?

INTRODUCTION

Meshed split thickness skin grafts are a common treatment for full thickness wounds because they allow for expansion of skin taken from a relatively small donor site. Meshed wound healing is not homogenous as sites that are in direct contact with the grafts display distinct healing characteristics compared to areas that are not in contact with the grafts, and this may affect study outcomes reliant on tissue biopsies. This study aims to characterize the differences between adhered split thickness skin (aSTS) sites and aSTS-free sites from tissue punch biopsies.

METHODS

Wounds were created in Duroc pigs and were excised down to subcutaneous tissue, split thickness skin graft was harvested, meshed, and was either applied to the prepared wound beds or wounds were left nongrafted. Full thickness punch biopsies (3 mm diameter) from either the aSTS area, aSTS-free, or nongrafted area were taken at each time point, processed, Hematoxylin and Eosin- or Herovici-stained, and imaged. Images were used to quantify histoarchitectural characteristics.

RESULTS

In the grafted wounds, epidermis formation and undulated rete ridge appendages were noticeable early in healing in aSTS sites. Dermal thickness was elevated in the aSTS-free and nongrafted wounds. Cellularity was greater in the aSTS-free compared to the aSTS sites. The aSTS site most closely resembled uninjured skin with respect to collagen types. Collagen fiber orientation was higher in the aSTS-free compared to the nongrafted sites (P < 0.05).

CONCLUSIONS

These data show that within a single grafted burn wound, healing is a heterogenous process. An improved understanding of the heterogeneity of healing wounds and timing of return to normal skin function in different areas will help researchers to conduct more nuanced histoarchitecture outcome-based translational research in preclinical and clinical trials.