Donor Site Healing Dynamics

Abstract

Understanding the physiology of donor site healing will lead to advances in how these wounds are treated and may ultimately allow faster healing, more frequent autografting, and more effective care of the burn-injured patient. Unfortunately, a paucity of data exists regarding perfusion metrics over the course of donor site healing. Furthermore, there are no studies that interrelate indices of perfusion with the molecular and cellular processes of donor site healing. Male Duroc pigs were anesthetized and donor site wounds were created using a Zimmer dermatome at a depth of 0.060 inch (1.52 mm). Digital photographs, laser Doppler images, and punch biopsies were obtained before and after excision and on days 2, 4, 7, 9, 11, 14, and 16 until wounds were healed. RNA isolation was performed and quantitative polymerase chain reaction was used to examine differential gene expression over the time course. Formalin-fixed biopsies were embedded in paraffin, sectioned, stained, and examined. Wound surfaces were 83% re-epithelialized by day 16. Perfusion peaked on day 2 then declined, but it remained significantly elevated compared to before excision (P < .05). From day 9 onward, mean perfusion units were not significantly different from baseline (P < .05). Twenty-two representative genes were selected for examination. RNA expression of collagen, tenascin-cytoactin, inflammatory cytokines, remodeling enzymes, growth factors, and Wnt was increased. Inflammatory cells and cytokines were demonstrated histologically. Nuclei per high powered field peaked at day 7 and neodermal thickness increased daily to day 14. A novel porcine model for donor site wound healing that interrelates re-epithelilaizationand perfusion with molecular and cellular indices has been demonstrated.

Burn wound healing and treatment: review and advancements

“…In fact, dipeptidyl peptidase IV and aminopeptidase have been identified in burn wound exudate with a significantly different ratio from that found in plasma [164]. Other work on local wound biomarkers using biopsies has shown that a host of proteins are upregulated during wound healing [165]. More work is needed to establish a biomarker profile that can accurately predict wound healing and to identify potential novel areas for therapeutic intervention.…”

Biphasic Presence of Fibrocytes in a Porcine Hypertrophic Scar Model

“…Swine with 3 inch by 3 inch wide and 0.06 inch deep wounds were biopsied every 2 days until healing at 2 weeks, and were the source of biopsies tested for the early presence of fibrocytes until day 14. Our partial thickness wounds reliably heal within 14 days and do not typically result in raised scar 18 . These wounds are well known to our lab to produce a model of normal partial-thickness wound healing, and were interesting to us for the purpose of demonstrating fibrocytes in a model that did not ultimately exhibit hypertrophic healing.…”

A Pilot Study of Negative Pressure Therapy with Autologous Skin Cell Suspensions in a Porcine Model

“…These data indicate that the application of higher viability ASCS increased the rate of % re-epithelialization. In addition, the previously published grading scale for % re-epithelialization 19 was validated here by comparing re-epithelialization scores from blinded assessors with actual measurements of % re-epithelialization made by digital planimetry. This comparison, which showed strong agreement between the two different measurements, indicates that scoring can be used as an option in lieu of actual measurements of % re-epithelialization in future studies.…”

“…Re-epithelialization was measured using two different techniques. In the first technique, digital pictures were used to grade percent re-epithelialization based on a previously published method 19 . Two individual blinded reviewers graded digital pictures from Days 5, 7, 12, and 14 for re-epithelialization and each picture was given a score from 0 to 5.…”