Use of epidermal skin grafts in chronic wounds: a case series

Use of Cultivated Epidermal Allograft in Chronic Wounds: A Novel Therapeutic Alternative

Introduction

Chronic wounds represent a frequent cause of consultation for plastic and reconstructive surgeons. The use of epidermal culture stands out because they provide complete epithelialization, adequate aesthetic-functional results, and no morbidity for the patient. Epifast® is a pre-manufactured cultured epidermal allograft derived from the amplification in vitro of human keratinocytes.

Materials and Methods

A prospective longitudinal multicenter study was carried out in four chronic wound reference centers, which were in charge of plastic and reconstructive surgery services. For a standardized wound bed preparation, the protocol synthesized by the acronym "TIME" was used. At the end of the "TIME" protocol, the pre-fabricated allograft was applied and removed 7 days after its application.

Results

A total of 133 patients with diagnosis of chronic wound were included in the study. The median age was 69.3 ± 13.6 years. The most common comorbidity found was diabetes mellitus type 2 in 71.4% of the patients (n = 95) and systemic arterial hypertension in 60.2% of the patients (n = 80). The most frequent location of chronic wounds was seen in the lower extremity with 45.1% (n = 60). The mean duration for it to close was 46 ± 14 days, in which they closed within the first 3 months in 93% (n = 125) of the cases. About 91.7% (n = 122) of the wounds achieved total closure.

Conclusion

Cultured epidermal allograft, combined with a meticulous technique and an adequate selection of patients, represents a safe and effective tool for chronic wounds.

A Concise Review on Tissue Engineered Artificial Skin Grafts for Chronic Wound Treatment: Can We Reconstruct Functional Skin Tissue In Vitro?

Chronic wounds occur as a consequence of a prolonged inflammatory phase during the healing process, which precludes skin regeneration. Typical treatment for chronic wounds includes application of autografts, allografts collected from cadaver, and topical delivery of antioxidant, anti-inflammatory, and antibacterial agents. Nevertheless, the mentioned therapies are not sufficient for extensive or deep wounds. Moreover, application of allogeneic skin grafts carries high risk of rejection and treatment failure. Advanced therapies for chronic wounds involve application of bioengineered artificial skin substitutes to overcome graft rejection as well as topical delivery of mesenchymal stem cells to reduce inflammation and accelerate the healing process. This review focuses on the concept of skin tissue engineering, which is a modern approach to chronic wound treatment. The aim of the article is to summarize common therapies for chronic wounds and recent achievements in the development of bioengineered artificial skin constructs, including analysis of biomaterials and cells widely used for skin graft production. This review also presents attempts to reconstruct nerves, pigmentation, and skin appendages (hair follicles, sweat glands) using artificial skin grafts as well as recent trends in the engineering of biomaterials, aiming to produce nanocomposite skin substitutes (nanofilled polymer composites) with controlled antibacterial activity. Finally, the article describes the composition, advantages, and limitations of both newly developed and commercially available bioengineered skin substitutes.

Inhibitory effect of red LED irradiation on fibroblasts and co-culture of adipose-derived mesenchymal stem cells

The objective of this study was to evaluate the effects of red Light Emiting Diode (red LED) irradiation on fibroblasts in adipose-derived mesenchymal stem cells (ASC) co-culture on the scratch assay. We hypothesized that red LED irradiation could stimulate paracrine secretion of ASC, contributing to the activation of genes and molecules involved in cell migration and tissue repair. ASC were co-cultured with NIH/3T3 fibroblasts through direct contact and subjected to red LED irradiation (1.45 J/cm²/5min6s) after the scratch assay, during 4 days. Four groups were established: fibroblasts (F), fibroblasts + LED (FL), fibroblasts + ASC (FC) and fibroblasts + LED + ASC (FLC). The analyzes were based on Ctgf and Reck expression, quantification of collagen types I and III, tenomodulin, VEGF, TGF-β1, MMP-2 and MMP-9, as well as viability analysis and cell migration. Higher Ctgf expression was observed in FC compared to F. Group FC presented higher amount of tenomodulin and VEGF in relation to the other groups. In the cell migration analysis, a higher number of cells was observed in the scratched area of the FC group on the 4^th day. There were no differences between groups considering cell viability, Reck expression, amount of collagen types I and III, MMP-2 and TGF-β1, whereas TGF-β1 was not detected in the FC group and the MMP-9 in none of the groups. Our hypothesis was not supported by the results because the red LED irradiation decreased the healing response of ASC. An inhibitory effect of the LED irradiation associated with ASC co-culture was observed with reduction of the amount of TGF-β1, VEGF and tenomodulin, possibly involved in the reduced cell migration. In turn, the ASC alone seem to have modulated fibroblast behavior by increasing Ctgf, VEGF and tenomodulin, leading to greater cell migration. In conclusion, red LED and ASC therapy can have independent effects on fibroblast wound healing, but the combination of both does not have a synergistic effect. Therefore, future studies with other parameters of red LED associated with ASC should be tested aiming clinical application for tissue repair.

Stratification of chronic and complex wounds according to healing characteristics: a retrospective study

OBJECTIVE

Wound risk-stratified analyses are clinically relevant as they can assist in identifying hard-to-heal wounds. The aim of the study is to develop risk categories for wound healing based on a limited number of reliably recordable clinical data.

METHOD

This retrospective study used observational data. The primary outcome measure was wound healing at the end of treatment and the secondary outcome measure was the time to wound healing. A stratification model using regression analyses was developed to assign the patients to risk categories for wound healing and the time-to-heal.

RESULTS

The study cohort comprised of 540 patients. The most common wound diagnoses were diabetic ulcers, wounds in irradiated areas and wound dehiscence after surgery. Average wound duration before starting treatment at the wound centre was 11.7 months. Healing was achieved in 382 (71%) wounds, after an average treatment time of 4.4 months. A total of four risk categories for wound healing were developed by combining wound diagnosis (favourable versus unfavourable) and duration (<3 months versus >3 months). These risk categories demonstrated healing percentages ranging from 69-97% (p=0.0004) and mean time-to-healing varying from 2.7-5.9 months (p=0.01).

CONCLUSION

Using two clinical wound variables, diagnosis and duration, stratification categories were identified with significant associations with wound healing outcomes. Longer wound duration and unfavourable diagnoses, when combined into unfavourable risk categories, were associated with a lower percentage of wound healing and a longer treatment time until healing.