Tissue-engineered Skin Products Research Articles

Analysis of attitudes toward the source of progenitor cells in tissue‐engineered products for use in burns compared with other disease states

The first trials using progenitor cells to improve burn wound healing are beginning. However, there remains a paucity of data on patients' opinions of the source of stem cells. In this study, 279 patients attending plastic surgery/burns outpatient and medical outpatient clinics were questioned to assess willingness to accept a tissue-engineered skin product derived from a variety of sources. Levels of acceptance for the use of progenitor cells derived from these sources for treatment across a range of disease states (burns, Parkinson's disease, diabetes, and for cosmetic use) were also assessed. Overall, 80% of those questioned would accept a tissue-engineered product. Autologous cells were the preferred choice of cells (acute burns 94%, diabetes 95%, Parkinson's 93.9%). Allogeneic cells were still widely accepted (acute burns 67%, diabetes 66.7%, Parkinson's 69.2%). There was no difference observed between plastic surgical patients and medical patients in acceptance of cell therapy for burns, Parkinson's disease, or diabetes. There is good potential acceptance for the use of both autologous and allogeneic cells for the treatment of acute burns and burns' scarring as well as in diabetes and Parkinson's disease. Disease state does not appear to influence overall acceptability and choice of cells.

A Pilot Study to Evaluate a Tissue‐Engineered Bilayered Cell Therapy as an Alternative to Tissue From the Palate

This study evaluated the safety and effectiveness of a tissue-engineered skin product composed of viable neonatal keratinocytes and fibroblasts and compared it to a free gingival graft (FGG) in a procedure to enhance keratinized tissue (KT) and wound healing around teeth that do not require root coverage. Twenty-five subjects were enrolled who had at least two non-adjacent teeth in contralateral quadrants exhibiting an insufficient zone of attached gingiva requiring soft tissue grafting where root coverage was not desired. One tooth was randomized to receive an FGG, and the other was randomized to receive bilayered cell therapy (BCT). The amount of KT was measured at baseline and 3 and 6 months, and the texture and color of the grafted tissue were compared to the surrounding tissue at months 1, 3, and 6. A questionnaire was used to determine subject preference at 6 months. Biopsies and persistence studies were performed on a subset of the subjects. The FGG generated statistically significantly (P <0.001) more KT than the test device (BCT) (4.5 +/- 0.80 mm versus 2.4 +/- 1.02 mm); no significant difference in recession or clinical attachment level was detected between treatment groups (P = 0.212 and P = 0.448, respectively); and no significant differences were detected at any time point for bleeding on probing (BOP), resistance to muscle pull, or inflammation. The BCT group had significantly better color and texture match with surrounding tissue (P <0.001), and subject preference was significantly greater for the BCT group (P = 0.041). No device-related adverse events or safety issues occurred during the course of the study. The tissue-engineered graft BCT was safe and capable of generating de novo KT without the morbidity and potential clinical difficulties associated with donor-site surgery. The amount of KT generated with FGG was greater than generated with BCT; however, 24 of 25 test sites demonstrated an increase in KT at 6 months, with more than three-quarters of the sites yielding > or =2 mm bands of KT.

Best‐practice algorithms for the use of a bilayered living cell therapy (Apligraf®) in the treatment of lower‐extremity ulcers

Tissue-engineered skin substitutes such as Apligraf have emerged over the past 20 years as among the most carefully studied and efficacious of the advanced wound modalities. These products have been proven as effective enhancements to general wound care, promoting wound closure particularly in instances where conventional wound care fails. Marketed for hard-to-heal wounds since 1998, Apligraf has become part of standard wound care in many wound centers across the United States. Despite this situation, few general wound care guidelines incorporate advanced and active wound-healing technologies, such as tissue-engineered skin products. Because of this deficiency, appropriate patient selection and proper use of these product remain largely unaddressed within the general wound care community. Here, we describe the development of guidelines surrounding optimal use of the bilayered living cell therapy, Apligraf, in the treatment of the two types of lower extremity ulcers for which the product is FDA approved: venous leg ulcer and diabetic foot ulcer. The guidelines detailed in this article focus on the identification and selection of patients who are at risk for failure of standard wound care therapy and thus appropriate for Apligraf treatment. The intended audience for these guidelines is the general wound care practitioner, for whom the developed treatment algorithms and accompanying figure legends should provide practical, user-friendly direction simplifying both patient selection and appropriate use of Apligraf within the context of good wound-healing practice.

Applied tissue engineering in the closure of severe burns and chronic wounds using cultured human autologous keratinocytes in a natural fibrin matrix.

Whereas in severe burns cultured human epithelial cells may well serve as a life saving method, the true value of tissue-engineered skin products in chronic wound care has yet to be clearly defined. Among other well-known clinical problems, the engraftment rate of commercially available multilayered "sheet grafts" has been shown to vary extremely. Adherence of transplanted cells to the wound bed--especially in the presence of potential wound contamination-- is one of the crucial aspects of this technique. Keratinocyte suspensions in a natural fibrin sealant matrix can potentially treat a variety of skin defects. In acute burn wounds, as well as in chronic wounds the clinical application of this type of tissue-engineered skin substitute demonstrates the capacity of cultured human autologous keratinocytes in a fibrin sealant matrix to adhere to wound beds, attach and spread over the wound resulting in reepithelialization of both acute and chronic wounds. In full thickness burns the combination of this new tool with allogenic dermis is a promising option to achieve complete dermal-epidermal reconstitution by means of tissue engineering and guided tissue repair. When transferring this technique into the treatment of chronic wounds we found an optimal preparation of such recipient wound beds to be crucial to the success. The additional application of continuous negative pressure (vacuum therapy) and preliminary chip skin grafting to optimally prepare the recipient site may be helpful tools to achieve such well-prepared and graftable surfaces. Prospective controlled comparative studies should be designed to further assess the clinical efficacy of this technique.

Effects of hormone and growth factor on formation of fibroblast-aggregates for tissue-engineered skin

To accelerate wound healing after implantation of tissue-engineered skin products, higher density inoculation of fibroblasts would be important. Therefore, we attempted to develop a tissue-engineered skin with a higher density of fibroblasts by formation of cell aggregates combined with a biodegradable polymer. Our method consisted of rotationally shaking with nontreated dishes, declining fibroblast-material interactions, and augmenting cell–cell interaction. Under the culture condition, normal neonatal human dermal fibroblasts formed spheroidal aggregates. The formation of the fibroblast-aggregates was accelerated by the addition of insulin, dexamethasone, basic fibroblast growth factor, and ascorbic acid to basal medium, and by the control of shaking time. In fibroblast-aggregates formed under a basal medium, the level of gene expression related to wound healing was higher than that of a monolayer when one added the hormones and growth factors. Therefore, tissue-engineered skin products with aggregates and scaffolds would become an artificial skin with potentiality of higher wound healing.

Experience with a new human skin equivalent for healing venous leg ulcers

Leg ulcers affect about 650,000 adults each year and in every setting—rural, urban, and both economically developed and impoverished areas. Both the physical and the psychologic aspects of treatment present challenges to the caregiver. The nurse must be aware of new techniques for treatment and be able to educate patients about potential modalities for healing. A human skin equivalent, Apligraf, will soon be available for treatment of these wounds. The results of controlled, multicenter studies indicate that human skin equivalent interacts with the patient's own cells, responds to individual wound characteristics, and promotes healing. The nursing professional can readily master the application technique and will find that this tissue-engineered skin product offers a new approach to wound management.