Randomized, controlled, single-blind study on use of autologous keratinocytes on a transfer dressing to treat nonhealing diabetic ulcers

A review of tissue-engineered skin bioconstructs available for skin reconstruction

Situations where normal autografts cannot be used to replace damaged skin often lead to a greater risk of mortality, prolonged hospital stay and increased expenditure for the National Health Service. There is a substantial need for tissue-engineered skin bioconstructs and research is active in this field. Significant progress has been made over the years in the development and clinical use of bioengineered components of the various skin layers. Off-the-shelf availability of such constructs, or production of sufficient quantities of biological materials to aid rapid wound closure, are often the only means to help patients with major skin loss. The aim of this review is to describe those materials already commercially available for clinical use as well as to give a short insight to those under development. It seeks to provide skin scientists/tissue engineers with the information required to not only develop in vitro models of skin, but to move closer to achieving the ultimate goal of an off-the-shelf, complete full-thickness skin replacement.

Development of biodegradable electrospun scaffolds for dermal replacement

Our objective is to develop a synthetic biodegradable replacement dermal substitute for tissue engineering of skin and oral mucosa. Our in vivo criteria were that candidate scaffolds should allow surrounding cells to migrate fully into the scaffolds, enabling vasculogenesis and remodelling without invoking a chronic inflammatory response. We examined a total of six experimental electrospun polymer scaffolds: (1) poly-l-lactide (PLLA); (2) PLLA+10% oligolactide; (3) PLLA+rhodamine and (4-6) three poly(d,l)-lactide-co-glycolide (PLGA) random multiblock copolymers, with decreasing lactide/glycolide mole fractions (85:15, 75:25 and 50:50). These were evaluated for degradation in vitro up to 108 days and in vivo in adult male Wistar rats from 4 weeks to 12 months. In vivo, all scaffolds permitted good cellular penetration, with no adverse inflammatory response outside the scaffold margin and with no capsule formation around the periphery. The breakdown rate for each scaffold in vitro versus in vivo was similar, and an increase in the ratio of polyglycolide to polylactide correlated with an increase in breakdown rate, as expected. Scaffolds of PLLA were stable in vivo even after 12 months whereas scaffolds fabricated from PLGA 85:15 and 75:25 revealed a 50% loss of mass after 4 and 3 months, respectively. In vitro PLGA 85:15 and 75:25 scaffolds were able to support keratinocyte, fibroblast and endothelial cell growth and extracellular matrix production, with evidence of new collagen production after 7 days. In conclusion, the data supports the development of PLGA 85:15 and 75:25 electrospun polymer scaffolds as potential degradable biomaterials for dermal replacement.

Simplifying the delivery of melanocytes and keratinocytes for the treatment of vitiligo using a chemically defined carrier dressing

Obtaining pigmentary function in autologous skin grafts is a current challenge for burn surgeons as is developing reliable robust grafting strategies for patients with vitiligo and piebaldism. In this paper, we present the development of a simple methodology for delivering cultured keratinocytes and melanocytes to the patient that is of low risk for the patient but also user friendly for the surgeon. In this study, we examined the ability of keratinocytes and melanocytes to transfer from potential cell carriers under different media conditions to an in vitro human wound bed model. The number of melanocytes transferred, their location within the neoepidermis, and their ability to pigment were evaluated as preclinical end points. Two inert substrates (polyvinyl chloride and silicone sheets) and three candidate plasma-polymerized coatings with controlled surface chemistry deposited on these substrates were explored. Two media for expansion of cells, Greens, currently used clinically (but which contains fetal calf serum), and a serum-free alternative, M2 (melanocyte medium), were explored. Reproducible transfer of physiologically relevant numbers of melanocytes capable of pigmentation from the coculture of melanocytes and keratinocytes was obtained using either Greens medium or M2 medium, and a silicone carrier pretreated with 20% carboxylic acid deposited by plasma polymerization.