Development of an Engraftable Skin Equivalent based on Matriderm® with Human Keratinocytes and Fibroblasts

A cell-based wound coverage with keratinocytes and fibroblasts on the basis of a commercially available dermal substitute (Matriderm (R), Kollagen/Elastin matrix) was generated, in order to treat wide burn wounds. First the expansion of keratinocytes was optimised and the culturing time was minimised. Raw material was 1-2 cm(2) split skin. Dermis and epidermis were separated by enzymatic treatment with thermolysin. After treatment of both compartments with trypsin and collagenase I, keratinocytes and fibroblasts were isolated and expanded in collagen I coated dishes. After 10 days fibroblasts were seeded on Matriderm (R). After cultivation of the fibroblasts-containing matrix for one week keratinocytes were seeded on top. After an additional week of submersed cultivation the matrix was lifted up to the air-liquid interface to initiate epidermal cell differentiation. After 16 days in the air-liquid interphase the matrix was fixed and underwent immunohistochemical and electron microscopic analysis. Histological analysis showed a regularly stratification of the epidermal part. We observed collagen IV, a marker for the basement membrane, between epidermis and dermis. Desmoglein and the differentiation markers involucrine and cytokeratin 10 were found in the suprabasal layers of the epidermis. Electron microscopic analysis showed the basement membrane in the epidermal junction zone as well as cell-cell connections in the form of desmosomes. Late differentiation characteristics, like granular structures and the cornified layer, were found in the stratum granulosum and stratum corneum. Our results demonstrate that a skin equivalent can be generated by using a collagen/elastin matrix, with an expansion rate of 50-100-fold. This skin equivalent may be useful for covering deep wounds.