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Introduction: Vascularization of the dermal equivalent of full-thickness skin constructs by endothelial cells is highly desirable, because such constructs closely mimic the architecture of real skin. Unfortunately, the realization of a capillary network in skin constructs is still difficult. In our study of full-thickness skin constructs, following the methodologies of Küchler et al. (2011), there were alterations in the epidermal differentiation after endothelialization of the dermal equivalent. The aim of this study wasto characterize these changes on a morphological level.
Material and methods: Non-endothelialized constructs (keratinocytes, fibroblasts) were prepared according to Küchler et al. (2011). To obtain endothelialized constructs, the dermal equivalent of the non-endothelialized constructs was enriched with endothelial cells. After two weeks of in vitro culture, the skin constructs were processed for quantitative as well as qualitative assessment by light and electron microscopy.
Results: Both types of skin construct developed all strata, i.e., stratum basale, spinosum, granulosum, corneum of a stratified soft-cornified epidermis, although the two constructs displayed differences in every stratum: Significantly more mitoses occurred in the epithelial germ layers of the endothelialized constructs (p=0.013). In addition, significantly more keratohyalin granules were counted within their stratum granulosum (p=0.010). 50% of the shapes of the spinous and the granulosum cells were irregular and these cells were separated by wide intercellular spaces. The typical epidermal lamellar bodies appeared in the endothelialized constructs more often than in the nonendothelialized ones. At the stratum granulosum – stratum corneum interface, no cohesion between the strata was present.
Conclusion: The endothelialization of the dermal equivalent caused changes in the epidermal layer of the endothelialized skin constructs that may be interpreted as features of excessive epidermal differentiation.