Tissue engineering concerns both the generation of healthy tissues and diseased tissues in order to better understand various pathological conditions. The establishment of human cell-based in vitro engineered disease model systems could represent a paradigm shift from inadequate conventional monolayer cell cultures, or moderately successful animal models, towards more physiologically tissue-relevant, patient-specific approaches.
This concept of in vitro diseased skin models is illustrated by the models for recessive epidermolysis bullosa simplex (REBS) and cutaneous squamous cell carcinoma (SCC) that were developed in our laboratory. REBS is characterised by severe intra-epidermal blister formation, resulting from fragility of the basal keratinocytes that lack keratin tonofilaments due to a homozygotic null mutation in the keratin 14 gene. In vivo EBS models, including murine and canine models, are limited and do not represent the human microenvironment. Earlier in vitro studies have indicated an essential role for fibroblasts in the REBS phenotype; however, the limited availability of human REBS skin samples hampered further in vitro research on dermal-epidermal interactions in REBS. To overcome this, an explant approach was used in which REBS skin biopsies were placed on a dermal equivalent in which REBS-associated fibroblasts were seeded (1).
A similar approach was used to construct an in vitro model for human SCC, which is a malignant tumour of epidermal keratinocytes characterised by invasive growth into the dermis (2). After basal cell carcinoma, SCC is the most common malignancy in white populations with epidemic incidence rates. Traditional in vivo SCC models rely on the use of chemical, genetic or mechanical induction or propagation of carcinogenesis in mice. Current in vitro approaches are limited to the use of cell lines, which often lack a true representation of primary skin cancer. The development of a representative in vitro skin carcinoma model based on primary SCC biopsies allows for a better understanding of fundamental carcinogenesis mechanisms and may serve as a validated pre-screening platform for candidate drugs, thereby eradicating the need for animals for these purposes.
Figure 2: Mimicking skin diseases in-vitro: (A) Clinical manifestation of Recessive Epidermolysis Bullosa Simplex (Blister disease); (B) REBS biopsy cultured onto the skin model; (C) Cross section of a skin model in which REBS has been mimicked; (D) Clinical manifestation of a squamous cell carcinoma; (E) SCC cultured onto the skin model; Cross section of a skin model mimicking SCC.
- ZONMW: “Development of validated organotypic in vitro models leading to improved therapy of skin cancer”. Project Leaders, Frank de Gruijl, Kees Tensen en A El Ghalbzouri.
- STW: "Generation of an atopic dermatitis reconstructed skin model as a tool to screen for therapeutics”. In collaboration with Prof.dr.J.Bouwstra, Faculty of Science, Leiden/Amsterdam Center for Drug Research, Drug Delivery Technology.