Perspectives On Medical Research
Volume 4, 1993
A New Method of Skin Research
Paul Contard
Traditionally, skin research has relied on three methods: animal models, tissue cultures, and mono-layer cell cultures (cells grown in a single layer on the bottom of a culture dish). All three research methods have serious drawbacks. Animal models are expensive, unreliable, and difficult to manipulate experimentally. Tissue cultures are often less inexpensive and more amenable to experimental manipulation than animal models, but microscopically they do not resemble normal tissue and often they do not synthesize the same substances as the normal tissues from which they were derived.
A newly developed cell-culture system in which skin cells are grown on a pre-treated nylon mesh(1) offers exciting possibilities. The technique uses human fibroblasts (cells that form connective tissue) derived from the dermis (lower skin layer). The fibroblasts are seeded into the mesh and allowed to grow in an incubator over several weeks. Cells from the epidermis (upper skin layer) are then seeded onto the cultured dermal cells and incubated for several more weeks. In cooperation with Advanced Tissue Sciences (Lajolla, CA), our laboratory has, over the past two years, studied this system's microscopic and biochemical aspects. Our findings have been highly encouraging.
In its microscopic features (as seen under both light and electron microscopes), this cell-culture system closely resembles normal human skin.(2,3) The system's cells, biochemical and histochemical (chemical composition determined by microscopy) analyses have shown, synthesize the same biological substances as normal human skin, in almost identical quantities -- including various types of collagen, laminin, and fibronectin.(4)
Most promising of all is the system's ability to grow an intact basement membrane completely in culture.(5) The basement membrane's major functions appear to include attaching the overlying epidermis to the underlying dermis and assisting the interaction between these two cell populations. The basement membrane is critical to the normal embryologic development of skin; its dysfunction contributes to several skin diseases characterized by blistering — among them, epidermolysis bullosa and bullous pemphigoid. In addition, the basement membrane plays a crucial role in many other body tissues, including tissues of the lungs, kidneys, gastrointestinal tract, and circulatory system; some diseases of these tissues are associated with basement membrane abnormalities.
This new cell culture technology promises to revolutionize biomedical research. Already, it is being marketed for in vitro toxicology testing, and it may prove highly valuable for studying the course and treatment of a variety of skin diseases. Other tissues, such as pancreatic, liver, and bone tissue,(6) also have been grown in laboratories using this new technology, which may soon render many areas of animal research totally obsolete.
References
1. Naughton G, Naughton BA. A physiologic skin model for in vitro toxicity studies, in Goldberg A (ed). In Vitro Toxicology: New Directions. New York, Mary A. Liebert, 1989.
2. Contard P, Jacobs L, Perlish JS, Fleischmajer R. Collagen fibrillogenesis in a three dimensional cell culture system. Cell Tissue Res, in press.
3. Fleischmajer R, Contard P, Schwartz E, MacDonald ED, Jacobs L, Sakai L. Elastin-associated microfibrils (l0mm) in a three dimensional fibroblast culture. J Invest Dermatol 1991;97:638.
4. Fleischmajer R, MacDonald ED, Contard P, Perlish JS. Immunochemistry of a keratinocyte-fibroblast co-culture model for reconstructing human skin. J Histochem Cytochem, in press.
5. Contard P, Bartel RL, Jacobs JS, et al. Culturing keratinocytes and fibroblasts in a 3-dimensional mesh results in epidermal differentiation and formation of a basal lamina-anchoring zone. J Invest Dermatol 1993;100:35.
6. Rhonda Bartel, Director, epithelial cell culture development, Advanced Tissue Sciences, La Jolla, California, personal communication, 1991.