Comparison of an in vitro skin model to normal human skin for dermatological research

EpiDerm, an in vitro human skin equivalent (HSE), was compared to normal human breast skin (NHS) to morphologically and biochemically assess its feasibility for dermatological research. Intralot and interlot variability was studied in day 0, 1, 2, and 3 in vitro cultures and in day 0, 3, 5, and 7 NHS. For NHS, light microscopy (LM) at day 0 showed stratified epidermis which exhibited an increase in vacuoles and dark basal cells as storage increased to 3, 5, and 7 days. Transmission electron microscopy (TEM) revealed typical organelles in the epidermis and a convoluted basement membrane at day 0. With increased storage, vacuoles and paranuclear clefts became numerous, necrosis increased, tonofilaments became less organized, and overall cellular integrity decreased. Biochemical data showed consistent MTT and glucose utilization (GU) through day 5, while lactate production decreased to 75% by day 3. By LM, day 0 HSE consisted of a thick, compact, stratum corneum that sent projections between the stratum granulosum cells. By TEM, the configuration organization, differentiation, distribution, and frequency of the organelles differed slightly from NHS. In addition, the basement membrane of the HSE was not completely differentiated, and the dermis was thin and acellular. Although day 1 and 2 cultures showed little change, day 3 exhibited an overall degeneration. Biochemical analysis showed GU and the lactate production decreased through day 3. In conclusion, the EpiDerm HSE, although exhibiting slight differences, was morphologically and biochemically similar to normal human epidermis and may be a valuable model in assessing the toxicology, metabolism, or pharmacology of nonvesicating compounds.