Core Technology

Stratatech’s products StrataGraft™ skin tissue and ExpressGraft™ skin tissue are all based on the NIKS™ (“Near-diploid Immortalized Keratinocytes that form Skin”) human keratinocyte progenitor cell line. The cell line was derived from keratinocytes (the most common and least immunogenic of the cells found in the epidermis) which were isolated from a normal human infant tissue. Of the thousands of cell cultures used in Dr. Allen-Hoffmann’s lab over the last two decades, cells in a single culture dish spontaneously became a “continuous cell line”. In other words, unlike cultured human keratinocytes from other normal skin tissue samples, the cell line can be grown indefinitely in the laboratory. The extensive study of the cell line has demonstrated that it is identical to normal human keratinocytes in its growth, differentiation and skin development properties.

The extraordinary value of the keratinocyte progenitor cell line is its ability to provide in each sample a fully stratified multi-layered human skin substitute with the physical strength and biological characteristics of intact human skin. In other words, when appropriately handled, a sample grows precisely as new human skin grows, exhibiting most of the physical, chemical, and histological properties of “real” skin, as well as stopping such growth when growth abuts neighboring keratinocytes. Because the cell line represents a single cell culture, and now that the culture has been tested for and demonstrated to be absent of pathogens or diseases, additional samples of NIKS™ skin cells can be utilized without costly and time-consuming additional testing.

The Company’s licensed patents on the NIKS™ cells (patent # 5,989,837 “Immortalized human keratinocyte cell line” and 4 additional NIKS™ cell based related patents) have issued and 3 additional applications are pending.

The published journal article on NIKS™ (“Normal Growth and Differentiation in a Spontaneously Immortalized Near-Diploid Human Keratinocyte Cell Line, NIKS” Allen-Hoffmann BL, Schlosser SJ, Ivarie CA, Sattler CA, Meisner LF, and O'Connor SL (2000) Journal of Investigative Dermatology 114 (3) 444-455) is available here.

Producing Human Tissue in the Laboratory

The Company’s human tissue products are made by plating a mixture of collagen and fibroblasts to form a “dermal layer” using standard tissue culture techniques. Once the collagen has gelled the NIKS™ cells are then plated on the collagen in our proprietary StrataLife™ medium. As they grow in the medium, the NIKS™ cells naturally differentiate into all the normal layers of human skin including the Basal, Spinous, Granular layers and ultimately form a true skin “barrier” or Stratum corneum. Full stratification is obtained in about fifteen days.