Xeno-free and Chemically Defined Human System for Culturing Human Epidermal Keratinocytes

Developing an effective xeno-free and defined system for human keratinocyte culture has been one of the fundamental measures in current cellular therapy. For keratinocytes, in particular, such system will not only fulfill clinical safety and quality criteria, it will allow for the management of less severe burns and other skin injuries such as chronic wounds. To date, the expansion of autologous keratinocytes in the clinical settings still relies on 3T3 feeder co-culture system. Here we report a completely xeno-free and defined culture system by using human recombinant laminins as feeder replacement. We have thoroughly characterized the cells cultured in this new system both in vitro and in vivo. We found that laminin-511/-521, and the unanticipated laminin-411/-421, but not -332, -111, -121, -211, or LN-221 support adult human skin keratinocytes and could maintain their self-renewal properties comparable to the 3T3 system. We believe our new culture method should facilitate broader use of cultured epithelial cell products for today's regenerative medicine. Overall design: RNA sequencing and analysis on whole adult human skin or freshly cultured human keratinocytes using two different methods: co-cultured with 3T3 feeder and laminin-coated tissue culture plates.