Cryopreserved tissue engineered mucosa.

Single cells suspensions used for grafting in the clinical setting may be reliably cryopreserved by established protocols. However, for tissue engineered constructs which now also get used as grafts in the clinic such established protocols and assays which indicate graft viability and their function as graft do not exist. a) The purpose was to develop a cryoprotocol and an animal model to test the efficacy of tissue engineered to act as graft after cryopreservation. b) Therefore, tissue engineered mucosa grafts consisting of keratinocytes and fibroblasts grown in a collagen sponge were cryopreserved and grafted in the nude rat to test its efficacy to function as mucosa graft. At different points after cryopreservation the mucosa was grafted into the nude rats. Healing of grafts was allowed for one or three weeks. c) Sufficient cells survived the cryopreservation allowing for the development of epithelial-fibroblast tissue in the collagen sponge. After three weeks of healing the formation of mucosa tissue was more complete and more collagen sponge had disappeared. d) The nude rat model is suitable to assess the efficacy of tissue engineered mucosa to function as graft after cryopreservation. The formation of human epithelial-fibroblast tissue in vivo has to be interpreted as proof of principle that the approach of cryopreservation of tissue engineered grafts is working.