Development of a cultured dermal substitute composed of a spongy matrix of hyaluronic acid and atelo-collagen combined with fibroblasts: Cryopreservation

An allogeneic cultured dermal substitute (CDS) was prepared by cultivating fibroblasts on a two-layered spongy matrix of hyaluronic acid (HA) and atelo-collagen (Col). The ability of fibroblasts to secrete cytokines is dependent on the conditions of freezing and thawing. The first experiment was designed to investigate the effects of supplements in a cryoprotective medium, that is, dimethylsulfoxide (DMSO), glycerol, and fetal bovine serum (FBS). In each experiment we measured the cell viability after thawing and the cell growth in CDS recultured after thawing. In addition, the amount of vascular endothelial growth factor (VEGF) released from the CDS recultured for one week after thawing was measured. The highest values of cell viability, cell growth, and the amount of VEGF released were obtained when CDS was frozen in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% DMSO and 40% FBS, and then thawed quickly in a water bath at 37degreesC. However, due to the high cost of FBS, in clinical applications CDS is usually frozen in DMEM supplemented with 10% DMSO and 20% FBS. In practice, however, physicians often cannot use CDS immediately after thawing, depending on clinical conditions. Therefore, in the second experiment we investigated cell viability at different time points after thawing. In addition, we investigated cell growth and the amount of VEGF released from fibroblasts in CDS at different time points after thawing under different conditions, and after further reculturing for one week. We recommend that CDS be rinsed with lactated Ringer's solution immediately after thawing, and that it be used within 4 h after thawing.