Clinical study of cell sheets containing allogeneic keratinocytes and fibroblasts for the treatment of partial-thickness burn wounds

Objective To evaluate the efficacy and safety of cell sheets containing allogeneic keratinocytes and fibroblasts in the treatment of partial-thickness burn wounds. Methods The cell sheets containing allogeneic keratinocytes and fibroblasts were constructed using polyurethane biofilm as carrier. Then gross observation and histological observation were conducted. From April 2016 to December 2017, Changhai Hospital of Naval Medical University recruited patients with acute partial-thickness burn wounds that met the inclusion criteria for this prospective and positively self-controlled clinical trial. Recruitment of 40 acute partial-thickness burn wounds were planned with each selected single wound being not smaller than 10 cm×10 cm and not more than 5% total body surface area (TBSA). Each wound was equally divided into two areas, which were recruited into cell sheet group and conventional treatment group according to the random number table. The wounds in cell sheet group were covered by cell sheet and then sterile gauze as secondary dressings. Depending on the wound healing and exudation, the sterile gauze was replaced every 1 to 3 day (s) after the treatment was started, and the cell sheet was replaced every 7 days (namely dressing changing). The wounds in conventional treatment group were covered by sulfadiazine silver cream gauze and then dressed with sterile gauze, with the dressings changed every 2 to 3 days depending on wound exudation. On treatment day 5, 7, 10, and 14, the wound healing rates in the two groups were calculated. The complete wound healing time, the total number of dressing changes, and the status of wound infection during treatment were recorded. The Visual Analogue Scale was used to score the pain at the first dressing change. Scar formation of patients was followed up for 6 to 12 months after injury. Safety indicators including vital signs, laboratory examination indexes, and adverse reactions during treatment were observed. Data were statistically analysed with Wilcoxon rank sum test and Bonferroni correction. Results (1) Each prepared cell sheet had a diameter of about 8 cm and was about 49 cm² in size, containing 2 or 3 layers of keratinocytes and fibroblasts. (2) A total of 43 patients were enrolled, of whom 3 patients dropped out of the study. Of the 40 patients who completed the treatment, there were 22 males and 18 females who were aged 1 to 57 year (s), with total burn area of 2% to 26% TBSA. (3) On treatment day 5, 7, 10, and 14, the wound healing rates in cell sheet group were significantly higher than those in conventional treatment group (Z=4.205, 4.258, 3.495, 2.521, P<0.05 or P<0.01). The complete wound healing time in cell sheet group was 7 (6, 8) days, which was significantly shorter than 11 (7, 14) days in conventional treatment group (Z=4.219, P<0.01). The total number of wound dressing changes in cell sheet group was 1 (1, 2) times, which was significantly less than 6 (4, 7) times in conventional treatment group (Z=5.464, P<0.01). (4) The wounds in cell sheet group in 31 patients healed before the first dressing change. The pain score of wounds in the first dressing change in cell sheet group of 9 patients was 1 (0, 1) point, while the pain score of wounds in the first dressing change in conventional treatment group of 40 patients was 2 (1, 3) points. There was no obvious infection in the wounds in both groups of 40 patients before the wound healing. Nine patients completed the follow-up after the trial. In 6 patients, no scar formation was observed in cell sheet group or conventional treatment group. The color of wounds in cell sheet group was consistent with normal skin, and there was only a small amount of pigment deposition in the wounds of conventional treatment group. Three patients developed pigment deposition only in the wounds of cell sheet group but obvious scars in conventional treatment group. (5) The abnormal fluctuations of vital signs including body temperature, blood pressure, heart rate, respiratory rate, and laboratory examination indexes of all patients during treatment were alleviated through the process of burn wound healing. No obvious adverse reactions or abnormalities related to the treatment were observed. Conclusions The cell sheet containing allogeneic keratinocytes and fibroblasts can reduce the number of dressing changes, accelerate wound epithelialization, shorten wound healing time, reduce pain during dressing change in the treatment of partial-thickness burn wounds, and it may reduce scar hyperplasia after wound healing because of accelerating wound epithelization. Its clinical application is simple, safe, and effective.