The Influence of Mesenchymal Stem Cells of Adipose Tissue and Paracrine Factors of Conditioned Medium on the Healing of Radiation Ulcers in the Treatment of Severe Radiation Injuries of Skin in Rats

Abstract

Purpose: Studying of the effects transplantation of cultured mesenchymal stem cells of adipose tissue (MMSC) and adipose-derived stromal vascular fraction (SVF), as well as the introduction of paracrine factors (PF) of conditioned medium in an isolated or combined application for severe local radiation skin lesions in the experiment.
 Material and methods: Rats of the inbred Wistar–Kyoto strain were irradiated to local X-rays exposure in the iliolumbar region of the back at a dose of 110 Gy. The transplantation of cultured MMSC was performed twice at doses of 2.1 × 106 and 2.6 × 106 on the 28th and 35th days after irradiation. Adipose-derived SVF was administered at the same time in doses of 3.2 × 106 and 2.8 × 106, respectively. PF were administered five times from the 1st to the 10th day after irradiation. The severity of radiation damage to the skin and the effects of therapy were evaluated in dynamics by clinical manifestations, using planimetry and histological methods.
 Results: Radiation exposure with these parameters caused severe radiation injuries of the skin with non-healing ulcers formed by the 21–25th day after irradiation. The area of radiation ulcers in rats of the control group in the period from the 26th to the 83rd day slowly decreased from 2.76 ± 0.12 cm2 to 1.85 ± 0.13 cm2. In 50 % of the animals in the control group, ulcers persisted for more than 4 months after irradiation. In rats of the experimental groups, more intensive healing and a decrease in the area of radiation ulcers was noted. With isolated administration of cultured MMSC or SVF, a statistically significant decrease in the area of ulcers compared with the control was observed on the 104–125th day, and with the introduction of PF on the 83rd day after irradiation, p <0.05. In the control group, by the118th day after irradiation, radiation ulcers healed only in 25 % of rats, and in the experimental groups with isolated administration of cultured MMSC, SVF and PF in 40–55 % of the rats showed complete epithelialization of wounds with the formation of an atrophic scar. Under the conditions of combined use of stem cells and conditioned medium factors, the number of animals with complete healing of radiation ulcers was 85–100 % by 118th days, p <0.05.
 Conclusion: Thus, transplantation of cultured MMSC of adipose tissue and adipose-derived SVF, as well as the introduction of PF of conditioned medium, can enhance the regeneration processes and stimulate skin regeneration, promoting earlier healing of chronic radiation ulcers in severe local radiation injuries. Moreover, with the combined introduction of PF and adipose-derived stem cell transplantation, the effectiveness of the healing of radiation ulcers was increases.