The efficacy of cryopreserved ex vivo expanded rat bone marrow-derived multipotent mesenchymal stromal cells in the repair of radiation injuries in rats
Authors:   Grigoriev Institute for Medical Radiology of the National Academy of Medical Sciences of Ukraine, Kharkiv, Ukraine, Uzlenkova N. , Skorobogatova N. ,   Grigoriev Institute for Medical Radiology of the National Academy of Medical Sciences of Ukraine, Kharkiv, Ukraine, Kryvko A. ,   Grigoriev Institute for Medical Radiology of the National Academy of Medical Sciences of Ukraine, Kharkiv, Ukraine, Krasnoselsky M. ,   Grigoriev Institute for Medical Radiology of the National Academy of Medical Sciences of Ukraine, Kharkiv, Ukraine
Published: August 2022

At present, applying multipotent mesenchymal stromal cells (MSCs) as cell therapy for radiation damages have gained increasing attention since current medical management remains far from satisfactory. The aim of the study is to examine the efficacy of cryopreserved ex vivo expanded bone marrow-derived MSCs (rBM-MSCs) to the repair of radiation injuries on rat models of total and local radiation exposure. Materials and methods. The MSCs were derived from bone marrow of non-irradiated female albino rats aged 4 months, short-term ex vivo expanded for two passages and cryopreserved under dimethyl sulfoxide cryoprotection for low temperature storage at -70 oC for 6-12 months. The cryopreserved samples from each batch of rBM-MSCs culture were tested for the viability and functional characteristics before being transplanted to rats in experiments in vivo. The acute radiation damages in rats were modeled by total body irradiation (TBI) at doses of 5.5 Gy (TBI 5.5) and 7.0 Gy (TBI 7.0) and locally irradiated in the right hip skin at a dose of 50 Gy. The cryopreserved rBM-MSCs (1.5•106 and 0.5•106 cells/animal) were intravenously transplanted within 24 h following TBI and locally injected (twice 1.5•106 Cells/animals) on days 15 and 21 following thigh irradiation. The efficacy of cryopreserved rBM-MSCs was assessed by survival and hematological study as well as the irradiated skin wound healing assay. Results. The cryopreserved ex vivo expanded rBM-MSCs were characterized by high level of functional activity with cell viability about 80 %, include at least 8.5 % of the colony forming MSCs and MSCs with ability to adipogenic and osteogenic differentiation In TBI 5.5 rats, cryopreserved transplanted rBM-MSCs (1.5·106 cells/animal) prevented acute leukopenia in the first critical days of the radiation injury by increasing the number of leukocytes by 3.7 times on day 2 and contributed to a more complete recovery of hematological disorders by increasing the BM cells number and platelet count on day 22, which led to the increase of the increase of overall survival up to 100 % with a regain of body weight. In TBI 7.0 rats, the lower transplanted dose of rBM-MSCs (0.5•106 cells/animal) was more effective in terms of general recovery and extended the overall survival time for 6 days. The locally injected rBM-MSCs (twice 1.5•106 cells/animals) reduced the severity and promoted the healing of radiation skin wounds according to the results of scoring and wound size assay. Conclusion. The present study confirms that the cryopreserved ex vivo expanded rBM-MSCs were functionally complete for the therapeutic use on rat models of experimental radiation damage and were effective for the recovery of hematopoietic system and severe skin wound after radiation exposure.