Effects of systemically transplanted allogeneic bone marrow multipotent mesenchymal stromal cells on rats' recovery after experimental polytrauma

Background: The aim of this study was to evaluate impact of transplantation of bone marrow mesenchymal stromal cells (BM MMSCs) on recovery after polytrauma and bone fracture repair. Methods: A total 27 Wistar-Kyoto rats were divided into three groups (n = 9): normal control (A), polytrauma (B), and polytrauma treated with BM MMSC transplantation (C). The experimental polytrauma model was made on male rats by causing multiple fractures and hemorrhagic shock. At 36 hours 9 days after surgery, nine rats received allogeneic BM MMSCs (1 × 10⁶ cells per kilogram) intravenously. The day before operation and at Days 3 and 10 after surgery as well as at the end of the experiment, blood analysis was carried out. At 10, 20, and 30 days after surgery the rats' locomotor activity was assessed in an open-field test. At Day 30, rats were euthanized, and macroscopic and histologic observations of rats' lower extremities was performed. Results: The treated animals gained weight faster regained their physical activity earlier. These outcomes were associated with locomotor activity test results, blood glucose and lactate ratios, as well as less marked muscle atrophy. Rat treatment with BM MMSC transplantation stimulated bone fracture healing - bone edge consolidation and enhanced callus formation, as well as the size and maturity of newly formed trabeculae. Red blood cell analysis results showed delayed recovery after hemorrhage in the rats receiving allogeneic BM MMSCs: restoration of red blood cell counts, hematocrit level, and hemoglobin level was slower in the untreated animals. Conclusion: Allogeneic BM MMSC transplantation improved rats rehabilitation scores after experimental polytrauma.