EFFECT OF REPEATED BONE MARROW MESENCHYMAL STEM CELL BY INTRAPERITONEAL INJECTIONS IN A MODEL OF COMPRESSIVE SPINAL CORD INJURY IN MICE

Background: Spinal cord injury (SCI) causes motor and sensory complications, due to the death of neurons, glial cells and demyelination. Cell therapy, has been considered a treatment with potential for functional repair after SCI. Although several studies use different models of spinal cord injury with different types of cell therapy, it is important to emphasize that some questions regarding the benefit that the administration of repeated doses, are doubts that are part of the range of questions that still lack some answers. The aim of this study was to evaluate the effect of applying 2 doses of mesenchymal stem cells (MSCs) in a model of compressive SCI. Methods: Adult female C57BL/6 mice were underwent laminectomy at T9 level, followed by spinal cord compression for 1min with a 30g vascular clip. The animals received an intraperitoneal (i.p.) injection of MSCs (8x10⁵in500μL) or DMEM (500μL), 1 or 1 and 2 weeks after SCI. After that, up to 9 weeks, we performed behavior testing. Than the animals were anesthetized and sacrificed and the samples were processed for light and transmission electron microscopy. Results: The animals that received MSC had a significantly higher score on the BMS scale (MSCI=3,83±0,10,MSCII=5,2±0,33,DMEMI=1,25±0,17 and DMEMII=1,5±0,18) than the animals in other experimental groups and the MSCII animals had a significantly higher score on the BMS than the MSCI animals. In all other functional evaluations, the groups receiving the MSCs transplant demonstrated significant improvements compared to the DMEMs group. The semithin sections analysis revealed tha the number of myelin fibers was higher in the MSC groups than in the DMEM groups (MSCI=962±86,44,MSCII=989,DMEMI=425±51,65 and DMEMII=426±51,55). Conclusions: These findings suggest that the injection of MSCs by i.p. route is a good choice for SCI treatment and the administration of 2 doses of MSCs is more efficient than the administration of a single dose for locomotor recovery.