Is the subarachnoid administration of mesenchymal stromal cells a useful strategy to treat chronic brain damage?

Background aims. Traumatic brain injury (TBI) is a leading cause of mortality and morbidity worldwide. Developing effective protocols for the administration of mesenchymal stromal cells (MSCs) is a promising therapeutic strategy to treat TBI. It is important to develop alternatives to direct parenchymal injection at the injury site because direct injection is an expensive and invasive technique. Subarachnoid transplantation, a minimally invasive and low-risk procedure, may be an important and clinically applicable strategy. The aim of this study was to test the therapeutic effect of subarachnoid administration of MSCs on functional outcome 2 months after an experimental TBI in rats. Methods. Two months after TBI, 30 female Wistar rats were divided into 3 groups (n = 10 in each group): sham, MSC (received 2 x 106 MSCs) and saline (received only saline) groups. Neurological function, brain and spinal cords samples and cerebrospinal fluid were studied. Results. No significant differences were found in neurological evaluation and after histological analysis; differences in the expression of neurotrophins were present but were not statistically significant. MSCs survived in the host tissue, and some expressed neural markers. Conclusions. Similar to direct parenchymal injections, transplanted MSCs survive, migrate to the injury cavity and differentiate into mature neural cell types for at least 6 months after engraftment. These results open the possibility that MSC administration through subarachnoid administration may be a treatment for the consequences of TBI. The transplantation technique and cell number should be adjusted to obtain functional outcome and neurotrophin production differences.