Delayed intralesional transplantation of bone marrow stromal cells increases endogenous neurogenesis and promotes functional recovery after severe traumatic brain injury

Primary objective: To investigate the utility of delayed transplantation of bone marrow stromal cells (BMSC) to improve the neurological sequels after traumatic brain injury (TBI). Methods: Adult Wistar rats were subjected to weight-drop impact causing severe brain injury, and 2 months later, BMSC in saline, or saline alone, were injected into injured brain tissue. Both experimental groups were evaluated by means of rotarod and modified neurologic severity scores (mNSS) tests in the course of the two following months. At this time, the animal were sacrificed and their brains were studied by means of histological and immunohistochemical techniques. Results: Rotarod and mNSS tests showed progressive functional recovery in the BMSC- transplanted rats, compared with controls. Two months after transplantation, BMSC survived in the host tissue, and some of them showed expression of Neu-N or GFAP, suggesting neuronal and astroglial transdifferentiation. Furthermore, significant increase of endogenous neurogenesis was found in BMSC-transplanted rats, compared with controls. Conclusions: These findings suggest the utility of delayed intracerebral transplantation of BMSC for the treatment of established sequels after TBI.