Proliferation, migration, and differentiation of human neural stem/progenitor cells after transplantation into a rat model of traumatic brain injury

Object. Cultures containing human neural stem and progenitor cells (neurospheres) have the capacity to proliferate and differentiate into the major phenotypes of the adult brain. These properties make them candidates for therapeutic transplantation in cases of neurological diseases that involve cell loss. In this study, long-term cultured and cryopreserved cells were transplanted into the traumatically injured rat brain to evaluate the potential for human neural stent/progenitor cells to survive and differentiate following traumatic injury. Methods. Neural stem/progenitor cell cultures were established from 10-week-old human forebrain. Immunosuppressed adult rats received a unilateral parietal cortical contusion injury, which was delivered using the weight-drop method. Immediately following the injury, these animals received transplants of neural stem/progenitor cells, which were placed close to the site of injury. Two or 6 weeks after the procedure, these animals were killed and their brains were examined by immunohistochemical analysis. At both 2 and 6 weeks postoperatively, the transplanted human cells were found in the perilesional zone, hippocampus, corpus callosum, and ipsilateral subependymal zone of the rats. Compared with the 2-week time point, an increased number of HuN-positive cells was observed at 6 weeks. In addition, at 6 weeks post-injury/transplantation, the cells were noted to cross the midline to the contralateral corpus callosum and into the contralateral cortex. Double labeling demonstrated neuronal and astrocytic, but not oligodendrocytic differentiation. Moreover, the cortex appeared to provide an environment that was less hospitable to neuronal differentiation than the hippocampus. Conclusions. This study shows that expandable human neural stem/progenitor cells survive transplantation, and migrate, differentiate, and proliferate in the injured brain. These cells could potentially be developed for transplantation therapy in cases of traumatic brain injury.