1. Section2 Role of Mesenchymal Stem cells in Treatment of TBI

2. Double-labeling of brain sections The numbers of BrdU positive cells in the ipsilateral hemisphere 9627±463 The numbers of BrdU positive cells in the contralateral hemisphere 2627±651 Double staining showed that 4.9±2.3% of BrdU-labeled cells expressed NeuN,and 6.7±3.1% expressed GFAP

3. Immunohistochemical staining

4. Neurological and motor function evaluation

5. DISCUSSION The major findings of our study were: (1) MSCs injected i.v. enter brain and reduce motor and neurological deficits by day 14 after MSC administration (2) some cells migrating into the parenchyma of the brain express the neuronal marker NeuN and the astrocytic marker GFAP (3) MSCs are also present in other organs and primarily localize to the vascular structures, without any obvious adverse effects.

6. The mechanisms responsible for MSC engraftment into brain MSCs may enter brain from blood brain barrier disruption or in response to signals from cytokines and cell surface receptors and antigens MSCs produce an array of trophic factors and cytokines,and express receptors for trophic factors