Caspase inhibition by Z-VAD increases the survival of grafted bone marrow cells and improves functional outcome after MCAo in rats

Marrow stromal cells (MSCs) transplantation into brain has been employed to treat experimental ischemia. However, MSCs undergo apoptosis and few survive in the ischemic brain. We test the hypotheses that coadministration of bone marrow cells (BMCs) with a cell-permeable inhibitor of caspases, Z-Val-Ala-DL-Asp-fluoromethylketone (Z-VAD), into the ischemic boundary zone (IBZ) of brain promotes BMCs survival and improve outcome. Experimental groups consist of: 24 h after MCAo, either phosphate-buffered saline (PBS, n=4), dead BMC (n=4), fresh BMC (n=10), Z-VAD only (n=4), or BMC with Z-VAD (n=6) were intracerebrally injected. BMCs were harvested from donor adult rats labeled with bromodeoxyuridine (BrdU). Rats were subjected to an adhesive-removal somatosensory and motor-rotarod functional tests before MCAo and at 1 and 7 days after MCAo. Rats treated with a combination of Z-VAD and BMCs exhibited significant improvement in the adhesive-removal test at 7 days compared with the control group (combined MCAo+PBS and MCAo+dead BMC) (p<0.01), and the numbers of BrdU-BMC increased (p<0.05) and apoptotic cells decreased (p<0.05) compared with BMC alone transplantation. Our data suggest that intracerebral coadministration of BMC with Z-VAD enhances the survival of grafted BMC and improves neurological functional recovery after MCAo.