Coadministration of bone marrow cells and an inhibitor of apoptosis (Z-VAD) promotes bone marrow cell survival and neurological functional recovery after focal cerebral ischemia in adult rat
Most bone marrow cells (BMCs) transplanted into the ischemic brain of adult rodents die shortly after they are grafted, similar to the 90%-95% of the fetal cells that die after transplantation into Parkinson s patients. We tested whether coadministration of BMCs and Z-Val-Ala-DL-Asp-fluoromethylketone (Z-VAD), an inhibitor of apoptosis, into the ischemic boundary zone of the striatum and the cortex in rat brain promotes BMC survival. Adult Wistar rats were subjected to transient (2 h) middle cerebral artery occlusion (MCAo). At 1 d after ischemia, saline (n=9, Group 1); BMCs (1x106 in 10 :l, n=8, Group 2); or BMCs with Z-VAD (50 nM/ml, n=4, Group 3) were injected into brain. BMCs were harvested from donor adult rats injected with bromodeoxyuridine (BrdU, as a tracer). Rats were subjected to rotarod-motor and adhesive-removal somatosensory functional tests before MCAo and at 1 and 7 d after MCAo. Rats in Group 3 exhibited significant improvement (10.3±2.6 seconds, p<0.05) on the adhesive-removal test at 7 d, compared with those in Group 1 (29.3±9.4 seconds) and Group 2 (21.3±5.5 seconds), respectively. Immunohistochemistry staining was employed to identify BrdU-BMCs, and TUNEL staining was used to identify in situ DNA fragmentation of apoptotic cells. Even though the infarct volume in Group 3 (29.9±9.2%) did not change significantly, compared with Group 1 (34.3±4.0%) and Group 2 (26.6±3.8%); the number of BrdU-BMCs (88,200±7,400, ∼8.8% of 106 transplanted cells) increased significantly (p<0.05) in rats in Group 3, compared with that in Group 2 (31,700±9,100, ∼3.2% of 106 cells) at 7 d. In the grafting areas, apoptotic cells were less clustered (<90 vs.>240 per region) and apoptotic cells were significantly decreased (12.3±1.7/mm2 vs. 25.9±2.1/mm2, ∼47%, p<0.05). Our data suggest that intracerebral coadministration of bone marrow cells and inhibitors of apoptosis enhance cellular survival of bone marrow cells and improves neurological functional recovery after cerebral ischemia.