Abstract:

BACKGROUND: The specific mechanism of tail vein transplantation of stem cells through the blood-brain barrier to reach the host brain damage region is not clear.
OBJECTIVE: To evaluate the safety of tail vein transplantation of human umbilical cord mesenchymal stem cells (hUC-MSCs) for the treatment of cerebral ischemia-reperfusion injury in Sprague-Dawley (SD) rats and to investigate its possible mechanism.
METHODS: hUC-MSCs were isolated using density gradient centrifugation combined with adherent screening method, and then labeled with BrdU. SD rats were used to establish the middle cerebral artery ischemia-reperfusion model with modified suture method. Rats of transplantation group A at 7 days after injury and group B at 14 days were given hUC-MSCs through the tail vein. Rats in the model group were left intact. 
RESULTS AND CONCLUSION: (1) The mNSS score of transplantation group A and group B was lower than that of model group after transplantation for 7, 14, 28, 35, 42, 49 and 56 days (P < 0.05), and the mNSS score of transplantation group A was lower than that of transplantation group B after transplantation for 7, 14, 28, 35, 42 and 49 days (P < 0.05). The mNSS score reached the plateau phase at 35 days in model group, 42 days in transplantation group A and 49 days in transplantation group B. (2) Brdu+Nestin, Brdu+microtubule-associated protein 2, Brdu+glial fibrillary acidic protein, Brdu+factor Ⅷ and Brdu+vascular endothelial growth factor immunohistochemical double staining positive cells could be seen at the center of damage site in rats of the group A and group B, there were no CD11b and MPO immunohistochemical single staining positive cells. hUC-MSCs transplantation through tail vein is able to survive in the host brain damage region and improve the recovery of the neural function of ischemic brain injury rats. The mechanism may be related to the transplanted cells differentiating into neuron-like and glial-like cells, which promote the angiogenesis and secret the neurotrophic factors. In this study, no obvious immune rejection and tumor cells were found, and the transplantation has high safety.