In the South Korean study, researchers transplanted human mesenchymal stem cells, or hMSCs, into animal stroke models with cerebral artery occlusion. The animals were monitored by magnetic resonance imaging at two days, one week, two weeks, six weeks and 10 weeks after transplant.

"Cells started showing indications of migration as early as one or two weeks following transplantation," said lead author Jihwan Song of the Pochon CHA University College of Medicine. "At 10 weeks, the majority of the cells were detected in the core of the infarcted area.

"We speculate that the extensive migratory nature of stem cells and their utilization will provide an important tool for developing novel stroke therapies," Song said.

In the joint Canadian-Chinese study, bone marrow stromal cells, or BMSCs, were injected into animals 24 hours following stroke. Researchers found that within seven days the animals exhibited significant reductions in scar size and cell death and improvements in neurological function when compared to controls receiving no BMSCs.

Both studies are reported in the journal Cell Transplantation.