Human umbilical cord blood stem cells for spinal cord injury: early transplantation results in better local angiogenesis.

Aim: We aim to explore the repair mechanism after the transplantation of CD34(+) human umbilical cord blood cells (HUCBCs) in traumatic spinal cord injury (SCI) in rats. Materials & methods: Wistar rats with SCI were randomly divided into three groups: DMEM injection (group A); CD34(+) HUCBC transplantation on the first day after injury (group B); and CD34(+) HUCBC transplantation on the sixth day after injury (group C). The Basso, Beattie and Bresnahan scores were used to evaluate motor behavior. At the injured site, the infarct size, blood vessel density, and survival and neural differentiation of transplanted cells were analyzed. Results: It was found that the Basso, Beattie and Bresnahan score in group B was significantly higher than other groups (p < 0.05), and the infarct size and blood vessel density at the injured site were significantly different (p < 0.01). However, the transplanted cells survived at least 3 weeks at the injured site, but did not differentiate into neural cells. Conclusion: These results suggested transplantation of CD34+ HUCBCs during the acute phase could promote the functional recovery better than during the subacute phase after SCI by raising blood vessel density, suggesting the possible clinical application for the treatment of spinal injury.