Significant clinical, neuropathological and behavioural recovery from acute spinal cord trauma by transplantation of a well-defined somatic stem cell from human umbilical cord blood.

Stem cell therapy is a potential treatment for spinal cord injury and different stem cell types have been grafted into animal models and humans suffering from spinal trauma. Due to inconsistent results, it is still an important and clinically relevant question which stem cell type will prove to be therapeutically effective. Thus far, stem cells of human sources grafted into spinal cord mostly included barely defined heterogeneous mesenchymal stem cell populations derived from bone marrow or umbilical cord blood. Here, we have transplanted a well-defined unrestricted somatic stem cell isolated from human umbilical cord blood into an acute traumatic spinal cord injury of adult immune suppressed rat. Grafting of unrestricted somatic stem cells into the vicinity of a dorsal hemisection injury at thoracic level eight resulted in hepatocyte growth factor-directed migration and accumulation within the lesion area, reduction in lesion size and augmented tissue sparing, enhanced axon regrowth and significant functional locomotor improvement as revealed by three behavioural tasks (open field Basso–Beattie–Bresnahan locomotor score, horizontal ladder walking test and CatWalk gait analysis). To accomplish the beneficial effects, neither neural differentiation nor long-lasting persistence of the grafted human stem cells appears to be required. The secretion of neurite outgrowth-promoting factors in vitro further suggests a paracrine function of unrestricted somatic stem cells in spinal cord injury. Given the highly supportive functional characteristics in spinal cord injury, production in virtually unlimited quantities at GMP grade and lack of ethical concerns, unrestricted somatic stem cells appear to be a highly suitable human stem cell source for clinical application in central nervous system injuries. * Abbreviations : BDA : biotinylated dextrane amine GFAP : glial fibrillary acidic protein HGF : hepatocyte growth factor MSC : mesenchymal stem cell USSC : unrestricted somatic stem cells USSC-CMFBS : USSCfoetal bovine serum-conditioned medium