Intravenous infusion of adipose-derived stem/stromal cells improves functional recovery of rats with spinal cord injury

Abstract

Background aimsAdipose tissue has therapeutic potential for spinal cord injury (SCI) because it contains multipotent cells known as adipose-derived stem/stromal cells (ASCs). In this study, we attempted intravenous ASC transplantation in rats with SCI to examine the effect on functional recovery. MethodsASCs (2.5 × 106) were intravenously infused into SCI rats, after which hindlimb motor function was evaluated. Distribution of transplanted ASCs was investigated and growth factor/cytokine levels were determined. ResultsIntravenous transplantation of ASCs promoted the functional recovery in SCI rats and reduced the area of spinal cord cavitation. A distribution study revealed that ASCs gradually accumulated at the site of injury, but long-term survival of these cells was not achieved. Levels of growth factors increased only slightly in the spinal cord after ASC transplantation. Unexpectedly, cytokine-induced neutrophil chemoattractant (CINC)-1 showed a transient but substantial increase in the spinal cord tissue and blood of the ASC group. CINC-1 was secreted by ASCs in vitro, and the sponge implantation assay showed that CINC-1 and ASCs induced angiogenesis. CINC-1 promoted functional recovery in SCI rats, which was similar to the ASCs. Expression of glial cell line-derived neurotrophic factor was greater in the ASC group than in the CINC-1 group, although both promoted extracellular signal-regulated kinase (ERK)1/2 phosphorylation; Akt phosphorylation was enhanced in the spinal cord after ASC transplantation. ConclusionsOur findings indicated that intravenously transplanted ASCs gradually accumulated in the injured spinal cord, where cytokines such as CINC-1 activated ERK1/2 and Akt, leading to functional recovery.