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

Abstract

Adipose 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. ASCs (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. Intravenous 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. Our 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.