Background: While pure mesenchymal stem cell (MSC) treatment for spinal cord injury (SCI) is known to be safe, its efficacy is insufficient. Therefore, gene-modified stem cells are being developed to enhance the effect of pure MSCs. We investigated the effect of stem cell therapy through the transfection of a Wnt3a-producing gene that stimulates axonal regeneration.
Method: MSCs obtained from the human umbilical cord blood (hMSCs) were multiplied, cultivated, and transfected with the pLenti-Wnt3a-GFP viral vector to produce Wnt3a-secreting hMSCs. A total of 50 rats were injured with an Infinite Horizon impactor at the level of the T7-8 vertebrae. Rats were divided into five groups according to the transplanted material: (1) phosphate-buffered saline injection group (sham group, n = 10); (Pertz et al. Proc Natl Acad Sci USA 105:1931-1936, 39) Wnt3a protein injection group (Wnt3a protein group, n = 10); (3) hMSC transplantation group (MSC group, n = 10); (4) hMSCs transfected with the pLenti vector transplantation group (pLenti-MSC group, n = 10); (5) hMSCs transfected with the pLenti+Wnt3a vector transplantation group (Wnt3a-MSC group, n = 10). Behavioral tests were performed daily for the first 3 days after injury and then weekly for 8 weeks. The injured spinal cords were extracted, and axonal regeneration markers including choline acetyltransferase (ChAT), growth-associated protein 43 (GAP43), and microtubule-associated protein 2 (MAP2) were investigated by immunofluorescence, RT-PCR, and western blotting.
Results: Seven weeks after the transplantation (8 weeks after SCI), rats in the Wnt3a-MSC group achieved significantly higher average scores in the motor behavior tests than those in the other groups (p < 0.05). Immunofluorescent stains showed greater immunoreactivity of ChAT, GAP43, and MAP2 in the Wnt3a-MSC group than in the other groups. RT-PCR and western blots revealed greater expression of these proteins in the Wnt3a-MSC group than in the other groups (p < 0.05).
Conclusions: Wnt3a-secreting hMSC transplantation considerably improved neurological recovery and axonal regeneration in a rat SCI model.
Keywords: Functional recovery; Mesenchymal stem cell; Spinal cord injury; Spinal cord regeneration; Transfection; Wnt3a.