ENGINEERED tissue containing human stem cells has allowed paraplegic rats to walk independently and regain sensory perception. The implanted rats also show some degree of healing in their spinal cords.
The research, published in Frontiers in Neuroscience, demonstrates the great potential of stem cells — undifferentiated cells that can develop into numerous different types of cells — to treat spinal cord injury.
Spinal cord injuries often lead to paraplegia. Achieving substantial recovery following a complete spinal cord tear, or transection, is an “as-yet unmet challenge”.
Led by Dr Shulamit Levenberg, of the Technion-Israel Institute of Technology, the researchers implanted human stem cells into rats with a complete spinal cord transection. The stem cells, which were derived from the membrane lining of the mouth, were induced to differentiate into support cells that secrete factors for neural growth and survival.
The work involved more than simply inserting stem cells at various intervals along the spinal cord. The research team also built a three-dimensional scaffold that provided an environment in which the stem cells could attach, grow and differentiate into support cells. This engineered tissue was also seeded with human thrombin and fibrinogen, which served to stabilize and support neurons in the rat’s spinal cord.
Rats treated with the engineered tissue containing stem cells showed the higher motor and sensory recovery compared to control rats. Three weeks after introduction of the stem cells, 42 percent of the implanted paraplegic rats showed a markedly improved ability to support weight on their hind limbs and walk. 75 percent of the treated rats also responded to gross stimuli to the hind limbs and tail. In contrast, control paraplegic rats that did not receive stem cells showed no improved mobility or sensory responses.
In addition, the lesions in the spinal cords of the treated rats subsided to some extent. This indicates that their spinal cords were healing.
While the results are promising, the technique did not work for all implanted rats. An important area for further research will be to determine why stem cell implantation worked in some cases but not others.