Skin cells bridge injured spinal cords.

Skin cells genetically engineered to produce a protein called nerve growth factor (NGF) can spur the regrowth of nerves within a partially severed spinal cord, according to a new study involving rats. The technique offers hope as a means of treating spinal cord injuries in humans.

A group led by Mark H. Tuszynski of the University of California, San Diego, inserted the gene for either NGF or a control, marker enzyme into fibroblasts isolated from the skin of adult rats. The researchers then injected slurries of cells containing either the NGF gene or the marker gene into the partially severed spinal cords of two groups of rats.

Because fibroblasts normally secrete collagen and fibronectin -- two major constituents of connective tissue -- Tuszynski and his colleagues predicted the cells would generate connective-tissue bridges to heal the rats' spinal cords. In addition, they hoped that the NGF-containing cells would stimulate severed nerves within the rats' spinal cords to grow across the injured gap and rejoin.

When Tuszynski's group examined the rats two weeks after implanting the cell grafts, they found that both types of cell implant had survived and grown. Moreover, Tuszynski reported at the conference, the rats that had received cells containing the NGF gene showed signs of nerve-cell regeneration.

Tuszynski says the new technique may obviate the need for nervous tissue from aborted human fetuses, which has shown promise in repairing patients' damaged spinal cords. A U.S. government ban now bars federally funded researchers from performing transplants using such tissue (SN: 10/17/92, p.271).

Tuszynski also notes that the procedure would avoid tissue rejection problems because physicians could treat spinal cord injuries using genetically engineered fibroblasts taken from a patient's own skin.