Natalie DeWitt
 

Pigs are generally viewed as an ethically acceptable source of tissue for human organ transplantation and cell-based therapies; unfortunately, however, their cells are rapidly rejected by the human immune system. Here Imaizumi et al. demonstrate the feasibility of using transgenic pigs to obtain large quantities of cells engineered to be more immunologically compatible, as a source of cells to repair damaged spinal cords of rats. The researchers generated transgenic pigs expressing an inhibitor of human complement—a modification they expect will help mitigate graft rejection. From the pigs' olfactory bulbs, they collected olfactory ensheathing cells and Schwann cells, which have been previously shown to promote remyelination and axonal regeneration when cultured in vitro and grafted into rats. One month after injection into the spinal cord of immunosuppressed rats, the transplanted cells had migrated along the host spinal cord, promoted remyelination, and restored conduction of the regenerated axons across the transected spinal cord (see pp. 925 and 949).