This finding is in contrast to research that shows many other cell types, when injected into the spinal cord, amplify neuropathic pain, a common long-term complication of spinal cord injury in humans, the company said.
Allodynia, a painful response to a stimulus that normally does not elicit pain, was assessed on large numbers of GRNOPC1-treated and untreated spinal cord-injured rats at three, six, and nine months post-injury. Both mechanical and cold stimuli were repeatedly applied at the injury site and on the paws by observers blinded to the animals’ treatment. GRNOPC1-treated animals exhibited no increase in allodynia or neuropathic pain compared to untreated spinal cord-injured animals at any time.
GRNOPC1 is an allogeneic population of cells containing oligodendroglial progenitors that is intended for transplantation into the lesion site of patients with spinal cord injury to induce tissue repair. Geron’s development plan for the product calls for the filing of an investigational new drug application with the FDA and, pending the agency’s review, initiation of human clinical trials in 2008.
Thomas Okarma, Geron’s president and CEO, said: “These important results speak to both the long-term safety and duration of effectiveness of GRNOPC1. A comparison of the GRNOPC1-treated rats at nine months after injection against untreated control rats shows dramatic evidence of durable remyelination of intact rat axons traversing the lesion. These results show that a single injection of GRNOPC1 cells produces significant and persistent remyelination of the damaged spinal cord.”