The researchers are currently using these cABC nanospheres to treat spinal cord injury in rats. They have injected 3 or 6 m l of nanospheres immediately or one week following spinal contusion injury, or into uninjured spinal cord. Results so far show that the nanospheres remain near the injection site, and do not cause any major inflammation of spinal tissue, Stelzner says.
"A unique feature of the nanosphere delivery system," Stelzner says, "is its ability to encapsulate other agents, in addition to cABC, that can be administered together, but released at various times, to counteract the inhibitory substances, and to target and promote regrowth in the spinal cord."
Aside from blocking the growth-inhibiting molecules present after injury to aid in spinal cord regeneration, nerve cells also can be altered internally so they no longer recognize the inhibitory molecules as hindering growth, and instead grow right through them. Marie Filbin, PhD, in the department of biological sciences at Hunter College and her team were able to use this approach to regrow spinal cord nerve cells using a drug called Rolipram.
First, researchers conducted in vitro studies in which nerve cells were removed from Rolipram-treated rats and exposed them to molecules that inhibited nerve regrowth. They found that if cyclic AMP (cAMP)--a molecule found in every cell in our bodies--was elevated in nerve cells, the blockers of growth did not inhibit regeneration. The drug Rolipram blocks an enzyme--phosphodiesterase (PDE)--that breaks down cAMP, thus inhibiting PDE , which leads to an accumulation of cAMP and nerve regrowth.