COLLAGEN CONTAINING NEUROTROPHIN-3 (NT-3) ATTRACTS REGROWING INJURED CORTICOSPINAL AXONS IN THE ADULT-RAT SPINAL-CORD AND PROMOTES PARTIAL FUNCTIONAL RECOVERY

During development, neurotrophic factors play an important role in the guidance and outgrowth of axons. Our working hypothesis is that neuro trophic factors involved in the development of axons of a particular C NS tract are among the most promising candidates for stimulating and d irecting the regrowth of fibers of this tract in the lesioned adult an imal. The neurotrophin NT-3 is known to be involved in the target sele ction of outgrowing corticospinal tract (CST) fibers. We studied the c apacity of locally applied NT-3 to stimulate and direct the regrowth o f axons of the CST in the lesioned adult rat spinal cord. We also stud ied the effect of NT-3 application on the functional recovery of rats after spinal cord injury, using the gridwalk test. NT-3 was applied at the site of the lesion dissolved into rat tail collagen type I. Four weeks after spinal cord injury and collagen implantation, significantl y more CST fibers had regrown into the collagen matrix containing NT-3 (22 +/- 6%, mean +/- SEM) than into the control collagen matrix witho ut NT-3 (7 +/- 2%). No CST fibers grew into areas caudal to the collag en implant. Despite the absence of regrowth of corticospinal axons int o host tissue caudal to the lesion area, functional recovery was obser ved in rats with NT-3 containing collagen implants. (C) 1998 Academic Press.