The Experimental Study On The Application Of Neural Stem Cells In Brachial Plexus Roots Avulsion Injury

Brachial plexus lesion is a common injury today, but it is very difficult to treat. With the development of industry, agriculture and acceleration of communication,it will become more frequent. About 65% of the adult and 75% of the obstetrical brachial plexus lesions that have been operated upon suffer from avulsion injuries. These lesions are not situated in the peripheral nervous system(PNS),but confined to the central nervous system(CNS). After brachial plexus roots avulsion, degenetation of motoneurons will take place in the ventral horn of the spinal cord, and severely affects the results of therapy, so the prognosis is very bad.Object: To investigate the regularity and mechanisms of secondarydegeneration of motoneurons hi the ventral horn of spinal cord after brachial plexus roots avulsion , to research the survival effect and mechanisms of Neural Stem Cells on motoneurons after being transplanted into the spinal cord and observe the survival and differentiation of Neural Stem Cells in the spinal cord.Materials and methods:1. Neural Stem Cells are isolated from the brain tissue of fetal rats which are obtained from a pregnant Wistar rat (P15-18) and cultured .expanded in vitro. Before tranplantation the Neural Stem Cells are labeled with BrdU.2. The experiments were performed on adult Wistar rats( male: 18 and female :18;n=36), The surgical procedures were carried out with the animals under general anaesthesia using Chloral Hydrate. Laminectomy of C4-T1 was performed via a posterior approach..The ventral and dorsal roots of C5-T1 were selectively avulsed from the spinal cord outside the dura mater and within the vertebral canal. The Neural Stem Cells were injected into the spinal cord nearby the ventral horn with a microinjector.3. At 1,2,4,6,8,12 weeks postoperatively ,the rats were deeply anaesthetized with an overdose of Chloral Hydrate. The C5-T1 spinal segment were removed , fixed and embedded. The change of number and morphology of motoneurons were observed on HE-stained sections; The Neural Stem Cells were identified using immunohistochemistry assay and the lost motoneurons were counted on Tunel-stained sections.Result:1. All animals displayed unilateral upper limb paralysis postoperatively and other limbs were not affected.2. At each time point postoperatively, the HE-stained transverse sections showed : The number of motoneurons decreased significantly with soma atrophied . At 12 weeks postoperatively, the number of lost motonertons of control rats and experimental rats reached 80.3% and 63.7%,respectively. The survival rate of motoneurons of experimental rats is higher than control rats at all time points.3. Immunohistochemistry assay showed BrdU positive cells scattered in the operational side of the spinal cord of experimental rats at 12 weeks postoperatively,and these cells still maintained nondifferentiated character.4. Tunel-stained transverse sections revealed that apoptotic motoneurons scattered in the ventral horn of the control and experimental group.Conclusion:1. After brachial plexus roots avulsion, degeneration of motoneurons will take place in the ventral horn of the spinal cord.2. The mechanisms for motor neuron delayed degeneration in adult spinal cord following brachial plexus root avulsion is apoptosis.3. The Neural Stem Cells can survive and protect motorneurons of theventral horn from delayed degeneration after brachial plexus roots avulsion.