Sensorimotor recovery after transection and spinal dorsal roots repair with platelet rich plasma (PRP) and human embryonic stem cells treatment (hESC).

Abstract

Motor coordination involves specific neural processes ranging from the perception of the stimulus until execution of the answer, being dependent in sensorimotor integration, which is particularly evident in the spinal cord. Injuries in the spinal roots can result in sensory and motor losses, depending on the affected roots. This type of injury has become an important medical problem and commonly affects the brachial plexus due to a high-energy trauma. The repair of such lesions is a delicate assignment due of the possibility of further damage in the spinal cord and surrounding structures and, despite substantial progress in microsurgical techniques, the recovery after brachial plexus surgery is far from ideal. Also, due to the possibility of generating neuropathic pain, the restoration surgical procedures in the lesions roots are restricted only to the repair of ventral roots (motor component), discarding the sensory component (dorsal roots). In this context, new therapies need to be developed for the repair of dorsal roots. A promising treatment would be the use of platelet rich plasma (PRP) as an alternative in the repair of injured dorsal roots. Furthermore, the use of PRP along with human embryonic stem cells (hESC), can potentiate an eventual tissue regeneration. PRP is currently used in a wide range of surgical procedures, and several scientific studies demonstrate benefits in the treatment of various types of lesions. On the other hand, the use of stem cells in tissue repair has also been employed in some experimental models, with satisfactory results. In addition to cell therapy hESC, we propose the use of Poly L-lactic acid (PLLA) nanofibers in order to provide a mechanical support for stabilizing the dorsal roots that will be repaired. Currently, various biomedical applications have employed the nanofiber technology to promote the recovery after traumatic nerve injuries. To find out the effectiveness of PRP, as an adhesive and inductive element of axonal regeneration, as well as its association with hESC and PLLA nanofiber, female Lewis rats, with 7 weeks old, will be submitted to sensitive roots transection (dorsal roots) that will be repaired using PRP, with or without polymers and cell therapy. The production of gene transcripts related to neurotrophic factors BDNF and GDNF, as well as the profile and production of anti and pro inflammatory cytokines, of the transected and reimplanted animals, will be analyzed 1 week after injury by qRT-PCR. Furthermore, the expression of VGLUT1 (presynaptic glutamatergic terminals), vimentin (astrocytic reaction) and Iba-1 (microglial reactions) in the spinal cord, will be investigated by immunohistochemistry, 8 weeks after injury. At last, behavioral tests in different experimental groups will be performed using the "walking track test" (Catwalk) and Von Frey eletronic for 8 weeks. We consider that our results will provide the basis for better understanding of PRP use, alone or in combination with cell therapy and PLLA nanofiber in accelerating nerve regeneration and may contribute to the future clinical use of these therapeutic approaches, filling an important gap in reparative procedures after this type of injury.