Abstract
In spinal cord injury (SCI) there is damage to the nervous tissue, due to the initial damage and pathophysiological processes that are triggered subsequently. There is no effective therapeutic strategy for motor functional recovery derived from the injury. Several studies have demonstrated neurons growth in cell cultures on polymers synthesized by plasma derived from pyrrole, and the increased recovery of motor function in rats by implanting the polymer in acute states of the SCI in contusion and transection models. In the process of transferring these advances towards humans it is recommended to test in mayor species, such as nonhuman primates, prioritizing the use of non-invasive techniques to evaluate the injury progression with the applied treatments. This work shows the ability of diffusion tensor imaging (DTI) to evaluate the evolution of the SCI in nonhuman primates through the fraction of anisotropy (FA) analysis and the diffusion tensor tractography (DTT) calculus. The injury progression was analysed up to 3 months after the injury day by FA and DTT. The FA recovery and the DTT re-stabilization were observed in the experimental implanted subject with the polymer, in contrast with the non-implanted subject. The parameters derived from DTI are concordant with the histology and the motor functional behaviour.
Highlights
spinal cord injury (SCI) has a great medical and socioeconomic impact, due to a severe neurological disability [1–3] and, so far it doesn’t exist an effective treatment to recovery after the injury.The pathophysiological mechanisms triggered after SCI are complex [2], small animal studies have contributed greatly to a better understanding of these mechanisms
In this work a SCI transection (SCIT) was carried out in non-human primates, one with implanted of PPPyI (RHI) and other just with the injury (RHC), the effect of the PPPyI in RHI is in accordance with the previous work in murines, in which, the use of PPPy in different models of SCI has promoted mechanisms of neuroprotection, contributing in the stimulation of motor plasticity mechanisms and in the histoarchitecture conservation, increasing the motor functional recovery of the experimental subjects [14–16]; diffusion tensor imaging (DTI) showed capacity to evaluate the evolution in vivo of the SCIT in NHP emphasizing the difference between the RHI
fraction of anisotropy (FA) is a sensitive marker for SCI and is strongly related to the severity of the lesion [21]
Summary
SCI has a great medical and socioeconomic impact, due to a severe neurological disability [1–3] and, so far it doesn’t exist an effective treatment to recovery after the injury.The pathophysiological mechanisms triggered after SCI are complex [2], small animal studies have contributed greatly to a better understanding of these mechanisms. To facilitate the translation of advances made in the laboratory to the clinic it is recommended the use of mayor species [4–6], including methods which allow the information collected per animal to be maximized in order to reduce the use of animals [7], prioritizing the use of non-invasive techniques to evaluate the injury progression with the applied treatments, according to organizations such as “The National Centre for the Replacement, Refinement & Reduction of Animals in research” (NC3Rs) in the UK’s that practice the principles of replacement, reduction and refinement (3Rs) Polymers such as collagen/silk fibroin, polyethylene glycol, poly-β-hydroxybutyrate, chitosan tube, poly(ε-caprolactone), poly(lactic-co-glycolic acid), and polymers synthesized by plasma derived from pyrrole (PPPyI) have been proposed with encouraging results in the treatment of SCI [8–16], it has been described that polymers implanted after a SCI have beneficial effects such as: promoting functional recovery, axonal remyelination, preservation of nervous tissue adjacent to the epicentre of the injury, decrease in the number of reactive astrocytes, among others; commonly the aforementioned effects do not occur together, in addition to not being attributed only to the polymer, but have been associated with the combination with drugs, cells or other agents [8–13]. This can be attributed to the plasma synthesis of the polymer, with which polymers with physical-chemical characteristics different are obtained [17]
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