Neuroinflammation and apoptosis after surgery for a rat model of double-level cervical cord compression.

INTRODUCTION: Cervical spondylotic myelopathy (CSM) is the most prevalent type of non-traumatic spinal cord injury. The pathological process of CSM is relatively complicated. Most of the chronic cervical cord compression animal models established using hydrophilic expanding polymer are single-segment compression, which was deviated from clinical practice with double-segment or multi-segment compression. This study aims to better mimic the actual clinical compression by using a new type of hydrophilic expanding polymer to establish an animal model of double-level cervical cord compression. MATERIALS AND METHODS: Progressive cord compression was done with implantation of polyvinyl alcohol-polyacrylamide hydrogel in the spinal canal at the C3-4 and C5-6 levels. Sprague-Dawley rats (n = 32) were divided into three groups: sham (no compression, n = 12) and screw compression group (n = 8), and hydrogel compression group (n = 12). Functional deficits were characterized using motor function scores, forelimb grip strength, hindlimb pain threshold, and gait analysis, while compression was imaged with magnetic resonance imaging. The apoptosis, inflammation, and demyelination were assessed by hematoxylin and eosin staining, Luxol fast blue staining, TUNEL assay, immunofluorescence staining, and Western blot analysis. RESULTS: Motor function scores for rats with cervical cord hydrogel compression were significantly decline in motor function scores, an increase in allodynia, neurons and oligodendrocytes apoptosis related to B cell lymphoma-2 (Bcl-2)/Bcl-2 associated X (Bax)/cleaved caspase-3, and impaired axonal conduction, as well as neuroinflammation zone related to microglia or macrophages aggregation related to the nucleotide-binding domain, leucine-rich-repeat-containing family, pyrin domain-containing 3 (NLRP3) inflammasome activation, and activation of astrocytes, as well as oxidative stress were observed. CONCLUSION: We believe that this model utilizing compression on double-level cervical cord will allow researchers to investigate of translationally relevant therapeutic methods for CSM.

Supramolecular micellar nanoaggregates based on a novel chitosan/vitamin E succinate copolymer for paclitaxel selective delivery.

BACKGROUND: Nowadays, many cytotoxic anticancer drugs exhibit low solubility and poor tumor selectivity, which means that the drug formulation is very important. For example, in the case of paclitaxel (PTX), Cremophor EL(®) (BASF, Ludwigshafen, Germany) needs to be used as a solubilizer in its clinical formulation (Taxol(®), Bristol-Myers Squibb, New York, NY), although it can cause serious side effects. Nanomicellar systems are promising carriers to resolve the above problems, and the polymer chosen is the key element. METHODS: In this study, a novel amphiphilic chitosan/vitamin E succinate (CS-VES) copolymer was successfully synthesized for self-assembling polymeric micelles. Proton nuclear magnetic resonance spectroscopy and infrared were used to characterize the molecular structure of the copolymer. The PTX-loaded CS-VES polymeric micelles (PTX-micelles) were characterized by dynamic light scattering, transmission electron microscopy, X-ray diffraction, and differential scanning calorimetry. RESULTS: The critical micelle concentration of CS-VES was about 12.6 µg/mL, with the degree of amino group substitution being 20.4%. PTX-micelles were prepared by a nanoprecipitation/dispersion technique without any surfactant being involved. PTX-micelles exhibited a drug loading as high as 21.37% and an encapsulation efficiency of 81.12%, with a particle size ranging from 326.3 to 380.8 nm and a zeta potential of +20 mV. In vitro release study showed a near zero-order sustained release, with 51.06%, 50.88%, and 44.35% of the PTX in the micelles being released up to 168 hours at three drug loadings of 7.52%, 14.09%, and 21.37%, respectively. The cellular uptake experiments, conducted by confocal laser scanning microscopy, showed an enhanced cellular uptake efficiency of the CS-VES micelles in MCF-7 cells compared with Taxol. The PTX-micelles exhibited a comparable but delayed cytotoxic effect compared with Taxol against MCF-7 cells, due to the sustained-release characteristics of the nanomicelles. More interestingly, blank nanomicelles based on CS-VES copolymer demonstrated significant cytotoxicity against MCF-7 cells. CONCLUSION: The supramolecular micellar aggregates based on CS-VES copolymer is a promising nanocarrier and efficacy enhancer when used as an anticancer drug-delivery system.