Functional silica nanoparticle-mediated neuronal membrane sealing following traumatic spinal cord injury
ABSTRACT The mechanical damage to neurons and their processes induced by spinal cord injury (SCI) causes a progressive cascade of pathophysiological events beginning with the derangement of ionic equilibrium and collapse of membrane permeability. This leads to a cumulative deterioration of neurons, axons, and the tissue architecture of the cord. We have previously shown that the application of the hydrophilic polymer polyethylene glycol (PEG) following spinal cord or brain injury can rapidly restore membrane integrity, reduce oxidative stress, restore impaired axonal conductivity, and mediate functional recovery in rats, guinea pigs, and dogs. However there are limits to both the concentration and the molecular weight of the application that do not permit the broadest recovery across an injured animal population. In this study, PEG-decorated silica nanoparticles (PSiNPs) sealed cells, as shown by the significantly reduced leakage of lactate dehydrogenase from damaged cells compared with uncoated particles or PEG alone. Further in vivo tests showed that PSiNPs also significantly reduced the formation of reactive oxygen species and the process of lipid peroxidation of the membrane. Fabrication of PSiNPs containing embedded dyes also revealed targeting of the particles to damaged, but not undamaged, spinal cord tissues. In an in vivo crush/contusion model of guinea pig SCI, every animal but one injected with PSiNPs recovered conduction through the cord lesion, whereas none of the control animals did. These findings suggest that the use of multifunctional nanoparticles may offer a novel treatment approach for spinal cord injury, traumatic brain injury, and possibly neurodegenerative disorders.
[Show abstract] [Hide abstract]
ABSTRACT: An injury potential is the direct current potential difference between the site of spinal cord injury and the healthy nerves. Its initial amplitude is a significant indicator of the severity of spinal cord injury, and many cations, such as sodium and calcium, account for the major portion of injury potentials. This injury potential, as well as injury current, can be modulated by direct current field stimulation; however, the appropriate parameters of the electrical field are hard to define. In this paper, injury potential is used as a parameter to adjust the intensity of electrical stimulation. Injury potential could be modulated to slightly above 0 mV (as the anode-centered group) by placing the anodes at the site of the injured spinal cord and the cathodes at the rostral and caudal sections, or around -70 mV, which is resting membrane potential (as the cathode-centered group) by reversing the polarity of electrodes in the anode-centered group. In addition, rats receiving no electrical stimulation were used as the control group. Results showed that the absolute value of the injury potentials acquired after 30 minutes of electrical stimulation was higher than the control group rats and much lower than the initial absolute value, whether the anodes or the cathodes were placed at the site of injury. This phenomenon illustrates that by changing the polarity of the electrical field, electrical stimulation can effectively modulate the injury potentials in rats after spinal cord injury. This is also beneficial for the spontaneous repair of the cell membrane and the reduction of cation influx.Neural Regeneration Research 09/2013; 8(27):2531-9. DOI:10.3969/j.issn.1673-5374.2013.27.004 · 0.23 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Collagen is one of the most widely used biomaterial for various biomedical applications. In this paper, we present a novel approach of using collagen hydrolysate, smaller fragments of collagen, as an alternative to traditionally used collagen scaffold. Collagen hydrolysate composite scaffold (CHCS) was fabricated with sol-gel transition procedure using tetraethoxysilane as the silica precursor. CHCS exhibits porous morphology with pore sizes varying between 380 to 780 µm. Incorporation of silica conferred CHCS with controlled biodegradation and better water uptake capacity. Notably, 3T3 fibroblast proliferation was seen to be significantly better under CHCS treatment when compared to treatment with collagen scaffold. Additionally, CHCS showed excellent antimicrobial activity against the wound pathogens Staphylococcus aureus, Bacillus subtilis and Escherichia coli due to the inherited antimicrobial activity of collagen hydrolysate. In vivo wound healing experiments with full thickness excision wounds in rat model demonstrated that wounds treated with CHCS showed accelerated healing when compared to wounds treated with collagen scaffold. These findings indicate that the CHCS scaffold from collagen fragments would be an effective and affordable alternative to the traditionally used collagen structural biomaterials.ACS Applied Materials & Interfaces 08/2014; 6(17). DOI:10.1021/am502948g · 5.90 Impact Factor
Neural Regeneration Research 11/2014; 9(21):1876-7. DOI:10.4103/1673-5374.145475 · 0.23 Impact Factor