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Sulejczak D.♦, Taraszewska A.♦, Chrapusta S.J.♦, Dziewulska D.♦, Nakielski P., Rafałowska J.♦, Nanofiber mat spinal cord dressing-released glutamate impairs blood-spinal cord barrier,
FOLIA NEUROPATHOLOGICA, ISSN: 1641-4640, DOI: 10.5114/fn.2016.64818, Vol.54, No.4, pp.392-404, 2016Abstract: An excessive glutamate level can result in excitotoxic damage and death of central nervous system (CNS) cells, and is involved in the pathogenesis of many CNS diseases. It may also be related to a failure of the blood-spinal cord barrier (BSCB). This study was aimed at examining the effects of extended administration of monosodium glutamate on the BSCB and spinal cord cells in adult male Wistar rats. The glutamate was delivered by subarachnoidal application of glutamate-carrying electrospun nanofiber mat dressing at the lumbar enlargement level. Half of the rats with the glutamate-loaded mat application were treated systemically with the histone deacetylase inhibitor valproic acid. A group of intact rats and a rat group with subarachnoidal application of an ‘empty’ (i.e., carrying no glutamate) nanofiber mat dressing served as controls. All the rats were euthanized three weeks later and lumbar fragments of their spinal cords were harvested for histological, immunohistochemical and ultrastructural studies. The samples from controls revealed normal parenchyma and BSCB morphology, whereas those from rats with the glutamate-loaded nanofiber mat dressing showed many intraparenchymal microhemorrhages of variable sizes. The capillaries in the vicinity of the glutamate-carrying dressing (in the meninges and white matter alike) were edematous and leaky, and their endothelial cells showed degenerative changes: extensive swelling, enhanced vacuolization and the presence of vascular intraluminal projections. However, endothelial tight junctions were generally well preserved. Some endothelial cells were dying by necrosis or apoptosis. The adjacent parenchyma showed astrogliosis with astrocytic hypertrophy and swelling of perivascular astrocytic feet. Neurons in the parenchyma revealed multiple symptoms of degeneration, including, inter alia, perikaryal, dendritic and axonal swelling, and destruction of organelles. All the damage symptoms were slightly less severe in the rats given valproic acid treatment, and were absent from both the intact rats and the rats with ‘empty’ nanofiber mat dressing. These results demonstrate that glutamate-loaded nanofiber mat dressing can locally create glutamate levels capable of damaging BSCB and that the resulting damage can be mitigated with concurrent systemic valproate treatment. Keywords: astrocyte, blood-spinal cord barrier, CNS damage, degeneration, endothelium, excitotoxicity, glutamate, neuron, valproate, vessels Affiliations:
Sulejczak D. | - | other affiliation | Taraszewska A. | - | other affiliation | Chrapusta S.J. | - | Mossakowski Medical Research Centre, Polish Academy of Sciences (PL) | Dziewulska D. | - | Mossakowski Medical Research Centre, Polish Academy of Sciences (PL) | Nakielski P. | - | IPPT PAN | Rafałowska J. | - | other affiliation |
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Rafałowska J.♦, Sulejczak D.♦, Chrapusta S.J.♦, Gadamski R.♦, Taraszewska A.♦, Nakielski P., Kowalczyk T., Dziewulska D.♦, Non-woven nanofiber mats – a new perspective for experimental studies of the central nervous system?,
FOLIA NEUROPATHOLOGICA, ISSN: 1641-4640, DOI: 10.5114/fn.2014.47841, Vol.52, No.4, pp.407-416, 2014Abstract: (Sub)chronic local drug application is clearly superior to systemic administration, but may be associated with substantial obstacles, particularly regarding the applications to highly sensitive central nervous system (CNS) structures that are shielded from the outer environment by the blood-brain barrier. Violation of the integrity of the barrier and CNS tissues by a permanently implanted probe or cannula meant for prolonged administration of drugs into specific CNS structures can be a severe confounding factor because of the resulting inflammatory reactions. In this study, we tested the utility of a novel way for (sub)chronic local delivery of highly active (i.e., used in very low amounts) drugs to the rat spinal cord employing a non-woven nanofiber mat dressing. To this end, we compared the morphology and motoneuron ( + ) counts in spinal cord cervical and lumbar segments between rats with glutamate-loaded nanofiber mats applied to the lumbar enlargement and rats with analogical implants carrying no glutamate. Half of the rats with glutamate-loaded implants were given daily valproate treatment to test its potential for counteracting the detrimental effects of glutamate excess. The mats were prepared in-house by electrospinning of an emulsion made of a solution of the biocompatible and biodegradable poly(L-lactide-co-caprolactone) polymer in a mixture of organic solvents, an aqueous phase with or without monosodium glutamate, and sodium dodecyl sulfate as an emulsifier; the final glutamate content was 1.4 µg/mg of the mat. Three weeks after mat implantation there was no inflammation or considerable damage of the spinal cord motoneuron population in the rats with the subarachnoid dressing of a glutamate-free mat, whereas the spinal cords of the rats with glutamate-loaded nanofiber mats showed clear symptoms of excitotoxic damage and a substantial increase in dying/damaged motoneuron numbers in both segments studied. The rats given systemic valproate treatment showed significantly lower percentages of damaged/dying motoneurons in their lumbar enlargements. These results demonstrate the capacity of nanofiber mats for generation of neurotoxic glutamate in the rat CNS. However, the tested nanofiber mats need further improvements aimed at extending the period of effective drug release and rendering the release more steady. Keywords: CNS injury, electrospinning, excitotoxicity, glutamate, motoneuron, nanofibers, neurodegeneration, spinal cord, valproate Affiliations:
Rafałowska J. | - | other affiliation | Sulejczak D. | - | other affiliation | Chrapusta S.J. | - | Mossakowski Medical Research Centre, Polish Academy of Sciences (PL) | Gadamski R. | - | Mossakowski Medical Research Centre, Polish Academy of Sciences (PL) | Taraszewska A. | - | other affiliation | Nakielski P. | - | IPPT PAN | Kowalczyk T. | - | IPPT PAN | Dziewulska D. | - | Mossakowski Medical Research Centre, Polish Academy of Sciences (PL) |
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