RESUMO
Background: Traumatic brain injury (TBI) has a dramatic impact on mortality and quality of life and the development of effective treatment strategies is of great socio-economic relevance. A growing interest exists in using polymeric nanoparticles (NPs) as carriers across the blood-brain barrier (BBB) for potentially effective drugs in TBI. However, the effect of NP material and type of surfactant on their distribution within organs, the amount of the administrated dose that reaches the brain parenchyma in areas with intact and opened BBB after trauma, and a possible elicited inflammatory response are still to be clarified. Methods: The organ distribution, BBB permeation and eventual inflammatory activation of polysorbate-80 (Tw80) and sodiumdodecylsulfate (SDS) stabilized poly(L-lactide) (PLLA) and poly(perfluorodecyl acrylate) (PFDL) nanoparticles were evaluated in rats after intravenous administration. The NP uptake into the brain was assessed under intact conditions and after controlled cortical impact (CCI). Results: A significantly higher NP uptake at 4 and 24 h after injection was observed in the liver and spleen, followed by the brain and kidney, with minimal concentrations in the lungs and heart for all NPs. A significant increase of NP uptake at 4 and 24 h after CCI was observed within the traumatized hemisphere, especially in the perilesional area, but NPs were still found in areas away from the injury site and the contralateral hemisphere. NPs were internalized in brain capillary endothelial cells, neurons, astrocytes, and microglia. Immunohistochemical staining against GFAP, Iba1, TNFα, and IL1ß demonstrated no glial activation or neuroinflammatory changes. Conclusions: Tw80 and SDS coated biodegradable PLLA and non-biodegradable PFDL NPs reach the brain parenchyma with and without compromised BBB by TBI, even though a high amount of NPs are retained in the liver and spleen. No inflammatory reaction is elicited by these NPs within 24 h after injection. Thus, these NPs could be considered as potentially effective carriers or markers of newly developed drugs with low or even no BBB permeation.
RESUMO
With increasing evidence for the existence of a cerebral thrombin system, coagulation factor IIa (thrombin) is suspected to influence the pathogenesis of secondary injury progression after intracerebral hemorrhage (ICH). We hypothesized that mechanisms associated with local volume expansion after ICH, rather than blood constituents, activate the cerebral thrombin system and are responsible for detrimental neurological outcome. To test this hypothesis, we examine the local thrombin expression after ICH in a C57BL/6N mouse model in the presence and absence of blood constituents. ICH was established using stereotaxic orthotopic injection of utologous blood (n = 10) or silicone oil as inert volume substance (n = 10) into the striatum. Intracranial pressure (ICP), cerebral blood flow (CBF), and mean arterial blood pressure (MAP) were monitored during and 30 min after the procedure. No significant differences between ICP, CBF, and MAP were found between both groups. Prothrombin messenger RNA expression was upregulated early after ICH. Immunohistochemistry showed an increase of perilesional thrombin in both groups (blood, 4.24-fold; silicone, 3.10-fold), whereas prothrombin fragment (F1.2) was elevated only in the absence of whole blood. Thrombin expression is colocalized with neuronal antigen expression. After 24 h, lesion size and neuronal loss were similar. Perihematomal thrombin correlated with increased neuronal loss and detrimental neurological outcome in vivo. In our study, we demonstrate, for the first time, that the local cerebral thrombin system is activated after ICH and that this activation is independent of the presence of whole-blood constituents. In our study, neuronal damage is driven by local thrombin expression and leads to an adverse clinical outcome.
