Scanning laser-induced endothelial injury: a standardized and reproducible thrombosis model for intravital microscopy.

Vascular injury models are indispensable for studying thrombotic processes in vivo. Amongst the available methods for inducing thrombosis, laser-induced endothelial injury (LIEI) has several unique advantages. However, a lack of methodological standardization and expensive instrumentation remain significant problems decreasing reproducibility and impeding the adoption of LIEI in the wider scientific community. In this, study, we developed a standardized protocol for scanning laser-induced endothelial injury (scanning-LIEI) of murine mesenteric veins using the intrinsic 405 nm laser of a conventional laser scanning confocal microscope. We show that our model produces thrombi with prominent core-shell architectures and minimal radiation-related fluorescence artefacts. In comparison with previous methods, the scanning-LIEI model exhibits reduced experimental variability, enabling the demonstration of dose-response effects for anti-thrombotic drugs using small animal cohorts. Scanning-LIEI using the intrinsic 405 nm laser of a confocal laser scanning microscope represents a new method to induce standardized vascular injury with improved reproducibility of thrombus formation. The reduced need for instrument customisation and user experience means that this model could be more readily adopted in the research community.

Role of proteolysis in polyglutamine disorders.

To date, nine polyglutamine disorders have been characterised, including Huntington's disease (HD), spinobulbar muscular atrophy (SBMA), dentatorubral-pallidoluysian atrophy (DRPLA), and spinocerebellar ataxias 1, 2, 3, 6, 7 and 17 (SCAs). Although knockout and transgenic mouse experiments suggest that a toxic gain of function is central to neuronal death in these diseases (with the probable exception of SCA6), the exact mechanisms of neurotoxicity remain contentious. A further conundrum is the characteristic distribution of neuronal damage in each disease, despite ubiquitous expression of the abnormal proteins. One mechanism that could possibly underlie the specific distribution of neuronal toxicity is proteolytic cleavage of the full-length expanded polyglutamine tract-containing proteins. There is evidence found in vitro or in vivo (or both) of proteolytic cleavage in HD, SBMA, DRPLA, and SCAs 2, 3, and 7. In HD, cleavage has been demonstrated to be regionally specific, occurring as a result of caspase activation. These diseases are also characterised by development of intraneuronal aggregates of the abnormal protein that co-localise with components of the ubiquitin-proteasome pathway. It remains unclear whether these aggregates are pathogenic or merely disease markers; however, at least in the case of ataxin-3, cleavage promotes aggregation. Inhibition of specific proteases constitutes a potential therapeutic approach in these diseases.