Forsøksdyr: #2 Influence of NLRP3 knockout and ASC knockout bone marrow chimeras on cardiac function after a myocardial infarction (copy)


Godkjenningsdato 02.03.2018

This is a copy of FOTS application 6895. The application was expired, however not all needed experiments were performed.
Due to the results obtained in application 6895 we expect reviewers to ask us to repeat the experiments which we have done before, in order to proof the consistency of the obtained results. Therefore all experimental groups of FOTS 6895 are included in this new application. The experiments who are carried out before will only be executed when the reviewers ask for it.

Purpose:
Recent studies in our group showed that the NLRP3/ASC complex plays a significant role in the pathogenesis after an acute myocardial infarction. We observed that after the induction of a myocardial infarction there is a different phenotype between ASC knock out mice and NLRP3 knock out mice. In the current application we apply for a study where we can investigate if the observed phenotype is immune cell (bone marrow) derived.

Expected adverse effects:
The mice will undergo radiation and injection to receive bone marrow. After bone marrow engraftment myocardial infarction surgery will take place. Mice will be monitored closely after the procedures regarding pain/discomfort, especially during the acute phase (day 1-14 bone marrow transplant, first hours/days infarct surgery) as death due to non engraftment (bone marrow) or arrhythmia/rupture of the left ventricle (infarct surgery) might occure. Adverse effects during the study will be moderate.

Expected scientific/societal benefit:
The results from this study will help us to understand more about the specific role the NLRP3 inflammasome plays during and after a myociardial infarction and might uncover potential treatment effects of NLRP3 and ASC in this process.

Number of mice: 720 mice, consisting of WT, NLRP3-/- and ASC-/-.

Replacement:
We want to study the effect of the gene deletions of NLRP3 and ASC. To be able to find the mechanism behind the improved survival and remodeling in the NLRP3 knock out mice we need to study the complex relation in between cardiac remodeling, fibrosis and cardiac dysfunction after a myocardial infarction, and this can not be studied by means of an in vitro experiment.

Reduction:
We have experience with this model and the phenotype of the mice (FOTs number 6895, 5926). As a result; we can make a better prediction on the number of mice who are needed for this experiment.
Furthermore, we have refined the methods for the usage of heart tissue after sacrifice and we can use the same heart for histology, RNA and protein analysis.

Refinement:
The mice are handled by the same, trained researchers, assuming to reduce stress. We will follow well established methods regarding infarct surgery, anaesthesia and analgesia. In addition, mice will be euthanized if body weight is reduced more than 15% of their original weight or they show signs of severe HF with inactivity and tachopnoea. Furthermore, we follow the guidelines for housing and environmental enrichment applicable to our department.