Faculteit Dierengeneeskunde
 

In a series of interviews with researchers of Utrecht University, Utrecht Medical Center or other ULS-partners, we want to give more insight into current developments in the replacement, reduction and refinement of laboratory animal experimentation within these research facilities.

February 2016

New refinement technique in a murine heart failure model

Nowadays, a major human health problem is posed by congestive heart failure, especially due to the ageing population1. Due to an increased survival rate in myocardial infarction patients, the number of heart failure patients is rapidly increasing. Besides, several common comorbidities also contribute to the development of heart failure, such as hypertension and type 2 diabetes. Because no curative treatment for heart failure is currently available, there is an urgent need to develop effective treatments.

Around 50% of heart failure patients fall into the category of diastolic heart failure, also called heart failure with preserved ejection fraction (HFpEF)2, which is the percentage of outbound blood pumped from the left ventricle with each contraction. Persons with HFpEF are often women with a history of hypertension. Despite seemingly normal or near-normal ejection fractions, they have heart failure, because of insufficient ventricular relaxation (caused by stiffness of the heart muscles) leading to smaller amounts of blood in the heart ventricle and as a consequence a lower output1.


Constriction of the transverse aorta

The research group of dr. de Jager, Laboratory of Experimental Cardiology at the University Medical Centre Utrecht, unravels possible health effects of and treatments for HFpEF in clinically relevant animal models. The research group refined a microsurgical technique in mice for the reproducible induction of pressure overload on the myocardium, resulting in myocardial stiffening, mimicking HFpEF. In this new surgical procedure, the thoracic cavity of the anesthetized mouse is opened with a small incision of 0.5 cm at the left upper sternal border in the second intercostal space. Constriction of about 60% of the transverse aorta occurs by passing a 7-0 silk suture between the first and second branch of the aortic arch (the brachiocephalic trunk and the left common carotid artery). Tying against a 27 G needle guarantees a similar pressure on the aorta in all procedures. This procedure is called Transverse Aortic Constriction (TAC), see picture below. 

A Picture of the Tranverse Aortic Constriction

Depending on the research question, mice received different treatments during the experiment. Mice are euthanized after 6-8 weeks and heart and kidneys are isolated for immunohistochemistry and protein isolation. 


Refinement

The formerly applied procedure involved opening the sternum of the mouse, a very invasive technique. Mice needed long recovery after the surgery because of broken ribs and did not always survive during the experiment. With the modified TAC-technique, recovery period is very short without any damage to the sternum or ribs. Above this, mice receive analgesics for three days after the TAC surgery. Without even realizing that this new technique is really an improvement for mice welfare, dr. de Jager and her research group applied this method successfully in several experimental designs.

Consortium

Dr. de Jager mentioned that they are more than happy to collaborate with other research groups that are interested in their improved TAC-surgery. At the moment, the technique is only applied at the University of Singapore by a former PhD-student of the group of dr. de Jager. The Laboratory of Experimental Cardiology is part of a Dutch consortium3 that studies the connection between renal dysfunction and heart failure, called CVON RECONNECT. The murine TAC model does not represent human comorbidities like renal dysfunction, hypertension or type 2 diabetes. Together with research groups from Rotterdam (Erasmus MC), Utrecht and Leiden (LUMC) dr. de Jager aims to develop better animal models mimicking HFpEF in the future.

1: Rich M.W., Heart failure in the 21st Century, a cardiogeriatric syndrome (2001), 56 (2): M88-M96. 
2: Schläpfer-Pessina A. et al., Does treatment improve prognosis of heart failure with preserved ejection fraction? (2015), Rev Med Suisse 2015, 11(458): 199-205.
3:For more information about the CVON RECONNECT Consortium, read more here.