Age is something that scientists still struggle to understand. It seems to be built into the DNA and affects the human body. In particular, aging has a strong effect on cardiac health, and efforts to develop ways of understanding this interaction are advancing every day.
In biology, model systems are everything. Model systems are well-researched organisms that allow scientists to examine anything from organ systems to genetic mutations work. The plant Arabidopsis thaliana, the bacteria Escherichia coli, and the yeast Saccharomyces cerevisiae are examples of model systems. For humans, macaques and marmosets have been used as the model system quite effectively in several fields.
In an effort to help elucidate how aging affects cardiac health, a group from the Leibniz Institute for Primate Research in Germany put forward an idea. Using marmosets, which have a relatively short lifespan, as a human model system, they would develop a protocol of using magnetic resonance imaging (MRI) to observe the effects of aging on cardiac health.
To conduct the MRI on marmosets, the team had to rely on a method called IntraGate Flash, which allowed them to get images with certain limitations. This method allowed them to get quantifiable images from most of the marmosets in the test population. An early observation they had was that marmosets did not have sex-linked heart sizes. This is not true for all primates and allowed the team to pool test data from both males and females for better results.
The other observation they made was the reduction of diastolic, or filling, and systolic, or pumping volumes of both ventricles of marmosets with increasing age. The ventricles are the actual blood-pumping portions of the heart. Oddly, common indicators of a weakening heart such as ejection fraction showed there was no loss of heart strength with age. The team hypothesized this could be due to a change in the myocardium’s, or heart muscle, density as marmosets aged.
All in all, the group successfully uses marmosets as a model system for examining heart health in an aging population. One issue they had was simply the lack of clear right ventricle images, which made much of their data concerning the right ventricle statistically insignificant. They also suspected the long Intragate Flash MRI process affected the quality of their MRI. Regardless, they managed to observe a possible change in myocardium density in the ventricles of aging marmosets using the MRI protocol they developed.
The team concluded, “Taking into account the cardiovascular similarities that share marmosets with humans and the recent achievements in genetic manipulation of these monkeys, these findings strongly support marmosets for the use as model system for age related cardiovascular diseases.”