Image credit: Adapted from figure by Ward and Gilad (CC BY 4.0)
Understanding why some people get heart disease and others do not could help scientists find better ways to treat or prevent the condition. Genetics likely plays a role, and one way to identify genes that are important for heart health is to compare genes in humans and their closest evolutionary relatives, the chimpanzees. Though it is not exactly the same as seen in humans, chimpanzees do get heart disease. Differences in the genes involved in heart disease in humans and chimpanzees may help explain what leads to the disease in humans.
Studying heart disease in chimpanzees and humans has been challenging because heart tissue from humans and chimpanzees is hard to come by. Yet scientists can now convert easy-to-access skin cells from humans and chimpanzees into heart cells and grow them under laboratory conditions.
Ward and Gilad have used exactly this approach to see how human and chimpanzee cells respond when they are starved of oxygen, which simulates a heart attack. First, skin cells collected from eight humans and seven chimpanzees were coaxed into becoming heart cells and grown in the laboratory. Ward and Gilad then compared the activity levels of about 12,000 genes in these heart cells when their oxygen was limited. The responses were very similar, with 1,920 genes switching on or off in both species. But the activity of hundreds of other genes differed between humans and chimpanzees. For example, a gene called RASD1, which is known to be important in human heart disease, became active in oxygen-starved human cells but not in chimpanzee cells.
Genes that vary in their activity between healthy human individuals are thought to be important in disease. However, Ward and Gilad found that the activity of genes that switch on or off in both species after oxygen starvation did not vary a lot in a collection of heart samples from hundreds of individuals. These experiments may help scientists narrow down which genes are likely most important in heart disease. More studies are needed to understand what these genes do and how they contribute to heart disease.
