In certain kinds of heart failure, trouble begins when the heart fails to relax completely. Staying partially clenched reduces the amount of blood the heart can move, leading to high pressures in the heart chamber, exhaustion, and fluid retention. Most patients with this condition have high blood pressure. Under these stresses, the muscular walls of the heart thicken and scar, further impairing the heart’s function. Approximately 2.5-3.5 million Americans are diagnosed with this disorder, which accounts for roughly half of all heart failure cases. Brant Isakson, PhD, studies diastolic heart failure to understand the biological and physiological factors that affect its progression and patient outcomes. Isakson incorporates extreme physiology into his research; he studies the adaptations animals develop to successfully survive in extreme environments and uses those insights to inform his research of the human body. In this case, this research philosophy led the Isakson lab to Denmark, where they recently retrieved samples from a giraffe’s heart.
To compensate for their extremely high blood pressure in their long necks, giraffes have large hearts with very thick walls—not unlike human hearts with diastolic heart failure. Unlike those human hearts, though, a giraffe heart has none of the scarring that inhibits its function. Isakson wanted samples to identify genetic or physiological factors that allow giraffes to have such large, powerful hearts, but protect them from developing the major symptom of heart failure – exercise intolerance. When he learned a giraffe at a zoo in Denmark was scheduled to be euthanized for health reasons and that his team would be able to collect heart tissue, he jumped at the opportunity. “I found out about this trip on Thursday afternoon, and my flight for Denmark left Monday evening,” remembered Skylar Loeb, a third-year graduate student in Isakson’s lab. Skylar was joined by Luke Dunaway, PhD, a postdoc on the research team. The pair flew eight hours to Copenhagen, then drove another five to Aalborg, where the giraffe was located.
Wednesday morning, they joined several teams of Danish researchers who were also interested in studying the giraffe. “The heart was the size of a human head,” Skylar explained, “so we were able to collect all the tissue we needed.” The samples will be used for RNA sequencing, to identify genetic markers that might explain why the giraffe heart remains functional despite its structural similarity to a heart in diastolic failure. After collecting what they needed, Loeb and Dunaway drove back to Copenhagen, where they delivered the samples to a collaborator of Isakson’s, who will ship the tissue to Charlottesville. “We had a couple hours to explore Copenhagen before our flight on Thursday. It was my first time in Europe, and it was beautiful,” said Loeb.
Traveling to Denmark was beneficial for Loeb beyond just collecting samples, however. “This trip was a great opportunity to see all the work people are doing. I’m so used to thinking about biomedical science, so it was really cool to see what other relevant work, specifically in the field of comparative physiology, that other researchers are doing,” she said. When the samples arrive in Charlottesville, Loeb and Dunaway will have plenty of work annotating the giraffe genome, performing bulk RNA-sequencing and proteomic experiments, and analyzing histology. Until then, their work continues in mouse models of diastolic heart failure.
Dunaway (left) & Loeb (right) in Copenhagen