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Rather than finding a heart that avoids aging altogether, the researchers uncovered something more surprising. <\/p>\n
The Greenland shark heart shows many classic signs of aging, yet it continues to function without obvious problems.<\/p>\n
The research, led by teams from the Biology Laboratory at Scuola Normale Superiore<\/a>, points to an unusual strategy<\/a> for long life: not resistance to aging, but resilience in the face of it.<\/p>\n Aging hearts that still work<\/p>\n In most animals, including humans, aging hearts undergo structural changes that often lead to disease. One common change is fibrosis,<\/a> where excess collagen builds up in heart tissue.<\/p>\n This stiffens the heart and reduces its ability to pump blood effectively. Over time, fibrosis raises the risk of heart failure and rhythm problems.<\/p>\n When scientists examined heart tissue from Greenland sharks, they found extensive fibrosis throughout the ventricle. Both the compact outer layer and the spongy inner layer of the heart were affected. <\/p>\n This pattern appeared in males and females alike. Under the microscope, collagen surrounded blood vessels and filled spaces between heart muscle cells.<\/p>\n Healthy sharks after centuries<\/p>\n What makes this finding remarkable is that the sharks appeared healthy at the time they were caught. <\/p>\n Their hearts showed no signs of failure, despite the level of fibrotic remodeling that would be considered harmful in other species.<\/p>\n To understand whether this was a general feature of deep-sea life, the researchers compared the Greenland shark to a smaller deep-sea shark species, Etmopterus spinax. <\/p>\n That species showed no such fibrosis. This suggests the changes are linked to extreme longevity rather than habitat<\/a> alone.<\/p>\n Cellular wear and tear<\/p>\n Another hallmark of aging is the accumulation of lipofuscin. Often called age pigment, lipofuscin forms from damaged proteins and lipids that cells cannot fully break down. <\/p>\n It builds up inside long-lived cells like neurons and heart muscle cells and is widely used as a marker of cellular aging.<\/p>\n In the Greenland shark, lipofuscin<\/a> was found in massive amounts inside heart muscle cells. The pigment filled much of the cell interior, far more than what is typically seen in shorter-lived animals.<\/p>\n The researchers confirmed its identity using several techniques, including special stains, natural autofluorescence, and resistance to photobleaching.<\/p>\n For comparison, the team also studied hearts from the African turquoise killifish, a species that lives only a few months and is often used in aging research. <\/p>\n Older killifish hearts did contain lipofuscin, but at much lower levels and often outside the muscle cells themselves. The contrast highlights just how extreme the Greenland shark pattern is.<\/p>\n Survival despite cellular breakdown<\/p>\n At an even finer level, electron microscopy revealed what lies behind this pigment buildup. Greenland shark heart cells contained large numbers of damaged mitochondria<\/a>, along with oversized lysosomes packed with dense material.<\/p>\n Many of these structures appeared to be autophagosomes, compartments where cells try to recycle worn-out components.<\/p>\n In most animals, such extensive mitochondrial damage would compromise energy production and trigger cell death. Yet Greenland shark heart cells persist. <\/p>\n The findings suggest that these cells tolerate a high burden of damaged components without losing function. Instead of aggressively clearing every defect, the cells appear able to coexist with them.<\/p>\n This tolerance may be a key feature of resilience. Rather than preventing damage entirely, the Greenland shark heart seems built to endure it over extremely long timescales.<\/p>\n Stress without heart collapse<\/p>\n The study also looked at 3-nitrotyrosine, a marker of oxidative and nitrosative stress. This molecule forms when reactive oxygen and nitrogen species modify proteins, a process linked to aging and tissue damage. <\/p>\n High levels of 3-nitrotyrosine are often associated with declining heart function. Greenland shark hearts showed abundant 3-nitrotyrosine staining, especially in the spaces between cells.<\/p>\n This pattern was similar to what is seen in aged killifish<\/a> hearts, but again, without obvious signs of disease. In contrast, the shorter-lived deep-sea shark showed almost no signal.<\/p>\n These results challenge the idea that long life necessarily depends on low oxidative stress. Instead, they support a growing view that some long lived species survive by coping with oxidative damage rather than avoiding it.<\/p>\n Lessons from the Greenland shark<\/p>\n Together, these findings paint a striking picture. The Greenland shark heart displays many classic features of aging: fibrosis, lipofuscin accumulation, mitochondrial damage, and oxidative stress. <\/p>\n Yet these changes do not translate into clear functional decline, even after a century or more of life.<\/p>\n This disconnect points to resilience as a central principle of extreme longevity. The Greenland shark does not escape aging at the molecular level. Instead, its tissues remain stable and functional despite it. <\/p>\n Understanding how this resilience is achieved could reshape how scientists think about aging, not as something to eliminate, but as something that living systems can learn to live with.<\/p>\n By studying animals like the Greenland shark, researchers gain a rare window into biological strategies that allow vital organs to keep working far beyond the limits seen in humans. <\/p>\n These insights may one day help inform new approaches to protecting the aging human heart.<\/p>\n The study is published in the journal BioRxiv<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"The Greenland shark is one of the most mysterious animals in the ocean. Living in cold, deep waters…\n","protected":false},"author":2,"featured_media":415307,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[51],"tags":[1147,79,201],"class_list":{"0":"post-415306","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-wildlife","8":"tag-animals","9":"tag-science","10":"tag-wildlife"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/415306","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=415306"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/415306\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/415307"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=415306"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=415306"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=415306"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}