University of Utah biologists, led by assistant professor Jamie Gagnon, have been studying how some animals are able to regenerate cardiac tissue while humans are not. Zebrafish and medaka fish were the focus of their research, with zebrafish being able to regenerate their hearts while medaka cannot. The team found that zebrafish have an immune response to cardiac injuries that is absent in medaka. By comparing these two fish, the researchers hoped to identify the main differences that allow zebrafish to heal their hearts.
The study conducted involved using a cryoprobe device to injure the fish hearts in ways that resembled human heart attacks. By examining how the hearts responded differently to the injury, the researchers were able to identify markers that indicated how the two species reacted. Zebrafish showed an immune response similar to what occurs during a viral infection, whereas medaka did not. The study also highlighted differences in heart structure and makeup between the two fish species, with medaka lacking certain muscle cells that are present in zebrafish.
The researchers believe that the ability to regenerate cardiac tissue may be an ancestral trait common to all teleost fish. Understanding how this ability was lost in some species could provide insights into why mammals cannot regenerate heart tissue as adults. The study suggests that zebrafish’s regenerative abilities are linked to their immune system. The immune response triggers the growth of new blood vessels and the replacement of damaged cardiac tissue with new muscle over time.
The team found that zebrafish form a transient scar after cardiac injuries that promotes healing, unlike medaka whose scars calcify into rigid tissue. The presence of specialized immune cells called macrophages in zebrafish may play a key role in promoting tissue regeneration. The researchers hope that by studying how animals can regenerate tissues and identifying how these features have been lost in humans, they can develop strategies to overcome these limitations. The knowledge gained from studying animals like zebrafish in detail could lead to focused experiments in mammals and eventually in human patients in the future.
Overall, the research conducted by the University of Utah biologists sheds new light on the mechanisms involved in heart regeneration in zebrafish. By comparing zebrafish and medaka fish, the researchers were able to identify differences in immune responses and cellular features that contribute to zebrafish’s ability to heal cardiac tissue. The findings from this study could have implications for developing medical treatments for human cardiac patients in the future, by understanding how animals like zebrafish are able to regenerate damaged heart muscle.
