Why can't humans replicate hearts like newts?

Stem cell researchers at UCLA, USA, have discovered for the first time: Because the human body is much larger than newts and salamanders, so we need to More heart to maintain optimal blood pressure and circulation. As a result, adult cardiac muscle cells (specialized cardiac muscle cells) have lost their ability to proliferate quickly. This finding helps explain why the human heart has very little ability to regenerate.

Newts,

The study, done in cell lines and mice, could lead to the resurgence of the reprogramming of cardiac muscle cells inside the patient's heart, in order to produce cardiac muscle cells. new to replace damaged heart muscle cells, according to Dr. Robb MacLellan, a researcher working at Eli and Edythe Broad's Center for Regenerative Stem Cells and Medicine, UCLA University, United States. States and the main author of the study.

Unlike newts and salamanders, the adult's body cannot spontaneously regrow damaged parts like the heart. However, recent research shows that mammals have the ability to regenerate the heart, but only for a very short time, in the first week of life.

If our bodies once did it once, according to Dr. MacLellan, we need to deepen our research to restore that ability.

The results of this study were published in Cell Biology , August 8, 2011.

MacLellan believes that it may be possible to reverse the cell's biological clock to the point where cardiac muscle cells are able to proliferate rapidly and regrow the heart muscle itself.

" The salamanders and low-level organisms have the ability to regenerate the heart muscle cells, or bring the heart muscle cells back to a more primitive state, allowing these heart muscle cells to return The period of self-growth rapidly develops, and creates new heart muscle , "according to MacLellan. " In mammals, the human body has lost this potential. If we know how to recover, or know why the heart muscle cells of an adult cannot do it. We can try to find a way to use natural methods to rebuild the heart. "

During the development of the human body, cardiac muscle cells are formed from progenitor stem cells, and these cardiac muscle cells multiply themselves to form the heart. Once the heart is formed, these cardiac muscle cells transform themselves from immature cells into mature cells and are unable to reproduce themselves.

This process does not happen to newts and salamanders, which have cardiac muscle cells that can return between the mature and immature or immature cardiac muscle cells, to continue to join the cycle. Cardiac muscle cells multiply rapidly and replace damaged cells. After the damage is repaired, the heart muscle cells regenerate themselves, and become mature cells.

MacLellan believes that the reason why the human body cannot do this is quite simple: When the heart muscle cells of a person are in a primitive state, they are not suitable for contraction, while this is functional. important of the heart. Because the human body is much larger than newts and salamanders, we need more heart contraction to maintain optimal blood pressure and circulation.

"It is the way the human body develops, to maintain blood pressure and blood flow, as a result our bodies have to give up the ability to self-regenerate heart muscle ," MacLellan said. "This is really a trade-off for a healthy heart with effective heart muscle. "

MacLellan said that by temporarily removing the cell cycle inhibitory proteins, to help adult cardiac muscle cells re-enter the cell cycle and return to the state they have can multiply quickly. These treatments will need to do the reverse of the action of the manipulated protein, until the damage is corrected. Then the heart muscle cells will mature again and assist in the contraction of heart muscle with a healthy heart muscle to be regenerated.

Currently, MacLellan is seeking to use nanoparticles to inject interference RNAs deep inside the heart to eliminate manipulating proteins that keep the heart muscle cells mature.

When a heart attack occurs, part of the organ is oxygenated, causing some heart muscle cells to die and resulting in scar tissue. It is easy to locate damaged areas of the heart, and if there is a way that can be developed to reprogram a patient's heart muscle cells, the system of manipulating proteins (Keeping the heart muscle cells mature) can be injected into the damaged area, re-affecting the cardiac muscle cells that are in their original state and replacing the dead heart muscle cells with cardiac muscle cells. new healthy, MacLellan said.

" We talked about the ability of low-level organisms to reproduce for a long time and why this doesn't happen in humans, " MacLellan said. " This is the first study to provide a reason and mechanism for troubleshooting above ."

I have heard a lot about the use of human embryonic stem cells or reprogramming induced pluripotent stem cells to recreate the heart. However, no one knows exactly how much rebirth is needed and the real benefits received.

" From my point of view, this is a mechanism capable of reproducing cardiac muscle cells without having to harvest or expand stem cells ," MacLellan said. " Each person will use his own heart muscle cell source in the process of regenerating healthy heart muscle cells. "

This study was carried out for 5 years and received funding from the US National Institutes of Health.