Skip to comments.Heart cells coaxed to divide and conquer
Posted on 12/06/2012 12:33:50 AM PST by neverdem
The heart does have a limited ability to heal itself and a genetic 'trick' can harness this.
Can heart cells renew themselves, and can scientists help them do so? Two papers published online in Nature today suggest that heart muscle cells can make copies of themselves at a very low rate1, but that a genetic trick can prompt them to do a better job2. Those results give hope that hearts damaged by cardiovascular disease which causes the deaths of almost 17 million people a year could be coaxed to regenerate themselves.
Heart muscle cannot renew itself very well. Researchers would like to help that process by finding populations of cells in the heart that can do so, and then boosting that capacity. But it has not been easy to find evidence of these regenerating cells, or to assess the extent of their powers.
The two Nature papers aim to get to the heart of the matter. In one, a team led by Richard Lee at the Brigham and Womens Hospital and Harvard Medical School, both in Boston, Massachusetts, traced the birth and fate of heart muscle cells in mice. Lee and his colleagues found that a small proportion of heart cells less than 1% can regenerate themselves normally. After a heart attack that proportion goes up, but only to 3%.
These studies dispel any notion of the heart having a robust ability to regenerate, says Charles (Chuck) Murry, who studies heart regeneration at the University of Washington in Seattle.
That those cells exist at all is heartening, however. If there is some capacity for the heart to produce new heart muscle cells, thats a foothold that we can work with, says Matthew Steinhauser, a co-author on the paper and a member of Lees...
(Excerpt) Read more at nature.com ...
I don't know how scientists did that, unless they have bred mice that can be triggered for heart attacks.
Anyway, they could use my BIL. He relates that while relaxing on a porch, a mouse approached. The mouse looked directly at him and keeled over, dead.
I see one problem here. The heart and brain have cells that don’t divide rapidly and for good reason, you don’t want swelling or hypertrophy to occur in such vital organs, the brain because of the confined area and the heart beacause the electrical system is very complicated and precise and arrhthymias can easily occur if there is an abundance of abnormal cells.
After a decade of participating in a program which his cardiologist figured no one would make it past the first year, the dye shot showed new blood vessel development in the scarred area, indicating some regeneration. The natural process is slow, but it happens. Accelerating that too much could be bad, but if the regeneration could be regulated there might be benefit.
The rats and mice get general anesthesia and surgery. Their coronary arteries are located. Surgical clamps are applied to those arteries. Voila! Those critters just had surgically induced myocardial infarctions, aka heart attacks.
To more closely mimic the natural process, one would induce an artery-blocking clot, not clamp an open artery which, once the clamp is removed, becomes fully open again rather than having to deal with biologically clearing the clot away. Since the point is to track the recovery process, not to kill the mouse.
But it also ought to be possible to breed a variety of mouse that is prone to these clots in the first place.
Cool - if they con control the regeneration.
Thanks for the post
con control = can control
That model is not cheap. For their purposes, a general model of ischemic heart disease, also known as myocardial ischemia, i.e. an impaired blood supply, will suffice. Mimicing the pathogenesis and critical or terminal events of coronary artery disease, i.e. the building up of atherosclerotic plaque, its eventual rupture and formation of a blood clot at the site of that rupture simply costs too much. Coronary artery disease, CAD, is also called coronary heart disease, CHD.
Since the point is to track the recovery process, not to kill the mouse.
The surgical clamping of various coronary arteries is a versatile technique depending on what the investigators want to do. If you want to kill a region of myocardium and induce fibrotic scar tissue formation, then clamp for a long enough period of time that branch of the coronary arteries in mice or rats. For example, if you want to mimic the worst type of congestive heart failure in humans, you apply the clamp long enough to the branch called the left anterior descending, LAD. That can knock out a part of the left ventricle depending on how high up or low down on the LAD the clamp is placed.
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