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Good news on the stem cell research front
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A STEP IN THE RIGHT DIRECTION: Progress in stem cell research may have positive implications for those suffering from heart disease.
Scientists have found a way to turn mouse embryonic stem cells into beating heart muscle cells -- a result that could lead to the use of embryonic stem cells in cardiac therapy, and possibly even drugs that can prompt the body to regenerate heart cells on its own.
The research tackles a number of the obstacles thwarting practical applications of embryonic stem cells, while also pointing to a viable path around the ethical and political concerns encompassing the debate. Because embryonic stem cells can turn into any type of cell in the body, many scientists believe they hold incredible promise for treating a variety of degenerative diseases. Quite a few scientific hurdles, however, stand in the way of tangible therapies for such maladies as diabetes, Alzheimer's, Parkinson's and heart disease.
Scientists from The Scripps Research Institute in La Jolla, California have discovered a synthetic chemical, named cardiogenol, which can selectively differentiate embryonic stem cells into beating cardiac muscle cells. Embryonic stem cells represent a potentially unlimited source of cardiomyocytes -- cells that can repair damaged heart tissue in the body -- but until now scientists have been unable to control the direction of embryonic stem cells to use them in the treatment of heart disease. They screened a vast library of compounds in search of molecules with the potential to cause stem cells to grow into heart muscle cells.
They found four such molecules, which they named cardiogenol A-D. They tested the cardiogenol compounds by using embryonic stem cells from mice.
After seven days growing in a tissue culture dish, the majority of the stem cells were converted into beating cardiac muscle cells. While the tests were done only with mouse cells, the fundamental biology should transfer well to higher organisms.
It was found that another small molecule called reversine appears to convert adult cells normally programmed to create skeletal muscles back into precursor cells with similar properties as stem cells.
This type of research may ultimately facilitate development of drugs that can stimulate tissues to regenerate themselves, without any need to harvest external stem cells. This represents an exciting medical opportunity.
Much more work is required to understand the biological properties and mechanisms of reversine, but these preliminary results raise the tantalizing possibility that it may be possible to synthesize a compound that creates viable stem cells from adult tissue.
Such cells would not be rejected by the immune system, since they come directly from the patient who needs them. A molecule like reversine could be combined with a cardiogenol-type molecule to produce a drug that kindles regeneration of heart tissue.
Almost every tissue has its own reserve of stem cells, so ultimately we hope we don't have to isolate those cells from the body. We can stimulate tissue to regenerate by just stimulating cells within the body.
This type of regeneration already occurs in a number of natural processes. In lower organisms, for example, urodele amphibians can regenerate lost limbs and tails. In humans and other mammals, the liver can regenerate naturally. And young children can even regenerate fingertips.
All of these processes are directed by molecular signaling. If people can develop small molecule therapeutics to precisely mimic and control those signals for correcting defects or repairing damaged tissues, we could eventually buy those in a pharmacy as a prescription drug. Not only would this alleviate some of the ethical concerns surrounding stem cells, but also a less-frequently discussed downside to stem cell treatments: their invasiveness.
Small-molecule therapies involving regenerative medicine are probably years away from clinical use. At present, scientists are focusing on understanding cardiogenol's mechanism of action, and designing future experiments to test these molecules in disease models.
Mohammad Badrud Duza
Final M.Tech, Centre for Biotechnology and
Syed Parveen
Final MBBS,
Deccan Medical College
Biosensor for a risk-free world
The largest application of biosensors at present is in medicine. Enzymes are being used increasingly for routine automatic analysis of body fluids for metabolites and hormones. They are particularly useful for clinical diagnosis. Using biosensors reduces the risk of errors in diagnosis and also reduces costs once the biosensors are mass produced. Less time and less expertise is needed. Biosensors, which are more sensitive and smaller, could be developed by using biochips. Biochips would be small enough to be implanted in human body. Devices such as artificial sense organs and heart pacemakers might then become possible.
An example of a commonly used biosensor is the one developed for detecting glucose in diabetics. This contains the enzyme glucose oxidase in an immobilised form. The enzyme oxidises glucose in the body to release electrons.
These are collected and converted into an electrical current. The current generated is proportional to the amount of glucose present. It is extremely sensitive and can measure the glucose concentration in a single drop of and display the result within 20 seconds.
It is hoped that eventually it will be possible to implant such devices in vessels in the skin of diabetics, allowing them to monitor more accurately their insulin requirements.
If this is linked to a mini-pump so that insulin is automatically released when needed, the diabetic will have, in effect, an automatic pancreas. This fine control would reduce the common secondary effects of diabetes, such as eye and kidney damage, suffered by some diabetics as a result of the relatively crude peaks and troughs of insulin concentration obtained with occasional injections.
Musheer Riaz
B.Tech (Biotechnology ) 2nd year, BERC Rai Foundation Colleges
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