Scientists Regrow an Entire Rat Limb in the Lab

A team of regenerative scientists and surgeons at Massachusetts General Hospital successfully grew a semi-functional rat forelimb in the lab, employing a technique previously used to build bio-artificial organs. The same technique has been used to regenerate kidneys, ears and lungs in the lab. However, a limb is a bit trickier since it requires a wider variety of cells than these organs.

Scientists first used a special detergent to strip away every living cell except the protein-based collagen that gives vessels, tendons and muscles their shape. Then, researchers inserted muscle and vessel progenitor cells from a different rat.

In the future, these cells would be taken from the limb recipient, so that the final product would be biologically compatible with his or her body. To encourage growth, scientists placed the limb in a bioreactor that supplies nutrients, oxygen and electrical stimulation to the developing limb. It took about two to three weeks for it to finish growing, after which it was ready for testing. When scientists stimulated the forelimb with electricity, the paw clenched and unclenched, showing that the muscles were functional. When they attached it to anesthetized rats, blood flowed through the new limb, though it they didn’t test it for movement

Around the world, roughly 70 patients have undergone a hand transplant with favorable outcomes. However, the immune system tends to reject an unfamiliar hand, so these patients need to enroll in life-long immunosuppressive therapy. In the new approach, the big advantage is that the regrown cells are the recipient’s, so the risk of immune rejection is low.

The next challenge for scientists is to ensure nerves take root within a bio-artificial limb, which does occur in hand transplants. It isn’t clear if the same will occur in bio-artificial limbs.

Fig. 1: Scientists’ regrown rat limb

Fig. 2: Scientists’ rat limb grows in the bioreactor

Ref: Bernhard J. Jank et al., 2015, Biomaterials

doi:10.1016/j.biomaterials.2015.04.051

Scientists synthesise novel low-calorie fats

Scientists have developed novel low-calorie fats based on edible oils like sunflower that provide 5.2 K cals/g as against 9 K cals/g by the vegetable oils; they have shown promising health benefits in studies conducted in rats and rabbits. Ethyl behenic acid was incorporated into refined sunflower and soybean oils after about 25 per cent of fatty acids was removed. The fats have shown to lower serum, liver cholesterol and triglycerides in rats and reduce fat accumulation in arteries in rabbits. 

Source: Dr. R.B.N. Prasad, Head of Centre for Lipid Research, Indian Institute of Chemical Technology, Hyderabad.

Antibiotics in most honey brands

Scientists found high levels of six harmful antibiotics in 11 samples including  those made by Indian companies such as Dabur, Himalaya, Patanjali, Baidyanath and Khadi as well as by two foreign companies based in Switzerland and Australia except only the Indian Hitkari brand coming out clean.

The contamination begins when antibiotics are fed to bees to prevent disease which, promote growth and increase honey production to meet commercial targets. These substances could damage the blood, kidneys, liver, bones and teeth. More importantly, they create resistance in the body to prescribed antibiotics when you really do fall ill.

Dabur Honey, which has captured 75 per cent of the Indian market had the antibiotic Oxytetracycline at nine times the level that is permitted for exported honey. It also had significant amounts of two other drugs completely banned for use in honey. If the sample was placed for export to the United States or the European Union, it would have been rejected.

Nectaflor Natural Blossom Honey, made by Narimpex of Switzerland, had the largest number five of the six antibiotics that it was tested for, including the highest levels of ampicillin and erythromycin, both of which are not permitted for beekeeping in any country. It would be illegal to sell it even in Switzerland itself. Similarly, the Australian brand, Capilano Pure & Natural Honey, which is sold in 40 countries, violated standards set in its home country.

It is clear that foreign companies are taking advantage of the lack of regulations in India. After all, if our government does not care about the health of its people, why should these companies care? said CSE director, Sunita Narain.

Source: Sunita Narain, Director, Pollution Monitoring Laboratory, Centre for Science and Environment

Mapping the human brain without distortions

To study the fine structure of the brain including its connections between neurons and the synapses, scientists generally use electron microscopes. However, the brain tissue must first be fixed to prepare it for this high magnification imaging method. This process causes the brain to shrink and as a result, microscope images can be distorted showing neurons to be much closer than they actually are.

Researchers now solved the problem by using a technique that rapidly freezes the brain, preserving its true structure. The innovative method called "cryofixation" to prevent brain shrinkage during the preparation for electron microscopy. The method uses jets of liquid nitrogen to "snap-freeze" brain tissue down to -90 degrees celsius within milliseconds. The brain tissue here was mouse cerebral cortex. "The high-pressure 'cryofixation' is a very attractive method for brain imaging.

Source: Graham Knott, Natalya Korogod and Carl Petersen,  Swiss Federal Institute of Technology in Lausanne