Year: 2013 (page 8 of 36)

manufactured burgers

in vitro meat

In vitro meat. Image from the New York Times

Last week, the New York Times brought news of an upcoming burger taste test in London. Scientists have been hard at work developing new lab grown meat that they hope to turn into hamburger patties.

Dr. Post, one of a handful of researchers in the field, has made strides in developing cultured meat through the use of stem cells — precursor cells that can turn into others that are specific to muscle, for example — and techniques adapted from medical research for growing tissues and organs, a field known as tissue engineering. (Indeed, Dr. Post, a physician, considers himself first and foremost a tissue engineer, and about four-fifths of his time is dedicated to studying how to build blood vessels.)

Yet growing meat in the laboratory has proved difficult and devilishly expensive. Dr. Post, who knows as much about the subject as anybody, has repeatedly postponed the hamburger cook-off, which was originally expected to take place in November.

His burger consists of about 20,000 thin strips of cultured muscle tissue. Dr. Post, who has conducted some informal taste tests, said that even without any fat, the tissue “tastes reasonably good.” For the London event he plans to add only salt and pepper.

But the meat is produced with materials — including fetal calf serum, used as a medium in which to grow the cells — that eventually would have to be replaced by similar materials of non-animal origin. And the burger was created at phenomenal cost — 250,000 euros, or about $325,000, provided by a donor who so far has remained anonymous. Large-scale manufacturing of cultured meat that could sit side by side with conventional meat in a supermarket and compete with it in price is at the very least a long way off.

The scientists hope to be able to preview the meat in a taste test sometime this year.

cloning human embryonic stem cells

Image from ScienceNews

Nature reports on the recent success in cloning human embryonic stem cells:

Mitalipov and his group began work on their new study last September, using eggs from young donors recruited through a university advertising campaign. In December, after some false starts, cells from four cloned embryos that Mitalipov had engineered began to grow. “It looks like colonies, it looks like colonies,” he kept thinking. Masahito Tachibana, a fertility specialist from Sendai, Japan, who is finishing a 5-year stint in Mitalipov’s laboratory, nervously sectioned the 1-millimetre-wide clumps of cells and transferred them to new culture plates, where they continued to grow — evidence of success. Mitalipov cancelled his holiday plans. “I was happy to spend Christmas culturing cells,” he says. “My family understood.”

The success came through minor technical tweaks. The researchers used inactivated Sendai virus (known to induce fusion of cells) to unite the egg and body cells, and an electric jolt to activate embryo development. When their first attempts produced six blastocysts but no stable cell lines, they added caffeine, which protects the egg from premature activation.

None of these techniques is new, but the researchers tested them in various combinations in more than 1,000 monkey eggs before moving on to human cells. “They made the right improvements to the protocol,” says Egli. “It’s big news. It’s convincing. I believe it.”

The experiments took only a few months, Mitalipov says. “People say, you did it in monkeys in 2007. Why did it take six years in humans?” Most of the time, he says, was spent navigating US regulations on embryo research.

The researchers carried out a battery of tests to prove that their SCNT cells could form various cell types, including heart cells that are able to contract spontaneously.

Their first cell lines were created using fetal skin cells; others were derived using donor cells from an 8-month-old patient with a rare metabolic disorder called Leigh syndrome, to prove that ESCs could be made from more mature donor cells. The technique does not require prohibitive numbers of eggs: it took 15 from one donor to produce one cell line and 5 from a different donor to make another. “The efficiency was the most impressive thing,” says George Daley, a stem-cell expert at Children’s Hospital Boston in Massachusetts.

fighting tuberculosis with rats

Image from NPR. Abdullah Mchumvu trains African giant pouched rats in Morogoro, Tanzania

Tuberculosis still kills 1.4 million people a year, mostly in the developing world. So it is still beneficial to create new diagnostic techniques, especially when they can be used in rural communities. NPR recently reported on a team of scientists who train African giant pouch rats to sniff out the bacterium in patients’ sputum:

The team trains the critters with a Pavlovian click-and-reward approach. When the rats are just a few weeks old, technicians teach the animals to associate a click sound with a small bite of mashed bananas and a special pellet of food. The next step is to link the scent of TB with the reward.

A trained rat can correctly pick out a TB sample about two-thirds of the time, Beyene says. The rate increases to about 80 percent when two or three animals are put on the task.

The rats aren’t as good as a trained pathologist in the U.S. with a microscope, but they get better results than many clinicians working in rural Africa can achieve, Beyene says. “In an African setting, the sensitivity of the microscopy ranges between 30 to 40 percent,” he explains.

So far APOPO only has around 32 rats in their TB program.

Currently the rats are being used to verify positive test results obtained from microscopic samples.