source - The Mojave Crater on Mars
- Heart cells on lab chip display 'nanosense' that guides behavior
- Researchers link calorie intake to cell lifespan, cancer development (w/ Video)
- Stem Cells from Fat Used to Grow Teen's Missing Facial Bones
- Humans still evolving as our brains shrink
- Canada doctor uses glue to aid open-heart recovery
- Mutant genes 'key to long life'
Heart cells on lab chip display 'nanosense' that guides behaviorDecember 15, 2009
Johns Hopkins biomedical engineers, working with colleagues in Korea, have produced a laboratory chip with nanoscopic grooves and ridges capable of growing cardiac tissue that more closely resembles natural heart muscle.
Surprisingly, heart cells cultured in this way used a "nanosense" to collect instructions for growth and function solely from the physical patterns on the nanotextured chip and did not require any special chemical cues to steer the tissue development in distinct ways. The scientists say this tool could be used to design new therapies or diagnostic tests for cardiac disease.Levchenko added that when he and his colleagues examined the natural heart tissue taken from a living animal, "we immediately noticed that the cell layer closest to the extracellular matrix grew in a highly elongated and linear fashion. The cells orient with the direction of the fibers in the matrix, which suggests that ECM fibers give structural or functional instructions to the myocardium, a general term for the heart muscle." These instructions, Levchenko said, are delivered on the nanoscale, activity at the scale of one-billionth of a meter and a thousandth of the width of a human hair.
Levchenko and his Korean colleagues, working with Deok-Ho Kim, a biomedical engineering doctoral student from Levchenko's lab and the lead author of the PNAS article, developed a two-dimensional hydrogel surface simulating the rigidity, size and shape of the fibers found throughout a natural ECM network. This bio-friendly surface made of nontoxic polyethylene glycol displays an array of long ridges resembling the folded pattern of corrugated cardboard. The ridged hydrogel sits upon a glass slide about the size of a U.S. dollar coin. The team made a variety of chips with ridge widths spanning from 150 to 800 nanometers, groove widths ranging from 50 to 800 nanometers, and ridge heights varying from 200 to 500 nanometers. This allowed researchers to control the surface texture over more than five orders of magnitude of length.
Furthermore, the researchers found improved coupling between adjacent cells, an arrangement that more closely resembled the architecture found in natural layers of heart muscle tissue.
Cells grown on smooth, unpatterned hydrogels, however, remained smaller and less organized with poorer cell-to-cell coupling between layers.Collaborating with Leslie Tung, a professor of biomedical engineering at the Johns Hopkins School of Medicine, the researchers found that, after a few more days of growth, cells on the nanopatterned surface began to conduct electric waves and contract strongly in a specific direction, as intact heart muscle would.
"Perhaps most surprisingly, these tissue functions and the structure of the engineered heart tissue could be controlled by simply altering the nanoscale properties of the scaffold. That shows us that heart cells have an acute 'nanosense,'" Levchenko said.
"This nanoscale sensitivity was due to the ability of cells to deform in sticking to the crevices in the nanotextured surface and probably not because of the presence of any molecular cue," Levchenko said. source
Researchers link calorie intake to cell lifespan, cancer development (w/ Video)December 17, 2009
Researchers from the University of Alabama at Birmingham (UAB) have discovered that restricting consumption of glucose, the most common dietary sugar, can extend the life of healthy human-lung cells and speed the death of precancerous human-lung cells, reducing cancer's spread and growth rate.
The UAB team conducted its tests by growing both healthy human-lung cells and precancerous human-lung cells in laboratory flasks. The flasks were provided either normal levels of glucose or significantly reduced amounts of the sugar compound, and the cells then were allowed to grow for a period of weeks.
"The pattern that was revealed to us showed that restricted glucose levels led the healthy cells to grow longer than is typical and caused the precancerous cells to die off in large numbers," Tollefsbol said.
In particular, the researchers found that two key genes were affected in the cellular response to decreased glucose consumption. The first gene, telomerase, encodes an important enzyme that allows cells to divide indefinitely. The second gene, p16, encodes a well known anti-cancer protein.
"Opposite effects were found for these genes in healthy cells versus precancerous cells. The healthy cells saw their telomerase rise and p16 decrease, which would explain the boost in healthy cell growth," Tollefsbol said. "The gene reactions flipped in the precancerous cells with telomerase decreasing and the anti-cancer protein p16 increasing, which would explain why these cancer-forming cells died off in large numbers."source
Stem Cells from Fat Used to Grow Teen's Missing Facial Bones
October 15, 2009 By Katherine Harmon
Stem cells so far have been used to mend tissues ranging from damaged hearts to collapsed tracheas. Now the multifaceted cells have proved successful at regrowing bone in humans. In the first procedure of its kind, doctors at Cincinnati Children's Hospital Medical Center replaced a 14-year-old boy's missing cheekbones—in part by repurposing stem cells from his own body.
The technique, should it be approved for widespread use, could benefit some seven million people in the U.S. who need more bone—everyone from cancer patients to injured war veterans.
Some bone tissue had previously been generated from stem cells in the lab, but this marks hope for a surgical solution for those who need additional bone.
In adult patients plastic and metal have often subbed in, in the absence of bone, but as Taylor notes: "What happens if someone gets a fracture? It's another surgery." In contrast, a natural bone regrown from stem cells should heal on its own. Another alternative, bone transplants—either repurposed from the patient's body or from cadavers—have high rejection and absorption rates, leading to many unsuccessful attempts.
To create the new bones, which have become part of the patient's own skull structure and have remained securely in place for four and a half months, the medical team used a combination of fat-derived stem cells, donated bone scaffolds, growth protein, and bone-coating tissue.
Unlike many other stem cell treatments, such as heart patches, the procedure Taylor and his colleagues used did not require any advance culturing or growth in the lab. The intensive, daylong surgical procedure included every step—from the stem cell harvesting through liposuction to bone implantation.
The group chose fat stem cells over those from bone marrow largely because of the ease of access.
For the surgery, Taylor and his team shaped donor bone—from cadaver-donated femurs—to resemble zygomatic bones and act as a biological scaffold for the bone to grow on. Mesenchymal stem cells, harvested from Guilkey's fat, and growth-encouraging morphogenetic protein-2 (BMP-2), were injected into holes drilled into the scaffolds. Before implanting the bone sections into Guilkey's face, Taylor and his team wrapped them in periosteum tissue, which covers bone surfaces and was harvested from Guilkey's leg. The surrounding material, especially the periosteum and the growth protein, helped to cue the stem cells to produce bone tissue.
The new technique may have applications across the board for those who need bone regeneration, but it may not be as successful—or as simple—in every case.
Some of the procedure's effectiveness may be due to Guilkey's youth.
Using the procedure in cancer patients may prove to be the most difficult due to intensive scarring and the fact that the growth protein, BMP-2, is not approved for use in people with cancer. Traumatic injuries will likely be the easiest to fix, provided the patient can wait six months to a year for scars to heal, says Taylor.source
My comment: Sounds awesome! I truly hope one day stem cell treatment will be just as normal as say transplantation today (even though transplantation is not so common in not so developed countries but what the hell - the technique is known and works well). It would be absolutely cool instead of complicated surgeries for hours, to be able just to seed the stem cells and provide scaffolding or growth factors so that the tissue heal as it should.
Canada doctor uses glue to aid open-heart recoveryTORONTO: A new surgical technique using glue to repair breastbones intentionally broken during open-heart surgery speeds up recovery time and is "substantially less painful" for patients, a University of Calgary scientist said on Thursday.
The standard practice in operating rooms is to sew the breastbone back together with wire after open-heart surgery. That procedure takes weeks to heal and often requires strong pain medication to withstand, said Dr. Paul Fedak, a cardiac surgeon at Foothills Medical Center in Calgary, Alberta, and a scientist at the university's faculty of medicine.
"We can now heal the breastbone in hours instead of weeks after open-heart surgery," Fedak, who pioneered the new procedure, said in a statement.
The procedure uses a special adhesive called "Kryptonite," made by Doctors Research Group Inc of Connecticut.
A study involving over 20 patients in Calgary found that people whose chests were glued back together were able to get back to full physical activity within days instead of the months it normally takes with the wire stitches.
Over 1 million open-heart surgeries are performed in the world each year by splitting the breastbone.
The study also found that pain and discomfort were substantially reduced by using the new procedure and that the use of pain-killers was reduced if not completely eliminated.
"I used to warn my open-heart surgery patients that they would feel like they had been hit by a truck during a long recovery period," Brent Mitchell, said in a statement. "I'm glad I don't have to say that any more." source
My comment: You know, I can't hold my tears reading this again. The first time I read it, I simply cried. Can you even imagine what is like for a doctor to tell you that you'll feel like you've been hit by a truck. Just after you have survived complicated open-heart surgery. It's so sad. But the news is wonderful. It will save so much pain to people. I hope the glue is safe and last long enough for the bone to heal and everything, but if they're already teaching doctors to use it, then it must be. A great great news!
Humans still evolving as our brains shrink
Evolution in humans is commonly thought to have essentially stopped in recent times. But there are plenty of examples that the human race is still evolving, including our brains, and there are even signs that our evolution may be accelerating.
Comprehensive scans of the human genome reveal that hundreds of our genes show evidence of changes during the past 10,000 years of human evolution.
Surprisingly, based on skull measurements, the human brain appears to have been shrinking over the last 5,000 or so years.
"When it comes to recent evolutionary changes, we currently maybe have the least specific details with regard the brain, but we do know from archaeological data that pretty much everywhere we can measure — Europe, China, South Africa, Australia — that brains have shrunk about 150 cubic centimeters, off a mean of about 1,350. That's roughly 10 percent," Hawks said.
"As to why is it shrinking, perhaps in big societies, as opposed to hunter-gatherer lifestyles, we can rely on other people for more things, can specialize our behavior to a greater extent, and maybe not need our brains as much," he added.
In contrast to our limited but growing knowledge regarding the modern evolution of the human brain, the best example we see of evolution of humans in recent history is linked with malaria, Hawks said.
Since the disease often targets humans early in life, there was a strong pressure to evolve defenses from malaria — any genetic factor that confers resistance against it would give descendents a chance to have offspring, while those without such protection were more likely to not reproduce.
There are lots of examples of defenses against malaria. Sickle cell anemia is the best known —the disorder deforms red blood cells into sickle shapes, which can impair blood flow, thus damaging tissues, this malformation also prevents the malaria parasite from infesting blood cells.
"Although sickle cell is best known in Africa, there is also an India-Pakistan variant of it that seems to have evolved separately," Hawks explained. "Both variants have evolved very recently, in the last three or four thousand years, and in that time have risen to as much as 10 to 15 percent of the populations. That's pretty rapid change."
Lactose tolerance is another recent example of a recent evolutionary change.
Most of the world remains lactose intolerant, unable to digest the complex milk sugar lactose as adults, but the evolution of lactose tolerance perhaps some 7,500 years ago in Europe enabled people there to take advantage of non-human milk, a highly nutritious food source one can sustainably procure instead of slaughtering animals.
Other evolutionary changes linked with diet appear to deal with genes conferring protection against type II diabetes.
There are signs that human evolution may not only be continuing, but that its rate has even accelerated in recent times. Hawks and his colleagues have found evidence of rapid change, with a host of new mutations originating in the last 40,000 years. source
My comment: I always get a lot of pleasure from pasting here articles about human evolution. People tend to think we're complete from evolutionary point of view, but for more and more people, it becomes clear we're not. So, enjoy :)
Mutant genes 'key to long life'
There is a clear link between living to 100 and inheriting a hyperactive version of an enzyme that prevents cells from ageing, researchers say.
Scientists from the Albert Einstein College of Medicine in the US say centenarian Ashkenazi Jews have this mutant gene.
They found that 86 very old people and their children had higher levels of telomerase which protects the DNA.
They say it may be possible to produce drugs that stimulate the enzyme.
Writing in the Proceedings of the National Academy of Sciences, the team say they studied the Ashkenazi Jewish community because they are closely related so it is easier to identify disease causing genetic differences.
They took blood samples from 86 very old, but generally healthy, people with an average age of 97; 175 of their offspring; and 93 other people who were the offspring of parents who had lived a normal lifespan and could therefore make up a control group, with which the results could be compared.
Telomeres are relatively short sections of specialized DNA that sit at the ends of all our chromosomes.
They have been compared to the plastic tips at the ends of shoelaces that prevent the laces from unravelling.
Each time a cell divides, its telomeres shorten and the cell becomes more susceptible to dying.Telomerase can repair the telomeres, preventing them from shrinking.
The team at Einstein found that the centenarians and their offspring had higher levels of telomerase and significantly longer telomeres than the unrelated people in the control group and that the trait was strongly heritable.
The scientists had previously shown that individuals in Ashkenazi families with exceptional longevity have generally been spared major age-related diseases, like heart disease and diabetes.
The centenarians in this study had a lower average body mass index than the controls and higher levels of good (HDL) cholesterol.source
My comment: That's quite interesting, but it's hard for me to comment. They found long telomeres and maybe genes for them, but so what. The question is how everybody to live longer.