Archive for April, 2009
Scientists Find New Way to Create Stem Cells
‘Chemical’ programming avoids problems genetic manipulation poses, study finds
From Forbes.com
April 23 (HealthDay News) — Scientists have converted adult cells into embryonic-like stem cells by using chemical programming instead of genetic manipulation.
Gene manipulation is an older method that has posed the risk of serious health problems such as cancer, the researchers explained.
The ability to make stem cells without genetically altering them could lead to the development of many new types of therapies for a wide range of diseases, including type 1 diabetes and Parkinson’s disease, the team noted.
“We are very excited about this breakthrough in generating embryonic-like cells from fibroblasts [cells that give rise to connective tissue] without using any genetic material. Scientists have been dreaming about this for years,” research leader Sheng Ding, an associate professor at the Scripps Research Institute in La Jolla, Calif., said in a Scripps news release.
Ding and his colleagues reprogrammed adult cells by engineering and using recombinant proteins, which are proteins made from the recombination of fragments of DNA from different organisms. They experimented with these proteins until they found the exact mix that enabled them to gradually reprogram the adult cells.
The reprogrammed embryonic-like cells from fibroblasts behaved the same as embryonic stem cells in terms of molecular and functional features, including differentiation into various cell types, such as neurons, pancreatic cells and beating cardiac muscle cells.
The study, published online April 23 in the journal Cell Stem Cell, was supported by Fate Therapeutics.
Guidelines for broader stem cell research unveiled
By Saundra Young, CNN.com
The Obama administration released a draft of guidelines for federal funding of human embryonic stem cell research Friday.
Under the new guidelines, federal funding would be allowed only for research using human embryonic stem cells from embryos created solely for reproductive purposes by in vitro fertilization. The embryos would have to no longer be needed for reproduction, and the donors would have to consent to their use for research.
Funding for research using adult stem cells and induced pluripotent stem cells will continue. Funding will not be allowed for stem cells obtained from other sources, including somatic cell nuclear transfer, also known as cloning; in vitro fertilization embryos created specifically for research purposes; and parthenogenesis, the development of an unfertilized egg.
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Stem Cell Therapy Makes Cloudy Corneas Clear, According to Pitt Researchers
From UPMC.com
Stem cells collected from human corneas restore transparency and don’t trigger a rejection response when injected into eyes that are scarred and hazy, according to experiments conducted in mice by researchers at the University of Pittsburgh School of Medicine. Their study will be published in the journal Stem Cells and appears online today.
The findings suggest that cell-based therapies might be an effective way to treat human corneal blindness and vision impairment due to the scarring that occurs after infection, trauma and other common eye problems, said senior investigator James L. Funderburgh, Ph.D., associate professor, Department of Ophthalmology. The Pitt corneal stem cells were able to remodel scar-like tissue back to normal.
“Our experiments indicate that after stem cell treatment, mouse eyes that initially had corneal defects looked no different than mouse eyes that had never been damaged,” Dr. Funderburgh said.
The ability to grow millions of the cells in the lab could make it possible to create an off-the-shelf product, which would be especially useful in countries that have limited medical and surgical resources but a great burden of eye disease due to infections and trauma.
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Surprise! Heart Muscle Can Replenish Itself
By Bernadine Healy, M.D., U.S. News and World Report
It’s humbling to see medical dogma overturned, but that is exactly what happened when, contrary to deeply embedded thought, scientists led by Jonas Frisen from the Karolinska Institute in Stockholm reported in Science today that the heart can grow new muscle cells, and does so regularly, albeit slowly, in the course of a lifetime.
To cardiologists, this is a blockbuster discovery, since the heart has been pegged as a disadvantaged organ in terms of injury, healing, and repair. Susceptible to coronary blockages that can cut off blood and destroy major hunks of heart muscle at one time in a heart attack, the heart can only heal itself slowly, often leaving behind thinned and baggy scar tissue devoid of healthy, beating muscle. And the distortion and remodeling of the heart that comes with this muscle loss sets the patient up for cardiac failure, blood clots, and nasty heart rhythms. It was always assumed the heart could do no better. But that does not seem to be so.
The clever piece of work from Sweden used carbon dating to figure out the age of human heart cells. The spike in concentration of atmospheric radioactive carbon-14 triggered by above-ground Cold War nuclear tests between 1955 and 1963 allowed the researchers (with the help of physicists and sophisticated mass spectrometry from the Lawrence Livermore National Laboratory in California) to discover that, lo and behold, the heart has slow and silent regenerative abilities. The evidence: the many heart cells whose nuclei—which last the life of the cell—had radioactive carbon levels that coincided with the atmospheric spikes, occurring many years after the person was born. The study found that younger adults renew about 1 percent of their heart cells per year. The growth falls off to roughly half of that in the elderly.
This is no abstract, ho-hum science factoid. It makes incredible sense of something that has always puzzled me: If hearts can’t make new heart tissue, why did ever efficient Mother Nature give them stem cells? Yes, for years, scientists have known that adult stem cells can be found in the heart. This has prompted numerous centers in many countries to pursue stem cell therapeutics in patients with heart attacks, heart failure, and even severe angina to repair muscle and improve blood supply.
The work looks more than promising. In several studies, using cocktails of patients’ own bone marrow stem cells, which can be sifted out of the bloodstream and infused back into the patients in a concentrated and enriched form, has produced better-than-expected heart function and blood flow. (Adult stem cells circulating in the blood are known repairmen that can hone in on injured tissue anywhere in the body.) Recent studies in rats have gone so far as to create a matrix for these cells to grow on that can become a healthy looking, growing and beating tissue graft after being implanted in damaged heart wall.
The work is moving fast and furiously to make stem cell technology a standard part of cardiac care. Even the greatest skeptics have taken note. The Cochrane Collaboration, a well-respected international group that assesses the latest technology with a very tough eye, concluded late last year that, based on its review of reports involving over 800 patients from several centers, stem cell infusions after heart attacks have shown some definite benefits. To be sure, more work needs to be done, though.
Smart medicine honors the rules of the human body as best they can be determined. For example, a sturdy immune system fights off most microbes we encounter; and vaccines and antibiotics work because they complement that already finely tuned inborn system. The discovery that the wounded heart can renew itself over time, giving reason for the naturally occurring stem cells found in its muscle, provides great encouragement that harnessing and accelerating the body’s own regenerative capacity will become a powerful technology in the not-too-distant future.
