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S.ravi
Advanced Member
India
4205 Posts |
 Posted - 01/18/2009 : 03:23:22
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London (PTI): Scientists claim to have achieved a major breakthrough in the fight against AIDS with a new stem cell treatment which "protects the immune system from HIV that causes the disease".
According to them, the pioneering technique involves isolating three genes which curb the spread of HIV inside the body, introducing them into human stem cells in a lab and then transplanting the stem cells into a patient's bone marrow.
"What we are doing is genetically modifying a fraction of the patient's stem cells with genes that target three diffe -rent aspects of HIV that allow it to get in the immune cells and replicate.
"When those stem cells are transplanted into patients, they create mature immune cells that circulate in the patient and protect against HIV," 'The Daily Telegraph' quoted David DiGiusto of City of Hope Medical Centre in California, where the research was carried out, as saying.
In the first human trial, the scientists transplanted anti-HIV stem cells into five AIDS patients undergoing bone- marrow replacement as part of treatment for a form of cancer known as lymphoma.
Preliminary results showed that small quantities of the transplanted stem cells were able to grow and produce new white blood cells resistant to HIV resulting in an improvement in the patients' conditions.
Now, they are planning further research to establish whether the treatment could even rid patients of HIV infection altogether.
"It is still an experimental treatment at the moment, but
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S.ravi
Advanced Member
India
4205 Posts |
Posted - 07/22/2009 : 01:48:00
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Stem cells 'can rescue the memory from Alzheimer's'
London (PTI): Here's a ray of hope for those suffering from Alzheimer's -- scientists have claimed that it could eventually be reversed after discovering that stem cells can rescue the memory from the disease.
An international team, led by California University, has shown for the first time that stem cells injected into the brain, destroyed by advanced Alzheimer's disease, could rescue memory in laboratory mice, rebuilding neurons and memory.
"Essentially, the cells were producing fertiliser for the brain," co-scientist Frank LaFerla of the university Institute for Memory Impairments and Neurological Disorders was quoted by 'The Daily Telegraph' as saying.
In their study, the team examined the mouse brains after the injection and found six per cent of the stem cells had turned into neurons with the majority becoming other types of brain cells which aided growth.
The stem cells were found to have secreted a protein called brain-derived neurotropic factor, or BDNF which caused existing tissue to sprout new neuritis -- the connections between neurons.
Lead author Mathew Blurton-Jones said: "The neural stem cells were helping the brain form new synapses and nursing the injured neurons back to health. This gives us a lot of hope that stem cells or a product from them, such as BDNF, will be a useful treatment for Alzheimer's -- the most common form of dementia."
The findings of the study have been published in the latest edition of the 'Proceedings of the National Academy of Sciences' journal.
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S.ravi
Advanced Member
India
4205 Posts |
Posted - 08/10/2009 : 09:09:19
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Veterinarians using stem cells to treat animals
MIAMI (AP): Lucy the Labradoodle pulls herself along the ground to grab a bone.
At only 5 years old, she's unable to walk, crippled by rheumatoid arthritis that has rendered her back limbs unusable.
However, her owners say she has improved. She no longer yelps or whimpers in pain, and she needs far less medicine than before.
Lucy's owners credit a costly stem cell treatment, despite what experts say is a lack of evidence such treatments work.
``We didn't think she'd live anywhere near this long, and I know it's because of the stem cells,'' says owner Carol Fischman, 57, of Vero Beach.
Thousands of dogs and horses with degenerative arthritis have had stem cell treatments, costing around $2,500 to $3,000 per procedure. There are no independent studies verifying their effectiveness, and some experts say such studies are needed to assess their potential.
University of Florida veterinarian Kristin Kirkby, who performed Lucy's procedure, said that the outcomes on five similar treatments have all been positive. But that's from owner-reported results, not scientific scrutiny.
Owners tell her their dogs have an easier time getting around the house and getting into position to urinate. Mostly, they just report their dogs appear to be more comfortable overall.
To get hard results, Kirkby says the university plans to start taking a pain inventory of each animal at the beginning of the process, followed by an evaluation and checkups afterward to measure changes.
``I think it's an exciting field. Undoubtedly the future of scientific research is going this way,'' Kirkby said. ``It's early on, especially in the small animal side, to know what the results can be.''
Vet-Stem, a California company, is developing the stem cell therapy and began treating horses in 2003. It derives stem cells from fat samples taken from dogs and horses across the country.
The procedure has been used mainly to treat osteoarthritis, which involves loss of cartilage in the joints, but Vet-Stem is researching treatments for other diseases. Vet-Stem claims the therapy enables animals to replace cartilage and other tissue.
Since 2003, the privately held company has treated 3,500 horses and 1,500 dogs and plans to begin treating cats later this year. More than 1,500 vets are licensed to use the procedure.
Dr. Bob Harman, veterinarian and Vet-Stem founder, said it made sense to use these fat-based adult stem cells, which the body uses to create scar tissue and repair damage, to treat chronic disease in animals.
``Really, all we're doing is harnessing the existing repair machinery in the body, concentrating it, and putting it right where an injury occurs, where healing is needed, to heal naturally,'' he said
Adam Gassel has used stem cells to treat almost 40 dogs at his Irvine, California, veterinary clinic during the past two years.
``I was pretty skeptical,'' he said. ``I was hoping that dogs would just be more comfortable.''
But for about 25 percent of dogs, their owners report they are like puppies again, able to get back to normal activities, he said.
Another 25 percent are able to stop taking medicines they were dependent upon. In all, Gassel said, all but 20 percent of the animals show some positive response to the therapy, according to their owners and the requests for pain medicine.
One peer-reviewed study by researchers at Cornell University, published in the American Journal of Veterinary Research and sponsored in part by Vet-Stem, found that tendinitis in horses was improved by injection of the adult stem cells.
Two other studies published in Veterinary Therapeutics found that dogs with osteoarthritis showed improvements in lameness after stem cell injections. Those studies also were sponsored by Vet-Stem and conducted by Vet-Stem researchers and other veterinarians.
Jonathan Slack, director of the University of Minnesota's Stem Cell Research Institute, said adult stem cells from fat can become cartilage in a laboratory cell culture. Conclusive results on whether the stem-cell injection process actually makes new bone cells in animals don't exist, to his knowledge.
``I guess from the dog's point of view,'' Slack said, ``it's good if it does work.''
Whatever the scientific merits of the therapies, Lucy's owners say they would do it again for the Labradoodle a cross between a standard poodle and a Labrador.
She's had her stem cell treatments through an IV three times, and the Fischmans want to give her a fourth one soon, despite the $3,000-per-procedure cost.
``I like the dog as much as I like my kids,'' said Dr. Charles Fischman, 59, who is an immunologist. ``People will spend more on their dogs than they will on themselves.''
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S.ravi
Advanced Member
India
4205 Posts |
Posted - 08/10/2009 : 09:12:11
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An HIV-blocking gel for women
Salt Lake City: University of Utah scientists developed a new kind of "molecular condom" to protect women from AIDS in Africa and other impoverished areas. Before sex, women would insert a vaginal gel that turns semisolid in the presence of semen, trapping AIDS virus particles in a microscopic mesh so they can't infect vaginal cells, reports Eurekalert in one of its despatches.
"The first step in the complicated process of HIV (human immunodeficiency virus) infection in a woman is the virus diffusing from semen to vaginal tissue. We want to stop that first step," says Patrick Kiser, an associate professor of bioengineering at the University of Utah's College of Engineering. "We have created the first vaginal gel designed to prevent movement of the AIDS virus. This is unique. There's nothing like it."
"We did it to develop technologies that can enable women to protect themselves against HIV without approval of their partner," he adds. "This is important particularly in resource-poor areas of the world like sub-Sahara Africa and south Asia where, in some age groups, as many as 60 percent of women already are infected with HIV. In these places, women often are not empowered to force their partners to wear a condom."
A study testing the behavior of the new gel and showing how it traps AIDS-causing HIV particles will be published online later this week in the journal Advanced Functional Materials. Kiser is the senior author.
"Due to cultural and socioeconomic factors, women often are unable to negotiate the use of protection with their partner," says Julie Jay, the study's first author and a University of Utah doctoral candidate in pharmaceutics and pharmaceutical chemistry.
So the researchers developed a vaginal gel that a woman could insert a few hours before sex and "could detect the presence of semen and provide a protective barrier between the vaginal tissue and HIV," Jay says. "We wanted to build a gel that would stop HIV from interacting with vaginal tissue."
Kiser estimates that if all goes well, human tests of the gel would start in three to five years, and the gel would reach the market in several more years. He and Jay want to incorporate an antiviral drug into the gel so it both blocks HIV movement and prevents the virus from replicating.
A Rocky Road to Microbicides against AIDS
The effort to develop microbicides intravaginal gels, rings and films to prevent transmission of the AIDS virus has been halting. The few that have reached human clinical trials in Africa failed to prevent HIV transmission either because they carried antiviral drugs that were not long-lived or strong enough, or because patients failed to use them. Some experimental microbicides increased the risk, possibly by irritating vaginal tissue and attracting immune cells that are targeted by the virus.
In 2006, Kiser and colleagues published a study on their development of another "molecular condom" to be applied vaginally as a liquid, turn into a gel coating at body temperature, then, in the presence of semen, turn liquid and release an anti-HIV drug.
Unfortunately, few antiviral drugs bind to and attack HIV in semen. And in Africa, high air temperatures prevent the gel from turning liquid so it could coat the vagina evenly, Kiser says.
The new "molecular condom" gel in the current study works in the opposite way. Like the old version, it changes in response to changes in pH acidity or alkalinity in the vagina caused by the introduction of semen during sex. But unlike the old gel, which became liquid at the higher (less acidic) pH of semen, the new "molecular condom" becomes a semisolid at the pH of semen, forming a mesh of "crosslinked" molecules.
The new gel is applied as a gel, and then becomes more solid and impenetrable as changes in pH alter the strength of the bond between the gel's two key components, both of which are polymers, or long, chain-like molecules made of many smaller, repeating units: PBA, or phenylboronic acid, and SHA, or salicylhydroxamic acid.
Slowing and Blocking the AIDS Virus
Kiser's team first published a study about the invention of the polymers and their behavior in 2007. A patent is pending on the invention.
The chemical bonds between the two polymers constantly attach and detach at normal, acidic vaginal pHs of about 4.8, allowing the gel to flow, Kiser says. But at a pH of 7.6 the slightly alkaline condition when semen enters the vagina the PBA and SHA polymers "crosslink" and stick tightly together, he adds.
Part of the new study characterized the flow of the gel.
"It flows at a vaginal pH, and the flow becomes slower and slower as pH increases, and it begins to act more solid at the pH of semen," Jay says. HIV moves slowly within the gel, even when the gel is at lower pHs (higher acidity) and still flowing, but the virus is blocked at higher pHs caused by the entry of semen into the vagina.
The crosslinked polymers form a mesh that is smaller than microscopic, and instead is nanoscopic on the scale of atoms and molecules with a mesh size of a mere 30 to 50 nanometers or 30 to 50 billionths of a meter. (A meter is about 39 inches.)
By comparison, an HIV particle is about 100 nanometers wide, sperm measure about 5 to 10 microns (5,000 to 10,000 nanometers) in cross section, and the width of a human hair is roughly 100 microns (100,000 nanometers).
Kiser says the gel should block other viruses and sperm, thus could work as a contraceptive and possibly prevent infection by herpes viruses and human papillomavirus (HPV), a major cause of cervical cancer.
The gel also could help prevent AIDS by blocking movement of immune system cells that try to combat infectious agents but instead get hijacked by the AIDS virus.
During the study, coauthors from Northwestern University in Chicago used a sophisticated microscope to track how fast HIV particles marked with fluorescent dye moved when they were caught in the gel, and how the speed varied with changes in pH.
The researchers compared movement of HIV particles with latex particles, which revealed that under somewhat acidic conditions, the HIV particles are slowed down in part because their surfaces react chemically with the polymers.
By adding an anti-AIDS drug such as tenofovir to the gel, "the virus would have two barriers to get through: the polymer barrier and then the drug barrier," Kiser says. Unlike an antiviral used with the old gel, tenofovir would not attack HIV directly, but protect immune cells in the vagina from infection.
Kiser says that after sex, the vagina gradually becomes acidic again, and any residual HIV particles would be inactivated both by acidity and an antiviral drug within the remaining gel, which still impedes HIV to some extent at normal vaginal acidity.
Kiser and Jay conducted the study with four other University of Utah researchers: bioengineering undergraduates Kristofer Langheinrich and Melissa Hanson, bioengineering graduate student Todd Johnson, and bioengineering researcher Meredith Clark. Other coauthors were from the Department of Cell and Molecular Biology at Northwestern University Medical School in Chicago: Thomas Hope, Shetha Shukair and Gianguido Cianci.
The study was funded by National Institutes of Health. Kiser's research team is continuing the effort to develop microbicides to prevent AIDS thanks to a $100,000 grant from the Bill and Melinda Gates Foundation.
Upcoming work includes assessing the HIV-prevention potential of other polymers, testing the safety of the new gel on vaginal cells, and studying how well the new gel blocks the transport of HIV into samples of human vaginal and penile tissue from hysterectomies and circumcisions, respectively.
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S.ravi
Advanced Member
India
4205 Posts |
Posted - 09/08/2009 : 09:58:34
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The goal is to use skin cells of patients with retinal problems and reprogramme them into induced Pluripotent Stem (iPS) cells. These cells will then be directed to become one of the types of retinal cells. As the iPS cells will still have the defective gene, a normal gene, which will be synthesised and delivered into the iPS cells using a viral vector, is expected to cure the patient.
After establishing a procedure to restore vision that has been damaged by physical or chemical injury, saving the eye sight of over 300 patients by harvesting limbal stem cells from the healthy eye and transplanting them to the eye that has been damaged, the Hyderabad based LV Prasad Eye Institute has moved to the next stage. The Institute has successfully converted skin cells of mice into induced pluripotent stem cells (iPS cells) that behave like embryonic stem cells.
The work on standardising the procedure of reprogramming skin cells into iPS cells started 6-7 months ago. It took 3-4 months to establish the protocol for converting skin cells into iPS cells.
We were able to produce iPS cells 2-3 months ago, said. Dr. D. Balasubramanian, Research Director of the Institute. They are now in the process of characterising the iPS cells in order to do the same with human skin cells.
The protocol [of converting skin cells to iPS cells] is the same, but human cells [when compared to mouse cells] behave differently, he said. The real test is when we try doing it using human cells.
The central idea behind the work on iPS cells is to find a way to treat people with hereditary (genetic) diseases such as retinitis pigmentosa.
When the technique of producing human iPS cells is perfected, the skin cells of patients with retinal problems such as retinitis pigmentosa will be reprogrammed into iPS cells. The iPS cells will then be directed to become one of the types of retinal cells. Since the iPS cells will still have the defective gene, a normal gene will be synthesised and delivered into the iPS cells using a viral vector. The delivered normal gene is expected to cure the patient.
The presence of defective genes [in addition to the normal gene] will not be a problem. We want to see if the normal gene overrides the effect of the defective gene, he said.
There is hope that this procedure should work as research in 2007 at MIT, Cambridge, showed that a mouse suffering from sickle cell anaemia could be cured. In this case, the researchers first converted the skin cells of the mouse into iPS cells and then directed the iPS cells to become red blood cells. A normal gene was introduced into the iPS cells and these cells were then transplanted into the mouse. The mouse no longer suffered from anaemia.
The LV Prasad Eye Institute is working on introducing the normal gene through two routes. The first will use a viral vector, mostly a weak attenuated adeno virus that cannot cause any disease. The second alternative is the non-viral introduction.
The efficiency of gene delivery into the host cell is much higher when a viral vector is used, he said. But we would prefer a non-viral vehicle.
Having produced iPS cells using mice, work is on to deliver a normal gene into the iPS cells. We should be able to convert human skin cells into iPS cells and introduce the cells with the normal gene in a years time, he said. A patient with retinitis pigmentosa has already been chosen for the human study to treat the disease through cell therapy.
The biggest advantage of using iPS cells is that skin cells from the patient suffering from a disease are used for the cell therapy. Therefore, the question of rejection due to tissue mismatch does not arise.
The iPS cells have another advantage. As adult cells from the skin are used, the technique sidesteps the ethical problems that embryonic stem cell research faces. The technique of producing induced pluripotent stem cells by reprogramming adult skin cells was first done in 2006 by Dr. Shinya Yamanaka at Kyoto University.
Two Chinese teams in Beijing recently succeeded in producing mouse pups using iPS cells. Pups created by one of the teams were able to sire over 200 second-generation pups. More than 100 third-generation pups werthvsse also produced.
Keywords: eye-care, vision, research, stem cells, iPS cells, LV Prasad Eye Institute, reprogramming stem cells,
Related
PHOTOS
The picture shows the mouse skin fibroblast cells that have become induced Pluripotent Stem (iPS) cells. The iPS cell colony is seen in the foreground and the background cells are the feeder cells. Photo: Special arrangement
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A stem cell treatment 'against AIDS'
