December 09, 2009

More Stem Cell and Gene Therapy Progress Roundup

1. Researchers from the UCLA AIDS Institute and colleagues have for the first time demonstrated that human blood stem cells can be engineered into cells that can target and kill HIV-infected cells -- a process that potentially could be used against a range of chronic viral diseases they have made the equivalent of a genetic vaccine.

These studies lay the foundation for further therapeutic development that involves restoring damaged or defective immune responses toward a variety of viruses that cause chronic disease, or even different types of tumors."

Taking CD8 cytotoxic T lymphocytes -- the "killer" T cells that help fight infection -- from an HIV-infected individual, the researchers identified the molecule known as the T-cell receptor, which guides the T cell in recognizing and killing HIV-infected cells. These cells, while able to destroy HIV-infected cells, do not exist in enough quantities to clear the virus from the body. So the researchers cloned the receptor and genetically engineered human blood stem cells, then placed the stem cells into human thymus tissue that had been implanted in mice, allowing them to study the reaction in a living organism.

The engineered stem cells developed into a large population of mature, multifunctional HIV-specific CD8 cells that could specifically target cells containing HIV proteins. The researchers also found that HIV-specific T-cell receptors have to be matched to an individual in much the same way that an organ is matched to a transplant patient.

The next step is to test this strategy in a more advanced model to determine if it would work in the human body

2. Researchers from Yale University and Mirna Therapeutics, Inc., reversed the growth of lung tumors in mice using a naturally occurring tumor suppressor microRNA.
The study reveals that a tiny bit of RNA may one day play a big role in cancer treatment, and provides hope for future patients battling one of the most prevalent and difficult to treat cancers.

3. A gentler form of blood stem cell transplant can reverse severe sickle cell disease in adults lucky enough to find a matched donor.

Patients with sickle cell disease have a genetic mutation that results in defective crescent-shaped red blood cells. Severe disease causes stroke, severe pain, and often fatal damage to major organs.

Blood stem cell transplants have reversed sickle cell disease in some 200 children. But the procedure, which requires destruction of the patients' defective cells by radiation and chemotherapy to make room for the transplanted cells -- is too intense for adults weakened by sickle cell disease.

Moreover, adult patients are more prone to deadly graft-versus-host disease ( GVHD), in which the transplanted cells attack the recipient.

But recent studies show that in some stem cell transplant recipients, some host cells survive the toxic "conditioning regimen" of radiation and drugs -- and their progeny happily coexist with those of the transplanted stem cells

New Scientist on the stem cell treatment of 9 out of 10 people with sickle cell disease

4. There are problems associated with direct stem cell injections to try to restore heart attack muscle. UC San Diego bioengineers are proposing to use cells placed in a supportive material that changes stiffness with time by exhibiting time-dependent crosslinking. This could help repair heart attack damage.

5. Cells from heart attack survivors' own bone marrow reduced the risk of death or another heart attack when they were infused into the affected artery after successful stent placement.

* At two years, no patients from the bone marrow cell group had suffered a heart attack while seven patients from the placebo group had -- a statistically significant difference.

* Compared with placebo patients, cell-infused patients were less likely to die (three vs. eight in placebo group), need new revascularizations (25 vs. 38), or be rehospitalized for heart failure (one vs. five).

6. Stem cell derived neurons may allow scientists to determine whether breakdowns in the transport of proteins, lipids and other materials within cells trigger the neuronal death and neurodegeneration that characterize Alzheimer's disease (AD) and the rarer but always fatal neurological disorder, Niemann-Pick Type C (NPC).

Using human embryonic stem cells (hESCs), Goldstein and his team have produced human neurons in which the NPC gene is switched off, providing the first close look at cellular transport in a human neuron lacking normal function of the gene.

7. Gene Therapy and Stem Cells Save Limb

Blood vessel blockage, a common condition in old age or diabetes, leads to low blood flow and results in low oxygen, which can kill cells and tissues. Such blockages can require amputation resulting in loss of limbs. Now, using mice as their model, researchers at Johns Hopkins have developed therapies that increase blood flow, improve movement and decrease tissue death and the need for amputation.

Activating the HIF-1 gene in the cells appeared to turn on a number of genes that help these cells not only home to the ischemic limb, but to stay there once they arrive. To figure out how the cells stay where they're needed, the research team built a tiny microfluidic chamber and tested the cells' ability to stay stuck with fluid flowing around them at rates mimicking the flow of blood through vessels in the body. They found that cells under low oxygen conditions were better able to stay stuck only if those same cells had HIF-1 turned on.

"Our results are promising because they show that a combination of gene and cell therapy can improve the outcome in the case of critical limb ischemia associated with aging or diabetes," says Semenza. "And that's critical for bringing such treatment to the clinic."

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