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January 12, 2010

Gene Therapy and Stem Cell News - Molecular Security System, China Rising Star in Regenerative Medicine

1. Researchers at the University of Minnesota have discovered a molecular security system in human cells that deactivates and degrades foreign DNA. This discovery could open the door to major improvements in genetic engineering and gene therapy technologies.

Led by Reuben Harris, associate professor of biochemistry, molecular biology and biophysics in the College of Biological Sciences, the report's findings will be published online by Nature Structural and Molecular Biology on Jan. 10.

In the study, Harris and colleagues show how APOBEC3A, an enzyme found in human immune cells, disables double-stranded foreign DNA by changing cytosines (one of the four main bases in DNA) to uracils (an atypical DNA base). Persisting DNA uracils result in mutations that disable the DNA. In addition, the authors show that other enzymes step in to degrade the uracil-containing foreign DNA and sweep its remains out of the cell.

"Scientists have known for a long time that some human cells take up DNA better than others, but we haven't had good molecular explanations," Harris says. "This is definitely one of the reasons. Foreign DNA restriction is a fundamental process that could have broad implications for a variety of genetic diseases."

By understanding how the mechanism works, scientists can develop ways to manipulate it to enable more effective methods to swap bad genes for good ones. Harris is also intrigued to learn why the mechanism doesn't affect a cell's own DNA.


2. Chinese researchers have become the world's fifth most prolific contributors to peer-reviewed scientific literature on clock-reversing regenerative medicine (RM)even as a skeptical international research community condemns the practice of Chinese clinics administering unproven stem cell therapies to domestic and foreign patients. Chinese contributions to scientific journals on RM topics leapt from 37 in year 2000 to 1,116 in 2008, exceeded only by the contributions of experts in the USA, Germany, Japan and the UK.







MRC researchers report that until May 2009 clinical trials to determine the effectiveness of stem cell therapies were not required. Now proof of safety and efficacy through clinical trials is required by China's Ministry of Health for all stem cell and gene therapies.

The change was made after international experts, joined by top Chinese researchers, protested that treatment centers were acting "against commonly accepted principles of modern scientific research" and successfully called on China to regulate new treatments and ensure patient safety.

Despite the new rules, however, stem cell treatments are still available at over 200 hospitals across China to patients of diseases such as ataxia, Lou Gehrig's disease, traumatic brain and spinal cord injury, diabetes, Parkinson's, multiple sclerosis, autism, cerebral palsy, stroke, optic nerve hypoplasia and many others.

Controversial stem cell therapies provided at Beijing Xishan Institute for Neuroregeneration and Functional Recovery, involve injecting cells from aborted fetuses to treat spinal cord injury and a variety of central nervous system diseases. About 1,500 patients have received this treatment, including roughly 1,000 foreigners

Among the country's scientific firsts:


By transferring the nucleus of a human skin cell into the immature ovum cell of a rabbit, researchers from a Shanghai hospital successfully produced embryonic human cells (a finding popular scientific journals held off publishing for two years due to skepticism and of mistrust Chinese scientific integrity).


China to date has created at least 25 human embryonic stem cell lines (some estimate over 70 stem cell lines), four of which are of a specialized type that at that time only two other groups worldwide had managed to create.


A Shanghai hospital cultivated and reintroduced human brain tissue in 2002 after taking a sample from the end of a chopstick implanted in a patient's frontal lobe following a disagreement at a restaurant. (H/T to Marginal Revolution for highlighting this sentence)


Several human tissue types created artificially include blood vessel, tendon, bone, cartilage, skin, cornea and muscle fiber.

Notable research underway

Current research of note includes the efforts of ChinaSCINet, a consortium of 27 medical facilities, starting phase 2 clinical trials to test the efficacy and safety of using cord blood stem cells and oral lithium to treat about 40 patients with spinal cord injuries.

Other clinical trials are underway on the use of stem cell therapies to treat patients of heart attacks, artery obstruction, and liver and neural diseases.

Elsewhere in China, studies are underway on the potential use of stem cells to treat Type 1 diabetes, Parkinson's disease, heart, liver and blood diseases, eye cataracts, and to combat aging.

China’s gross domestic expenditure on R&D in science and technology has grown from $5.9 billion in 1996 to $44 billion today. Stem cell research, tissue engineering and gene therapy are key areas receiving priority funding, largely centralized in the universities, hospitals and research institutes of China's main urban centers, especially Beijing and Shanghai.

Approximately 78% of China's R&D funding in RM is reserved for product development, with an additional 16.8% for applied research.







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