Gene Therapy: Chinese Researching Gene Replacement

When I mention the words gene therapy, you might immediately think of the horrifying eugenics experiments conducted by the Nazis in World War II.

Since then, however, fantastic advances in technology have allowed scientists to learn an incredible amount about how the human body works. As a result, gene therapy and genetic medicine have become a huge boon to mankind since the practice originally emerged.

Indeed, initiatives like the Human Genome Project have shed more light on genetic expression and how various traits and diseases are passed from generation to generation.

In fact, gene therapy currently in its infancy holds the promise of suppressing (or even curing) any number of genetic diseases or disorders.

And in this regard, scientists in China have just taken a bold new step forward. One that others have feared to take

Along with the very first thought about gene therapy came a huge concern: The very same therapies that could modify human genes in existing patients could be used to modify people before they were even born.

You see, when gene therapy is conducted on fully formed, living people, the results arent heritable. So if something goes wrong, its limited to that person any man-made genetic mistake wouldnt spread into the wider population.

But a genetically modified embryo could theoretically carry the new genetic information through every cell it ever grew including reproductive cells and pass the modification on to his or her children.

This fear, not to mention the specter of less ethical gene modifications in the future, has previously blocked scientists from performing gene replacement experiments on human embryos.

But not anymore

Scientists at Sun Yat-sen University in Guangzhou, China recently took an unprecedented step.

They replaced the genes in a single-cell embryo.

Their motives were well-intentioned the experiment was to try to replace a gene that causes a serious and sometimes fatal blood disorder, and which replicated similar gene replacement therapies tested on adult human cells and animal embryos.

They also took some precautions to allay ethical concerns. Lead scientist, Junjiu Huang, insisted on using non-viable embryos i.e., castoffs from fertility clinics that could never become fully developed humans.

Nevertheless, some scientists are up in arms about the experiment, despite the precautions taken. And despite the significance of the research, it caused enough controversy that the resulting report was said to have been rejected by some larger scientific journals.

Unfortunately, the experiment didnt produce the expected results anyway. The existing gene-replacement regimen didnt result in successful gene replacement often enough to justify any further experimentation along the same line.

But still, the step has been taken and its an important one

Ultimately, were nearing a day when it will be possible to cure diseases and disorders before people get them even before theyre born! Thats obviously a goal worth pursuing. And while some scientists dislike gene experimentation, others are more philosophical, reasoning that its only a matter of time before such trials are commonplace.

But were not there yet.

Gene replacement therapy is still a young science, and despite hundreds of therapies that have gone to human clinical trials, there isnt a single gene replacement therapy in widespread use.

Indeed, one of the more successful gene replacement treatments was actually stopped. Scientists found that while it did cure the disease it targeted, the new genetic code also seemed to cause leukemia.

Thats a prime example of how complex this field is and the danger of using such therapy on embryos. An unintended disease or disorder could be passed down from parent to child but perhaps not becoming apparent for many generations and long after that code is widespread.

However, with the experiment at Sun Yat-sen University having been completed, its clear that we no longer have the luxury of deferring the argument about the ethics of genetic changes to human embryos to some point in the future. Because the future has just occurred.

To living and investing in the future,

Greg Miller

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Gene Therapy: Chinese Researching Gene Replacement

Home Page of the Human Gene and Cell Therapy Center

Although there appears to be no definitive cure for many human genetic diseases, there are some gene therapy products awaiting for FDA approval and expected to be released in the near future. So far, more than 2,000 clinical gene therapy trials were conducted worldwide involving tens of thousands of patients. Some of the gene therapy drugs are commercialized and already in the market. Consequently, there is a dramatic progress made in the clinical outcome of current gene therapy trials such as those conducted against Leber's Congenital Amaurosis (LCA), Thalassemia, SCID, Hemophilia and Muscular Dystrophy etc.

In October 2012, the European Commission granted marketing authorization for Glybera (alipogene tiparvovec) under exceptional circumstances as a treatment for adult patients diagnosed with familial lipoprotein lipase deficiency (LPLD) confirmed by genetic testing, and suffering from severe or multiple pancreatitis attacks despite dietary fat restrictions. Glybera is a gene therapy drug that is designed to restore the LPL enzyme activity required to enable the processing, or clearance, of fat-carrying chylomicron particles formed in the intestine after a fat-containing meal. The product consists of an engineered copy of the human LPL gene packaged with a tissue-specific promoter in a non-replicating AAV1 vector, which has a particular affinity for muscle cells.

Human Gene and Cell Therapy Center of Akdeniz University Hospitals and Clinics was initially established as the Human Gene Therapy Unit of College of Medicine by Dr. Salih Sanlioglu in 2003. In 2010, the unit was restructured as a center to include cell therapy studies as well. The Gene and Cell Therapy Center is currently located on the first floor of the Institute for Transplantation, Akdeniz University Hospitals and Clinics. Since clinical grade vector production requires cGMP laboratories, the Center has been scheduled to be relocated to a new R&D building in the near future.

Although, initial studies concerned the development of novel gene therapy methods for various cancer types such as cancers of the lung, prostate and breast etc. including auto-immune diseases like rheumatoid arthritis, gene and cell therapy of diabetes became the priority in research due to alarming incidence of diabetes in the whole world. Accordingly, pancreatic islet transplantation fortified with gene delivery became a popular area of interest in the Center. These scientific projects relating to the diabetes treatment necessitated international collaboration to complete.

Some of the gene delivery vectors constructed and produced in the lab are shown on the right. These gene delivery vehicles are the most advanced gene therapy vectors normally used in gene therapy clinical trials. Adenovirus vectors are prefered in cancer gene therapy applications due to their antigenicity while AAV or Lentivirus vector is chosen when long term gene expression is desired.

For an instance, Alipogene tiparvovec (marketed under the trade name Glybera) is a AAV based gene therapy treatment designed to compensate for lipoprotein lipase deficiency (LPLD). It is the first of its kind to be approved as a gene therapy vector in the western world.

Nonetheless, due to outstanding quality of research and the scientific accomplishments, the center stands out to be one of the pioneering gene and cell therapy research facilities in the country. Accordingly, experimental gene and cell therapy protocols developed in the Center are published in the leading gene therapy journals like Human Gene Therapy, Cancer Gene Therapy, and Current Gene Therapy and diabetes journals etc. The founder of the Gene and Cell Therapy Center and his research activities are outlined below:

After graduating from the School of Veterinary Medicine, Selcuk University, Turkiye, Dr. Salih Sanlioglu attended the Ohio State University College of Medicine, where he obtained his Master's (1992) and PhD (1996) degrees in the field of Molecular Genetics.

Following completion of his postdoctoral training at the Human Gene Therapy Institute of University of Pennsylvania (1997) and internal medicine research fellowship at the Gene Therapy Center of University of Iowa (2002), Dr. Sanlioglu has joined the medical faculty of Akdeniz University, Antalya, Turkiye, and subsequently established the first human gene therapy facility in the country.

Although, his initial studies mainly concerned gene therapy of cancer, his latest research interest specifically focused on gene and cell therapy of diabetes due to widespread prevalence of the disease. As being the author of numerous research articles published in the prominent gene therapy journals, Dr. Sanlioglu constantly thrives upon novel genetic discoveries, which might one day make diabetes a treatable disease. One of his ultimate goals is to treat diabetes using 3rd generation of HIV-based Lentiviral vectors with antidiabetic properties.

For this purpose, genes with antidiabetic potential like VIP or GLP-1 have been cloned into the most advanced gene therapy vectors currently available. Dr. Sanlioglu has currenlty been working as a full professor at the Human Gene and Cell Therapy Center of Akdeniz University Hospitals and Clinics.

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Home Page of the Human Gene and Cell Therapy Center