The first ever clinical trial of human embryonic stem cell-based therapy on a human patient is now underway, according to the first and presently only company in the United States with the license to use the controversial cells to treat people.

The California-based biopharmaceuticals company, Geron, announced the enrollment of the first patient in its clinical trial at the Shepherd Center in Atlanta on Monday, where it hopes to see the first major breakthrough for human embryonic stem cell research.

A patient with severe spinal injuries is the first to undergo the treatment.

"Initiating the … clinical trial is a milestone for the field of human embryonic stem cell-based therapies," said Dr Thomas B Okarma, Geron's president and CEO.

“We look forward to participating in clinical trials that may help people with spinal cord injury," added Dr Donald Peck Leslie, medical director of the Shepherd Center, a 132-bed spinal cord and brain injury rehabilitation hospital and clinical research centre.

Less than three months ago, the US Food and Drug Administration gave Geron approval to proceed with its trial on a therapy for patients with spinal-cord injury. The trial involves injecting a stem-cell treatment into patients with severe spinal cord injury with the hope that it will help damaged nerve cells regrow and eventually allow patients to regain movement.

The FDA had originally approved the study in January 2009 and the trial was scheduled to begin last summer. But Geron found that animals used in a preclinical study had developed small cysts that appeared with “a higher frequency” than other studies, resulting in an FDA hold on the trial.

Despite the latest green light, opponents and even some proponents of embryonic stem cell research have raised concern about the clinical trial.

FDA officials have declined to comment on why they decided to lift their hold on the study, leaving only Geron to report that the federal agency determined the cysts "did not lead to any adverse consequences to the animals" and that the company changed some of its procedures "to minimise the likelihood of cyst formation".

"When we started working with hESCs in 1999, many predicted that it would be a number of decades before a cell therapy would be approved for human clinical trials,” noted Okarma on Monday.

“This accomplishment results from extensive research and development and a succession of inventive steps to enable production of cGMP master cell banks, scalable manufacture of differentiated cell product, and preclinical studies in vitro and in animal models of spinal cord injury, leading to concurrence by the FDA to initiate the clinical trial," he added.

Aside from the cysts issue, the research has also drawn protests over the destruction of the embryo during the process of harvesting the stem cells. Many pro-life groups insist human embryonic stem cell research is unethical and equate it with abortion because it destroys a potential life. They also argue that adult stem research is an alternative that is both ethical and has proven results.

Just last month, a team of researchers revealed its development of a new technique that can quickly and more efficiently create safe alternatives to human embryonic stem cells.

The new method, which is featured in the October issue of Cell Stem Cell, uses synthetic RNA to drive the expression of stem cell-inducing proteins without irreversibly altering the cells' genetic material.

The resulting stem cells then are able to recapitulate the functional and molecular properties of human embryonic stem cells, and therefore can be transformed into specialized cells to treat disease.

"These new iPS cells are safer; there is no evidence of a risk of causing cancer by using viruses to insert genes into cells,” noted Dr David Stevens, CEO of the 16,000-member Christian Medical Association (CMA), which hailed the breakthrough.

“The new cells are produced more efficiently, taking just 17 days to create. The new iPS cells are cheaper to develop, can easily tissue match the patient that the therapy are given too and are morally acceptable to all,” Stevens added. “The fact that these iPS cells strategy can then turn those cells into ones that could be used for transplants is a huge step forward as well."

While encouraged by the new technique, Derrick J Rossi of the Children's Hospital Boston, who led the team of researchers, said that embryonic stem cell research was still crucial because, among other things, embryonic stem cells are irreplaceable for validating alternatives.

National Institutes of Health Director Francis S Collins echoed Rossi’s remarks saying that the new “report provides a substantial advance … [b]ut this research in no way reduces the importance of comparing the resulting iPS cells to human embryonic stem cells”.

“Previous research has shown that iPS cells retain some memory of their tissue of origin, which may have important implications for their use in therapeutics. To explore these important potential differences, iPS research must continue to be conducted side by side with human embryonic cell research," he told The Washington Post.

While the debate over the controversial research rages on, the team at the Shepherd Center will be moving forward with the first phase of its study, the primary objective of which is to assess the safety and tolerability of human embryonic stem cell-derived oligodendrocyte progenitor cells, GRNOPC1, in patients with spinal cord injuries less than 14 days-old.

"Our medical staff will evaluate the patients' progress as part of this study,” reported Leslie.

"This clinical trial represents another step forward in Shepherd Center's involvement in an attempt to find a cure for paralysis in people with spinal cord injury,” added Dr David Apple, Shepherd Center's medical director emeritus and principal investigator of the trial at the hospital.

The Shepherd Center is one of seven potential sites in the United States that may enroll patients in the clinical trial. In addition to Shepherd Center, Northwestern Medicine in Chicago is also open for patient enrollment.

In announcing the clinical trial’s commencement, Geron cautioned investors that its statements regarding potential applications of its human embryonic stem cell technology constitute “forward-looking statements that involve risks and uncertainties”.

“Actual results may differ materially from the results anticipated in these forward-looking statements,” it added.