The use of embryonic stem cells to treat debilitating illness is still being hotly contested in the U.S.

Meanwhile, two clinics in Germany report success using adult stem cell therapy for the past four years to treat such illnesses as Parkinson's, diabetes, cerebral palsy, heart disease, autism and even AIDS.

Researchers in Germany announced that they have used adult stem cell therapy to cure a man afflicted with both leukemia and HIV, the virus that causes AIDS.

Doctors from the Charite-University of Medicine in Berlin say that in 2007, a 44-year-old American patient volunteered to receive a then-experimental adult stem cell therapy to treat his leukemia. At the same time, the researchers decided to perform a stem-cell transplant in an effort to fight his HIV.

Not only was the stem cell donor a good blood match for the patient, wrote the researchers, but he also had what the doctors determined was a gene mutation that demonstrated a natural resistance to HIV.

Stunning success

Now, three years later researchers say the patient shows no signs of either leukemia or HIV infection, and they are guardedly optimistic that he has been cured.

The researchers say he has been taken off anti-retroviral drugs nearly a year ago and neither disease has shown signs of returning in the 20 months since he received the stem cells.

Parkinson's treatment

In Dusseldorf, Germany, the XCell-Center has been performing adult stem cell therapy since 2007 and has treated 4,000 patients.

Recently, the personal doctor of a 61-year-old Australian painter who suffered from Parkinson's disease confirmed that his patient showed spectacular improvements after his successful stem cell treatment at the XCell-Center. The doctor described the patient as being 80 percent recovered.

Embryonic stem cell controversy

As for the controversial use of embryonic stem cells, two American companies won regulatory approval earlier this year to start the first experiments using embryonic stem cells on humans suffering from spinal cord injury and blindness.

Doctors have known for some time now that embryonic stem cells can transform into nearly any cell in the human body, opening a path toward eliminating such ills as Parkinson's disease, paralysis, diabetes, heart disease, and maybe even aging.

Critics of embryonic stem cell research argue that it should be banned because it involves the destruction of early human life. American scientist James Thomson's team isolated human embryonic stem cells for the first time 12 years ago and the field has been cloaked in controversy ever since.

Legal wrangling

Former President George W. Bush restricted federal funding for the research because it involves the disposal of human embryos -- a ban that President Barack Obama reversed shortly after taking office in 2009.

But in August of 2010, Judge Royce Lamberth blocked federal government funding for embryonic stem cell research after ruling in favor of a coalition of groups.

While the funding has since been permitted to go ahead pending appeal, the legal wrangling has left some scientists wondering about the future.

Scientific workaround

To get around the problems associated with embryonic stem cell research, scientists in 2010 forged new paths toward creating induced pluripotent cells, which can transform into skin, blood or heart cells. Embryonic stem cells are pluripotent cells.

Writing in the journal Nature, Canadian researchers described their method of turning adult human skin cells into blood without manipulating them back into pluripotent cells, making the process more time efficient and potentially safer.

And a Harvard University scientist, Derrick Rossi, discovered a way to avoid risky genetic modification and instead use RNA molecules to reprogram adult human cells into pluripotent cells without altering the DNA.

Clinical trials

Bob Lanza, chief scientist at Advanced Cell Technology, says that after a decade of intense controversy, the field of embryonic stem cell therapy is finally ready to start proving itself and to actually start helping patients suffering from a range of diseases.

His company was cleared in November by the Food and Drug Administration to begin testing a therapy derived from embryonic stem cells to treat a rare form of blindness that strikes in childhood, known as Stargardt's disease. Clinical trials are expected to start in the coming months, and results could be known within six weeks.

In October, Geron Corporation announced it had begun the first-ever test of human embryonic stem cells in a patient suffering from spinal cord injury. About a dozen patients are expected to participate in the year-long study. The primary aim of both studies is to gauge its safety, and not necessarily to restore mobility or vision.

The major concern with stem cell therapies is that the transforming cells could form tumors. But if the methods appear safe, both companies aim to expand their trials to wider populations in the hopes of eventually curing paralysis and blindness.