The transplant recipients are children suffering from the rare and fatal genetic disorder Batten disease, a degenerative disease that renders its young victims blind, speechless and paralyzed before it kills them.
The FDA says that doctors at Stanford University Medical Center can begin the testing on six children, but an internal Stanford review board must still approve the test, and that process that could take weeks.
It seems that the stem cells to be transplanted in the brain are not human embryonic stem cells, which are derived from days-old embryos, but are instead immature neural cells that are destined to turn into the mature cells that makeup a fully formed brain.
Some Parkinson's disease patients and stroke victims have received transplants of fully formed brain cells before, but the brain cells in this process have never before been implanted.
Apparently Batten disease is caused by a defective gene that fails to create an enzyme needed in the brain to help dispose of brain cellular waste, and as the waste accumulates healthy cells are killed until the patient dies.
Most victims die before they reach their teens.
The plan is to inject the children with healthy, immature neural stem cells that will "engraft" in a brain that will then hopefully direct them to turn into cells able to produce the missing enzyme.
Experiments with Batten-afflicted mice have been promising but such a test has never been undertaken before in humans.
Although Arthur Caplan, the director of the University of Pennsylvania's Center for Bioethics says he is sure there is no threat to anyone's identity, but there are ethical issues involved as some of the brain cells to be implanted will be derived from aborted fetuses.
According to Stem Cells Inc. the biotechnology company developing the treatment, it receives the fetal tissue from a nonprofit California foundation that also collects tissue from miscarriages and other surgical processes.
Stem Cells chief executive Martin McGlynn says the FDA wants more information on where the transplanted brain cells were expected to go in the brain and other related health issues such as the chances the transplant might cause tumors.
McGlynn also said the agency wanted more information on its manufacturing process and more details about the design of the six-patient test.
He says the unique nature of the pioneering endeavor warrants the demands from the FDA.
During the procedure Stanford University neurosurgeon chief Dr. Stephen Huhn will bore small holes through each child's skull and then inject the neural cells into the patients' brains.
In order to protect the new cells and the childrens' immune systems drugs will be given and the children will be closely monitored for a year.
The initial trial says Huhn will test whether the millions of new cells each child receives is safe for them, but ultimately, more tests with many more patients over several years will be needed to determine whether the transplanted cells do help Batten patients.
If successful, people afflicted by other brain disorders could benefit from such treatment and it may herald future therapies for regenerative medicine, says Huhn.
McGlynn says the brutal, fatality of the disease and the availability of mice genetically engineered with it, were important factors the FDA considered when granting approval for such a novel human experiment.