Researchers from the University of Rochester (U.R.) Medical Center say that with a single shot of human fetal stem cells they cured lab mice suffering from a nervous disorder that causes tremors, seizures and premature death.
The scientists report today in the journal Cell Stem Cell that the finding could bring them closer to finding a treatment for incurable neurological conditions, such as Pelizaeus-Merzbacher's disease and adrenoleukodystrophy, the mysterious, debilitating disorder portrayed in the 1992 film Lorenzo's Oil.
Patients who suffer from these genetic conditions experience symptoms ranging from muscle weakness and paralysis to seizures and dementia. The problems are caused by disruptions in nerve cell (neuron), communication triggered by a lack of myelin, which, in normal nerve cells, coats and insulates their axons. (An axon is a fingerlike projection on a neuron that carries signals other nerve cells, thereby allowing impulses to and from the brain and other parts of the nervous system.
"Children [born with myelin-related illnesses] initially look okay, but as they start to grow and myelin is not being made properly, the transmission of information in their nervous system begins to degrade," says study co-author Steve Goldman, a Professor of Neurology, Neurosurgery and Pediatrics at the U.R. Medical Center. "These kids undergo progressive neurodegeneration as they grow and [often] die at a couple years of age."
Lorenzo Odone, the subject of Lorenzo's Oil, surpassed all expectations living, with adrenoleukodystrophy until a week ago, when he died at age 30. (When he was diagnosed at age six, physicians told his parents that he would live no longer than two more years.) Determined to find a treatment, his parents poured over research on myelin formation, eventually treating him with a regimen of olive and rapeseed oils designed by a U.K. chemist to supply their son with the fat he theoretically needed to manufacture the missing myelin.
For their study, Goldman and his colleagues injected fetal human stem cells into 26 newborn mice with nerve cells that did not produce myelin. Such animals, known as "shiverer mice," shake almost constantly, have awkward gaits and poor balance and become paralyzed and eventually die when they're around five months old from long-lasting seizures. (The average life span of a normal mouse is two years.)
Twenty of the animals died when they were about 20 weeks old; two lived for about nine months and four were still alive at 14 months or age (when scientists killed them to examine their brains). At the time of their deaths, the final four animals were free of their symptoms.
"I hate to use the word 'cure,' but in fact that's the case here," Goldman says. "About nine months after birth, by that point, they basically looked as if they'd restored all neurological functions."
Much to researchers surprise, when they performed autopsies on the mice, they found that all of their nerve cells now had sheaths of myelin. "We never expected the entire nervous system [to be covered]," says Goldman, who notes that previous attempts at stem cell transfer had resulted in the new myelin production in only 10 percent of the nervous system.
He estimates that it took about two months for the stem cells to mature into oligodendrocytes, cells that manufacture myelin. Arnold Kriegstein, director of the Institute for Regeneration Medicine at the University of California at San Francisco, says the research is proof that stem cell transplants may prompt proper myelin production.
"We're hoping that we can do the same thing in people," Goldman says, noting that he wants to extend the research to include other diseases caused by missing myelin, such as multiple sclerosis and cerebral palsy.