YOKOHAMA, JAPAN -For more than a decade, stem cell therapies have been touted as offering hope for those who suffer from genetic and degenerative diseases. The promise took a step towards reality last week with announcements here at the annual meeting of the International Society for Research on stem cells (ISSCR) that both groups progressing to human clinical research, one putting the focus on a rare genetic neurological disease and the other for vision loss in the elderly.
StemCells Inc. of Newark, California, reported encouraging results from an initial human trial using human neural stem cells to treat Pelizaeus-Merzbacher disease (PMD). PMD is a progressive and fatal disease in which a genetic mutation inhibits the normal growth of myelin, a protective material that surrounds nerve fibers in the brain. Without myelin, nerve signals are lost and the patient, usually an infant suffers degenerating motor coordination and other neurological symptoms. In his presentation, Ann Tsukamoto, StemCells Vice President for Research, said the company chose to test its approach to neural stem cells on PMD because there is currently no cure for the condition and a diagnosis can be confirmed by genetic testing and MRI. "This creates an opportunity for early intervention when it can best help."
The company has created highly purified neural stem cell banks that are isolated from adult neural tissue. Injected into rodents, the cells do not form tumors; instead, they migrate through the animal brain, where they differentiate into different types of neuronal cells, including cells that create the myelin that protects nerves. When neural stem stems were injected into mice, they showed "robust registry and migration, new myelin formation," said Tsukamoto.
The company now sponsored an initial safety test the strategy in four infants with PMD. in each patient, researchers at the University of California, San Francisco, 75 million transplanted neural stem cells in each of the four sites in the brain and followed this with immunosuppressive therapy so that the recipient would not reject foreign cells. no safety concerns were raised during the trial, Tsukamoto reported. in addition, the MRI taken 18 months later showed the formation of new myelin around axons and clinical observations of patients reported that their motor functions remained stable or enjoyed modest gains. The company is now planning larger trials. Tsukamoto said that if the treatment is effective, it could lead to treatments of neural stem cells for multiple sclerosis, cerebral palsy and Alzheimer's disease.
In a second speech at the meeting, cell researcher stem Masayo Takahashi Biology of RIKEN Centre for Development in Kobe report on progress in the preclinical work her wet targeting group degeneration age-related macular (AMD). In AMD, the cells of the retinal pigment epithelium (RPE) of the retina that supports the eye cells that detect light wear, and there is also the growth of abnormal, leaky blood vessels under the retina . These conditions lead to an impairment of vision in the central part of the eye. The strategy proposed by the group is to surgically remove the problematic blood vessels and replace the damaged RPE cells with new RPE cells derived from a patient own cells. Using a known cellular reprogramming process, researchers take skin cells of a patient, be converted into the so-called induced pluripotent stem (iPS) cells, which can differentiate into all cells in the human body. They then transform these iPS cells into RPE cells and form them into sheets in the laboratory. Since iPS approach uses the patient's own cells, they avoid the need for immunosuppressive drugs.
The RPE cells generated by the team Takahashi shows the pattern of the structure and expression of genes characteristic of human RPE cells authentic. Injections of the cells into mice triggered no tumors, it was also reported, and the cells survived for more than 6 months when transplanted into monkeys. The research team has not tested directly whether the transplanted RPE cells improved the vision of the animal. But Takahashi noted that some people with AMD had transplanted RPE cells from the periphery to the center of them, improving their central vision. She hopes to have all necessary authorizations for research involving humans within a year.
Earlier this year, scientists from the University of California, Los Angeles, and Advanced Cell Technology of Marlborough, Massachusetts, reported in The Lancet on safe and successful use RPE cells derived from human embryonic stem cells rather than iPS cells to treat a different type of AMD in a limited number of human patients. Takahashi predicted that in the future, choosing from different stem cell therapies will "depend on the target disease and the status of the host."
The positive results reported in The Lancet paper presented at ISSCR will help the field "to grow," said Fiona Watt, stem cell researcher UK Cambridge Research Institute Cancer Research. And George Daley, a scientist on stem cells at Harvard Medical School in Boston, is even more optimistic. Noting the progress reported at the conference this year, he said, "Wait until next year in Boston, "the site of the 2013 meeting ISSCR.
* This article was corrected on June 21 original caption refers only to insert the image. the legend has been corrected to describe the bigger picture.
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