The Kyoto team, led by Mitinori Saitou, used a three-step process. First they developed a very specific cocktail of three factors that were able to differentiate the stem cells into epiblast-like cells, a cell type that appears very transiently around Day 8 of embryo formation in mice.
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Coverage of the latest news and updates from the field of stem cells.
When the researchers tracked the transplanted cells they found they migrated to a brain region known to support the growth of neurons, where the cells then developed into three types of neural tissue: neurons, astrocytes and oligodendrocytes.
To generate the iPSCs, the team followed the standard four-gene reprogramming procedure, but sought to minimize other potential sources of DNA mutations that might have influenced some previously reported results.
The findings were also published online in the Journal of the American Medical Association.
So far, however, nuclear transfer has not yet been successful in human cells. Many scientists have turned instead to stem cell lines created by reprogramming adult cells (usually skin cells) taken from patients.
Thirty-five patients received the cell transplant while 36 had sham surgery. After 12 months, the investigators found no significant difference in the motor scores of the two groups, with both improving approximately 21 percent.
Ten days later a second team of Stanford researchers, this time in the lab of Gerald Crabtree, published a Nature online report demonstrating how they had improved on Wernig's method and greatly increased the efficiency of converting skin to neuron.
The California Institute of Regenerative Medicine had agreed to lend Geron up to $25 million to pay for the trial, which was designed mainly to test the safety of embryonic stem cells on patients with severe spinal cord injury. Dr.
The Moorfields' surgeons will inject between 50,000 and 200,000 cells behind the retina through a fine needle in an outpatient operation expected to take up to an hour. Only patients with advanced Stargardt's will be admitted to the trial.
NEWCASTLE, United Kingdom, Dec.