Scientists are reporting that monkeys with Parkinson's disease symptoms show significant improvement over two years after being transplanted neurons prepared from human iPS cells. The study, published in Nature, is an expected final step before the first iPS cell-based therapy for neurodegenerative diseases.
Parkinson's disease damages a specific type of cell in the brain known as dopaminergic (DA) neurons. It is known that by the time symptoms are first detected, a patient will have already lost more than half of his or her DA neurons. Several studies have shown the transplantation of DA neurons made from fetal cells can mitigate the disease. The use of fetal tissues is controversial, however. On the other hand, iPS cells can be made from blood or skin.
To test the safety and effectiveness of DA neurons made from human iPS cells, researchers transplanted the cells into the brains of monkeys.
It is generally assumed that the outcome of a cell therapy will depend on the number of transplanted cells that survive, but the scientists found this was not the case. More important than the number of cells was the quality of the cells.
To understand why, the team looked for genes that showed different expression levels, finding 11 genes that could mark the quality of the progenitors.
Another feature of the study that is expected to extend to clinical study is the method used to evaluate cell survival in the host brains. The study demonstrated that magnetic resonance imaging (MRI) and position electron tomography (PET) are options for evaluating the patient post-surgery.
Reprinted from materials provided by the Center for iPS Cell Research and Application – Kyoto University.