The rats were weighed and tested for strength twice a week for 15 weeks. Weight loss, according to Koliatsos, indicates disease onset. On average, rats injected with live stem cells started losing weight at 59 days and lived for 86 days after injection, whereas control rats injected with dead stem cells started losing weight at 52 days and lived for 75 days after injection.
The rats were coaxed to crawl uphill on an angled plank, and their overall strength was calculated by considering the highest angle they could cling to for five seconds without sliding backwards. While all the rats grew progressively weaker, those injected with live cells did so much more slowly than those injected with dead cells.
Close examination of the transplanted cells also revealed that more than 70 percent of them developed into nerve cells, and many of those grew new endings connecting to other cells in the rat's spinal cord.
"These stem cells differentiate massively into neurons," says Koliatsos, "a pleasant surprise given that the spinal cord has long been considered an environment unfavorable to this type of transformation."
Another important feature of the transplanted cells is their ability to make nerve-cell-specific proteins and growth factors. The researchers measured five-times more of one particular factor, known as GNDF (short for glial cell derived neurotrophic factor) in spinal cord fluid. The transformation of the transplanted cells also may allow them to deliver these growth factors to other cells in the spinal cord through physical connections.
Cautioning that clinical applications are still far from possible, Koliatsos hopes to take further advantage of his rodents with ALS to learn as much as possible about how human stem cells behave when tran
Source:Johns Hopkins Medical Institutions