Paralyzed marmoset monkeys are walking again after a Japanese research team transplanted induced pluripotent stem cells (iPS cells) into the animals’ spines — the first time the treatment has succeeded in a primate subject. Getting closer to restoring paralyzed humans. Treatment works best within 9 days of injury, so it will work best to prevent newly injured people from remaining paralyzed. Need to have stem cell bank to enable timely treatment.
Okano and his team began their research with damaging the spinal cords of marmosets, paralyzing them from the neck down. They then transplanted cells that would become nerve tissue, produced from iPS cells, into the damaged area nine days after the injury — the most effective timing for such transplant treatment.
The researchers found that the marmosets soon began to regain some motor function, and could both stand on their hind legs and grip things with their hands around a month after the transplant. The team believes the transplanted cells did become nerve cells, regenerating the damaged spinal tissue. They used a type of iPS that has little chance of becoming cancerous — one of the primary challenges of stem cell research — and none of the marmosets had developed tumors three months after the procedure.
“The marmosets have dramatically recovered from their injuries to the extent that they can repeatedly jump,” Okano said, adding that he hoped to proceed with research into transplants using even safer types of iPS cells.
The injection was given on the ninth day after the injury, considered the most effective timing, and the monkey started to move its limbs again within two to three weeks. After six weeks, the animal had recovered to the level where it was jumping around. Its gripping strength on the forefeet also recovered to up to 80 percent.
One challenge to providing the treatment to humans is timing. It takes six months or more to create iPS cells — not nearly quick enough for timely transplants to recent accident victims. To overcome this problem, the research group is also partnering with Osaka National Hospital to study the creation of an iPS cell bank that would make the stem cells available on demand.
We are studying the regulatory mechanisms of neural development and stem cell biology of the central nervous systems by focusing on 1) Developmental genetics of Drosophila and mammalian CNS stem cells, 2) Regulatory mechanism of mammalian CNS development, 3) Induction of particular neurons from ES cells, 4) Adult neurogenesis, and 5) Stem cell transplantation into the damaged brain and spinal cord.
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