Saturday, 22 December 2012

Experiments show retinitis pigmentosa is treatable

Yesterday, researchers of the Columbia University Medical Center revealed the results of two treatments they have been experimenting on, for retinitis pigmentosa. The first treatment involved the use of induced pluripotent stem cells (iPSCs) while the second one involved the use of adeno-associated viruses (AAV) which transferred the correct copies of DNA into the retina cells (gene therapy). All experiments were carried out on an animal model (mice).

In the iPSCs study, researchers transplanted the cells via injection under the retina, five days after the mice were born. After the injection, all stem cells managed to assimilate into the retina without problem and no cases of tumours were reported. Researchers observed that the IPSCs cells expressed certain markers specific to retinal pigmented epithelium (the cell layer adjacent to the photoreceptor layer), indicating that they have the capacity to develop into normally functioning retinal cells. 

Image showing how a healthy person sees and how someone with retinitis pigmentosa sees
Left normal vision, right view of a patient with Retinitis Pigmentosa
Later, scientists tested the mouse for any visual improvements. The results were highly encouraging. Visual function had improved and it was shown that the effect was long lasting. 

Stephen H. Tsang, leader of both studies,said ,

“We’ve never seen this type of improvement in retinal function in mouse models of RP. We hope we may finally have something to offer patients with this form of vision loss.”

He also added that this is the first time a study shows stem cells can be a viable option for treating retinitis pigmentosa.

“This is the first evidence of lifelong neuronal recovery in an animal model using stem cell transplants, with vision improvement persisting throughout the lifespan,” 

In the second study researchers decided to give gene therapy a go. The gene therapy consisted of  adeno-associated viruses (AAV) which transferred the correct copies of DNA into the retina cells. The viruses where injected only to one eye, while the second remained untreated to act as a control. Once again the results were promising and encouraging. All treated mice showed great visual improved. That is, in the treated eye of course as the untreated eyes lost all functional vision.

“These results provide support that RP due to PDE6α deficiency in humans is also likely to be treatable by gene therapy,” said Tsang.

Retinitis pigmentosa (RP) is an inherited, degenerative eye disease that causes severe vision impairment and often leads to total blindness. The progress of RP is not consistent, as some people exhibit symptoms from infancy while others, notice symptoms later in their life. As of now, there is no real cure for the condition but only treatments that slow down its progress .

Fundus of patient with mid range retinitis pigmentosa
Stephen H. Tsang, MD, PhD, is an associate professor of pathology & cell biology and of ophthalmology at CUMC and an ophthalmologist at NewYork Presbyterian Hospital

Read the official announcement here

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  1. When does the University plan to experiment with human subjects already affected with rp eye?

  2. I'm also interested in the same question as Jonnelle. My father and two of his siblings all have RP. It is hard to watch my father not be able to do all the things he used to do and my mother having to take care of him and his two siblings. What a great blessing that would be. I hope to see something soon.


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