I Can See Again

By Medical Discovery News

Nov. 24, 2012

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Blind mice don’t only exist in nursery rhymes, but in scientific laboratories. Scientists have been able to restore the vision of some such mice that were impaired by the same family of eye diseases that cause blindness in millions of Americans. The landmark study successfully transplanted immature photoreceptor cells, which are nerve cells in the retina responsible for sight.

Photoreceptor cells gradually die off in people with certain degenerative eye diseases. Once enough of the cells are gone, a person goes blind and no treatment can reverse the damage.

The research team from University College London Institute of Ophthalmology proved they can reverse the damage in adult mice with nonfunctioning rods. Rods and cones are the two types of photoreceptor nerve cells that make up the retina. These nerve cells convert light energy into signals that travel the optic nerve to the brain. Cones detect such things as color and detail and provide the center field of vision. Rods detect black and white and enable peripheral and low-light vision.

In the study, researchers took mice without functioning rods and injected their retinas with immature rod receptor cells from young, healthy mice. In four to six weeks, one in six of the mice with transplanted rod precursor cells seemed to be functioning nearly as well as mice with normal rod photoreceptors. These transplanted cells formed nerve connections resembling normal rod cells and generated signals that were transmitted to the brain for visual processing.  This is the first time that transplanted photoreceptor cells have been shown to integrate into the circuitry of the retina and improve vision.

To test their results, researchers placed treated mice and diseased mice into a dimly lit water maze. Recall the diseased mice do not have functioning rods, which means they can’t see in low light. If the transplant works, the mice with new rods should be able to spot a visual cue for a hidden platform and get out of the water. The mice with implants had no difficulty finding the platform and climbing out. The untreated, diseased mice took much longer and did a thorough search of the maze before finding the platform.

Researchers say the study’s success was due to the large number of photoreceptor cells they implanted – 200,000 compared to less than 1,000 cells in other studies. Next, researchers plan to test whether the procedure is as successful in transplanting precursor cones in mice.

A similar but separate study in humans is already undergoing clinical trials involving 12 patients with Stargardt disease, the most common form of inherited juvenile macular degeneration. By age 50, half are legally blind. The participants have been injected with 50,000 to 200,000 embryonic stem cells. The aim of these early clinical trials is to determine if the implant of embryonic stem cells is safe and well tolerated. So far, the trials are promising.

For a link to this story, click here.

Can You See The Light?

Family hopeful that Chinese stem cell injections can restore young boy’s vision

By Pamela Bond

Victoria Advocate

May 4, 2008

The first time I met 7-year-old Paden Lane McDonald, he sat right next to me on his couch and peered at me out of the corner of his eyes. After asking my name, he slid to the floor and felt my purse with his hands.

“Do you have anything that lights up in here?” he asked.

As I watched Paden take apart and put back together my cell phone, the only thing I had in my purse that lit up, his mother, Shannon Dehn, said that watching Paden adapt to life with Optic Nerve Hypoplasia, an underdevelopment of the optic nerve during pregnancy, had been hard.

“It’s the leading cause of childhood blindness,” Dehn said. “But usually there are so many other problems involved, the vision issues get pushed to the back. We probably would never have heard of it if he didn’t have it. We are lucky that he has his peripheral vision and light perception.

There is Hope

When Paden was three months old, Dehn and his father, Roger McDonald Jr., noticed that he was not tracking things with his eyes. Paden was diagnosed six months later with ONH and told there was no cure. However, in December Dehn heard the story of a girl with ONH who had received treatment that restored some of her sight.

At Xiaoshan Hospital in Hang Zhou, China, patients with ONH are receiving treatments of umbilical cord stem cells through IV and spinal injections that restored some of the underformed cells of the optic nerve and therefore their sight. After months of research and consultations, Paden will receive five treatments, which consist of 10 million to 15 million stem cells, between May 19 and June 17 in China.

The treatment alone costs more than $20,000 and does not include travel and living expenses in China or follow-up appointments. Dehn took out a loan to pay for the medical treatment and Paden’s family has been holding fundraisers since January to pay off the loan that include selling T-shirts with the slogan “Can you see the light?”

Dehn said that doctors told them not to expect changes until six to nine months after the treatments, but she said that other patients often see subtle improvements within a week to a month.

“We may come home, a year down the road, and not see a thing, but even if nothing happens, we tried,” Dehn said. “And at least he does have some vision. It’s hard to keep my hopes in check because just watching the videos of how the other kids responded after treatment gives you hope. That makes it more real.”

Dehn said she is nervous about living in China for a month, but said it’s comforting to know that other American families will be at the hospital as well. Paden, however, loudly affirmed that he’s “not scared.”

Through Paden’s Eyes

Looking through Paden’s eyes would be like having a blind spot when looking straight ahead. His vision is 20/400, so he is legally blind, but since he has peripheral vision he can see out of the corner of his eyes, which his mom said gives him an advantage compared to most children with ONH.

“He sees very well for his condition. He’s adapted well,” Dehn said. “It’s hard for me. I tried to see like he does, through the corners of my eyes, and I could only do it for a few minutes. It killed my eyes.”

Paden, who is in kindergarten at Northside Baptist Church, said he doesn’t like school.

His mother said that homework is a constant struggle because his eyes are tired by the end of the day, but he does know all the colors and can read letters and numbers. Using a larger print on yellow instead of white paper and light boxes help him see the worksheets better.

“Teachers were nervous to deal with him at first,” Dehn said. “He tries to be lazy and get others to do stuff for him. There’s lots of pushing, but not too hard because he’ll get turned off. He gets frustrated very easily.”

The other children do not usually pick on Paden because of his condition, but Dehn said that another girl in his class has a walking problem, so most of Paden’s classmates knew how to treat someone with a disability. The school’s Christian environment also helps because they teach a lot of acceptance, she said.

“There were times when kids would say that he’s blind, which is not a word we’ve used with him, and it would hurt his feelings,” Dehn said. “He didn’t know how to handle it but I told him people talk, here’s how we handle it and then we move on. One of the worst nights of my life was when I went to register him for public school, in case he didn’t get into Northside, and we weren’t there for 10 minutes when these boys came up and started picking on him. It was hard to watch.”

Although things like feeding himself took longer to learn, Paden is very musically inclined and likes to play the keyboard and drums and make up his own songs. He is also interested in all kinds of batteries and is very mechanical. He can take apart and put together almost anything, mostly by touch.

“In public you’d never know anything was different about him because he gets in just about as much trouble as any other kid,” Dehn said. “Now we can go on with a new chapter in our lives and hopefully we’ll be extremely happy with the results.”