Stem cell stories that caught our eye: 3 blind mice no more and a tale of two tails

Stem cell image of the week: The demise of Three Blind Mice nursery rhyme (Todd Dubnicoff)
Our stem cell image of the week may mark the beginning of the end of the Three Blind Mice nursery rhyme and, more importantly, usher in a new treatment strategy for people suffering from vision loss. That’s because researchers from Icahn School of Medicine at Mount Sinai, New York report in Nature the ability to reprogram support cells in the eyes of blind mice to become photoreceptors, the light-sensing cells that enable sight. The image is an artistic rendering of the study results by team led Dr. Bo Chen, PhD.

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An artist’s rendering incorporates the images of the Müller glia-derived rod photoreceptors. Image credit: Bo Chen, Ph.D.

The initial inspiration for this project came from an observation in zebrafish. These creatures have the remarkable ability to restore vision after severe eye injuries. It turns out that, in response to injury, a type of cell in the eye called Muller glia – which helps maintain the structure and function of the zebrafish retina – transforms into rod photoreceptors, which allow vision in low light.

Now, Muller glia are found in humans and mice too, so the research team sought to harness this shape-shifting, sight-restoring ability of the Muller glia but in the absence of injury. They first injected a gene into the eyes of mice born blind that stimulated the glia cells to divide and grow. Then, to mimic the reprogramming process seen in zebrafish, specific factors were injected to cause the glia to change identity into photoreceptors.

The researchers showed that the glia-derived photoreceptors functioned just like those observed in normal mice and made the right connections with nerve cells responsible for sending visual information to the brain. The team’s next steps are to not only show the cells are functioning properly in the eye and brain but to also do behavioral studies to confirm that the mice can do tasks that require vision.

If these studies pan out, it could lead to a new therapeutic strategy for blinding diseases like retinitis pigmentosa and macular degeneration. Rather than transplanting replacement cells, this treatment approach would spur our own eyes to repair themselves. In the meantime, CIRM-funded researchers have studies currently in clinical trials testing stem cell-based treatments for retinitis pigmentosa and macular degeneration.

A tale of two tails: one regenerates, the other, not quite so much (Kevin McCormack) One of the wonders of nature, well two if you want to be specific, is how both salamanders and lizards are able to regrow their tails if they lose them. But there is a difference. While salamanders can regrow a tail that is almost identical to the original, lizard’s replacements are rather less impressive. Now researchers have found out why.

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In these fluorescence microscopy images, cross sections of original lizard and salamander tails (left) show cartilage (green) and nerve cells (red). In the regenerated tails (right), the lizard’s is made up mostly of cartilage, while the salamander also has developed new nerve cells. Image: Thomas Lozito

The study, published in the Proceedings of the National Academy of Sciences, shows how a lizard’s new tail doesn’t have bone but instead has cartilage, and also lacks nerve cells. The key apparently is the stem cells both use to regenerate the tail. Salamanders use neural stem cells from their spinal cord and turn them into other types of nervous system cell, such as neurons. Lizards neural stem cells are not able to do this.

The researchers, from the University of Pittsburgh, tested their findings by placing neural stem cells from the axolotl salamander into tail stumps from geckos. They noted that, as those tails regrew, some of those transplanted cells turned into neurons.

In an interview in Science News, study co-author Thomas Lozito says the team hope to take those findings and, using the CRISPR/Cas9 gene-editing tool, see if they can regenerate body parts in other animals:

 “My goal is to make the first mouse that can regenerate its tail. We’re kind of using lizards as a stepping-stone.”

Eyeing Stem Cell Therapies for Vision Loss

Back by popular demand (well, at least a handful of you demanded it!) we’re pleased to present the third installment of our Stem Cells in Your Face video series. Episodes one and two set out to explain – in a light-hearted, engaging and clear way – the latest progress in CIRM-funded stem cell research related to Lou Gehrig’s disease (Amyotrophic Lateral Sclerosis, or ALS) and sickle cell disease.

With episode three, Eyeing Stem Cell Therapies for Vision Loss, we turn our focus (pun intended) to two CIRM-funded clinical trials that are testing stem cell-based therapies for two diseases that cause severe visual impairment, retinitis pigmentosa (RP) and age-related macular degeneration (AMD).

Two Clinical Trials in Five Minutes
Explaining both the RP and AMD trials in a five-minute video was challenging. But we had an ace up our sleeve in the form of descriptive eye anatomy animations graciously produced and donated by Ben Paylor and his award-winning team at InfoShots. Inserting these motion graphics in with our scientist and patient interviews, along with the fabulous on-camera narration by my colleague Kevin McCormack, helped us cover a lot of ground in a short time. For more details about CIRM’s vision loss clinical trial portfolio, visit this blog tomorrow for an essay by my colleague Don Gibbons.

Vision Loss: A Well-Suited Target for Stem Cell Therapies
Of the wide range of unmet medical needs that CIRM is tackling, the development of stem cell-based treatments for vision loss is one of the furthest along. There are a few good reasons for that.

The eye is considered to be immune privileged, meaning the immune system is less accessible to this organ. As a result, there is less concern about immune rejection when transplanting stem cell-based therapies that did not originally come from the patient’s own cells.

The many established, non-invasive tools that can peer directly into the eye also make it an attractive target for stem cell–based treatment. Being able to continuously monitor the structure and function of the eye post-treatment will be critical for confirming the safety and effectiveness of these pioneering therapies.

Rest assured that we’ll be following these trials carefully. We eagerly await the opportunity to write future blogs and videos about encouraging results that could help the estimated seven million people in the U.S. suffering from disabling vision loss.

Related Links:

Stem Cellar archive: retinitis pigmentosa
Stem Cellar archive: macular degeneration
Video: Spotlight on Retinitis Pigmentosa
Video: Progress and Promise in Macular Degeneration
CIRM Fact Sheet on Vision Loss

What…exactly…do you do? How 12 year olds helped me learn how to talk about science

Jackie Ward in her lab at UC San Diego

Jackie Ward in her lab at UC San Diego

Jackie Ward is a graduate student at the University of California, San Diego (UCSD), and received a training grant from CIRM while studying for her PhD. At UCSD Jackie uses stem cells as a model to study rare neurodegenerative diseases in the lab of Albert La Spada. Her work as a PhD student focuses on a rare form of inherited neurodegeneration called spinocerebellar ataxia. From time to time Jackie shares her experiences with us. Here’s her latest.

One of the many questions I get over my annual trek home during the holidays is “What…exactly…do you do?” This is usually couched somewhere between “have you learned to surf yet?” and “how’s the weather?” In the past, I preferred to talk about my surfing skills (very minimal) and the sunshine (always amazing, thanks San Diego), more than what I do every day. It’s amazing how this seemingly innocuous question can be the most difficult to answer. Because we’re used to presenting our work in lecture formats or lengthy scientific papers, summing it up in three sentences of non-jargon can be difficult. A similar thought was outlined recently at UCSD, by the actor and science advocate Alan Alda. The title of his presentation, “Getting the Public Past a Blind Date with Science,” highlighted the uncomfortable feelings many people have towards science. Like any relationship, sustained communication and trust is necessary for success. Unfortunately, on many scientific issues, that relationship has suffered. As a PhD student, I am constantly surrounded by my peers—other scientists who know exactly what I mean when I use terms like “reprogramming” or “retinal photoreceptor.” While these scientist-to-scientist conversations are vital to our work, we often forget that it is equally, or perhaps more, important to have conversations with people who have no idea what we do. As any CIRM- or NIH-funded lab is well aware, a significant portion of our funding comes from taxpayer dollars. It’s these “investors” to whom we ultimately report back. This conversation is challenging. Not only do we have to change our language, we have to remember what it was like to not know everything we do now. The best practice I’ve gotten in this regard is talking to kids. Seventh graders seem to be less afraid to ask you questions or call you out on something that doesn’t make sense to them. (Now that I think about it, it might be beneficial to include some 13-year-olds on our grant review panels.) My graduate program allows students to fulfill their teaching requirement by doing science outreach activities. I chose to do this with the Salk Institute’s mobile science lab, where real scientists are connected to local middle schools to discuss their jobs and lead hands-on science labs. I didn’t realize how valuable this experience was until it started to become easier for me to answer the “what do you do” question. I changed the words I use. I replaced the word “reprogram” with “rewind” and “retinal photoreceptor” with “eye cell.” Unexpectedly, I think this practice helped me become a better communicator when I talk to other scientists now too. I try not to assume a certain level of knowledge with anybody. While I still love talking about pretending to surf and gloating about the weather, I’ve become more fond of the “what do you do” question. I hope to only improve with time. It’ll be my small contribution for getting science to that second date.