Researchers discover retinal stem cells in adult mammals

March 15, 2000

When it comes to stem cells, it appears the eyes have it. Researchers at the University of Toronto and the Hospital for Sick Children (HSC) have identified retinal stem cells in the adult mammalian eye, opening the door for retinal regeneration as a possible cure for damaged or diseased eyes.

"Before our study, it wasn't known whether retinal regeneration was possible in adult mammals, especially humans," says Vincent Tropepe, a PhD student in U of T's developmental biology program and lead author of the study that appears in the March 17 edition of the journal Science. "We've shown that by removing these cells from the eye, we can encourage the production of new neurons even after the retinas have fully matured and cell division has stopped."

Stem cells give rise to a lineage of other cells by simultaneously dividing and self-renewing, beginning in the embryo and continuing throughout post-natal life and into adulthood. When this cell division occurs, one of the two new cells is identical to the original while the other is slightly different. These new cells continue to divide and can become specialized and replace others that die or are lost.

In their study, researchers discovered retinal stem cells in the tissue of adult mice, cows and humans. Previously, only amphibians and fish were thought to have retinal stem cells capable of regenerating and making new neurons. "The stem cells we discovered appear to be under inhibitory control while still in the eye, but proliferate once they are removed," says Roderick McInnes, holder of the Anne and Max Tannenbaum Chair in Molecular Medicine at HSC and U of T.

The research team now hopes to be able to stimulate the stem cells in their natural region inside the eye in order to generate new neurons to help return the eyes to their proper function. "Our next goal is to find those factors that inhibit them from proliferating in their natural region inside the eye and release that inhibition so as to give the cells the ability to regenerate and ultimately produce the different types of cells needed to make a new retina," says Derek van der Kooy, professor of anatomy and cell biology in U of T's Faculty of Medicine.

While finding that elusive inhibitory factor would be ideal, researchers say other methods can be explored. "If we can't find a way to relieve the inhibitory factors in the real eye then an alternative would be to remove and culture the cells, make the right tissue type that's missing and then put them back," adds Tropepe, who conducted the research as part of his thesis on characterizing neural stem cells during development of the brain. "We now need to determine if these cells are completely committed to producing their own tissue or if they can be convinced to make other tissue types."

Tropepe says this finding contributes to the rapidly growing body of evidence that the adult brain has more potential to regenerate and grow new neurons than people previously thought. "It's a matter of trying to figure out how we can generate new neurons from these stem cells in vivo."

This research was partly funded by the Medical Research Council of Canada, University Medical Discoveries Inc. and two members of the federal Networks of Centres of Excellence program - the Canadian Genetic Diseases Network and the NeuroScience Network.

Steven de Sousa
U of T Public Affairs
(416) 978-5949

University of Toronto

Related Stem Cells Articles from Brightsurf:

SUTD researchers create heart cells from stem cells using 3D printing
SUTD researchers 3D printed a micro-scaled physical device to demonstrate a new level of control in the directed differentiation of stem cells, enhancing the production of cardiomyocytes.

More selective elimination of leukemia stem cells and blood stem cells
Hematopoietic stem cells from a healthy donor can help patients suffering from acute leukemia.

Computer simulations visualize how DNA is recognized to convert cells into stem cells
Researchers of the Hubrecht Institute (KNAW - The Netherlands) and the Max Planck Institute in Münster (Germany) have revealed how an essential protein helps to activate genomic DNA during the conversion of regular adult human cells into stem cells.

First events in stem cells becoming specialized cells needed for organ development
Cell biologists at the University of Toronto shed light on the very first step stem cells go through to turn into the specialized cells that make up organs.

Surprising research result: All immature cells can develop into stem cells
New sensational study conducted at the University of Copenhagen disproves traditional knowledge of stem cell development.

The development of brain stem cells into new nerve cells and why this can lead to cancer
Stem cells are true Jacks-of-all-trades of our bodies, as they can turn into the many different cell types of all organs.

Healthy blood stem cells have as many DNA mutations as leukemic cells
Researchers from the Princess Máxima Center for Pediatric Oncology have shown that the number of mutations in healthy and leukemic blood stem cells does not differ.

New method grows brain cells from stem cells quickly and efficiently
Researchers at Lund University in Sweden have developed a faster method to generate functional brain cells, called astrocytes, from embryonic stem cells.

NUS researchers confine mature cells to turn them into stem cells
Recent research led by Professor G.V. Shivashankar of the Mechanobiology Institute at the National University of Singapore and the FIRC Institute of Molecular Oncology in Italy, has revealed that mature cells can be reprogrammed into re-deployable stem cells without direct genetic modification -- by confining them to a defined geometric space for an extended period of time.

Researchers develop a new method for turning skin cells into pluripotent stem cells
Researchers at the University of Helsinki, Finland, and Karolinska Institutet, Sweden, have for the first time succeeded in converting human skin cells into pluripotent stem cells by activating the cell's own genes.

Read More: Stem Cells News and Stem Cells Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to