Survival of the Fittest: Sustaining Cells Through Transplantation

December 18th, 2017 by Dr. Chad Andrews

In many retinal diseases, vision loss occurs when cells that are crucial for vision are damaged or lost. This is the case, for example, in age-related macular degeneration (AMD), retinitis pigmentosa, choroideremia, and Stargardt disease. To reverse vision loss resulting from these and similar diseases, we need to develop and refine our ability to replace the eye’s sight-related cells.

Thankfully, Dr. Valerie Wallace’s work in focused on this critical issue, and your support of her research is advancing the field in incredible ways. Building on a key discovery from 2016, Dr. Wallace and her team have made significant progress towards designing a cell transplantation process that allows cells to be moved from one place to another and to survive in their new environment.

The survival of these cells—in particular photoreceptors, which are responsible for converting light into the brain signals that give us sight—is one of the primary hurdles for stem cell therapies at this point in time.

When cells are transplanted to a new biological environment, they do not smoothly integrate and cooperate with existing cells; this is what Dr. Wallace and her team discovered last year, an insight that radically altered the trajectory of the field. Instead, newly introduced cells transfer some of their material to surrounding cells, altering the immediate biological material—in the case, the environment of the eye. This makes it clear that cell transplantation functions less like a set of Lego blocks, which piece together efficiently and smoothly to maintain the identity of individual pieces, and more like Play-Doh, which melds and mashes together to create entirely new colours and forms.

With funding from the FFB and, as announced this year, a grant from the Ontario Institute of Regenerative Medicine (OIRM), Dr. Wallace and her team of researchers are developing new techniques to turn stem cells into photoreceptors and allow them to survive transplantation into the eye.

An image of rod and cone photoreceptors taken with a scanning electron microscope. These are the essential cells that Dr. Wallace and her team would like to restore in patients using transplantation techniques.


At this point in time, several of the techniques the team is exploring show promise, including the use of a “delivery vehicle” that could safeguard cells through the transplantation process. Called a “biomaterial,” since it is engineered to interact with human biology, this vehicle would protect the cells while they are moved from one environment to the other, giving the researchers more control over the process and the cells a higher chance of survival.

Timing is of course an important factor in this process, and this is another critical issue that Dr. Wallace and her team are pushing forward. What is the ideal form for a stem cell to take to ensure optimal transplantation? Should it be in the form of the original stem cell and then converted into the required cell in the eye? Or should it be converted into a photoreceptor in vitro (in a glass) before being transplanted? Determining the ideal state of the cell will play an important role in the development of stem cell therapies, and Dr. Wallace is at the cutting-edge that process.

She and her team are committed to producing innovative solutions to the many hurdles presented by cell transplantation—with support from FFB donors they have made significant progress in 2017, and with continued support they could very well achieve their vision of transplanting stem cells and restoring vision for those who have lost it.