Hydrogels boost ability of stem cells to restore eyesight

Scientists and engineers in Toronto have made a breakthrough in cell transplantation using a gel-like biomaterial that keeps cells alive and helps them integrate better into tissue. In two early lab trials, this has already shown to partially reverse blindness and help the brain recover from stroke.

(c) Univ of Toronto Engg News

A team led by University of Toronto Professors Molly Shoichet and Derek van der Kooy, together with Professor Cindi Morshead, encased stem cells in a hydrogel that boosted their healing abilities when transplanted into both the eye and the brain. These findings are part of an ongoing effort to develop new therapies to repair nerve damage caused by a disease or injury.

Conducted through the U of T’s Donnelly Centre for Cellular and Biomolecular Research, their research was published in Stem Cell Reports, the official scientific journal of the International Society for Stem Cell Research.

Stem cells, as we know, hold great therapeutic promise because of their ability to turn into any cell type in the body, including their potential to generate replacement tissues and organs. While scientists are adept at growing stem cells in a lab dish, once these cells are on their own, when transplanted into a desired spot in the body, they may have trouble thriving. The new environment is complex and poorly understood, and implanted stem cells often die or don’t integrate properly into the surrounding tissue.

(c) Shoichet Lab, Univ of Toronto

Prof. Shoichet (left), a bioengineer who recently won the prestigious L’Oreal-UNESCO for Women in Science Award, and her team created the hydrogel several years ago as a kind of a bubble wrap to hold cells together during transport and delivery into a transplant site.

The authors consider this study one step further in stem-cell based therapy, demonstrating that the hydrogels not only hold stem cells together, but they also directly promote stem cell survival and integration.

The authors, in addition to examining how the stem cells benefit in hydrogels, also showed that these new cells could help restore function that was lost due to damage or disease. One part of the study involved the team injecting hydrogel-encapsulated photoreceptors, grown from stem cells, into the eyes of blind mice. With increased cell survival and integration in the stem cells, they were able to partially restore vision.

(c) Shoichet Lab, Univ of Toronto

After the cell transplantation, the measurements showed that mice with previously no visual function regained approximately 15% of their pupillary response. Their eyes began to detect light and respond.

In another part of the study, the authors studies the outcome from injecting the stem cells into the brains of mice who had recently suffered strokes. After transplantation, within weeks, the authors observed improvements in the mice’s motor coordination.The team wants to carry out similar experiments in larger animals, such as rats, who have larger brains that are better suited for behavioral tests, to further investigate how stem cell transplants can help heal a stroke injury.

Because the hydrogel could boost cell survival in two different parts of the nervous system, the eye and the brain, it could potentially be used in transplants across many different body sites. Another advantage of the hydrogel is that, once it has delivered cells to a desired place, it dissolves and is reabsorbed by the body within a few weeks. This remarkable material has only two components—methylcellulose that forms a gel and holds the cells together, and hyaluronan, which keeps the cells alive.

To read the abstract or the paper, please click here.

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