‘Hydrogels’ said to boost stem cell survival, integration

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Stem cell therapy is being looked upon as the answer to great many diseases, but there are still quite a few obstacles that need to be cleared before the therapy can be mainlined as well as made available to general public for cheap. One of the major obstacles is the survival of stem cells and their ability to integrate with the host cells – answers to which are possibly present in a new research carried out by scientists at University of Toronto.

In a new breakthrough, scientists and engineers have managed to transplant stem cells using a gel-like biomaterial dubbed ‘hydrogel’ that not only keeps them alive but also helps them integrate better into tissue. Early lab trials have turned to be promising as this method has shown to partially reverse blindness and help the brain recover from stroke.

In the research University of Toronto researchers Molly Shoichet, Derek van der Kooy, and 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.

Stem cells’ therapeutic abilities are promising as they can not only turn into any cell type in the body, they also are able to generate replacement tissues and organs. Growing stem cells in lab isn’t an issue, but transplanting them into a desired spot in the body is. The reason? They have a trouble thriving owing to a new and complex environment in which they are placed. This leads to their death or improper integration into the surrounding tissue, which eventually doesn’t provide desired results.

Shoichet, 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.

“This study goes one step further, showing that the hydrogels do more than just hold stem cells together; they directly promote stem cell survival and integration. This brings stem-cell based therapy closer to reality” says Shoichet, a professor whose affiliations span the Donnelly Centre, the Department of Chemical Engineering and Applied Chemistry and the Institute of Biomaterials & Biomedical Engineering at U of T.

Partially restoring vision

In addition to examining how the stem cells benefit from life in hydrogels, the researchers also showed that these new cells could help restore function that was lost due to damage or disease.

One part of the Stem Cell Reports study involved the team injecting hydrogel-encapsulated photoreceptors, grown from stem cells, into the eyes of blind mice. Photoreceptors are the light sensing cells responsible for vision in the eye. With increased cell survival and integration in the stem cells, they were able to partially restore vision.

“After cell transplantation, our measurements showed that mice with previously no visual function regained approximately 15% of their pupillary response. Their eyes are beginning to detect light and respond appropriately,” says Dr. Brian Ballios, an expert in stem cell biology and regenerative medicine for retinal degenerative disease, who led this part of the study.

Ballios’ background as an engineer stimulated his interest in biomaterial-based approaches to therapy in the eye. He recently completed his MD and PhD under the supervision of Shoichet and van der Kooy, and he’ll be continuing his medical training as an ophthalmologist, hoping to apply some of his research insights in the clinic one day.

Repairing the brain after strokes

In another part of the study, Dr. Michael Cooke, a postdoctoral fellow in both Shoichet’s and Morshead’s labs, injected the stem cells into the brains of mice who had recently suffered strokes.

“After transplantation, within weeks we started seeing improvements in the mice’s motor coordination,” says Cooke. His team now 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.

Advancing stem-cell based therapies

Leveraging engineering techniques–such as the design and manufacture of new biomaterials–to develop new stem-cell based therapies using hydrogels has always been on Shoichet’s mind.

“I always think that in engineering our raison d’être is to advance knowledge towards translation,” says Shoichet.

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.

“Through this physical blend of two materials we are getting the best of both worlds,” says Shoichet.

The research is published in Stem Cell Reports, the official scientific journal of the International Society for Stem Cell Research.