Media Releases

‘Hydrogels’ boost ability of stem cells to restore eyesight and heal brains

May 14, 2015

University of Toronto researchers show that engineered ‘hydrogels’ not only help with stem cell transplantation, but actually speed healing in both the eye and brain

Toron­to, ON — Toron­to sci­en­tists and engi­neers 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.

Led by Uni­ver­si­ty of Toron­to Pro­fes­sors Mol­ly Shoichet and Derek van der Kooy, togeth­er with Pro­fes­sor Cin­di Mor­shead, the team 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 today’s issue of Stem Cell Reports, the offi­cial sci­en­tif­ic jour­nal of the Inter­na­tion­al Soci­ety for Stem Cell Research.

Stem cells 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—transplanted into a desired spot in the body—they 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.

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.


For more infor­ma­tion, con­tact:

RJ Tay­lor
Com­mu­ni­ca­tions & Media Rela­tions Strate­gist
Uni­ver­si­ty of Toron­to