Media Releases

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

May 14, 2015

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.

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For more infor­ma­tion, con­tact:

RJ Tay­lor
Com­mu­ni­ca­tions & Media Rela­tions Strate­gist
Uni­ver­si­ty of Toron­to
416–978-4498
rj.taylor@utoronto.ca