A tissue-engineered approach towards retinal repair: scaffolds for cell transplantation to the subretinal space.

Background: Several mechanisms of retina degeneration result in the deterioration of the outer retina and can lead to blindness. Currently, with the exception of anti-angiogenic treatments for wet age-related macular degeneration, there are no treatments that can restore lost vision. There is evidence that photoreceptors and embryonic retinal tissue, transplanted to the subretinal space, can form new synapses with surviving host neurons.

Engineering angiogenesis following spinal cord injury: a coculture of neural progenitor and endothelial cells in a degradable polymer implant leads to an increase in vessel density and formation of the blood-spinal cord barrier.

Angiogenesis precedes recovery following spinal cord injury and its extent correlates with neural regeneration, suggesting that angiogenesis may play a role in repair. An important precondition for studying the role of angiogenesis is the ability to induce it in a controlled manner. Previously, we showed that a coculture of endothelial cells (ECs) and neural progenitor cells (NPCs) promoted the formation of stable tubes in vitro and stable, functional vascular networks in vivo in a subcutaneous model.

Photopolymerized poly(ethylene glycol)/poly(L-lysine) hydrogels for the delivery of neural progenitor cells.

Neural progenitor cells (NPCs) have shown promise in a number of models of disease and injury, but for these cells to be safe and effective, they must be directed to differentiate appropriately following transplantation. We have developed a photopolymerized hydrogel composed of macromers of poly(ethylene glycol) (PEG) bound to poly(L-lysine) (PLL) that supports NPC survival and directs differentiation. Green fluorescent protein (GFP) positive NPCs were encapsulated in these gels and demonstrated survival up to 17 days.

A macroporous hydrogel for the coculture of neural progenitor and endothelial cells to form functional vascular networks in vivo.

A microvascular network is critical for the survival and function of most tissues. We have investigated the potential of neural progenitor cells to augment the formation and stabilization of microvascular networks in a previously uncharacterized three-dimensional macroporous hydrogel and the ability of this engineered system to develop a functional microcirculation in vivo. The hydrogel is synthesized by cross-linking polyethylene glycol with polylysine around a salt-leached polylactic-co-glycolic acid scaffold that is degraded in a sodium hydroxide solution.