Injectable gels spring into shape

Sponge-like polymer gels 'remember' and regain their shape after being injected into mice, demonstrating their potential to deliver drugs and cells for tissue repair and regeneration.

A team led by David Mooney at Harvard University in Cambridge, Massachusetts, made the hydrogels أ¢â‚¬â€‌ porous structures that absorb water أ¢â‚¬â€‌ out of alginate, a complex sugar extracted from seaweed. The researchers placed star- and heart-shaped gels in a syringe and injected them beneath the skin of mice; two days later, the materials had regained their original shapes. Gels that were preloaded with either growth-promoting proteins or cells and similarly injected into mice slowly released their contents before dissolving. Gel-delivered cells showed higher levels of survival and engraftment for up to 15 days than cells injected alone.