Scaffold materials are widely used in regenerative research. They often take the form of gels, making it possible to inject and shape the scaffold in damaged internal tissue. These nanoscaled materials are mixed in with signal molecules that spur cell growth. The scaffold both supports cells structurally and encourages them to correctly rebuild natural tissue, complete with its extracellular matrix. The scaffold itself is degraded by cells and replaced by that tissue - at least in the ideal circumstance.
This has been demonstrated in a variety of tissues, particularly muscle, but here researchers have managed a much more challenging feat by convincing the brain to regenerate. It remains to be seen how well this restores lost function; that is much harder to evaluate in animals than the evident fact of structural repair. Nonetheless, this seems an important development. If the central nervous system can be induced to repair itself effectively, that will open a great many doors presently closed in the extension of human life.
In a first-of-its-kind finding, a new stroke-healing gel helped regrow neurons and blood vessels in mice with stroke-damaged brains. The results suggest that such an approach may someday be a new therapy for stroke in people. The brain has a limited capacity for recovery after stroke and other diseases. Unlike some other organs in the body, such as the liver or skin, the brain does not regenerate new connections, blood vessels, or new tissue structures. Tissue that dies in the brain from stroke is absorbed, leaving a cavity, devoid of blood vessels, neurons, or axons, the thin nerve fibers that project from neurons.
To see if healthy tissue surrounding the cavity could be coaxed into healing the stroke injury, researchers engineered a gel to inject into the stroke cavity that thickens to mimic the properties of brain tissue, creating a scaffolding for new growth. The gel is infused with molecules that stimulate blood vessel growth and suppress inflammation, since inflammation results in scars and impedes regrowth of functional tissue.
After 16 weeks, stroke cavities in treated mice contained regenerated brain tissue, including new neural networks - a result that had not been seen before. The mice with new neurons showed improved motor behavior, though the exact mechanism wasn't clear. "The new axons could actually be working. Or the new tissue could be improving the performance of the surrounding, unharmed brain tissue." The gel was eventually absorbed by the body, leaving behind only new tissue.