Wounds may be healed faster in the future just by shining a light on them, say researchers who've stimulated growth of blood vessels -- a vital part of the healing process -- by shining an ultraviolet light on skin.
While scientists have long been able to manipulate cell chemistry in a laboratory dish using light, doing the same in a living organism has proved a difficult proposition, say researchers at the Georgia Institute of Technology in Atlanta.
"There are hundreds of different types of cells; you have a lot more other biological molecules present," says bioengineer Andrés García, who along with research colleagues experimented with a water-based gel containing molecules known as RGD peptides, which in the body signal cells to attach to and grow on new tissue.
They purposefully attached another type of molecule to the RGD peptide that caused it to shut down its signaling process.
When a UV light was shone on the gel, this "inhibitor" molecule dropped away and the RGD peptide once again was active, the researchers report in the journal Nature Materials.
The inhibitor molecule can be used as a "disguise" to sneak biomaterials with the signaling peptide molecules into living tissue to be activated on demand, they say.
When biomaterials are introduced into the body, they normally stimulate an immune system response immediately, something not always desirable because the immune system will attack them as if they were a foreign body, they explain.
If the peptide in such a biomaterial can be left dormant for a period of time before activation, the immune response is much weaker, improving the chances of the biomaterial being accepted into the body.
The technique of triggering the peptide signaling at a chosen moment has been demonstrated in animal models, the researchers report, and in humans it could allow more precise timing for processes essential to regenerative medicine, immunology, cancer treatment, stem cell growth and a range of biological activity.
"Many biological processes involve complex cascades of reactions in which the timing must be very tightly controlled," says García. "Until now, we haven't had control over the sequence of events in the response to implanted materials.
"But with this technique, we can deliver a drug or particle with its signal in the 'off' position, then use light to turn the signal 'on' precisely when needed."
Of particular importance is the technique's ability to trigger the growth of blood vessels -- known as vascularization -- into a target tissue, a process critical in regenerative medicine but which must take place at the exact right moment to be successful, the researchers reported.