"Nano suturing" uses laser light--but not heat--to close wounds

FEBRUARY 13, 2009--Using lasers and light-activated dye, researchers at the Wellman Center for Photomedicine at Massachusetts General Hospital (Boston, MA) have developed a suture-replacement technique able to close wounds nearly instantaneously without damaging tissue. The technology is well suited for closing not only skin incisions but also those made in eye and nerve surgeries. It has been licensed to a startup company that plans to commercialize it following FDA approval.

FEBRUARY 13, 2009--Using lasers and light-activated dye, researchers Irene Kochevar and Robert Redmond of the Wellman Center for Photomedicine at Massachusetts General Hospital (Boston, MA) have developed a suture-replacement technique able to close wounds nearly instantaneously. The approach was developed to harness the laser's light but not its heat, which too easily damages biological tissue.

They have demonstrated their approach using Rose Bengal--a stain commonly used to highlight corneal lesions--and green laser light. They say the light helps transfer electrons between the dye molecule and collagen, which produces highly reactive free radicals that cause the molecular chains of collagen to chemically bond. "We call this nano suturing," Kochevar said in an interview with MIT's Technology Review, "because what you're doing is linking together the little collagen fibers. It's way beyond anything that a thread of any kind can do."

The technique seems to enable faster procedures, less scarring, and possibly fewer infections, since it seals openings completely and leaves no gap through which bacteria can penetrate. This makes it particularly well suited for closing not only superficial skin incisions but also those made in eye and nerve operations. In eye surgeries, such as corneal replacement, stitches that can cause irritation and infection must sometimes be left in place for months, which can aggravate complications. In nerve surgeries, damage from scar tissue can decrease the conduction of neural impulses. "If you put a needle through skin, it's not a big deal," says Redmond. "But if you put it through a nerve it's a big deal, because you're destroying part of the nerve."

According to Robert Stern, a professor of dermatology at Harvard Medical School and chief of dermatology at Beth Israel Deaconess Medical Center in Boston."It's a very interesting technology, which would be useful to anyone who does any kind of skin surgery--plastic surgeons, dermatologists." He isn't yet convinced, though, that the benefits will offset the costs of photochemical dyes and laser equipment, which are far pricier than a needle and thread.

Animal experiments have shown the technique to be useful in nerve, eye, and blood vessel surgeries, among others. Tests in humans have been limited to skin surgeries: In a clinical trial, 31 patients with skin cancers and suspicious moles had three-to-five-centimeter excisions closed with sutures on one side and photochemical tissue bonding on the other.
The dermatological procedure will be submitted to the U.S. Food and Drug Administration for approval, which the researchers are awaiting before beginning additional human trials.

The technology works only where light will penetrate, and thus could not replace subcutaneous sutures or treat dark or opaque tissue like liver and bone.
The scientists have licensed the technology to a startup company, still in stealth mode and seeking its first funding round, which plans to commercialize the technology once it receives FDA approval.

More information:
See the article, A Laser That Heals Surgeons' Incisions, in Technology Review.

posted by Barbara G. Goode, barbarag@pennwell.com, for BioOptics World

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