Repairing an injury to a blood vessel or an organ after traumatic internal injury, especially involving the lung, is typically done by sutures, stapling devices or electrocautery with specialized surgical instruments. Time is of the essence as patients can rapidly lose large amounts of blood, predisposing them to shock, which places organs at risk for viability as time goes on.
Bleeding inside the lungs is problematic due to continual movement associated with inflation and deflation. While sealants have been explored as potential solutions to stem bleeding and repair open wounds, none have been able to perform well as a result of issues related to tissue compatibility, tensile strength and mechanical properties. Beyond this, leakage of air from a surgically repaired lung injury typically requires a chest tube to be placed, which keeps a patient in the hospital for a number of additional days.
Now, one research group may have solved the problem with development of a new tissue glue derived from proteins naturally present in the human body--offering hope that one day this approach could be utilized as an intraoperative tool, on the battlefield, as well as in emergency departments.
The research was published last week in Science Translational Medicine.
Part of what makes the discovery such a breakthrough is that it is biocompatible, made from a highly elastic hydrogel sealant derived from a human protein which has been configured to react to ultraviolet (UV) light.
Referred to as “MeTro”, (methacryloyl-substituted tropoelastin), it is a protein derived from the elastic fibers that make up human tissue.
The gel is not yet ready for prime time, but will be a serious contender if future testing in humans is successful .
"A good surgical sealant needs to have a combination of characteristics: it needs to be elastic, adhesive, non-toxic and biocompatible," said lead author Nasim Annabi, PhD, of Northeastern University, and lecturer at Brigham and Women's Hospital and the Wyss Institute. "Most sealants on the market possess one or two of these characteristics, but not all of them. We set out to engineer a material that could have all of these properties."
The researchers have used MeTro in trials involving rats and pigs, successfully using the compound to seal surgical incisions in blood vessels. When researchers applied the glue to a wound and then placed it under UV light, the wounds sealed in 60 seconds, without rupture or leaking around the area of injury. The glue was effective in sealing wounds without interfering with the natural motion of the lungs (inflation and deflation) or the skin after its application, according to the findings of the study.
The researchers found that that the MeTro sealant was not toxic to the animals in which it was tested, and was naturally absorbed as its components were degraded. And compared to sealants already on the market, the investigators noted that the sealant was stronger and was more resistant to wound separation or breakdown. MeTro gel also represents a solution for not only tissue regeneration but repair, effectively healing and sealing incisions at the same time.
The researchers hope to begin testing the gel in clinical trials in humans in the near future, while investigating other applications in more newly developed, but untested versions of the compound.
The implications for such a gel are numerous and include roles in the operating room and emergency department with wounds involving extensive bleeding, as well as on the battlefield--potentially saving lives and reducing the need for blood transfusions.
As far as other tissue adhesives currently on the market, one competitor comes to mind, but has limitations when compared to the promises and implications of MeTro gel.
2 -Octyl cyanoacrylate (Dermabond, Ethicon, Inc., Somerville NJ), a compound often referred to as a "superglue" for the skin which has become widely used in emergency departments and in the operating room for closing external traumatic and surgical wounds, is quite distinct from the naturally derived MeTro gel.
While Dermabond possesses significant tensile strength and naturally dissolves in 7-10 days, it is not naturally derived from human tissue, and cannot be used on mucosal surfaces or junctions such as lips or in the mouth or inside the body on internal organs.
One additional issue is the theoretical risk of mild toxicityassociated with its breakdown to formaldehyde and cyanoacetate, both detectable in the urine. As the reasoning goes, longer alkyl chains on Dermabond lead to slower degradation, limiting exposure to its byproducts. That said, Dermabond's product labeling explicitly states that it is not carcinogenic or teratogenic, with no adverse health effects associated with intended use of the product for wound closure.
Of note, Dermabond has been used successfully off-label to repair a tongue laceration, as well as an adhesive for cleft palate and dental surgeries.