A new technique for the decontamination of organs before transplantation using ultraviolet and red light irradiation has been developed researchers and is described in an article published in the journal Nature Communications.
"This biophotonic technique is revolutionary, as it helps avoid the transmission of diseases during organ transplantation," said the principal investigator.
"Ten patients have so far been tested [using the biophotonic therapy]," another author said. "The new technique significantly reduced transplant organ viral load in eight of these patients. The procedure all but eliminated the virus in two others."
The method described in the article involves ultraviolet and red light irradiation to reduce viral and bacterial loads in infected organs to prevent the transmission of diseases such as hepatitis to transplant recipients.
Lungs are decontaminated before transplantation by having the blood replaced by a preservation liquid in a procedure known as perfusion. "Perfusion reduces the viral and bacterial loads but cannot eliminate them completely. As a result, the patient has to be treated with antibiotics and antivirals for three months after the transplant," the author explained.
During perfusion, while the researchers make the liquid circulate in the lung to be transplanted, they add molecules to the lung tissue, and biophotonic decontamination takes place directly in the organ through irradiation with red light with a wavelength of 660 nanometers (nm) until photodynamic oxidation eliminates the microorganisms in the tissue.
At the same time, the viral load is flushed away by the circulating liquid, which is continuously decontaminated by ultraviolet irradiation with a wavelength of 254 nm.
"The ultraviolet irradiation directly destroys microorganisms by breaking down the molecules present in bacteria and viruses. The bacteria are killed, and the viruses are completely inactivated. Red light irradiation decontaminates indirectly via photosensitization," another author said.
"The perfusion solution is special and very expensive," the author said. "It's made in such a way as to preserve the organ. Because of the cost, as little as possible is used in the procedure. Thanks to the technique and equipment we've developed, a liter of the perfusate can be flushed through the organ hundreds of times to remove the contaminants completely."
"The next step was to subject pig lungs to the same procedure and then transplant them to see if the procedure caused any biochemical or morphological damage to tissue. It did not," the author said.
Finally, the technique was tested on patients. "In the first ten transplants we performed, the new technique eliminated hepatitis C virus from organs donated to two patients. In the other eight patients, viral load fell sharply after surgery but rose again seven days later, and the patients had to be given antiviral treatment for three months," the author said.
"An important finding was that when the virus wasn't eliminated it reappeared in the patient's lab tests after seven days. With this information, we've since performed two other transplants where antiviral treatment concentrated in the first week after the operation. The virus was eliminated in both cases," the author said.
According to the authors this biophotonic therapy will be refined to assure even sharper reductions in the viral and bacterial loads, increasing the chances of successful transplants. "Our aim is to have light-based therapy eliminate all viral and bacterial contaminants in organs to be transplanted. If so, it may even be possible to do without the perfusate,"t he author said.
Eliminating bacteria and viruses in donor lungs using light therapies
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