Wavelengths of light could help heal chronic wounds.
Kyle Quinn, assistant professor in the department of biomedical engineering at the University of Arkansas, discusses this non-invasive technique.
Dr. Quinn received his B.S. degree in Biomedical Engineering from the University of Wisconsin-Madison in 2004. He earned his Ph.D in Bioengineering in 2010 from the University of Pennsylvania under the mentorship of Dr. Beth Winkelstein. He then joined the Department of Biomedical Engineering at Tufts University as a postdoctoral scholar in Dr. Irene Georgakoudi’s group. As a postdoc, he was awarded a Ruth L. Kirschstein National Research Service Award and an NIH Pathway to Independence Award (K99/R00). In September 2015, he joined the Department of Biomedical Engineering at the University of Arkansas, where he has secured over $2.5M in federal grant funding to develop advanced imaging methods for wound healing applications.
Chronic Skin Wounds
Skin wound healing is a complex, multi-step process in which different kinds of cells with unique metabolic demands must coordinate with each other to repair damaged tissue. When a group of cells does not respond as expected in this coordinated dance, healing can fail to progress, resulting in a chronic wound. Diabetic foot ulcers are a particularly costly and deadly form of chronic wounds. However, there are few quantitative measures available in the clinic to detect and characterize these ulcers.
Our lab has identified a non-invasive biomarker of wound healing by exploiting the natural fluorescence of cells. Using the correct wavelengths of light, we can detect and isolate weak fluorescent signals from NADH and FAD, two enzyme cofactors involved in cellular metabolism. Through multiphoton microscopy, we can collect high-resolution 3D maps of an optical redox ratio of NADH and FAD autofluorescence in skin. Because this technique does not require fluorescent dyes or destructive tissue biopsies, we can monitor wound metabolism non-invasively in live mice over time.
Using this microscopy technique, we monitored diabetic and control mice over 10 days after wounding and identified dynamic changes in the metabolism of the outer layer of skin during the healing process. The optical redox ratio of the epithelium decreased as cells grew and divided and then increased as the cells began migrating over the wound. Interestingly, diabetic wounds demonstrated a lower redox ratio 10 days after wounding, which is consistent with their delayed wound closure. In the future, we hope to combine both structural and metabolic data available through multiphoton microscopy to provide a suite of biomarkers to help guide wound treatment.
