Researchers funded by the National Institute of Biomedical Imaging and Bioengineering have developed a non-invasive imaging technique that accurately detects skin cancer without surgical biopsy. Multiphoton microscopy of mitochondria – small organelles that produce energy in cells – accurately identified melanomas and basal cell carcinomas by detecting abnormal clusters of mitochondria in both types of skin cancer.
Skin cancer is the most common type of cancer in the US and most types of skin cancer are highly treatable, especially if detected early. "The technology developed here has the potential to make the detection of skin cancers extremely rapid and feasible at very early stages," says Dr Behrouz Shabestari, director of the NIBIB Program in Optical Imaging and Spectroscopy. "Rather than taking a biopsy sample that must be processed and then examined under a microscope by a pathologist, this system involves simply looking through the microscope at the patient's skin and determining whether it is cancerous or not, within minutes."
A group of international collaborators led by co-senior author Dr Irene Georgakoudi, in the department of biomedical engineering at Tufts, found that mitochondria behave very differently in healthy versus cancerous tissue. They used a laser microscopy technique that takes advantage of the characteristics of a key molecule in mitochondria, nicotinamide adenine dinucleotide (NADH), that is central to energy production. They found that NADH, which naturally fluoresces without injecting any dye or contrast agent into the individuals being screened, can be detected using multiphoton microscopy to provide diagnostically useful information about the organization of the mitochondria in skin cells.
"The system allows us to obtain very high-resolution images of individual cells without having to slice the tissue physically," explained Georgakoudi. "With this technique, we found that in normal cells the mitochondria are spread throughout the cell in a web-like pattern. Conversely, cancerous skin cells show a very different pattern with the mitochondria found in clumps or clusters typically at the center of the cell along the border of the nucleus."
In this study the technique was tested in 10 patients with skin cancer (melanoma or basal carcinoma) and four who did not have skin cancer. The imaging technique results were compared to the traditional biopsy results obtained from each patient. The results demonstrated that the imaging technique correctly identified skin cancer in all 10 cancer patients, and made no false diagnoses in the four individuals without skin cancer.
Georgakoudi estimates that this test could be routinely used in doctor's offices within five years, although the $100,000 price tag for the laser used in this microscope could limit the medical facilities that would be able to make such an investment. "Less-expensive lasers are on the horizon," concludes Georgakoudi. "However, this approach would enable a doctor to make a quick diagnosis and begin treatment immediately, which could ultimately lower health care costs associated with these very common cancers."
The researchers from the department of biomedical engineering, Tufts University, the Laser Microbeam Programme and department of dermatology at the University of California Irvine, the department of biomedical engineering at the University of Arkansas, and the department of preventive medicine in University of Malaga, Spain were involved in the study.
Abstract
Active changes in mitochondrial structure and organization facilitate cellular homeostasis. Because aberrant mitochondrial dynamics are implicated in a variety of human diseases, their assessment is potentially useful for diagnosis, therapy, and disease monitoring. Because current techniques for evaluating mitochondrial morphology are invasive or necessitate mitochondria-specific dyes, their clinical translation is limited. We report that mitochondrial dynamics can be monitored in vivo, within intact human skin by relying entirely on endogenous two-photon–excited fluorescence from the reduced metabolic coenzyme nicotinamide adenine dinucleotide (NADH). We established the sensitivity of this approach with in vivo, fast temporal studies of arterial occlusion-reperfusion, which revealed acute changes in the mitochondrial metabolism and dynamics of the lower human epidermal layers. In vitro hypoxic-reperfusion studies validated that the in vivo outcomes were a result of NADH fluorescence changes. To demonstrate the diagnostic potential of this approach, we evaluated healthy and cancerous human skin epithelia. Healthy tissues displayed consistent, depth-dependent morphological and mitochondrial organization patterns that varied with histological stratification and intraepithelial mitochondrial protein expression. In contrast, these consistent patterns were absent in cancerous skin lesions. We exploited these differences to successfully differentiate healthy from cancerous tissues using a predictive classification approach. Collectively, these results demonstrate that our label-free, automated, near real-time assessments of mitochondrial organization—relying solely on endogenous contrast—could be useful for accurate, noninvasive in vivo diagnosis.
Authors
D Pouli, M Balu, CA Alonzo, Z Liu, KP Quinn, F Rius-Diaz, RM Harris, KM Kelly, BJ Tromberg, I Georgakoudi
[link url="https://www.sciencedaily.com/releases/2017/02/170213125824.htm"]National Institute of Biomedical Imaging and Bioengineering[/link]
[link url="http://stm.sciencemag.org/content/8/367/367ra169"]Science Translational Medicine abstract[/link]