New, less-invasive method to detect kidney disease

Researchers, including one of Indian-origin, have identified a new, less-invasive method using Raman spectroscopy to provide diagnostic information on kidney disease and its severity.

University of Houston researchers have used an optical probe and Raman spectroscopy to differentiate between healthy and diseased kidneys. Physicians traditionally use renal biopsy to directly observe kidney function. In addition to potential side effects, the number of renal biopsies a patient can undergo is limited because of damage to the kidney tissue.

For the study, Wei-Chuan Shih, assistant professor of electrical and computer engineering, and Chandra Mohan, Hugh Roy and Lillie Cranz Cullen Endowed Professor of biomedical engineering, did not look for a specific molecule or biomarker, such as creatinine, a molecular indicator of kidney function.

Instead, the researchers relied upon the fact that a healthy kidney and a diseased kidney produce different Raman signals. "There are some molecules that must be responsible for these different Raman signals, but we don't need to know what those molecules may be," Mohan said.

"As long as there's a difference in the signal, that's good enough - you can easily differentiate between a diseased kidney's Raman signal and a healthy kidney's Raman signal," he said.

"Raman spectroscopy provides molecular fingerprints that enable non-invasive or minimal invasive and label-free detection for the quantification of subtle molecular changes," researchers said. "It has the potential to largely reduce the complexity in diagnosing and monitoring anti-GBM (glomerular basement membrane) diseases.

"By adapting multivariate analysis to Raman spectroscopy, we have successfully differentiated between the diseased and the non-diseased with up to 100 per cent accuracy, and among the severely diseased, the mildly diseased and the healthy with up to 98 per cent accuracy," they said.

For the new study published in the Journal of Biophotonics, Shih and Mohan used mouse models with induced kidney disease to demonstrate the optical probe's ability to differentiate between a healthy and a diseased kidney without puncturing the organ.
Shih's research team developed a metric to broadly quantify the level of disease using the Raman scattering signals.

"We are proposing the nephrologist will puncture the patient's skin, go to the surface of the kidney, and not puncture the kidney, but probe the surface of the tissue and acquire Raman signals," Mohan said. "The patient will feel a little pinch and poke through the skin, but the kidney is not hurt at all," he said.