DNA-cage erasable labels for fluorescence-based imaging
Compositions and methods for analyzing multiple biomarkers without damaging tissue.
Histopathology is a cornerstone of tissue analysis used to diagnose many clinical conditions. Many of these diagnoses are based on identifying the presence of specific biomarkers, which can be indicated by colored labels. Currently, only 1-2 markers can be analyzed per slide, reducing accuracy and increasing time and cost for a diagnosis. Precision medicine will require labeling of multiple (10 or more) biomarkers simultaneously.
Fluorescence microscopy is a standard tool for analyzing many markers (3-4) simultaneously. However, labeling in tissue presents substantial challenges over that of dispersed cells because of tissue autofluorescence, diffusion issues, and loss of biomarker binding sites resulting from tissue processing (epitope damage).
One method currently utilized to address these issues is "erasable labels", wherein researchers add labels, run the analysis, and then remove labels by bleaching the fluorescense with high-intensity light or by using chemical to break down fluorescent molecules. This allows multiple labels to be used on the same slide; however, repeated use of the technique results in damage to the tissues. New technologies are needed to quantitatively and spatially evaluate biomarkers in a native environment without tissue damage in order to provide applicable tools for enhancement of pathology as it relates to precision medicine.
Ohio State inventors, led by Dr. Jessica Winter, with Elizabeth Jergens and Kil Ho Lee, have devised a system of erasable labels for fluorescent-based pathology that uses DNA molecules. The DNA molecules are configured to create a cage around dye- or quantum dot-containing micelles. The DNA molecules contain arms of ssDNA, which are used to target biomolecules. Targeting DNA and RNA can be done directly, and antibodies can be targeted using avidin-biotin coupling to allow ssDNA conjugation to the antibody surface. The system also involves a second ssDNA erasing molecule that interacts with the targeting and binding molecules to dissociate and erase the signal once the image has been captured. Multiple imaging systems can be used as long as each has unique ssDNA targeting, binding, and erasing molecules.