Spectroscopy for Monitoring Tumor Response to Immunotherapy
Immunotherapy in colorectal cancer aims to improve tumor response to chemotherapy and thus improve patient prognosis. Specifically, we are analyzing the effects of modulating tumor-associated macrophage pathways in mice using diffuse reflectance spectroscopy. This spectroscopy method can potentially be used to quantify various optical reporters of local vascularization and angiogenesis to non-invasively monitor tumor response to immunotherapy and chemotherapy.
Figure 1. The mobile mouse spectroscopy suite (left) is used to monitor perfusion response of murine colorectal carcinoma allografts using a custom spectroscopy probe (right).
Multiphoton Imaging for Gastrointestinal Cancer
Using two-photon microscopy and endogenous fluorescence, we are investigating changes in murine (mouse) colorectal tissue, specifically as it progresses from normal to dysplastic. This approach utilizes a myriad of optical markers acquired through label-free two-photon microscopy such as collagen structure, metabolic ratios, and spectral data.
Figure 2. The heat plate under the microscope objective used to maintain a 37 degree C environment for cells cultured on a glass slide (left) and an image of murine colorectal tissue showing endogenous fluorescence (right).
Light Sheet Confocal Microscopy
We have developed a light sheet confocal microscopy system that implements a linear sensor to image cells in suspension, such as whole blood. Considered high throughput image cytometry, this method could aid in rapid imaging of biological fluids on a slide (whole slide scanning) or within a microfluidics chamber (fluid flow). Furthermore, this system is used along with magnetohydrodymanic (MHD) fluid flow to control fluid flow for processing of large volumes of biological fluids.
Figure 3. The linear sensor and filter wheel of the light sheet confocal microscope system (left) and an image of beads flowing through the MHD channel (right).
Whole Blood Analysis
We are investigating alternative methods to perform a three-part leukocyte differential, which is the count of three subpopulations of cells (lymphocytes, granulocytes, and monocytes). One approach uses the light sheet confocal system for rapid high-throughput imaging of whole blood. The other approach aims to reduce complexity and cost of a device for a point-of-care application. Both methods utilize the fluorescent dye, acridine orange, where the period of time required for overall image acquisition greatly affects the accuracy of the differential due to the instability of the dye and cytotoxicity.
Figure 4. A portion of the optical components in the light sheet confocal system (left) and images of the three subpopulations of cells in a three-part leukocyte differential (right).