Collagen and Breast Cancer

While diagnosis of human breast cancers is advancing, current biomarkers cannot predict outcome for all patients.  Endogenous optical properties of cells and tissues could potentially be used as biomarkers in the clinic.  Collagen can be detected, without staining or labeling of tissue, using second harmonic generation (SHG) imaging, a multiphoton technique.  Collagen signatures, see in mouse models, could be used in breast cancer patients to predict outcomes. 

Metabolic Mapping

Eukaryotic cells depend upon the mitochondrial electron transport chain to produce energy in the form of ATP when oxygen is present.  The first complex of this chain oxidizes NADH to NAD+.  Conveniently, NADH is an intrinsically fluorescent molecule, while NAD+ is not.  Time-resolved studies of NADH fluorescence using fluorescence lifetime imaging (FLIM) can be used to obtain information about NADH and metabolic states in non-malignant and malignant cells. 

Multiphoton Flow Cytometry

Traditional flow cytometers are unable to accommodate cell aggregates and often require extrinsic fluorescent labeling for data analysis.  In an effort to analyze larger cell aggregates, a multiphoton flow cytometry (MPFC) instrument has been constructed.  The system is comprised of a flow cell through which large particles and aggregates travel, an optics system with multiphoton excitation capabilities, and data acquisition software.  The flow cell is mounted on an adjustable stage insert compatible with most microscope stages. 

Collagen Signatures

Collagen organization and density can have a profound effect on the behavior of breast cancer cells.  Using second harmonic generation (SHG), the structure of collagen in intact mammary mouse mammary glands can be visualized.  In collaboration with the Keely Lab, a metastatic collagen signature (TACS3) has been identified leading to useful characterization of breast tissue and tumors.