Dual-channel in-situ optical imaging system for quantifying lipid uptake and lymphatic pump function.

Nearly all dietary lipids are transported from the intestine to venous circulation through the lymphatic system, yet the mechanisms that regulate this process remain unclear. Elucidating the mechanisms involved in the functional response of lymphatics to changes in lipid load would provide valuable insight into recent implications of lymphatic dysfunction in lipid related diseases. Therefore, we sought to develop an in situ imaging system to quantify and correlate lymphatic function as it relates to lipid transport.

Low-cost microcontroller platform for studying lymphatic biomechanics in vitro.

The pumping innate to collecting lymphatic vessels routinely exposes the endothelium to oscillatory wall shear stress and other dynamic forces. However, studying the mechanical sensitivity of the lymphatic endothelium remains a difficult task due to limitations of commercial or custom systems to apply a variety of time-varying stresses in vitro. Current biomechanical in vitro testing devices are very expensive, limited in capability, or highly complex; rendering them largely inaccessible to the endothelial cell biology community.

Engineering the Lymphatic System.

The recent advances in our understanding of lymphatic physiology and the role of the lymphatics in actively regulating fluid balance, lipid transport, and immune cell trafficking has been furthered in part through innovations in imaging, tissue engineering, quantitative biology, biomechanics, and computational modeling. Interdisciplinary and bioengineering approaches will continue to be crucial to the progression of the field, given that lymphatic biology and function are intimately woven with the local microenvironment and mechanical loads experienced by the vessel. This is particularly the case in lymphatic diseases such as lymphedema where the microenvironment can be drastically altered by tissue fibrosis and adipocyte accumulation.

Synthesis and evaluation of self-calibrating ratiometric viscosity sensors.

We describe the design, synthesis and fluorescent profile of a family of self-calibrating dyes that provide ratiometric measurements of fluid viscosity. The design is based on covalently linking a primary fluorophore (reference) that displays a viscosity-independent fluorescence emission with a secondary fluorophore (sensor) that exhibits a viscosity-sensitive fluorescence emission. Characterization of fluorescent properties was made with separate excitation of the units and through Resonance Energy Transfer from the reference to the sensor dye.

Detection of liposome membrane viscosity perturbations with ratiometric molecular rotors.

Molecular rotors are a form of fluorescent intramolecular charge-transfer complexes that can undergo intramolecular twisting motion upon photoexcitation. Twisted-state formation leads to non-radiative relaxation that competes with fluorescence emission. In bulk solutions, these molecules exhibit a viscosity-dependent quantum yield.

Characterization of changes in the viscosity of lipid membranes with the molecular rotor FCVJ.

Membrane viscosity is a key parameter in cell physiology, cell function, and cell signaling. The most common methods to measure changes in membrane viscosity are fluorescence recovery after photobleaching (FRAP) and fluorescence anisotropy. Recent interest in a group of viscosity sensitive fluorophores, termed molecular rotors, led to the development of the highly membrane-compatible (2-carboxy-2-cyanovinyl)-julolidine farnesyl ester (FCVJ).