UC Davis researchers successfully test new tool for imaging live cells
High-speed structured illumination microscope could lead to breakthroughs in disease research
As exclusive beta testers of the world's most powerful wide-field fluorescence imaging platform, researchers at the UC Davis-based Center for Biophotonics Science and Technology (CBST) have for the first time successfully imaged the movement of fluorescently labeled nanoscale compartments inside live tumor cells.
The achievement holds promise for future breakthroughs in understanding the molecular causes and biomechanics of cancer and a wide range of other diseases while also advancing neuroscience and stem cell research, among other disciplines.
"Biomedical research is the final frontier in looking at biology at the cellular and molecular levels," explains Frank Chuang, CBST associate director of research. "This tool helps us see living biology as it's occurring. Its potential research applications are very exciting, including monitoring how cells respond to chemotherapy, looking at the mechanisms of radiation resistance, and investigating how viruses transfer from cell to cell."
For their platform, researchers used the first commercially available microscope featuring true 3-D high-speed structured illumination, a microscopy technique developed by UC researchers that improves the resolution of a fluorescence light microscope by at least a factor of two.
In a technology transfer success story, in 2007 Seattle-based Applied Precision (API) licensed intellectual property from UC San Francisco for commercialization of a structured illumination microscope custom prototype, dubbed OMX version 1.0, with OMX standing for Optical Microscope eXperimental.
In the intervening years, API, a GE Healthcare company, refined the microscope's capabilities, and working with CBST, established with a grant from the National Science Foundation on the UC Davis Health System campus. Three months ago, CBST became the first lab to install and demonstrate the capabilities of the much faster commercial prototype, the DeltaVision OMX V4 SI™.
It incorporates an ultra-fast structured illumination module and advanced high-speed scientific cameras. Combined, they enable true 3-D super-resolution fluorescence imaging of live cells over a large area for the first time. Thus the microscope is capable of resolving intracellular structures with greater detail than previously thought possible with any light microscope.
"The breakthrough is using structured illumination with moving objects, including live cells," reports CBST chief scientific officer Stephen Lane. "Previously, commercial optical microscopes using structured illumination have only been able to image fixed, or non-moving, samples."
CBST has been providing testing results to API for the last three months. Based on CBST feedback, the company will further refine the instrument before making the resulting new version commercially available to labs around the world.
Three dimensional renderings of a group of fluorescent
autophagosomes using Blaze.
As a proof of concept, CBST biomedical researchers led by UC Davis Professor Hsing-Jien Kung recently used the tool for the first-ever imaging of the movement of nanoscale compartments inside live tumor cells. These compartments, which capture organelles and macromolecules for delivery to lysosomes, are key components of an intracellular recycling process known as autophagy.
"In autophagy, or self-eating, cells eat away wasted materials to regenerate energy during stress," explains Kung, whose lab focuses on the identification of genetic and related factors contributing to the development of human malignancies. "Tumor cells often utilize the same process to prolong their survival, diminishing drug efficacies."
UC Davis scientists are developing techniques to better quantify and characterize the autophagic response in prostate cancer cells, with the goal of improving cancer chemotherapy through the effective modulation of autophagy. Until now, it has been nearly impossible to study the early events associated with the induction of autophagy, because newly formed autophagosomes are too small and move too quickly to be imaged with conventional microscopes.
"The development of a high-resolution, live-cell imaging approach should accelerate our understanding of this enigmatic process," says Kung, "paving the way for the development of autophagy modulators."
CBST scientists anticipate that, with its 3-D capabilities, high speed and high-spatial resolutions, this microscope and its follow-ons will greatly facilitate the visualization of biological processes at the subcellular level, enabling new discoveries and the advancement of molecular medicine.
The instrument's many technical advances include super-resolution so high that objects as small as 1/10th of a micron can be imaged; eight times better contrast than conventional microscopes; the capacity to see two fluorescent wavelengths simultaneously for dual-color images and the ability to image a 3-D stack of 15 slices through the sample once per second, a high speed rarely, if ever before, achieved in a commercial instrument.