Fast-moving objects create blurry images in photography, and the same challenge exists when scientists observe cellular interactions within tissues constantly in motion, such as the breathing lung. In a recent study at UCSF, researchers developed a method to stabilise living lung tissue for imaging without disrupting the normal function of the organ. The method allowed the team to observe, reportedly for the first time, the live interaction of living cells in the context of their environment and the unfolding of events in the immune response to lung injury.
“The nature of disease is complex, so if scientists can observe in real-time what’s happening in tumours or immune responses as they occur, we can find new ways to intervene,” says senior author Max Krummel, PhD, UCSF associate professor of Pathology, whose lab developed the new imaging technique.
“We figured out a method for holding cells still enough to image them without interrupting their normal processes. This enabled us to observe cellular events as they happen naturally rather than the usual way, which is to stop the motion of cellular processes in order to photograph them.”
To achieve such clear imaging of the fast-moving lung cells, the team developed a custom rig device that applies a gentle amount of suction to the tissue surface, holding the region for viewing inside the range of their microscope. They then used super-fast imaging with a two-photon microscope to photograph the tissue. Footage was taken 30 times each second, revealing the full progression of cellular participants involved in different biological processes—for example: which cells worked together to mount a response to an injury. With that information, the team was able to identify the function of different cell types.
The fast, two-photon microscopy technique previously was developed by the team to monitor immune cells in the lymph nodes and other biological processes. Two-photon microscopy is a light-based high-resolution imaging technology using infrared pulsed lasers to penetrate deep into tissue layers, capturing details as small as one micron (or one ten-thousandth of a centimeter) in diameter. The study uses custom-built microscopes that the team constructed on-site at UCSF.
With more than 20 previously published articles using microscopy, the team is focused on continuing to improve the ability to observe molecules and cells deep within tissues.
“Imaging tissues or organs is ideally done within the living organism and as noninvasively as possible, but there are many challenges,” says Mark R. Looney, MD, co-first author and assistant professor in Medicine and Laboratory Medicine at UCSF.
More information on the research is available from UCSF.