Seeing a Clear Slice of Life in Crohn’s Disease
Dr. Gwendalyn Randolph
Dr. Gwendalyn Randolph started her career studying immune cell trafficking in and out of tissues, particularly myeloid cells that initiate immune responses and those that derive from monocytes in the blood. In the chronic cardiovascular disease atherosclerosis, she wondered if there was an association between disease progression and the accumulation of myeloid cells because they couldn’t traffic out of the area. As part of this research, she looked at lymphatic vessels, as they drain fluid and traffic certain immune cells to lymph nodes.
At an immunology meeting in Scotland a few years ago, a speaker discussed trafficking cells out of fat in the context of inflammatory bowel disease (IBD), and Dr. Randolph was intrigued. Work in her lab confirmed a somewhat permeable nature of lymphatic vessels running through fat in a mouse model. This enabled the cells trafficked through these vessels to share intimate communication with immune cells outside of the vessels, around the fat cells. As her atherosclerosis research concluded, she made the fateful decision to launch new projects into diseases where lymphatics and immunology and fat intersect. A colleague in the IBD field told her a Crohn’s disease phenomenon was seen whereby fat grows up onto the gut wall; and it may be related to deficient lymphatic trafficking, which strengthened her intrigue. As her research shifted towards Crohn’s disease research, she applied for, and received, a Rainin Foundation grant for looking at adipose tissue and lymphatics in human intestines.
Diving head-first into this new world of Crohn’s disease, Dr. Randolph knew that she needed to image the lymphatic vessels in three-dimensional (3D) format to properly characterize the whole vessel. They ultimately developed a method to clarify thick slices of tissue for 3D confocal reconstruction, but the imaging of just one slice took up to two days, and finding small, specific regions of interest over the massive surface area of an intestine and connected adipose tissue was particularly challenging. Dr. Randolph recalls, “Using confocal only, it wasn’t possible for us to see the whole sample quickly, so we’d section from an area that we thought may contain interesting information, and make a blind stab at it.”
In 2015, fate struck again for Dr. Randolph. BioTek’s local sales representative was demonstrating the Cytation™ 5 Cell Imaging Multi-Mode Reader in Dr. Randolph’s building. She stopped by to discuss the instrument with him, and asked to try Cytation 5’s imaging capabilities on one of her tissue samples. “The image that we got from Cytation 5 was incredible,” she recalled. “We knew the sample was of interest, but we didn’t realize all of the information it contained; it was the perfect sample to really show why the Cytation 5 could be useful.” In addition to seeing a lymph node as expected, the image revealed some of the vessels that she was interested in but couldn’t immunostain appropriately for confocal imaging because the antigens on these vessels have not been totally defined. “What’s so cool is that the LED light coming from the Cytation 5 into the cleared sample allowed us to see these vessels because they made a shadow-type of appearance,” she explained. In fact, she used this demo image as she interviewed for, and ultimately received, the NIH Director’s Pioneer Award in 2015, part of the Common Fund’s High-Risk, High-Reward Research program that “supports individual scientists of exceptional creativity, who propose pioneering and transforming approaches to major challenges in biomedical and behavioral research.”
Some of the Pioneer Award funds were used to bring Cytation 5 into Dr. Randolph’s lab as a powerful intermediate step in the processing workflow. By imaging sample slices at low magnification in about 20 minutes, it allowed the lab to set clear priorities as to what what portions of the sample to focus on using the more time-consuming confocal imaging steps. The lab created a custom chamber with three wells for three different tissue samples, and hope to fine-tune it further for integration with a plate stacker to allow overnight processing. The lab also uses Cytation 5 for traditional multi-mode reading applications, such as photo-activated high-density lipoprotein tracking.
Dr. Randolph noted that imaging helped to define the problem in the lymph vessels, and progress her research to an upcoming clinical study. In the study, participants will ingest a special lipid tracer, and her team will track its movement through the intestine and to the bloodstream during absorption. She’s grateful that Cytation 5 brought speed to the process so her team can focus on understanding and solving such interesting problems.
Section of human mesentery, trimmed just along the edge of the intestinal wall - to make the tissue flatter (top of image). A combination of fluorescence and LED bright field modes using the Cytation 5 system highlighted a lymph node (asterisk) in the midst of mesenteric adipose tissue. The gray shadow-like vessel marked by arrowheads is the lymphatic vessel leading from the intestinal wall along the upper surface of the tissue to the lymph node. Blood vessels are observed to the right of this lymphatic vessel/lymph node grouping.
Thanks to Dr. Gwendalyn Randolph for relating her BioTek experience with us.