Category: Assay Development and Screening
Leukocyte trafficking plays a critical role in inflammation and infection. To reach a site of infection in a timely manner, leukocytes have to efficiently and constantly deform and migrate along chemical gradients through complex intercellular and interstitial spaces. Systematically investigating the leukocyte chemotaxis in conditions that require active deformation can provide new insights into host inflammatory responses in health and disease and open new opportunities in therapeutic screening of anti-inflammatory compounds. However, conventional transwell assays and recent microfluidic assays offer very limited information on the changes of leukocyte chemotaxis in conditions that require active deformation. Here, we developed a microfluidic assay to study the effect of active deformation on chemotactic human leukocytes. The unique feature of the device that enables this study is a tapered geometry of the chemotaxis microchannels. When migrating in a tapered channel along the pre-established chemokine gradient, leukocytes confront increasing level of physical constriction. Consequently, they have to progressively deform when migrating through the channel. We found that in these conditions, human neutrophils and T cells exhibited four migration behaviors including unidirectional passing, oscillational passing, arrest and retrotaxis. These chemotaxis phenotypes are not observed during migration in straight microchannels and are comparable to the migration patterns of neutrophils observed in vivo, in animal experiments. We studied the active deformation and migration of neutrophils and T cells and found that the deformation and migration are dependent on chemokines and cell types. We evaluated neutrophils from healthy donors, organ-transplant patients, and sepsis patients and found reduced and distinct active deformation signatures of neutrophils in these samples. We evaluated changes in migration signatures in neutrophils in response to various chemokine gradients and in the presence of various receptors, cytoskeleton, and motor protein inhibitors. Compared to previous chemotaxis assays, our microfluidic assay provided highly reliable and unique information on deformation of chemotactic leukocytes. Our device can not only serve as a tool for biological study of leukocyte deformation but also a high-throughput platform for therapeutic screening and clinical diagnosis.
Xiao Wang– Postdoctoral research fellow, BioMEMS Resource Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA
Postdoctoral research fellow
BioMEMS Resource Center, Massachusetts General Hospital, Harvard Medical School
I am a postdoctoral research fellow at Center of Engineering in Medicine at Massachusetts General Hospital and Harvard Medical School. I am passionate about working at the intersection of technology, biology, and art. My research interest is to develop tools with high spatiotemporal precision and throughput to enable new biological discoveries, to improve conventional clinical diagnostics and therapeutic development. I am currently working on developing microfluidic assays to study immune cells in homeostasis and diseases for clinical diagnosis and drug development applications. I am also working developing microfluidic assays for probing the efficacy of chimeric-antigen-receptor (CAR) T cells for cancer immunotherapy.