One of the major objectives of our lab is to study the influence of mechanical and geometrical properties of nanofibers on single cell dynamics. Cells are surrounded by extracellular matrix (ECM) inside the body. The ECM is composed of nano-micro fibrous proteins, non-fibrous proteins, proteoglycans and various cytokines. It continuously provides biochemical and biophysical cues to cells. Changes in ECM can influence cell differentiation, behavior and migration. Furthermore, mechanical changes in the ECM have been attributed to diseases like cancer and wound ulcers. Therefore obtaining a better understanding of single cell interactions with its immediate microenvironment has powerful implications in fields like tissue engineering and oncology.
Our lab focuses in understanding the biophysical reactions of single cells as they interact with the mechanically characterized STEP nanofibers. The fibers that are in the nano-sub micrometer range closely represent the dimensionality of the fibrous ECM in vivo. STEP enables the fine tuning of the mechanical and geometrical properties of these fibers which can be used to study single and collective cell behavior using time lapse video microscopy and immunofluorescence.
Cancer Cell Behavior
Cancer causes over a $100 billion in health and morbidity costs annually, and is the second leading cause of death in the U.S. The extracellular matrix (ECM) that surrounds cancer cells plays an essential role in the behavior of cancer cells and progression of cancer. However, platforms that closely represent the ECM are limited, compromising our ability to perform realistic in vitro experiments. Furthermore, the past few decades have been devoted mostly to understand the biochemical and genetic aspects of cancer, and the understanding of cancer biophysics in still in its infancy. The STEP technique enables the manufacturing of mechanistically tunable polymeric nanofibers that closely represent the dimensionality of fibrous proteins in the ECM. The migratory, genetic and protein expression of various cancer cells in response to changes in the mechanical and geometric properties of the nanofibers can be investigated. Currently, we are using highly metastatic cancer cell lines DBTRG-05MG, MDA-MB-231 and PC-3 (glioblastoma, breast cancer, and prostate cancer respectively) to investigate the cell protrusion dynamics, leader cell migration, and inside-out and outside-in cell forces. We intend to underscore the less probed field of cancer biophysics, and emphasize the fact that cancer should be viewed as a system that encompasses not only the biochemical, but also the biophysical aspects of a tumor.
Hepatic Tissue Engineering
Liver is a multifunctional organ and plays a vital role in homeostasis, drug metabolism and toxicity control. It detoxifies toxic elements and maintains homeostasis by regulating proteins, lipids and carbohydrates in our body. Therefore, its failure is often times catastrophic and fatal. Current treatments for acute liver failure are limited to liver transplantation involving a donor. Due to limited availability of healthy liver donors, the prognosis of liver failure is compromised. Therefore, hepatic tissue engineering opens a promising alternative avenue towards the treatment of liver failure. Providing long term functional maintenance of a large number of hepatocytes that represent a ‘significant liver mass’ in a true 3D environment is challenging using existing platforms used for hepatic engineering. . Using the STEP platform, we have recently demonstrated that primary hepatocytes are able to maintain their differentiated state when cultured on suspended cross-hatched pattern of polymeric nanofibers. Compared to other culturing methods where cells are either placed in suspension or attached to flat substrates, the STEP platform provides a 3D nanofiber assembly that allows the cells to attach onto suspended nanofibers. We have observed that the hepatocytes conform to the 3D environment by wrapping around the fibers over time. These hepatocytes form suspended acrobatic monolayers, are have been observed to maintain their differentiated state and function over significant amount of time.
Aortic aneurisms, or aortic dissections, are potentially fatal ruptures of the aorta that arise from a gradual loss of elasticity within endothelial cells over time. Our lab is studying the general behavior of both normal and compromised cells on various geometries in the hopes of detecting differing patterns between the two cell types