S3E4
Episode 4 (January 31, 2021)
Matthew Heinrich
Princeton University
Yuxiao Zhou
Johns Hopkins University
Nicholas G. Fischer
University of Minnesota
Escher-inspired tissues: growth and fusion in epithelial monolayers
Abstract of Talk 1
MDCK monolayers have become one of the most studied model systems of tissue growth and wound healing, yet their mechanics is still poorly understood, especially at large scales. We systematically study the growth and eventually collision and fusion of millimeter-scale tissue monolayers. First focusing on growth, we find that growing monolayers form an outwardly-expanding boundary zone and a more complex interior wake over the course of several cycles of cell divisions. The boundary zone controls the areal growth of the tissue and is markedly insensitive to changes in the interior of the tissue, while the interior of the tissue undergoes much different cell cycling behavior and even can feature millimeter-spanning vortices. We then study tissue collision and fusion, systematically determining the effect of mismatches in tissue shape, density, and size on boundary dynamics of pairs of homotypic epithelial monolayers. We find that the boundaries of tissues of similar density and size “freeze” upon collision, while initially larger or higher density tissues displace smaller and lower density tissues by 5-10 cell lengths upon collision. Putting these ideas together, we develop a model that closely predicts experiments whereby many tissues grow and fuse to form a single composite tissue tessellation.
Biosketch of Speaker 1
Matt Heinrich is a PhD candidate in the Department of Mechanical and Aerospace Engineering at Princeton University, where he studies the mechanics and collective dynamics of living tissues. Matt is coadvised, working in Dr. Daniel Cohen’s experimental bioengineering group and Dr. Andrej Kosmrlj’s theoretical mechanics and biological physics group. Matt received his B.E. in Mechanical Engineering at Stevens Institute of Technology in Hoboken, NJ and is looking to continue his research career in industry.
3D full field strain mapping in bone-implant and bone-tooth constructs
Abstract of Talk 2
Bone is a complex anisotropic hierarchical composite that consists of inorganic and organic components. The biomechanics of bone-tooth and bone-implant interfaces affects the outcomes of several dental treatments, such as implant placement, because bone, tooth and periodontal ligament are living tissues that adapt to the changes in mechanical stimulations. Mechanical testing coupled with micro-CT was performed on human cadaveric mandibular bone-tooth and bone-implant constructs. Using digital volume correlation, the 3D full-field strain in bone under implant loading and tooth loading was measured.
Biosketch of Speaker 2
Dr. Yuxiao Zhou is a postdoctoral fellow in School of Medicine and Biomedical Engineering at Johns Hopkins University. She received her B.S. from Energy Science and Engineering at Harbin Institute of Technology in 2012, M.S. from Mechanical and Aerospace Engineering at Rutgers University-New Brunswick in 2015, and PhD from Mechanical Engineering at Pennsylvania State University in 2020. Her current research focuses on bone regeneration and scaffold design for critical size defects in bone tissue engineering.
Strategies to prevent infection of percutaneous devices
Abstract of Talk 3
Percutaneous devices are widely used medical devices, yet infections lead to a multibillion dollar healthcare burden. The tooth, a Nature’s successful percutaneous organ, displays marked longevity/lack of infection because of a unique basement membrane surrounding it that mediates a durable soft tissue attachment to the tooth that prevents access of bacteria and thus, prevent biofilm formation. Resident keratinocytes form hemidesmosomes (HDs) that anchor cells to the tooth surface and secure the periorgan seal. Here, I will introduce some of our strategies for upregulating keratinocytes HDs and developing anti-infection materials. Our materials are a leading strategy to prevent infection through sound and durable soft tissue attachment to percutaneous devices.
Biosketch of Speaker 3
Nicholas G. Fischer is a graduate fellow in the University of Minnesota’s Dental Scientist Training Program. Nicholas completed his undergraduate degree at Creighton University in Environmental Sciences and Biology in 2017. His current research with Prof. Conrado Aparicio focuses on the functionalization of biomaterial surfaces at the Minnesota Dental Research Center for Biomaterials and Biomechanics. Nicholas is also interested in levering the secreted matrix to instruct cellular responses to biomaterials.
Guest Host: Jingjie Hu
Dr. Jingjie Hu is currently a postdoctoral research fellow at Mayo Clinic, where her research focuses on biomaterials for translational applications. Previously, she received her Ph.D. from Princeton University (2018) in the areas of materials science and mechanical engineering. She worked with Prof. Wole Soboyejo on tumor specific nanocarriers and cell mechanics for the early detection and localized treatment of breast cancer. Prior to that, she received her B.S.E. in mechanical engineering from the University of Michigan (2013), with minors in multidisciplinary design and mathematics. Her broad research interests include materials, nanotechnology, and mechanical behavior of biomedical materials and devices.