Juan Lasheras, Ph.D.
Department of Mechanical and Aerospace Engineering
Whitaker Institute of Biomedical Engineering
UNIVERSITY OF CALIFORNIA, SAN DIEGO

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Cell motility is essential for a variety of processes such as vertebrate embryonic development, tissue repair, and the metastatic spreading of some cancer cells. Cell crawling requires the integration and coordination of complex biochemical and biomechanical signals which regulate the traction forces exerted through the cytoskeleton at the local adhesion points on the substratum. Although it is generally accepted that actin and myosin are the common elements in most cell crawling movements, these proteins undergo many different transformation as the cell migrates. A complete understanding of the mechanisms of cell crawling must provide a molecular explanation for these transformations, explain how they are coordinated in time and space, and relate them to changes in the mechanical parameters such as the rheological properties of the cell and the adhesion forces to the substrate. This lecture will discuss new measurements of the spatial and temporal distribution of traction forces as well as the associated changes in the mechanical properties of the cell which take place during the crawling of the cell over deformable elastic substrates. In addition, the kinematics of the migration under the effects of varying degrees of chemo-attractant concentration gradients will also be discussed. The trajectory of the cell´s center of mass, as well as cells´ polarization along gradient lines, is shown to follow a quasi-periodic evolution with characteristic frequencies related to the biochemical processes regulating the internal remodeling of the cytoskeleton.

Juan C. Lasheras received his Ph.D. from Princeton University in 1982. After spending two years as research scientist at the Koninklijke Shell Laboratorium-Amsterdam in The Netherlands, he joined the faculty the University of Southern California in Los Angeles. In 1990 he was appointed Professor of Aerospace Engineering at UCSD where he has served as Chairman from 1999 to 2004. He was a Guggenheim Fellow and a George Van Ness-Lothrop Fellow. He received the F.N. Frenkiel Award for Fluid Dynamics from the American Physical Society in 1990, the 2003 Breakthrough Innovation in Medical Sciences given by BIOCOM and BIOSECTOR of Southern California, and the 2003 High Tech Award in Medical Devices and Instrumentation given by the American Electronics Association. He is an elected member of the Royal Academy of Engineering of Spain and a Fellow of the American Physical Society (APS). Lasheras holds 39 patents in medical devices technology.