Characterizing the Motogenic Response of Human Keratinocytes

Experiments were performed to quantitatively characterize the differential migratory response of human keratinocytes to the polypeptide growth factors EGF and TGF-a. Videomicroscopic tracking of single cells, on collagen IV surfaces, was used to examine the migratory response of cells to a range of growth factor concentrations, as well as to the EGF receptor blocking antibody 225. Results indicate that both EGF and TGF-0a increase the random motility coefficient of human keratinocytes, relative to control experiments and those in which EGFR blocking antibody is used. This increase in motility appears to occur in a dose-dependent manner, with TGF-a performing as a stronger motogen than EGF. Results also suggest that the addition of exogenous growth factor or receptor blocking antibody lowers cellular persistence times relative to the control state. This finding supports a model of autocrine pathways as cellular environmental sensing systems, a model that has been termed "cell sonar". Thesis Supervisor: Douglas A. Lauffenburger Title: Professor Acknowledgements I would like to thank my advisor, Doug Lauffenburger, for his advice, encouragement, and support throughout the course of this work. My tenure at M.I.T. has taken some interesting turns, and I appreciate the understanding he has shown along the way. Thanks also go to everyone in the Lauffenburger group for providing an enjoyable atmosphere in which to work, and without whose patience I may never have improved my cell culture techniques. Additional thanks to Gargi Maheshwari, Sean Palecek, Cartikeya Reddy, and Marti Ware for many insightful discussions on the theoretical and statistical analysis of experimental data. Finally, many thanks to Jenny and my entire family for their continued support of all my endeavors.