There is a growing interest in understanding how a cell senses its microenvironment and how these external cues influence important cellular functions. Such information may be particularly important from a fundamental perspective (e.g., defining the stem cell niche), as well as from the applied viewpoint of regenerating functional tissue equivalents. Though both chemical and mechanical signals have been implicated in dictating local cell behavior, isolated effects are difficult to assess in vivo due to the myriad of uncontrollable, ever-changing cues. In addition, many of these cues are presented in spatiotemporally-complex patterns. To better understand how cells receive instructive information from their extracellular niche, synthetic environments including hydrogels have proven beneficial at assaying cell function in well-defined systems where single cues can be introduced and subsequent effects can be individually elucidated. Unfortunately, few 3D culture platforms allow the experimenter to recapitulate the heterogeneous and dynamic nature of the native tissue environment through 4D control of the material properties in both time and space. In this work, we demonstrate that by utilizing multiple photoreactions that are each initiated with different wavelengths of light, we can independently induce changes to the local physical and chemical material properties at specific locations within a hydrogel culture platform to direct real-time changes in cell function. This talk will detail the synthesis and characterization of these dynamically-tunable hydrogel materials and will highlight several examples where user-triggered alterations in the cellular niche can be used to both better understand and direct stem cell fate.
Cole A. DeForest is a postdoctoral scholar with Dr. David Tirrell in the Divisions of Chemistry and Chemical Engineering at the California Institute of Technology. He received his B.S.E. degree from Princeton University in 2006, majoring in Chemical Engineering and minoring in Material Science Engineering and Bioengineering. He obtained his Ph.D. degree under the guidance of Dr. Kristi Anseth from the University of Colorado in Chemical and Biological Engineering with an additional certificate in Molecular Biophysics. He has authored and co-authored 18 articles in peer-reviewed journals including Nature Materials, Nature Chemistry, and Angewandte Chemie. Dr. DeForest has received numerous research awards and honors including the Biomedical Engineering Society Student Fellow Award (2013), DSM Polymer Technology Award (2011), ACS Excellence in Graduate Polymer Research Award (2010), MRS Graduate Student Research Gold Award (2009), Society for Biomaterials Outstanding Achievement Award (2009), Princeton University Material Science Student of the Year (2006), Princeton University Most Approachable Resident Adviser (2005), and Boulder High School Valedictorian (2002). He has been supported through fellowships from the National Institutes of Health and the US Department of Education. Dr. DeForest’s research seeks to develop and optimize bioorthogonal chemistries to probe and better understand fundamental cell function through user-programmable biomaterials whose physical and chemical properties can be tuned in time and space.