Compression Leads to Stiffening in Tissues But Not Biopolymer Gels

Even though the cells in soft tissue contain network of filamentous polymers and are imbedded within extracellular matrices made from chemically distinct but physically similar polymers, they respond differently to compression and stretch compared to the polymer networks alone. Work by two groups within the MRSEC reveal that this difference arises when volume conserving cells are placed in a filamentous network and constrain the way these networks can reorient when the system is deformed. This work,led by Paul Janmey, Professor in the Perelman School of Medicine’s Department of Physiology and in Penn Engineering’s Department of Bioengineering, and Vivek Shenoy, Eduardo D. Glandt President’s Distinguished Professor in Penn Engineering’s Department of Materials Science, resulted from extensive use of instrumentation in the viscoelastic characterization lab in the LRSM and on experimental and theoretical work supported by the MRSEC.