Reminder -- Purdue University School of Chemical Engineering Graduate seminar series Dr. Julie Renner "Modular Protein Matrices for Cartilage Repair" Tuesday, April 23, 2013 9:00-10:20 a.m. FRNY G140 Reception at 8:30 a.m. in Henson Atrium Abstract: Articular cartilage degradation (osteoarthritis) is a prevalent disease in the United States. Disadvantages of current treatments include poor mechanical integrity, degradation with time, and donor site morbidity. One tissue engineering approach combines artificial proteins with the use of human mesenchymal stem cells (MSCs). This approach has potential to be minimally invasive, low-cost and long-lasting. In this work, modular proteins are designed as matrices for cartilage tissue engineering. The proteins feature mechanical domains derived from the rubber-like protein resilin and attempt to mimic the mechanical properties of natural cartilage. Bioactive domains are incorporated to interact with the MSCs. Bioactive domains derived from fibronectin are included in the resilin-based proteins, and other promising bioactive sequences are identified. Lysine residues serve as crosslinking sites. Here we report oscillatory rheology experiments where the proteins exhibit dual-phase behavior and form weak gels in response to temperature. This behavior may be useful in tissue engineering and drug-delivery applications. Crosslinking the modular proteins with tris(hydroxymethyl)phosphine results in viscoelastic hydrogels with an unconfined compressive modulus of 2400 ± 200 kPa, which is on the same order as human cartilage. A LIVE/DEAD assay demonstrates that the recombinant proteins are cytocompatible with human MSCs and a cell-spreading assay shows cells interact with the fibronectin-derived domain in a sequence-specific manner. We also investigate a short peptide derived from bone morphogenetic-2 and found that it directs proteoglycan (cartilage matrix) production in human MSCs without increasing undesired markers for bone. This suggests the peptide is a promising tool for cartilage tissue repair. Bio: Dr. Renner completed her thesis work as a National Science Foundation Graduate Research Fellow at Purdue University in the summer of 2012. Her work focused on biomaterial design and characterization. She joined Proton Energy Systems in November 2012 as Small Business Postdoctoral Research Diversity Fellow supported by the National Science foundation under Grant# IIP-1059286 to the American Society for Engineering Education. She currently works on electrolysis technology as a membrane scientist.