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The 9th New Jersey Symposium on Biomaterials Science
The 9th New Jersey Symposium on Biomaterials Science and Regenerative Medicine: Accelerating the Bench-to-bedside Trajectory for Regenerative Therapeutics
October 29-31, 2008
Hyatt Regency Hotel, New Brunswick, NJ
Save the date for the 10th Symposium: October 26-29, 2010
Program Committee Joachim Kohn, Chair - Rutgers, the State University of New Jersey Joseph Rosen, Co Chair - Dartmouth Hitchcock Medical Center Daniel Anderson - MIT Richard Clark - Stony Brook University David Devore - Center for Military Biomaterials Research, Rutgers Jeffrey Hollinger - Carnegie Mellon University Carole Kantor - New Jersey Center for Biomaterials, Rutgers Adam Katz - University of Virginia George Muschler - Cleveland Clinic
Maria Siemionow - Cleveland Clinic Beth Sump - Cleveland Clinic Cathryn Sundback - Massachusetts General Hospital Michael Yaszemski - Mayo Clinic
Copyright 2008 New Jersey Center for Biomaterials.
A novel three-dimensional hydrogel system for the co-culture of neural cells on microelectrode arrays Lee, W. H.1, 2, Smith, K. L.3, Frampton, J. P4., Kim, J. W.1, 2, Kim, S. J.1, 2, Shain, W.3, Hynd, M. R.3 1 School of Electrical Engineering, Seoul National University, Seoul, Korea 2 Nano-Bioelectronics and Systems Engineering Research Center, Seoul, Korea 3 Wadsworth Center, New York State Department of Health, Albany, NY, USA 4 Department of Biomedical Sciences, SUNY, Albany, NY, USA
Hydrogels represent a unique class of non-toxic, optically transparent materials that have been extensively used in a variety of biomedical applications. Due to their high permeability for oxygen, nutrients, and other watersoluble molecules, hydrogels are ideal for in vivo use. Hydrogels are matrices that have been used to create defined 3D micro-environments for a variety of cell culture and in vivo experiments. In particular, protein-based hydrogels including the related family of amphiphilic peptide gels have been shown to promote the growth and differentiation of both primary neurons and neural stem cells. Under physiological conditions, protein-based hydrogels self-assemble into a 3D matrix that exhibits a nanometer scale fibrous structure able to support cell growth and differentiation. The use of a protein-based hydrogel permits the formation of pore sizes within the hydrogel that are large enough for neurite outgrowth to occur (0.5-1 µm), yet small enough to physically entrap cell bodies (~15 µm) within the hydrogel. Thermogelation of a gelatinous protein mixture composed of laminin, collagen IV, heparan sulfate proteoglycans, and entactin results in the formation of hydrogels that contain high water content, yet possess mechanical properties similar to those of biological tissue. Cells cultured using traditional 2D culture methods typically have very different morphology and biochemical functions compared to those found in vivo. The development of spatially-defined 3D cell culture methods will be critical to constructing tissue engineering scaffolds for implantation into the body. In vivo tissues are complex structures composed of many different kinds of cells. However, this cyto-architecture is very difficult to compose by culturing different cells simultaneously in vitro. Specifically, the requirements of different cell types (e.g., anchorage-dependence, speed of cell proliferation) can vary enormously. In this study we have developed a novel hydrogel system for the construction of spatially-defined, 3D matrices, for neural cell culture. Primary hippocampal neurons and astrocytes were encapsulated using thermogelation of a protein-based hydrogel. Four types of constructs were developed for analysis. For Type I samples, neurons were cultured on poly-L-lysine coated glass substrates to act as 2D controls; Type II: Hydrogel-encapsulated neurons only; Type III: a mixture of neurons and astrocytes encapsulated within the hydrogel; and Type IV: a spatially-separated system in which neurons encapsulated in the hydrogel were covered with another hydrogel layer containing astrocytes. 3D constructs were cultured on microelectrode arrays (MEAs) in order to record signals from encapsulated neurons. Both spontaneous and evoked action potentials were recorded from Type II, III and IV cultures. The synaptic activity marker, FM 1-43, was also used to further confirm the formation of synapse from encapsulated neurons. The impedance changes of MEA electrodes before and after hydrogel polymerization were measured and validated by electrochemical impedance spectroscopy. Impedance change was found to not be significantly different from un-coated MEAs. The rate and extent of neurite outgrowth from encapsulated cells, along with the number and distribution of synaptic contacts formed, was determined using laser scanning confocal microscopy. Encapsulated cells were found to maintain their defined positions within the 3D matrices over time. 3-D image sets were analyzed using automated image analysis software employing advanced tracing algorithms. This work was supported by the International Collaboration Program NBS-ERC/KOSEF (S.J.K) and by the National Institute of Biomedical Imaging and Bioengineering under Agreement Number R21-EB007782 (M.R.H).