AVS 50th International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuP

Paper BI-TuP17
Assembly and Disassembly of Hydrogels to Entrap, Grow, and Release Cells

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: G.F. Payne, University of Maryland Biotechnology Institute
Authors: G.F. Payne, University of Maryland Biotechnology Institute
T. Chen, University of Maryland Biotechnology Institute
L.-Q. Wu, University of Maryland Biotechnology Institute
D.A. Small, University of Maryland Biotechnology Institute
H. Yi, University of Maryland Biotechnology Institute
R. Ghodssi, University of Maryland
G.W. Rubloff, University of Maryland
W.E. Bentley, University of Maryland Biotechnology Institute
Correspondent: Click to Email
Hydrogels provide a bio-friendly environment for cultivating cells. Standard methods for entrapping cells within hydrogel matrices exploit the photopolymerization of synthetic monomers (or macromonomers). The strength of photopolymerization is that standard lithographic approaches can be exploited to exert considerable spatial and temporal control of hydrogel formation. The weaknesses of photopolymerization are that these methods are not always benign to cells, and the hydrogel matrices are generally permanent. We are examining an alternative method for in situ hydrogel formation based on biopolymers and enzymes. Specifically, we mix cells with the protein gelatin, and add the protein-crosslinking enzyme transglutaminase. Gel formation occurs over the course of 1-2 hours. In situ-entrapped bacterial cells (E. coli) were observed to grow to high densities within the crosslinked gelatin matrices, and these cultured cells could sense and respond to appropriate inducers (we examined the inducible expression of green fluorescent protein). After growing the cells, they could be released from the hydrogel using the protein-degrading enzyme, proteinase K. Cells were released over the course of 1 hour and they remained viable and inducible. This study demonstrates that; one enzyme (transglutaminase) can entrap cells within a hydrogel, the cells can proliferate to high densities within the matrix, and a second enzyme (proteinase K) can "dissolve" the hydrogel to release the cells. This capability should provide unique opportunities for microfluidic biosensors.