title: Integrating sensing hydrogel microstructures into micropatterned hepatocellular cocultures.
abstract: In this paper we describe a microfabrication-derived approach for defining interactions between distinct groups of cells and integrating biosensors with cellular micropatterns. In this approach, photoresist lithography was employed to micropattern cell-adhesive ligand (collagen I) on silane-modified glass substrates. Poly(ethylene glycol) (PEG) photolithography was then used to fabricate hydrogel microstructures in registration with existing collagen I domains. A glass substrate modified in this manner had three types of micropatterned regions: cell-adhesive collagen I domains, moderately adhesive silanized glass regions, and nonadhesive PEG hydrogel regions. Incubation of this substrate with primary rat hepatocytes or HepG2 cells resulted in attachment of hepatic cells on collagen I domains with no adhesion observed on silane-modified glass regions or hydrogel domains. 3T3 fibroblasts added onto the same surface attached on the glass regions around the hepatocytes, completing the coculture. Significantly, PEG hydrogel microstructures remained free of cells and were used to "fence" hepatocytes from fibroblasts, thus limiting communication between the cell types. We also demonstrated that entrapment of enzyme molecules inside hydrogel microstructures did not compromise nonfouling properties of PEG. Building on this result, horse radish peroxidase-containing hydrogel microstructures were integrated into micropatterned cocultures and were used to detect hydrogen peroxide in the culture medium. The surface micropatterning approach described here may be used in the future to simultaneously define and detect endocrine signaling between two distinct cell types.
authors.affiliation: Department of Biomedical Engineering, Applied Science Graduate Group, University of California, Davis, California 95616, USA.
authors.forename: Ji Youn
authors.initials: JY
authors.lastname: Lee
authors.forename: Sunny S
authors.initials: SS
authors.lastname: Shah
authors.forename: Jun
authors.initials: J
authors.lastname: Yan
authors.forename: Michael C
authors.initials: MC
authors.lastname: Howland
authors.forename: Atul N
authors.initials: AN
authors.lastname: Parikh
authors.forename: Tingrui
authors.initials: T
authors.lastname: Pan
authors.forename: Alexander
authors.initials: A
authors.lastname: Revzin
mesh_terms: D016475:3T3 Cells; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D018929:Cell Culture Techniques / Q000379:methods*; D003094:Collagen / Q000737:chemistry; D005347:Fibroblasts / Q000378:metabolism; D022781:Hepatocytes / Q000378:metabolism; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000378:metabolism; D020100:Hydrogels / Q000737:chemistry*; D008113:Liver Neoplasms / Q000378:metabolism*; D051379:Mice; D011092:Polyethylene Glycols / Q000737:chemistry; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D012821:Silanes / Q000737:chemistry; D013499:Surface Properties
chemical_list: D020100:Hydrogels; D012821:Silanes; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols; D003094:Collagen