Article

Cultivating liver cells on printed arrays of hepatocyte growth factor

Department of Biomedical Engineering, University of California, Davis, 451 East Health Sciences Dr. #2519, Davis, CA 95616, USA.
Biomaterials (Impact Factor: 8.56). 05/2009; 30(22):3733-41. DOI: 10.1016/j.biomaterials.2009.03.039
Source: PubMed

ABSTRACT

Growth factors are commonly present in soluble form during in vitro cell cultivation experiments in order to provide signals for cellular proliferation or differentiation. In contrast to these traditional experiments, we investigated solid-phase presentation of a hepatocyte growth factor (HGF), a protein important in liver development and regeneration, on microarrays of extracellular matrix (ECM) proteins. In our experiments, HGF was mixed in solution with ECM proteins (collagen (I), (IV) or laminin) and robotically printed onto silane-modified glass slides. Primary rat hepatocytes were seeded onto HGF/ECM protein microarrays and formed cellular clusters that corresponded in size to the dimensions of individual protein spots (500 microm diameter). Analysis of liver-specific products, albumin and alpha1-antitrypsin, revealed several fold higher levels of expression of these proteins in hepatocytes cultured on HGF/ECM microarrays compared to cells cultivated on ECM proteins alone. In addition, cultivation of hepatocytes on HGF/ECM protein spots led to spontaneous reorganization of cellular clusters from a monolayer into three-dimensional spheroids. We also investigated the effects of surface-tethered HGF on hepatocytes co-cultivated with stromal cells and observed a significantly higher level of albumin in co-cultures where hepatocytes were stimulated by HGF/ECM spots compared to co-cultures created on ECM protein islands without the growth factor. In summary, our study suggests that incorporation of HGF into ECM protein microarrays has a profound and long-lasting effect on the morphology and phenotype of primary hepatocytes. In the future, the number of growth factors printed on ECM microarrays will be expanded to enable multiplexed and combinatorial screening of inducers of cellular differentiation or proliferation.

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Available from: Caroline Jones, Sep 16, 2014
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    • "In another experiment, Lee et al showed that the function and behavior of cultivated cells on ECM micro-patterns could be analyzed through different ways such as gene expression levels (12). In their experiment, HepG2 cells were cultivated on collagen type I micropatterns and then the cells were extracted by laser catapulting for further gene expression analysis (12, 18). These studies reveal micropatterning as a very strong tool for both in vitro studies and tissue engineering. "
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    • "Our laboratory has recently reported that HGF molecules co-printed with ECM proteins (e.g. collagen (I), (IV), laminin) are retained on printed spots for several days under culture conditions [34]. Importantly, primary hepatocytes cultivated on top of the printed HGF/ECM arrays remained functional after 10 days in culture. "
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    • "Furthermore, heparin-based hydrogel may be fabricated into miniature constructs suitable for cell delivery/transplantation [30] and was found to cause little or no inflammation and hemolysis in vivo [28]. As a step towards development of heparin hydrogel scaffolds for hepatocyte or stem cell transplantation, the present study sought to characterize cultivation of primary rat hepatocytes in this gel and to test the effects of incorporating hepatocyte growth factor (HGF) [31] [32] [33]-a potent liver morphogen – into the hydrogel. Future applications of heparin hydrogel as a microenvironment niche for hepatocyte or stem cell differentiation and as a vehicle for cell transplantation are envisioned. "
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