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M. A. Princz, H. Sheardown; Release and Tethering of Growth Factors From Dendrimer Crosslinked Heparinized Collagen Gels for Artificial Cornea Applications. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1500.
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Epithelial downgrowth and keratoprosthesis extrusion may be hindered by complete epithelial coverage over the device’s anterior surface. Here, we investigate the effects of epidermal growth factor (EGF) and heparin-binding epidermal growth factor (HB-EGF) tethered within dendrimer crosslinked collagen gels, and released HB-EGF from heparinized dendrimer crosslinked collagen gels, in vitro.
Radiolabeled HB-EGF was immobilized to and released from dendrimer crosslinked collagen gels with covalently incorporated heparin of varying concentrations. The release of HB-EGF was measured under physiologically relevant and wound-healing conditions. The amount of released growth factor required to stimulate human cornea epithelial cells (HCEC) in vitro was determined through cell proliferation and migration. Tethering of HB-EGF and EGF was achieved through amide reaction with dendrimers prior to collagen gel fabrication; tethering was verified with SDS-PAGE. Gel stability through swelling, DSC and collagenase digestion was also investigated. HCEC were seeded on the gels and control surfaces. Immunofluorescence was used to assess production of proteins including fibronectin, laminin and cytokeratin.
In vitro results demonstrate that HB-EGF concentrations suitable for stimulating corneal epithelial cells are in the nano-range, with similar effects to EGF. Heparin availability influenced HB-EGF immobilization, which may allow for tailoring to achieve the desired wound healing response. HB-EGF released from gels demonstrated a gradual first order release profile. Growth factor tethering of HB-EGF and EGF to the dendrimer was achieved, and verified with SDS-PAGE. Dendrimer crosslinked collagen gels were fabricated with tethered growth factor. Cells demonstrated enhancement in proliferation and migration in the presence of tethered growth factor, compared to controls, and was dependent on growth factor concentration.
Dendrimer crosslinked heparinized collagen gels are able to act as delivery vehicles for soluble and tethered growth factors and have potential for improving native host integration with an artificial cornea.
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