RESUMEN
A four-step soft lithographic process based on micro-contact printing of organic monolayers, hyperbranched polymer grafting, and subsequent polymer functionalization results in polymer/n-alkanethiol patterns that direct the growth and migration of mammalian cells. The functional units on these surfaces are three-dimensional cell "corrals" that have walls 52+/-2 nm in height and lateral dimensions on the order of 60 microm. The corrals have hydrophobic, methyl-terminated n-alkanethiol bottoms, which promote cell adhesion, and walls consisting of hydrophilic poly(acrylic acid)/poly(ethylene glycol) layered nanocomposites that inhibit cell growth. Cell viability studies indicate that cells remain viable on the patterned surfaces for up to 21 days, and fluorescence microscopy studies of stained cells demonstrate that cell growth and spreading does not occur outside of the corral boundaries. This simple, chemically flexible micropatterning method provides spatial control over growth of IC-21 murine peritoneal macrophages, human umbilical vein endothelial cells, and murine hepatocytes.
Asunto(s)
Técnicas de Cultivo de Célula/métodos , Resinas Acrílicas , Adsorción , Animales , División Celular , Células Cultivadas , Electrólitos , Endotelio Vascular/citología , Oro , Hepatocitos/citología , Humanos , Macrófagos Peritoneales/citología , Mamíferos , Ratones , Proteínas/metabolismoRESUMEN
A method for the production of microporous poly(D, L-lactide-co-glycolide) foams containing encapsulated proteins using supercritical carbon dioxide is described. Foams generated as aqueous protein emulsions in a polymer-solvent solution were saturated with carbon dioxide at supercritical conditions, and then suddenly supersaturated at ambient conditions causing bubble nucleation and precipitation of the polymer. Proteins contained in the water phase of the emulsion were encapsulated within the foams, including basic fibroblast growth factor (bFGF), an angiogenic factor of interest in tissue engineering applications. The release and activity of bFGF from these foams was determined in vitro and compared with similar porous scaffolds prepared by traditional solvent casting-salt leaching techniques. Total protein release rate was greater from structures made in CO(2) than those made by the salt leaching technique, however a large initial burst of bFGF was released from the salt leached structures. This initial burst was not observed from the polymer foams processed in CO(2) and active bFGF was released at a relatively constant rate. Residual methylene chloride levels were measured in the foams made with CO(2) and were found to be above the limits imposed by the US Pharmacopoeia implying that further solvent removal would be required prior to in vivo use.