Modified polyelectrolyte complex fibrous scaffold as a matrix for 3D cell culture

The paradigm of scaffold tissue engineering relies on the provision of an appropriate environment for cell growth, which includes both structural support and the presentation of cellular signals. In terms of biosignal presentation, fibrous scaffolds by interfacial polyelectrolyte complexation (IPC) offer a clear advantage over other scaffold types as IPC scaffolds are formed using an aqueous-based, room-temperature process compatible with the incorporation of biological molecules. This paper establishes two primary methods for the chemical and biochemical modification of these scaffolds: (i) physical entrapment of the bioactive component, and (ii) covalent binding of the bioactive component. For the first method, extracellular matrix (ECM) proteins, collagen, fibronectin and laminin were drawn into the IPC fiber. For the second method, the cell adhesion peptide, RGD, was chemically conjugated to a thiol-active maleimidylated form of the scaffold. Immobilization of the bioactive components was characterized by confocal fluorescence microscopy, scanning electron microscopy (SEM) and BCA protein assay. The ECM proteins were distributed throughout the bulk and surface of the fiber. The ratio of covalently bound to physisorbed RGD was ∼ 2:3. The performance of the various scaffolds as a matrix to maintain the differentiated function of primary hepatocytes showed that albumin levels in the supernatant were in the order of RGD-modified scaffold > collagen Type I-modified scaffold > fibronectin- or laminin-modified scaffold > unmodified scaffold > plate, while no clear trend in urea production could be discerned. Thus, IPC scaffolds offered a promising platform for the presentation of signals to cells, in this case, to influence their differentiated function.