A polyelectrolyte multilayer platform for investigating growth factor delivery modes in human liver cultures.

Polyelectrolyte multilayers (PEMs) of chitosan and heparin are useful for mimicking growth factor (GF) binding to extracellular matrix (ECM) as in vivo. Here, we developed a PEM platform for delivering bound/adsorbed GFs to monocultures of primary human hepatocytes (PHHs) and PHH/non-parenchymal cell (NPC) co-cultures, which are useful for drug development and regenerative medicine. The effects of ECM protein coating (collagen I, fibronectin, and Matrigel®) and terminal PEM layer on PHH attachment/functions were determined.

Two-Phase Electrospinning to Incorporate Polyelectrolyte Complexes and Growth Factors into Electrospun Chitosan Nanofibers.

Growth factors are potent signaling proteins for tissue engineering, but they are susceptible to loss of activity when exposed to solvents used for polymer processing. This work explores preservation of fibroblast growth factor-2 (FGF-2) activity in chitosan nanofibers using two-phase electrospinning via a compound coaxial needle and from a water-in-oil emulsion FGF-2 in aqueous poly(vinyl alcohol) is added on either the inside (A/O) or the outside (O/A) of an organic chitosan phase, using the compound needle. FGF-2 is further stabilized by complexation to heparin-based nanoparticles.

Preparation of Proteoglycan Mimetic Graft Copolymers.

Proteoglycans are proteins with pendant glycosaminoglycan polysaccharide side chains. The method described here enables the preparation of graft copolymers with glycosaminoglycan side chains, which mimic the structure and composition of proteoglycans. By controlling the stoichiometry, graft copolymers can be obtained with a wide range of glycosaminoglycan side-chain densities.

Synthesis and characterization of proteoglycan-mimetic graft copolymers with tunable glycosaminoglycan density.

Proteoglycans (PGs) are important glycosylated proteins found on the cell surface and in the extracellular matrix. They are made up of a core protein with glycosaminoglycan (GAG) side chains. Variations in composition and number of GAG side chains lead to a vast array of PG sizes and functions.

Nanostructured biomaterials from electrospun demineralized bone matrix: a survey of processing and crosslinking strategies.

In the design of scaffolds for tissue engineering biochemical function and nanoscale features are of particular interest. Natural polymers provide a wealth of biochemical function, but do not have the processability of synthetic polymers, limiting their ability to mimic the hierarchy of structures in the natural extracellular matrix. Thus, they are often combined with synthetic carrier polymers to enable processing.

Aggrecan-mimetic, glycosaminoglycan-containing nanoparticles for growth factor stabilization and delivery.

The direct delivery of growth factors to sites of tissue healing is complicated by their relative instability. In many tissues, the glycosaminoglycan (GAG) side chains of proteoglycans like aggrecan stabilize growth factors in the pericellular and extracellular space, creating a local reservoir that can be accessed during a wound healing response. GAGs also regulate growth factor-receptor interactions at the cell surface.

Layer-by-layer assembly of polysaccharide-based polyelectrolyte multilayers: a spectroscopic study of hydrophilicity, composition, and ion pairing.

Polyelectrolyte multilayers using the polycations chitosan and N,N,N-trimethyl chitosan and the polyanions hyaluronan, chondroitin sulfate, and heparin are studied. Chitosan and hyaluronan behave as a weak polycation and weak polyanion, respectively, whereas N,N,N-trimethyl chitosan, chondroitin sulfate, and heparin behave as strong polyelectrolytes. Hydrophilicity is determined by water contact angle measurements and by comparing wet and dry film thickness measurements.

Enhanced osteoblastic differentiation of mesenchymal stem cells seeded in RGD-functionalized PLLA scaffolds and cultured in a flow perfusion bioreactor.

The present study combines chemical and mechanical stimuli to modulate the osteogenic differentiation of mesenchymal stem cells (MSCs). Arg-Gly-Asp (RGD) peptides incorporated into biomaterials have been shown to upregulate MSC osteoblastic differentiation. However, these effects have been assessed under static culture conditions, while it has been reported that flow perfusion also has an enhancing effect on MSC osteoblastic differentiation.