Developing Biocompatible Polycations for Cell Encapsulation

In cell encapsulation, a cationic polymer is often used to form a semi-permeable polyelectrolyte complex membrane. Many currently used polycations such as poly(L-lysine) (PLL) often cause severe immune responses. Using combinatorial polymerization, we synthesized a new library of cationic polymers. When used as surface coatings, these polymers elicited different levels of foreign body responses depending on their chemical structures. We identified the polymer coatings that inhibited macrophage activation in vitro, reduced the recruitment of inflammatory cells 24 hours and the fibrosis 30 days after subcutaneous implantation of the carboxylated polystyrene microparticles. These polymers offer great alternatives to the typically used PLL for cell encapsulation and many other applications.