Investigation of PSBMA-PU Ternary Copolymer-Based Semipermeable Membrane for Macro-Encapsulation of Cells

Cell macro-encapsulation necessitates semi-permeable membrane materials with strong resistance to fibrotic encapsulation in vivo. In this study, segmented polyzwitterionic-polyurethane block copolymers (SPU) were synthesized to meet this requirement. Fourier-transform infrared and X-ray photoelectron spectroscopy confirmed the molecular structure of the successfully synthesized SPU. When incorporated into commercial polyurethane, SPU significantly reduced the hydrophilicity of electrospun fiber membranes and exhibited minimal protein adsorption. The resulting membranes demonstrated favorable mechanical properties, well-defined porous architecture, and efficient transmembrane mass transfer. Encapsulation experiments using BMSCs confirmed that the membrane effectively retained cells while supporting normal cellular growth, allowing secreted factors to diffuse through the membrane and induce M1-to-M2 macrophage polarization. In vivo subcutaneous implantation in rats showed that membranes containing the zwitterionic block copolymer elicited significantly thinner fibrous capsules than both unmodified polyurethane and PTFE controls at 14 and 28 days, with no signs of acute or chronic inflammation.