Perfusable Cells

A rapid vascular casting approach that uses polymer microparticle as a sacrificial template allows cells to survive in suspension until needed for transplantation. Blood vessel transplantation is the most convenient treatment for blood vessel defects. The defected area has recently been treated with autologous vessels or synthetic grafts, but the materials used should support cell adhesion, cell growth activity, cell differentiation, and maturation to the desired phenotype. To combat these challenges, we focus on engineering scaffold microparticles (MPs) to provide structural support to human umbilical-vein endothelial cells (HUVEC) while in suspension. The perfusable MP-embedded HUVEC use the U.S. food and drug administration (FDA)-approved biocompatible and biodegradable poly(lactic-co-glycolic acid) (PLGA) polymer as scaffolding. PLGA MPs of approximately 50 µm were produced using the solvent diffusion method. A bright field microscope and scanning electron microscope (SEM) were used to characterize the MP size and shape, respectively. The surface of MPs was conjugated with fibronectin, a glycoprotein involved in wound healing, to enhance HUVEC adhesion. Bioconjugation was accomplished by coupling primary amines of fibronectin with carboxyl groups of PLGA, forming amide bonds. The conjugation reaction was validated and quantified by using the Bradford assay. Fibronectin per milligram of PLGA MPs was calculated as 58.7 µg. HUVEC were seeded onto fibronectin-conjugated particles via gentle mixing and incubation, and the resulting cell-particle system was imaged with bright field, phase, and fluorescence microscopy over a period of one to two weeks for visualization of seeding efficacy and cell behavior. HUVEC exhibit promising cell adhesion on fibronectin-coated PLGA particles. Our results indicate perfusable cells can be cultured in suspension in vitro. More studies are under consideration on quantification of the cell population, molecular characterization, transport through blood vessel mimicking channels in vitro, and in vivo animal models. The perfusable cell therapies represent a possible solution in vascular tissue engineering.