Achieving nutrient pumping and strain stimulus by magnetic actuation of tubular scaffolds

Methods of forming magnetically actuable tubular scaffolds for use in engineering smooth muscle tissues such as those of the intestines, blood vessels, and urethra are described. The scaffolds are fabricated from sheets of electrospun fibrils of biocompatible and biodegradable polymers containing spatially uniform dispersions of nanoscale magnetic Fe2O3 particles. The sheets are wound into tubes, which are designed to contain a uniform seeding of cells from inner to outer layer in the wound structure, as reported elsewhere. The tubes undergo a crimping deformation when exposed to a magnetic field, similar to the deformation of peristalsis. The deformation creates both strains in the tube walls and fluid pumping through the walls, which are desired to promote cell proliferation and differentiation. In this paper, the physical properties of the electrospun sheets and the wound tubes are reported, including the magnitude of the displacements and the flux through the walls induced by a given magnetic field. A model is presented that can be used to predict the deformation and fluid flow for given field strength and material and geometrical parameters. The model can be used to optimize tube design and interpret measurements from future experiments on cell culture.