Magnetically orientated tissue-equivalent tubes: application to a circumferentially orientated media-equivalent.

Circumferential orientation of collagen fibrils in a media-equivalent (ME) is achieved in a simple and effective way using the orientating effects of a strong magnetic field during collagen fibrillogenesis when the ME is first created. Circumferential orientation of the entrapped smooth muscle cells (SMC) is achieved subsequently via cell contact guidance, the induced SMC orientation along orientated fibrils. After describing the methods used, several lines of evidence are provided showing that the magnetically orientated ME is circumferentially orientated, including collagen birefringence, circumferential SMC orientation, accelerated ME compaction and increased ME stiffness with reduced creep in the circumferential direction as compared to control MEs not exposed to a magnetic field during fibrillogenesis. The optimization of these methods is discussed in order to better mimic the circumferential orientation and mechanical properties of a natural medium. Other applications of magnetically orientated tissue-equivalents are indicated.