Mechanisms of stiffening and strengthening in media-equivalents fabricatedusing glycation

We have recently reported that glycation can be exploited to increase the c ircumferential tensile stiffness and ultimate tensile strength of media-equ ivalents (MEs) and increase their resistance to collagenolytic degradation, all without loss of cell viability (Girton et at., 1999). The glycated MEs were fabricated by entrapping high passage adult mt aorta SMCs in collagen gel made from pepsin-digested bovine dermal collagen, and incubated for up to 10 weeks in complete medium with 30 mM ribose added. We report hei-e on experiments showing that ME compaction due to traction exerted by the SMCs with consequent alignment of collagen fibrils was necessary to realize the glycation-mediated stiffening and strengthening, but that synthesis of ext racellular matrix constituents by these cells likely contributed little, ev en wizen 50 mug/ml ascorbate was added to the medium. These glycated MEs ex hibited a compliance similar to arteries, brit possessed less tensile stren gth and much less burst strength. MEs fabricated with low rather than high passage adult rat aorta SMCs possessed almost ten times greater tensile str ength, suggesting that alternative SMCs sources and biopolymer gels may yie ld sufficient strength by compositional remodeling prior to implantation in addition to the structural remodeling (ie., circumferential alignment) alr eady obtained.