Substantial expression of mature elastin in arterial constructs

, doi:10.1073/pnas.1017834108

Mature elastin synthesis is a key challenge in arterial tissue engineering. Most engineered vessels lack elastic fibers in the medial layer and those present are poorly organized. The objective of this study is to increase mature elastin synthesis in small diameter arterial constructs. Adult primary baboon smooth muscle cells (SMC) were seeded in the lumen of porous tubular scaffolds fabricated from a biodegradable elastomer, poly (glycerol sebacate) (PGS) and cultured in a pulsatile flow bioreactor for 3 weeks. We tested the effect of pore sizes on construct properties by histological, biochemical, and mechanical evaluations. Histological analysis revealed circumferentially organized extracellular matrix proteins including elastin and the presence of multilayered SMCs expressing calponin and alpha smooth muscle actin. Biochemical analysis demonstrated that the constructs contained mature elastin equivalent to 19% of the native arteries. Mechanical tests indicated that the constructs could withstand up to 200 mmHg burst pressure and exhibited compliance comparable to native arteries. These results show that nontransfected cells in PGS scaffolds in unsupplemented medium produced a substantial  amount of mature elastin within 3 week and the elastic fibers has similar orientation as those in native arteries. The 25-32 micro meter pore size supported cell organization and elastin synthesis more than larger pore sizes. To our knowledge, there was no prior report of the synthesis of mature and organized elastin in arterial constructs without exogenous factors or viral transduction.