A modular tissue engineering construct containing smooth muscle cells and endothelial cells

Human umbilical vein endothelial cells (HUVEC) were seeded on sub-mm sized collagen cylinders containing embedded umbilical vein smooth muscle cells (UVSMC). These cylindrical "modules" are intended to be used as a vascularized construct, in which HUVEC lined channels are created by the random packing of the modules in situ or within a larger container. Embedding UVSMC cultured in medium containing 10% FBS had an adverse effect on subsequently seeded HUVEC junction morphology; HUVEC/UVSMC co-culturing was done in HUVEC medium (2% FBS with the addition of 0.03 mg/mL endothelial cell growth supplement) as compared to HUVEC seeded on collagen-only modules. In contrast, embedding UVSMC cultured in serum-free medium prior to embedding improved EC junction morphology. Such serum-free culturing, also prevented the UVSMC induced contraction of the collagen modules. On the other hand, embedding serum-free cultured UVSMC promoted HUVEC proliferation and NO secretion compared to those modules embedded with 10% serum cultured UVSMC. These results suggest, not surprisingly, that embedded UVSMC phenotype plays an important role in the seeded HUVEC phenotype, and that the response can be modulated by the UVSMC culture medium serum concentration. These studies were undertaken with a view to using the UVSMC to modulate the thrombogenicity of the HUVEC. Exploration of this outcome awaits further studies directed to understanding the mechanism of the cellular interactions.