A human tissue-engineered vascular media: a new model for pharmacological studies of contractile responses

Our method for producing tissue-engineered blood vessels based exclusively on the use of human cells, i.e., without artificial scaffolding, has previo usly been described (1). In this report, a tissue-engineered vascular media (TEVM) was specifically produced for pharmacological studies from cultured human vascular smooth muscle cells (VSMC). The VSMC displayed a differenti ated phenotype as demonstrated by the re-expression of VSMC-specific marker s and actual tissue contraction in response to physiological stimuli. Becau se of their physiological shape and mechanical strength, rings of human TEV M could be mounted on force transducers in organ baths to perform standard pharmacological experiments. Concentration-response curves to vasoconstrict or agonists (histamine, bradykinin, ATP, and UTP) were established, with or without selective antagonists, allowing pharmacological characterization o f receptors (H-1, B-2, and P-2Y1, and pyrimidinoceptors). Sustained agonist -induced contractions were associated with transient increases in cytosolic Ca2+ concentration, suggesting sensitization of the contractile machinery to Ca2+.ATP caused both Ca2+ entry and Ca2+ release from a ryanodine- and c affeine-sensitive store. Increased cyclic AMP or cyclic GMP levels caused r elaxation. This human TEVM displays many of functional characters of the no rmal vessel from which the cells were originally isolated, including contra ctile/relaxation responses, cyclic nucleotide sensitivity, and Ca2+ handlin g mechanisms comparable to those of the normal vessel from which the cells were originally isolated. These results demonstrate the potential of this h uman model as a versatile new tool for pharmacological research.