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Paclitaxel (PTx) is reported to have an nonuniform steady-state concentration profile in the arterial wall. We utilized epifluorescence microscopy to make precise measurements of fluorescently-labeled PTx (F-PTx) distribution through an in vitro tissue mimic which contained varying concentrations of fibrin, elastin, soybean oil, palmitic acid, and solid glass beads. As little as 0.5 mg/mL of elastin in agarose produced a 50% drop in the measured diffusion coefficient, while as much as 10 mg/mL of fibrin in agarose was required for the same reduction in rate of transport. Because no reduction in the measured diffusion coefficient was observed for solubilized, extracted elastin or unassembled elastin-like polypeptides, the effect was specific to elastic fibers that closely resembled the native elastin network. Collectively, this work identifies a potential source for the high degree of partitioning observed for PTx in native tissue and further develops an in vitro technique for exploring complex tissue−drug interactions. [ABSTRACT FROM AUTHOR]

Bone marrow stromal cells (MSCs) are a promising cell source for a variety of tissue engineering applications, given their ready availability and ability to differentiate into multiple cell lineages. MSCs have been successfully used to create neotissue for cardiovascular, urological, and orthopedic reconstructive surgical procedures in preclinical studies. The ability to optimize seeding techniques of MSCs onto tissue engineering scaffolds and the ability to control neotissue formation in vitrowill be important for the rational design of future tissue engineering applications using MSCs. In this study we investigated the effect of centrifugal force on seeding MSCs into a biodegradable polyester scaffold. MSCs were isolated and seeded onto porous scaffold sections composed of nonwoven polyglycolic acid mesh coated with poly(L-lactide-co--caprolactone). Compared to standard static seeding techniques, centrifugal seeding increased the seeding efficiency by 38 (p< 0.007) and significantly improved cellular distribution throughout the scaffold. Overall, centrifugal seeding of MSCs enhances seeding efficiency and improves cellular penetration into scaffolds, making it a potentially useful technique for manipulating neotissue formation by MSCs for tissue engineering applications. [ABSTRACT FROM AUTHOR]