Figure1: In-vitro release of rapamycin from ReGel. The release rate is relatively constant over 45 days with no significant initial burst release. Each data point represents the mean ± SD of 3 experiments.

Table 1: The in vitro drug release parameters of Dipyridamole and Rapamycin from ReGel and ReGel with microspheres.

Figure2: Uptake and release of rapamycin in human venous SMCs. The rate of uptake is faster than the rate of release. In addition, release is extended because rapamycin likely binds within the cell. Each data point represents the mean ± SD of 3 experiments.

Table 2: Pharmacokinetic parameters for uptake and release of rapamycin in human venous SMCs.

C_initial: initial rapamycin concentration in the medium; k_u: uptake rate constant; k_r, release rate constant; Q10, the factor by which the cellular drug concentration at steady state increases as the temperature is raised by 10°C. Each value represents the mean ± SD of 3 experiments

Figure3: Antiproliferative effect and toxicity of rapamycin in (A) human venous SMCs and (B) porcine venous SMCs. The results show that the in-vitro efficacy and therapeutic index is not different between these two cell models. Each data point represents the mean ± SD of 6 experiments.

Table 3: Pharmacodynamic parameters for antiproliferative effect and toxicity of rapamycin in human and porcine venous and arterial SMCs.

EC₅₀, concentration of rapamycin that produces 50% of the maximal antiproliferative Effect; LC₅₀: concentration of rapamycin that induces 50% of the maximal toxicity; therapeutic index, ratio of LC₅₀ to EC₅₀. Each value represents the mean ± SD of 6 experiments. * P < 0.05 vs. corresponding value in venous SMCs of the same species.

Figure4: The impact of rapamycin on venous smooth muscle cells after it was released from ReGel in-vitro. (A) Rapamycin shows a dose-dependent inhibitory activity on the proliferation of human and porcine venous SMCs. (B) The inhibitory activity of rapamycin (10 ng/mL) released from ReGel compared the drug directly from the vial diluted to the same concentration. ReGel does not alter rapamycin’s ability to inhibit SMCs. Samples of the plain culture medium alone was used as a control. Each data point represents the mean ± SD of 6 experiments. The smooth muscle growth medium was supplemented with 10% fetal calf serum, 5 μg/ml insulin, 0.5 ng/ml human recombinant epidermal growth factor (EGF), 2 ng/ml human recombinant fibroblast growth factor (FGF), 50 μg/ml gentamicin and 50 ng/ml amphotericin-B.