Dynamic flow alterations dictate leukocyte adhesion and response to endovascular interventions.

Although arterial bifurcations are frequent sites for obstructive atherosclerotic lesions, the optimal approach to these lesions remains unresolved. Benchtop models of arterial bifurcations were analyzed for flow disturbances known to correlate with vascular disease. These models possess an adaptable geometry capable of simulating the course of arterial disease and the effects of arterial interventions. Chronic in vivo studies evaluated the effect of flow disturbances on the pattern of neointimal hyperplasia. Acute in vivo studies helped propose a mechanism that bridges the early mechanical stimulus and the late tissue effect. Side-branch (SB) dilation adversely affected flow patterns in the main branch (MB) and, as a result, the long-term MB patency of stents implanted in pig arteries. Critical to this effect is chronic MB remodeling that seems to compensate for an occluded SB. Acute leukocyte recruitment was directly influenced by the changes in flow patterns, suggesting a link between flow disturbance on the one hand and leukocyte recruitment and intimal hyperplasia on the other. It is often impossible to simultaneously maximize the total cross-sectional area of both branches and to minimize flow disturbance in the MB. The apparent trade-off between these two clinically desirable goals may explain many of the common failure modes of bifurcation stenting.

Number-concentration of nanoparticles in liposomal and polymeric multiparticulate preparations: empirical and calculation methods.

The actual number of particles in formulations of nanoparticles (NP) is of importance for quality assurance, comprehensive physicochemical characterization, and pharmacodynamics. Some calculation methods that have been previously employed are limited because they rely on several assumptions and are not applicable for certain preparations. Currently there are no validated experimental methods for determining the particle number-concentration (Nc) of liposomal and polymeric nanoparticulate preparations (<500 nm). This study examines a new empirical method for counting the number of particles in nanoparticulate formulations including drug-containing liposomes and polymeric NP. In the new method, suspended NP are nebulized to form aerosol droplets which are dried and counted using a scanning mobility particle sizer (SMPS). Experiments were conducted with three different preparations, empty liposomes (200 and 400 nm), drug-loaded liposomes (200 nm), and polymeric NP (150 nm). It was verified that no detrimental morphological or structural changes of the formulations have been induced by the SMPS technique, and that the obtained Nc values represent the original particles. It is concluded that nano-formulations with concentrations of up to 10(7) particles per 1 cm3 air, corresponding to approximately 10(12) particles per 1 ml solution, can be directly counted within the size range of 30-900 nm. The measured values are compared to newly developed theoretical calculations to assess the viability of these calculations.

Technical advance: liposomal alendronate depletes monocytes and macrophages in the nonhuman primate model of human disease.

Nonhuman primates are critical animal models for the study of human disorders and disease and offer a platform to assess the role of immune cells in pathogenesis via depletion of specific cellular subsets. However, this model is currently hindered by the lack of reagents that safely and specifically ablate myeloid cells of the monocyte/macrophage Lin. Given the central importance of macrophages in homeostasis and host immunity, development of a macrophage-depletion technique in nonhuman primates would open new avenues of research. Here, using LA at i.v. doses as low as 0.1 mg/kg, we show a >50% transient depletion of circulating monocytes and tissue-resident macrophages in RMs by an 11-color flow cytometric analysis. Diminution of monocytes was followed rapidly by emigration of monocytes from the bone marrow, leading to a rebound of monocytes to baseline levels. Importantly, LA was well-tolerated, as no adverse effects or changes in gross organ function were observed during depletion. These results advance the ex vivo study of myeloid cells by flow cytometry and pave the way for in vivo studies of monocyte/macrophage biology in nonhuman primate models of human disease.