Safety assessment in rats and dogs of Acoustic Cluster Therapy, a novel concept for ultrasound mediated, targeted drug delivery.

Acoustic Cluster Therapy (ACT) represents a novel concept for targeted drug delivery. Ultrasound is applied to activate intravenously administered free-flowing clusters of microbubbles and microdroplets within the target pathology, depositing 20-30 µm large bubbles in the microvasculature for 5-10 min. Further application of ultrasound induces biomechanical effects which increase vascular permeability and enhance localized extravasation of coadministered drugs. Herein we report investigations done to assess the preclinical safety of ACT, using doses up to 1 mL/kg (3 µL perfluoromethyl-cyclopentane/kg). In dogs, half the animals were exposed to ultrasound activation in the heart for 1 min, no ultrasound was applied in the other half. Posttreatment observation time was 24 h. Clinical signs, ophthalmoscopy, clinical pathology, macro-, and microscopy were used as endpoints. No differences between groups with and without ultrasound activation were observed. Short-lasting leukopenia and thrombocytopenia, possibly secondary to a slight and short-lasting increase in plasma histamine and complement split products, were the only effects noted. In rats ACT was activated in the liver for 5 min. Histopathology and clinical chemistry parameters remained unchanged. Lastly, rats were treated with ACT activated in the heart and thereafter placed on a rotarod for evaluation of motor coordination. No differences were observed between animals treated with ACT and controls. In conclusion, ACT appeared safe at dose-levels up to 1 mL/kg and with activation either in the heart or the liver. These results, together with positive efficacy data upon coinjection with cytotoxic compounds encourage further preclinical safety studies with the objective of entering subsequent clinical trials.

Abnormal B cell differentiation in primary Sjögren's syndrome results in a depressed percentage of circulating memory B cells and elevated levels of soluble CD27 that correlate with Serum IgG concentration.

The percentage of CD27(+) B cells in peripheral blood (PB) of patients with primary Sjögren's syndrome (pSS) is significantly decreased compared to normals. In contrast, serum levels of the soluble form of CD27 (sCD27) are significantly higher in pSS patients, with a strong positive correlation between sCD27 and serum IgG levels. In vitro experiments demonstrate that normal B cells cultured under conditions driving plasma cell differentiation result in the production of substantial amounts of sCD27. Analyses of V(H)-region genes from sorted CD27(+) and CD27(-) B cells from pSS patients confirm that the CD27(+) population corresponds to the somatically mutated memory compartment, as in healthy individuals. Together our data indicate that in pSS, there is an abnormal differentiation of B cells to plasma cells resulting in a depression of the circulating memory B-cell pool and the release of significant amounts of sCD27 and IgG.