Dual Centrifugation-based Screening for pH-responsive Liposomes.

In liposomal drug delivery development, the delicate balance of membrane stability is a major challenge to prevent leakage (during shelf-life and blood circulation), and to ensure efficient payload release at the therapeutic destination. Our composite screening approach uses the processing by dual centrifugation technique to speed up the identification of de novo formulations of intermediate membrane stability. By screening binary lipid combinations at systemically varied ratios we highlight liposomal formulations of intermediate stability, what we termed "the edge of stability", requiring moderate stimuli for destabilization. Supplementation with a pH-sensitive cholesterol derivative (to obtain acid labile liposomes) and renewed assessment with cargo load led to the discovery of three formulations with sufficient shelf-life stability, acceptable cargo retention and efficient pH-responsive cargo release in vitro. The "lead candidates" exhibited promising in cellulo uptake with increased intracellular cargo release and revealed in vivo performance advantages compared to a control liposome. Our approach filters lipid compositions on "the edge of stability" that were introduced with a pH-sensitive cholesterol derivate leading pH-responsive liposomes, out of a multidimensional parameter space. Their discovery by rational approaches would have been highly unlikely, thus highlighting the potential of our screening approach.

Ultrasound diagnosis of an atypical axillary lesion.

We report on the case of a 41-year-old man with a recently diagnosed amelanotic ulcerated melanoma, with a Breslow thickness of 3.5 mm and Clark level IV. He had a pre-existing mass in the axilla, which had grown in parallel to the developing tumor. A large regional lymph node was clinically suspected. Ultrasound (US) examination of the axilla showed a large benign lipoma but also a very atypical peripheral perfusion. At the same time, a sentinel node showed a peripheral perfusion on US. Fine-needle aspiration cytology was performed of the different lesions and showed a melanoma metastasis in the sentinel node. Thereafter, a lymph node dissection was performed. The lipoma was seen in histopathology and even the peripheral perfusion was confirmed. US and US-guided fine-needle aspiration cytology can be easily applied in the diagnosis of lymph node metastases in melanoma patients and can help determine a benign or a malignant involvement.