Histopathological nerve and skeletal muscle changes in rats subjected to persistent insulin-induced hypoglycemia.

New insulin analogues with a longer duration of action and a flatter pharmacodynamic profile are developed to improve convenience and safety for diabetic patients. During the nonclinical development of such analogues, safety studies must be conducted in nondiabetic rats, which consequently are rendered chronically hypoglycemic. A rat comparator model using human insulin would be valuable, as it would enable differentiation between effects related to either persistent insulin-induced hypoglycemia (IIH) or a new analogue per se. Such a model could alleviate the need for an in-study-comparator and thereby reduce the number of animals used during development. Thus, the aims of the present study were i) to develop a preclinical animal model of persistent hypoglycemia in rats using human insulin infusion for four weeks and ii) to investigate histopathological changes in sciatic nerves and quadriceps femoris muscle tissue, as little is known about the response to persistent hypoglycemia in these tissues. Histopathologic changes in insulin-infused animals included axonal degeneration and myofibre degeneration. To our knowledge, this is the first study to show that persistent IIH provokes peripheral nerve and skeletal myofiber degeneration within the same animals. This suggests that the model can serve as a nonclinical comparator model during development of long-acting insulin analogues.

Posintro™-HBsAg, a modified ISCOM including HBsAg, induces strong cellular and humoral responses.

To improve the hepatitis B vaccines on the market new adjuvant systems have to substitute aluminium. In this study the hepatitis B surface antigen (HBsAg) was incorporated into a novel adjuvant system, the Posintro™, a modification of the traditional immune stimulatory complexes (ISCOMs). This new HBsAg vaccine formulation, Posintro™-HBsAg, was compared to two commercial hepatitis B vaccines including aluminium or monophosphoryl lipid A (MPL) and the two adjuvant systems MF59 and QS21 in their efficiency to prime both cellular and humoral immune responses. The Posintro™-HBsAg induced the strongest humoral response with high titers of HBsAg specific antibody, high number of antigen specific B-cells and a strong T helper 1 (Th1) antibody profile when compared to the other adjuvant formulations. The Posintro™-HBsAg was also a strong inducer of cellular immune responses with induction of delayed type hypersensitivity (DTH) reaction and CD4(+) T-cell proliferation. In addition, Posintro™-HBsAg was the only vaccine tested that also induced a strong cytotoxic T lymphocyte (CTL) response, with high levels of antigen specific CD8 T-cells secreting IFN-gamma mediating cytolytic activity. The results demonstrate that this novel experimental vaccine formulation, the Posintro™-HBsAg, is strongly immunogenic and can induce both class I and class II responses in experimental animals. This shows promise both for the protection against hepatitis B virus infection and as a potential therapeutic vaccine.

Solid lipid nanoparticles can effectively bind DNA, streptavidin and biotinylated ligands.

Cationic solid lipid nanoparticles (SLN) have recently been suggested for non-viral gene delivery, as these particles consist of well tolerated substances, can bind DNA directly via electrostatic interactions and mediate gene transfer in vitro. We here report the development of SLN complexes, which can be targeted to specific surface receptors. A formulation of SLN was prepared by the microemulsion technique comprising of stearylamine and the matrix lipid Compritol ATO 888 with a size of approximately 100 nm and a zeta-potential of +15. These SLN are able to condense DNA in complexes, which are very stable under physiological conditions, and they display low cytotoxicity in cell culture. In addition to binding of DNA, the SLN can simultaneously bind substantial amounts of streptavidin directly via electrostatic interactions. The SLN:DNA: streptavidin complexes are stable and are capable of binding biotinylated ligands, which can interact with surface receptors. This method allows for development of a fast and simple method of preparing a targeted non-viral gene therapy vector.