Michael Doser

Hyaluronic acid/chitosan multilayer coatings on neuronal implants for localized delivery of siRNA nanoplexes.

Binding, stabilizing and promoting cellular uptake of siRNA are all critical efforts in creating matrices for the localized delivery of siRNA molecules to target cells. In this study, we describe the generation of chitosan imidazole/siRNA nanoplexes (NPs) embedded in nano scope polyelectrolyte multilayers (PEMs) composed of hyaluronic acid and chitosan for sustained and localized drug delivery. Regular PEM build-up, successful integration of NPs and controlled release under physiological conditions were shown. Biological efficacy was evaluated in neuronal cell culture concerning cell adhesion, viability, NPs uptake and gene silencing. The additionally shown biological functionalization of neuronal implants possesses potential for future applications in the field of regenerative medicine and treatment of spinal cord injuries.

Bioartificial reconstruction of peripheral nerves using the rat median nerve model.

Different bioartificial tubes were recommended for peripheral nerve reconstruction in the past. In order to replace autologous nerve grafts this materials are still under review in different animal studies. Most of them are dealing with the rodent peripheral nerves. One very popular animal model to study different materials is the rat median nerve model. With its easy excess, simple behavioral tests and reliable long term results it is attractive to many scientists in this field. This review gives an overview about the past, current and future options in this model for bioartificial nerve tubes. It summarizes the evolution of successful implantation of different materials across short nerve gaps and demonstrates the obstacles arising from long nerve gaps and the problems associated to them.

Kapillarmembranen aus modifizierten Polysulfonen

The transplantation of islets of Langerhans would be the optimal treatment of insulin dependent diabetes. For this purpose capillary membranes are developed which show good diffusion characteristics for glucose, essential nutrient and insulin but at the same time protect the xenogenic transplant from immune rejection of the host. Modified udel® and radel* polysulfones are used as membrane materials which show, because of the introduced hydrophilic groups, lower protein adsorption compared to the source material. By phase inversion technique capillary membranes with different membrane structures are produced and the diffusion characteristics of insulin are observed. Capillaries made of hydroxymethylated polysulfone, having a degree of substitution of 1.7 and a finger-like structure, prove to be ideal relative to insulin due to their almost immediate and very good diffusion properties for the further development of a bioartifical pancreas. A c B O m a t e r i a l i e n 2 (2/3), 2001 Anja Enderle: Kapillarmembranen aus modifizierten Polysulfonen ORIGINAL· ARBEITEN