Novel agents for mucosal delivery of sirrna

Aim of the project: The project will provide fundamental understanding to underpin the design and early development of delivery platform for siRNA therapy based on compounds of interest to the industrial sponsor and suggest potential modifications in the chemistry of these compounds. Background to the project: Due to their physicochemical properties, therapeutic nucleic acids (including siRNA) applied externally are not efficiently and spontaneously internalized and processed by targeted cells spontaneously. Consequently the effectiveness of these agents is currently very low. The lack of efficient delivery systems is believed to be the main obstacle in the development of siRNA therapeutics [1]. New and effective delivery systems are therefore essential. Mucosal surfaces in the nose and lung are particularly important as locations of siRNA targets against viral infections and hence this project sits at the centre of extensive research activities [2]. Desired outcomes of the proposed project are to achieve proof of the concept and assessment of development potential of patented compounds belonging to Archimedes in formulating a mucosal siRNA delivery platform. Phase 1. Biophysical characterisation of siRNA delivery systems: The biophysical characterisation will assess the ability of the Archimedes' compounds to produce stable formulations in a colloidal size appropriate for cellular internalization and capable of efficiently incorporating siRNA. It will apply a combination of routine and state of the art 'nanotechnology' analytical techniques including: particle size and distribution, zeta potential, morphology (TEM and cryo-TEM). Further analysis of promising systems will include electrophoretic methods in conjunction with fluorescent intercalation, melting temperature (Tm) and atomic force microscopy in liquid [3}. These assessments will provide the required detailed information on the biophysical properties of the systems to suggest appropriate chemical modifications. The promising systems will be assessed for stability and maintenance of activity in biologically relevant media. 'Developability' of the product, by analogy with the early development stage of pharmaceutical formulation, will consider long term colloidal stability, chemical stability to degradation and lyophilisation to produce a dry powder formulation. Phase 2. Cellular uptake The aim of this phase of the project is to use established epithelial cell culture models to assess the level of cellular internalization and silencing. Cell cultures representative of nasal and lung epithelium will be used; monolayers of Calu3 and HBEC cells, generally considered as the most appropriate lower and upper airway epithelial cell models [4]. Phase 3. Silencing effect in vitro and in vivo biodistribution of candidate systems The end point efficiency (silencing effect) of the siRNA delivery systems will be assessed by measuring reduction in mRNA and resulting down-regulation of protein levels of GAP-DH, APRT and rpl32 genes (available primers and commercial kits). In vivo assessment of candidate systems will focus on the assessment of the delivery potential of the technology. It will be based on the complementary expertise of Archimedes' research team (nasal delivery) and the academic partner. Currently, the academic partner has a home office licence which will allow the biodistribution of radiolabelled nucleic acids to be determined in normal rat or mouse models. This will allow the delivery of RNA to a target tissue to be determined. References 1. Whitehead KA, Langer R and Anderson DG. Nature Reviews Drug Discovery 8 (2009) 516. 2. Durcan N et al. Molecular Pharmaceutics 5 (2008) 559. 3. eg Davies O et al. (S Stolnik) Langmuir 24 (2008) 7138, Chim YTA et al (S Stolnik) Langmuir 21 (2005) 3591-3598. 4. Forbes B and Ehrhardt C Eur J Pharm and Biopharm 60 (2005) 193.