Development of a “nose-to-brain” theranostic formulation of nanobodies for Alzheimer ‘s disease. – NoToBAlz

The overall aim of the NoToBAlz project is to develop an innovative theranostic approach, gathering a new nanobody-based strategy (i.e. small functional fragments of heavy chain antibodies), a straightforward route of administration (i.e. nose to brain) and an adapted molecules delivery system (i.e. thermogels) to improve the chances of success for Alzheimer's diagnosis and treatment. The molecular weight of nanobodies is about 15 kDa, 10 times smaller than that of a full-size Ig, and therefore corresponds to the smallest antigen-binding fragment possible. The nose-to-brain route is an innovative method that allows a direct access to the central nervous system, through the cribriform plate of the ethmoid bone, after a simple nasal administration. The consortium associates 3 highly complementary partners having the expertise to fulfill the project goals. It comprises specialists in encapsulation of fragile drug in polymeric drug delivery systems adapted to cross biological barrier, specialists in basic and preclinical aspects of Alzheimer disease and MR imaging and in nanobodies engineering. Monomers and innovative dimers (2 nanobodies linked by a peptidic linker) of R3VQ and A2 will be produced and engineered. Gadolinium conjugates will be prepared by specific site conjugation via the addition of a C-ter Cysteine to the nanobodies. Various thermogels will be prepared and characterized. The quantity of nanobodies able to cross the nasal mucosae after intranasal administration will be determined in mice (APPxPS1-Ki) by immunohistochemistry on brain sections and ELISA dosages on brain extracts. Neuroimaging performances of nanobodies conjugated to standard contrastophore (gadolinium, obtained and characterized) will be evaluated (MRI detection at 11.7 T). Finally, in the animal models, we will also evaluate if nanobodies are able to promote reduction of lesions loads, to recover cell-synaptic densities and to improve learning & memory functions.