There is an urgent need to develop new therapeutic approaches for the treatment of severe neurological trauma, such as stroke and spinal cord injuries. However, many drugs with potential neuropharmacological activity, like adenosine, are inefficient upon systemic administration because of their fast metabolisation and rapid clearance from the bloodstream. Here, we show that the conjugation of adenosine to the lipid squalene and the subsequent formation of nanoassemblies allow a prolonged circulation of this nucleoside, to provide neuroprotection in mouse stroke and rat spinal cord injury models. The animals receiving systemic administration of squalenoyl adenosine nanoassemblies showed a significant improvement of their neurologic deficit score in the case of cerebral ischaemia, and an early motor recovery of the hindlimbs in the case of spinal cord injury. Moreover, in vitro and in vivo studies demonstrated that the nanoassemblies were able to extend adenosine circulation and its interaction with the neurovascular unit. This paper shows, for the first time, that a hydrophilic and rapidly metabolised molecule like adenosine may become pharmacologically efficient owing to a single conjugation with the lipid squalene.

The inhibition of the caspase-3 enzyme is reported to increase neuronal cell survival following cerebral ischemia. The peptide Z-DEVD-FMK is a specific caspase inhibitor, which significantly reduces vulnerability to the neuronal cell death. However, this molecule is unable to cross the blood-brain barrier (BBB) and to diffuse into the brain tissue. Thus, the development of an effective delivery system is needed to provide sufficient drug concentration into the brain to prevent cell death. Using the avidin (SA)-biotin (BIO) technology, we describe here the design of chitosan (CS) nanospheres conjugated with poly(ethylene glycol) (PEG) bearing the OX26 monoclonal antibody whose affinity for the transferrin receptor (TfR) may trigger receptor-mediated transport across the BBB. These functionalized CS-PEG-BIO-SA/OX26 nanoparticles (NPs) were characterized for their particle size, zeta potential, drug loading capacity, and release properties. Fluorescently labeled CS-PEG-BIO-SA/OX26 nanoparticles were administered systemically to mice in order to evaluate their efficacy for brain translocation. The results showed that an important amount of nanoparticles were located in the brain, outside of the intravascular compartment. These findings, which were also confirmed by electron microscopic examination of the brain tissue indicate that this novel targeted nanoparticulate drug delivery system was able to translocate into the brain tissue after iv administration. Consequently, these novel nanoparticles are promising carriers for the transport of the anticaspase peptide Z-DEVD-FMK into the brain.