Monoolein-based nanoparticles for drug delivery to the central nervous system: A platform for lysosomal storage disorder treatment

Abstract

Lysosomal Storage Disorders (LSDs) are characterized by an abnormal accumulation of substrates within the lysosome and comprise more than 50 genetic disorders with a frequency of 1:5000 live births. Nanotechnology may be a promising way to circumvent the drawbacks of the current therapies for lysosomal diseases. The blood circulation time and bioavailability of the enzymes or drugs could be improved by inserting them in nanocarriers, which could decrease and/or avoid the need of frequent intravenous infusions along with the minimization or elimination of associated immunogenic responses. Considering the exposed, we aimed to build monoolein-based nanoparticles stabilized by polysorbate 80 as a smart platform able to reach the central nervous system (CNS) to deliver drugs or enzymes inside lysosomes. We developed and characterized the nanoparticles by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (Cryo-TEM). The nanoparticles showed a diameter of 115 nm, which is compatible with in vivo application. The SAXS patterns of the formulations displayed a single broad correlation peak that was fitted to the Teubner-Strey model confirming that disordered bicontinuous structures were obtained. Cryo-TEM images corroborated this finding and showed nanoparticles with size values that are similar to those determined by DLS. Furthermore, the nanoparticles did not present cytotoxicity when they were incubated with human fibroblasts, and demonstrated hemolytic activity proportional to the negative control, proving to be safe for parenteral administration. Through the use of a fluorescent dye to track the nanoparticles inside the cell, we demonstrated that they reached lysosomes after 1 h of treatment. More interestingly, the fluorescent dye was detected in the CNS of mice just after 3 h of treatment. The nanoparticles show great potential to improve the treatment of LSDs with brain impairment, acting as a smart platform to targeted delivery of drugs or enzymes.

Keywords: Brain; Coumarin-6; Lysosomal storage disorders; Lysosome targeting; Monoolein; Nanoparticles.