OBJECTIVE  To investigate an aromatic liposome containing icariin(ICA)(ICA-BO@Lips) and to evaluate its cognitive improvement and neuroprotective effects in mice models of Alzheimer’s disease(AD).

METHODS  ICA-BO@Lips was prepared by thin film dispersion method. Particle size, polydispersity index(PDI), potential and appearance of aromatic liposomes were detected by particle size analyzer and electron microscopy. The drug loading and encapsulation rate of ICA were determined by HPLC. The mRNA expression levels of inflammatory factors, including TNF-α, IL-1β, IL-12A, COX-2, NOS2, and IL-6, in microglia treated with 0.1, 1.0, 10.0 μmol·L⁻¹ ICA-BO@Lips were detected by RT-PCR. APP/PS1 mice were selected as the AD animal model. The cognitive function of the AD animal model and the related mechanism were comprehensively analyzed by the behavioral and pathological sections after injection into the tail vein 20 mg·kg⁻¹ ICA-BO@Lips. The behavior of mice was investigated by Morris water maze and nesting tests. HE staining, Nissl staining and immunohistochemical analysis were performed on mice brain sections, and HE staining was also performed on major organs, including the heart, liver, spleen, lung and kidney.

RESULTS  The measured ICA-BO@Lips particle size was (105.54±1.31)nm, PDI was 0.22±0.028, and potential was (−16.88±1.24)mV, indicating that the liposome was uniformly dispersed and negatively charged on its surface. Transmission electron microscopy showed that the liposome was smooth and spherical without adhesion. The drug loading capacity and encapsulation rate of ICA measured by HPLC were (2.10±0.024)% and (77.88±0.32)%, respectively. The RT-PCR test results showed that 10 μmol·L⁻¹ ICA-BO@Lips could significantly inhibit the mRNA expression of inflammatory cytokines in microglia. The results of Morris water maze and nesting experiment showed that 20 mg·kg⁻¹ ICA-BO@Lips significantly improved the cognitive function of AD mice. HE staining, Nissl staining and immunohistochemistry results showed that, 20 mg·kg⁻¹ ICA-BO@Lips can reduce the deposition of Aβ, protect the morphology of neurons, increase the level of BDNF in hippocampus and cortex, regulate the expression of pro-apoptotic protein Bax, Caspase-3 and anti-apoptotic protein Bcl-2 and other related factors. There were no obvious pathological changes to major organs, showing a good safety.

CONCLUSION  ICA-BO@Lips developed in this study shows significant cognitive improvement and neuroprotective effects in AD animal models, which has potential clinical application value.