Impact of hyaluronic acid-modified hafnium metalorganic frameworks containing rhynchophylline on Alzheimer's disease

Abstract

Rhynchophylline (Rhy) is an attractive candidate, harboring ameliorative effects on Alzheimer's disease (AD). Nevertheless, its application is impeded by its low water solubility and poor bioavailability. Here we synthesized and characterized the Rhy-loaded hyaluronic acid-modified hafnium metal-organic frameworks (HA@Rhy@Hf-MOF). The drug release profiles of free Rhy from HA@Rhy@Hf-MOF were evaluated, and the cellular toxicity was assessed through Cell Counting Kit-8 (CCK-8) assay. In vivo experiments included behavioral experiments of various murine capabilities, with neuronal damage appraised through Hematoxylin and Eosin staining and Nissl staining. Subsequently, the formation of AD-related amyloid beta (Aβ) plaques formation and Tau phosphorylation were measured. The HA@Rhy@Hf-MOF with spherical shape were presented as uniformly dispersed and with a negative charge, exhibiting a pronounced pharmacological sustained-release effect and minimal cellular toxicity. Findings from the Morris water maze test, novel object recognition test, and elevated plus maze test substantiated that HA@Rhy@Hf-MOF effectively mitigated cognitive deficiency and anxiety, and enhanced spatial learning in AD mice. Immunofluorescence staining and Western blot both illustrated that HA@Rhy@Hf-MOF could attenuate hippocampal Aβ formation and deposition, as well as tau hyperphosphorylation. In conclusion, HA@Rhy@Hf-MOF exerts its therapeutic efficacy against AD by targeting the deposition of Aβ plaques and inhibiting site-specific phosphorylation of Tau.

Keywords: Alzheimer’s disease; Rhynchophylline; amyloid beta; metal-organic frameworks; neurodegenerative disorder; tau protein phosphorylation.

Figure 1

Synthesis and anti-AD activity research of HA@Rhy@Hf-MOF. BBB: blood–brain barrier.

Figure 2

Characterization of HA@Rhy@Hf-MOF. (a) The morphology of Hf-MOF and HA@Rhy@Hf-MOF determined by TEM. (b) The zeta potential of Hf-MOF and HA@Rhy@Hf-MOF measured via zeta potential analyzer. (c) The average particle size distribution. (d) seven-day average particle size of Hf-MOF and HA@Rhy@Hf-MOF evaluated with nanoparticle size analyzer. (e) The crystal structures of Hf-MOF and HA@Rhy@Hf-MOF detected by XRD. (f) Drug release rate of Rhy with/without nanomaterial encapsulation. (g) Cell viabilities were assessed using CCK-8 assay following 24-h incubation with varying concentrations of Rhy, Hf-MOF, and HA@Rhy@Hf-MOF, respectively. The ANOVA results show: (Rhy), F (4, 25) = 2.896; (Hf-MOF), F (4, 25) = 1.822; (HA@Rhy@Hf-MOF), F (4, 25) = 1.752. N = 6.

Figure 3

Behavioral experimental indicators in mice. (a)–(d) The MWM test is used to assess the learning and memory capabilities of mice. (e) and (f) The NOR test is used to evaluate the cognitive memory ability of mice. (g) The EPM test is used to assess the impact of anxiety on mice. The ANOVA results show: (b) F (4, 25) = 18.04; (c) F (4, 25) = 23.31; (d) F (4, 25) = 46.68; (f) F (4, 25) = 13.48, and G (4, 25) = 15.62. N = 6. ***P < 0.001 vs Control; ^# P < 0.05, ^## P < 0.01, ^### P < 0.001 vs AD.

Figure 4

Pathomorphological examination of the mice hippocampus. (a) HE staining and (b) and (c) Nissl staining are used to observe neuropathological changes in neural tissue; N = 3.

Figure 5

Aβ plaques deposition in mice hippocampus. (a) IF staining and (b) Western blot are used to detect the expression levels of Aβ in mouse hippocampal tissue. The ANOVA results show: (a) F (4, 25) = 32.28; (b) F (4, 25) = 59.83. N = 3. ***P < 0.001 vs Control; ^## P < 0.01, ^### P < 0.001 vs AD.

Figure 6

The hippocampal protein levels of total Tau and phosphorylated Tau at several sites, including Ser396, Ser202, and Thr231 determined by Western blot. The ANOVA results show that for (p-Ser396): F (4, 25) = 57.78; (p-Ser202): F (4, 25) = 51.89; (p-Thr231): F (4, 25) = 66.75. ***P < 0.001 vs Control; ^## P < 0.01, ^### P < 0.001 vs AD. N = 3.