Intranasal Administration of N-acetyl-L-cysteine Combined with Cell-Penetrating Peptide-Modified Polymer Nanomicelles as a Potential Therapeutic Approach for Amyotrophic Lateral Sclerosis

Abstract

Intranasal administration is a promising route for direct drug delivery to the brain; its combination with nanocarriers enhances delivery. We have previously shown that intranasal administration combined with PEG-PCL-Tat (a nanocarrier) efficiently delivers drugs to the brain and exhibits excellent therapeutic efficacy against brain diseases. We aimed to clarify whether intranasal administration combined with PEG-PCL-Tat represents a useful drug delivery system (DDS) for amyotrophic lateral sclerosis (ALS) pharmacotherapy. We used N-acetyl-L-cysteine (NAC) as a model drug with low transferability to the spinal cord and determined the physicochemical properties of NAC/PEG-PCL-Tat. After intranasal administration of NAC/PEG-PCL-Tat, we measured the survival duration of superoxide dismutase-1 G93A mutant transgenic mice (G93A mice), widely used in ALS studies, and quantitatively analyzed the tissue distribution of NAC/PEG-PCL-Tat in ddY mice. The mean particle size and zeta potential of NAC/PEG-PCL-Tat were 294 nm and + 9.29 mV, respectively. Treatment with repeated intranasal administration of NAC/PEG-PCL-Tat considerably prolonged the median survival of G93A mice by 11.5 days compared with that of untreated G93A mice. Moreover, the highest distribution after a single administration of NAC/PEG-PCL-Tat was measured in the spinal cord. These results suggest that intranasal administration combined with PEG-PCL-Tat might represent a useful DDS for ALS therapeutics.

Keywords: N-acetyl-L-cysteine; nanocarrier; neurodegeneration; nose-to-brain; spinal cord.

Figure 1

Lifespan of G93A mice treated with intranasal administration of NAC/PEG-PCL-Tat. G93A mice were treated with NAC-IP (1 mg), NAC-IN (1 mg), PEG-PCL-Tat (IN), 0.2NAC/PEG-PCL-Tat (IN; 0.2 mg), or NAC/PEG-PCL-Tat (IN; 1 mg), starting at a late symptomatic stage (15 weeks old). (A) Survival curves were analyzed using Kaplan–Meier survival analysis with the log-rank test; (B) The graph shows the lifespan comparative result. The values are presented as mean ± SD. Statistical significance was determined using one-way ANOVA followed by Tukey’s post hoc test. * p < 0.05, ** p < 0.01, and *** p < 0.001.

Figure 2

Concentration-time profiles of [¹⁴C]-NAC in plasma after a single intranasal administration to ddY mice and the area under the plasma concentration time curve (AUC). (A) Plasma was obtained from the blood collected at the designated time after the intranasal administration of [¹⁴C]-NAC (○) or [¹⁴C]-NAC/PEG-PCL-Tat (●). The %ID in mL plasma represents the ratio of the distribution in plasma to the dosing volume of an intranasally administered drug. Values represent the mean ± SE (n = 6 or 7); (B) AUC_0–90 was calculated using a linear trapezoidal method and values for plasma concentration to the last time point (t = 90 min) were obtained. Values represent the mean ± SE (n = 6 or 7). The significant differences in mean plasma concentrations at the same time or AUC_0–90 between the two groups were analyzed using a t-test.

Figure 3

Tissue distribution of [¹⁴C]-NAC after a single intranasal administration to ddY mice. Each tissue, CSF, or plasma sample was collected 60 min after the intranasal administration of [¹⁴C]-NAC or [¹⁴C]-NAC/PEG-PCL-Tat. (A–C) The opened and closed columns represent [¹⁴C]-NAC and [¹⁴C]-NAC/PEG-PCL-Tat, respectively. Each column presents the mean ± SE (n = 10 or 11). Significance was assessed using a t-test.