Regression of Atherosclerotic Plaques of Cholesterol-Fed Rabbits by Combined Chemotherapy With Paclitaxel and Methotrexate Carried in Lipid Core Nanoparticles

In previous studies, it was demonstrated that lipid core nanoparticles (LDE) resemble the low-density lipoprotein structure and carrying the antiproliferative agent paclitaxel (PTX) strongly reduced atherosclerosis lesions induced in rabbits by cholesterol feeding. Currently, the aim was to verify whether combining LDE-PTX treatment with methotrexate (MTX) associated with LDE (LDE-MTX) could accelerate the atherosclerosis regression attained with single LDE-PTX treatment, after withdrawing the cholesterol feeding. Thirty-eight rabbits were fed 1% cholesterol chow for 8 weeks. Six of these rabbits were then euthanized for analyses of the aorta (controls). In the remaining rabbits, cholesterol feeding was withdrawn, and those 32 animals were allocated to 3 groups submitted to different 8-week intravenous treatments, all once/week: LDE-PTX (n = 10; 4 mg/kg), LDE-PTX + LDE-MTX (n = 11; 4 mg/kg), and LDE-alone (n = 11). Rabbits were then euthanized and aortas were excised for morphometric, immunohistochemical, and gene expression analyses. After cholesterol feeding withdrawal, in comparison with LDE-alone group, both LDE-PTX and LDE-PTX + LDE-MTX treatments had the ability to increase the regression of plaque areas: -49% in LDE-PTX and -59% for LDE-PTX + LDE-MTX. However, only LDE-PTX + LDE-MTX treatment elicited reduction in the intima area, estimated in -57%. Macrophage presence in aortic lesions was reduced 48% by LDE-PTX and 43% by LDE-PTX + LDE-MTX treatment. Matrix metalloproteinase 9 was reduced by either LDE-PTX (74%) or LDE-PTX + LDE-MTX (78%). Tumor necrosis factor gene expression was reduced 65% by LDE-PTX and 79% by LDE-PTX + LDE-MTX. In conclusion, treatment with LDE-PTX indeed accelerated plaque reduction after cholesterol feeding; LDE-PTX + LDE-MTX further increased this effect, without any observed toxicity. These results pave the way for the use of combined chemotherapy to achieve stronger effects on aggravated, highly inflamed atherosclerotic lesions.