关键词: 纳米探针, 易损斑块, 颈动脉套扎易损斑块模型

Abstract: Objective　Construction of a specific probe targeting triggering receptor expressed on myeloid cells-1 (TREM-1) for noninvasive in vivo precise identification of vulnerable plaques in mouse carotid arteries by fluorescence imaging.Methods　Synthesized specific nanoprobes targeting TREM-1. Thirty male apolipoprotein E knockout (ApoE-/-) mice were divided into carotid artery vulnerable plaque model group (AS group,n=20) and control group (n=10) based on whether unilateral carotid artery stenosis ring placement was performed and the type of diet administered. AS group mice underwent unilateral carotid artery stenosis ring placement and were fed a high-fat diet for 20-24 weeks. Afterward, six mice were randomly selected for in vivo fluorescence imaging. Based on the injected probe type, these mice were further divided into the AS+non-targeted nanoparticle group (AS+nNPs, n=3) and the AS+TREM 1-targeted nanoparticle group (AS+fNPs, n=3). Control mice received standard maintenance diet for the same duration. Subsequently, three mice were randomly selected for TREM-1-targeted nanoparticle injection (control+fNPs) followed by in vivo fluorescence imaging. This validated whether our constructed specific probes could accurately identify vulnerable plaques in vivo.Results　A specific molecular probe was successfully constructed, exhibiting uniform morphology under electron microscopy with a near-circular shape and a diameter of approximately 65 nm. In vitro fluorescence imaging demonstrates that the probe exhibits excellent near infrared region-Ⅱ (NIR-Ⅱ) luminescence capability. Following euthanasia, aortic vessels from AS group mice underwent gross oil red O staining.Results revealed extensive lipid plaques in the carotid arteries. Hematoxylin-eosin (HE), Masson’s trichrome, and oil red O staining of carotid arteries indicated substantial plaque formation beneath the intima, characterized by lipid-rich necrotic cores and reduced collagen content near the intima, meeting diagnostic criteria for vulnerable plaques. In vivo fluorescence imaging results demonstrated that, compared with the AS+nNPs group, mice in the AS+fNPs group exhibited significantly increased probe accumulation in the carotid artery region and markedly enhanced fluorescence signal intensity.The probe exhibited peak fluorescence intensity 3 h post-injection, with gradual attenuation thereafter,while faint fluorescence remained detectable at 24 h. In ApoE-/- mice fed standard chow and injected with TREM-1 targeted nanoprobes, no significant fluorescence signals were observed in the carotid artery region. The probes demonstrated no apparent toxic side effects on liver and kidney function, cardiac enzymes, or major organs.Conclusion　In vivo fluorescence imaging experiments in mice demonstrate that the specific probes in this study can accurately recognize arterial vulnerable plaques, exhibiting high sensitivity, a prolonged observation window, and excellent biosafety.

Key words: nanoprobe, vulnerable plaque, carotid sleeving vulnerable plaque model