The development of atherosclerotic plaque in blood vessel walls, narrowing and weakening those vessels, is a universal phenomenon in older people. It is worse in people with generally worse health, as it is driven by inflammation. Greatly reducing cholesterol carried from the liver to the rest of the body via LDL particles in the bloodstream slows the growth of plaque, but growth remains an inevitability on some time frame. Unfortunately the same can be said for reducing inflammation. Large plaques become unstable and rupture, and this kills a quarter of our species via heart attack and stroke.
Plaque growth occurs because the plaque environment is toxic, harmful to the macrophage cells that arrive from nearby tissue or the bloodstream in order to try to clean up the damage. The macrophages become overwhelmed and die, adding their mass to the plaque. Lowering LDL cholesterol slows plaque growth by reducing one of the inputs to this toxicity, but cannot on its own fix existing damage or entirely halt the process of plaque development and growth. Any true solution to atherosclerosis must function by in some way protecting macrophages from the plaque environment, or dramatically reducing the toxicity of the plaque environment. Only when macrophages can work unimpeded can plaque and a damaged vessel be repaired.
Many possible approaches to therapy to at least partially achieve these goals would become practical given a way to selectively carry a drug into atherosclerotic plaques. This is unfortunately challenging, but the most plausible class of approaches to this problem involves the development of forms of nanoparticle that selectively bind to distinctive features in plaque, or to cells in plaque, while ignoring the rest of the blood vessel wall. That would allow reasonable doses of a drug encapsulated within or attached nanoparticles to be injected intravenously.
Targeted Delivery of Nanoparticles to Blood Vessels for the Treatment of Atherosclerosis
The objective of atherosclerosis medication therapy is to enhance circulation, reduce cholesterol levels, and prevent thrombosis. Anti-inflammatory medication may have modest efficacy when combined with conventional regimens, given that inflammation is a pivotal factor in atherosclerosis. Nevertheless, it should be noted that all medication therapy has limitations in treating established plaques. Some medications, such as colchicine, rapamycin, and nucleic acid drugs, possess strong anti-inflammatory, lipid-lowering, or anti-proliferative properties, which means they have great potential in inhibiting atherosclerotic plaque growth and postoperative restenosis. Unfortunately, their utility in the therapy of atherosclerosis is limited by instability or dose-dependent toxicity. The introduction of nano drug delivery system (DDS) technologies has shed light on the utilization of these medications. By temporarily isolating the drug from the body's internal environment during delivery to reduce degradation and avoiding dose-related drug toxicity through effective targeted delivery, these use constraints of these promising drugs can be removed.
Nanoparticle carriers can be broadly divided into two groups: organic and inorganic. Polymers, liposomes, and micelles are typical examples of organic compounds, whereas inorganic compounds include silica, metals, and carbon, among others. According to some recent studies, nanoparticles showed great potential in both clinical diagnosis and therapy for atherosclerosis. Nevertheless, despite the encouraging outcomes observed in cell and animal studies, only a limited number of these designs have successfully transitioned to clinical trials and, even more rarely, to the market.
Nanoparticles have several notable applications in the diagnosis of atherosclerosis, including the identification of vulnerable plaques and the use of nanoparticles with both therapeutic and diagnostic functions. Nonetheless, even if the number of nanoparticle kinds is rapidly increasing, very few of them have gone to preclinical or clinical phases, and the majority of research has only formed conclusions from tests conducted in rodents (mice, rats) or other mammals (rabbits, pigs, dogs, and primates). Numerous nanoparticles have produced fairly acceptable results in cell or animal experiments; nonetheless, the evidence about their toxicity, biocompatibility, metabolic breakdown pathways, and efficacy is insufficient due to small sample sizes. Furthermore, the majority of the experimental research examined in this work yielded favorable outcomes, but the negative impacts or qualities of nanoparticles that need to be improved are hardly discussed.
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