Treatment Of Atherosclerotic Plaques Research Articles

Investigation of the size and shape of nano-microcarriers for targeted drug delivery to atherosclerotic plaque in ischemic stroke prevention

Recognizing the significance of drug carriers in the treatment of atherosclerotic plaque is crucial in light of the worldwide repercussions of ischemic stroke. Conservative methodologies, specifically targeted drug delivery, present encouraging substitutes that mitigate the hazards linked to invasive procedures. With the intention of illuminating their considerable significance and prospective benefits, this study examines the impact of the geometry and dimensions of drug-loaded nano-microcarriers on atherosclerotic plaque. The research utilizes a finite element approach to simulate the motion and fluid dynamics of nano-microcarriers loaded with drugs within the carotid arteries. Carriers are available in a variety of shapes and sizes to accommodate patient-specific geometries, pulsatile fluid flow, and non-Newtonian blood properties. Optimization of drug delivery is achieved through the examination of carrier interaction with the inner wall. The results demonstrated that the interaction data between particles and the inner wall of atherosclerotic plaques exhibits micro- and nanoscale patterns that are distinct. Symmetric plaques demonstrate that nanoparticles with a 0.4 shape factor and diameters below 200 nm show the highest interaction rate. Conversely, larger particles (200 and 500 nm) with shape factors of 1 demonstrate comparatively elevated interaction rates. The optimal shape factor for drug-loaded microparticles has been determined to be one, and the number of interactions increases as the diameter of the nanoparticles increases, with a significant increase observed at a shape factor of one. Asymmetric plaques exhibit the maximum interaction rates among particles that have a shape factor of 0.4 and have diameters smaller than 500 µm. The findings establish a foundation for novel therapeutic strategies, establishing nano-microparticles as auspicious contenders for accurate and efficacious drug delivery systems that inhibit plaque proliferation.

Deciphering smooth muscle cell heterogeneity in atherosclerotic plaques and constructing model: a multi-omics approach with focus on KLF15/IGFBP4 axis

BackgroundRuptured atherosclerotic plaques often precipitate severe ischemic events, such as stroke and myocardial infarction. Unraveling the intricate molecular mechanisms governing vascular smooth muscle cell (VSMC) behavior in plaque stabilization remains a formidable challenge.MethodsIn this study, we leveraged single-cell and transcriptomic datasets from atherosclerotic plaques retrieved from the gene expression omnibus (GEO) database. Employing a combination of single-cell population differential analysis, weighted gene co-expression network analysis (WGCNA), and transcriptome differential analysis techniques, we identified specific genes steering the transformation of VSMCs in atherosclerotic plaques. Diagnostic models were developed and validated through gene intersection, utilizing the least absolute shrinkage and selection operator (LASSO) and random forest (RF) methods. Nomograms for plaque assessment were constructed. Tissue localization and expression validation were performed on specimens from animal models, utilizing immunofluorescence co-localization, western blot, and reverse-transcription quantitative-polymerase chain reaction (RT-qPCR). Various online databases were harnessed to predict transcription factors (TFs) and their interacting compounds, with determination of the cell-specific localization of TF expression using single-cell data.ResultsFollowing rigorous quality control procedures, we obtained a total of 40,953 cells, with 6,261 representing VSMCs. The VSMC population was subsequently clustered into 5 distinct subpopulations. Analyzing inter-subpopulation cellular communication, we focused on the SMC2 and SMC5 subpopulations. Single-cell subpopulation and WGCNA analyses revealed significant module enrichments, notably in collagen-containing extracellular matrix and cell-substrate junctions. Insulin-like growth factor binding protein 4 (IGFBP4), apolipoprotein E (APOE), and cathepsin C (CTSC) were identified as potential diagnostic markers for early and advanced plaques. Notably, gene expression pattern analysis suggested that IGFBP4 might serve as a protective gene, a hypothesis validated through tissue localization and expression analysis. Finally, we predicted TFs capable of binding to IGFBP4, with Krüppel-like family 15 (KLF15) emerging as a prominent candidate showing relative specificity within smooth muscle cells. Predictions about compounds associated with affecting KLF15 expression were also made.ConclusionOur study established a plaque diagnostic and assessment model and analyzed the molecular interaction mechanisms of smooth muscle cells within plaques. Further analysis revealed that the transcription factor KLF15 may regulate the biological behaviors of smooth muscle cells through the KLF15/IGFBP4 axis, thereby influencing the stability of advanced plaques via modulation of the PI3K-AKT signaling pathway. This could potentially serve as a target for plaque stability assessment and therapy, thus driving advancements in the management and treatment of atherosclerotic plaques.

Study on the ultrasonic cavitation damage to early atherosclerotic plaque

Ultrasonic cavitation can damage surrounding material and be used for destruction of the target tissue. In this paper, we investigated the interaction between atherosclerotic plaque (AP) and cavitation bubbles to determine whether the mechanical effect of cavitation damage could be potentially useful in therapy for treating atherosclerotic plaques. A two-bubble–fluid–solid model was established to study the dynamic behavior of bubbles near the AP and the AP damage by ultrasound-induced cavitation. A low-intensity focused ultrasound (LIFU) transducer was used for testing cavitation-based AP damage. We found that the nonlinear oscillation of bubbles causes the relative positions of the bubbles to shift, either toward or away from one another, these phenomena lead to changes in the bond failure rate between the fiber bundles, and the value of BRF exhibits an upward trend, this is the reason why the fibers suffered from reversible stretching and compressing. However, the AP damage is irreversible and diminishes as the number of cycles in the ultrasonic burst. It appears that the bigger the radii, regardless of whether the bubble (3 − i)’s and bubble i's radii are equal, the greater the AP damage. Ultrasonic cavitation therapy may not be appropriate for advanced AP patients, and the calcified tissue has a greater impact on the stability of the plaque. The damage area should be strictly selected. Additionally, the tissue damage phenomenon was found in experimental results. This work shows that the severity of AP damage is correlated with acoustic parameters and the surrounding environment from both simulation and experimental perspectives. The results show that ultrasonic cavitation may provide a new choice for the treatment of AP.

Near Infrared Light-Activatable Platelet-Mimicking NIR-II NO Nano-Prodrug for Precise Atherosclerosis Theranostics.

Atherosclerosis is a chronic inflammatory disease that affects arteries and is the main cause of cardiovascular disease. Atherosclerotic plaque formation is usually asymptomatic and does not manifest until the occurrence of clinical events. Therefore, early diagnosis and treatment of atherosclerotic plaques is particularly important. Here, a series of NIR-II fluorescent dyes (RBT-NH) are developed for three photoresponsive NO prodrugs (RBT-NO), which can be controllably triggered by 808nm laser to release NO and turn on the NIR-II emission in the clinical medicine "therapeutic window". Notably, RBT3-NO is selected for its exhibited high NO releasing efficiency and superior fluorescence signal enhancement. Subsequently, a platelet-mimicking nano-prodrug system (RBT3-NO-PEG@PM) is constructed by DSPE-mPEG5k and platelet membrane (PM) for effectively targeted diagnosis and therapy of atherosclerosis in mice. The results indicate that this platelet-mimicking NO nano-prodrug system can reduce the accumulation of lipids at the sites of atherosclerotic plaques, improve the inflammatory response at the lesion sites, and promote endothelial cell migration, thereby slowing the progression of plaques.

Anti-inflammation-based treatment of atherosclerosis using Gliclazide-loaded biomimetic nanoghosts

In the study, a biomimetic platform for anti-inflammatory-based treatment of atherosclerotic plaque was developed. Gliclazide (GL) as an anti-inflammasome agent was encapsulated in PLGA nanoparticles (NP), which were coated by monocyte membrane using an extrusion procedure. The size and zeta potential of the nanoghost (NG) changed to 292 and – 10 nm from 189.5 to −34.1 in the core NP. In addition, the actual size of 62.5 nm with a coating layer of 5 nm was measured using TEM. The NG was also showed a sustained release profile with the drug loading content of about 4.7%. Beside to attenuated TNFα, decrease in gene expression levels of NLRP3, MyD88, NOS, IL-1β, IL-18 and caspases 1/3/8/9 in LPS-primed monocytes exposed to NG strongly indicated remarkable inflammation control. After systemic toxicity evaluation and pharmacokinetic analysis of NP and NG, intravenous NG treatment of rabbits with experimentally induced atherosclerosis revealed remarkably less plaque lesions, foam cells, lipid-laden macrophages, and pathological issues in tunica media of aorta sections. Higher expression of CD163 than CD68 in aorta of NG-treated rabbits strongly reveals higher M2/M1 macrophage polarization. The bio/hemocompatible, biomimetic and anti-inflammatory NG can be considered as a potential platform for immunotherapy of particularly atherosclerosis in the field of personalized medicine.

Osteopontin-Targeted and PPARδ-Agonist-Loaded Nanoparticles Efficiently Reduce Atherosclerosis in Apolipoprotein E–/– Mice

Atherosclerosis is the leading cause of vascular pathologies and acute cardiovascular events worldwide. Early theranostics of atherosclerotic plaque formation is critical for the prevention of associated cardiovascular complications. Osteopontin (OPN) expression in vascular smooth muscle cells (VSMCs) has been reported as a promising molecular target for the diagnosis and treatment of atherosclerotic plaques. The PPARδ agonist GW1516 has been shown to inhibit VSMC migration and apoptosis. However, GW1516 has low aqueous solubility and poor oral bioavailability, which are major obstacles to its broad development and application. In this study, GW1516@NP-OPN, which is anti-OPN-targeted and loaded with the PPARδ agonist GW1516, was synthesized using a nanoprecipitation method. The uptake of GW1516@NP-OPN was examined using fluorescence microscopy and flow cytometry assay in VSMC in vitro models. Using the Transwell assay and acridine orange/ethidium bromide staining methods, we observed that the inhibition of VSMCS migration and apoptosis was significantly higher in cells treated with GW1516@NP-OPN than those treated with free GW1516. The western blot assay further confirmed that GW1516@NP-OPN can increase FAK phosphorylation and TGF-βprotein expression. The effect of NPs was further tested in vivo. The atherosclerotic lesion areas were greatly decreased by GW1516@NP-OPN compared with the free drug treatment in apolipoprotein E–/– mice models. Consequently, our results showed that GW1516@NP-OPN stabilizes the PPARδ agonist aqueous formulation, improves its anti-plaque formation activities in vivo and in vitro, and can therefore be recommended for further development as a potential anti-atherosclerotic nanotherapy.

Effects of diagnostic ultrasound with cRGD-microbubbles on simultaneous detection and treatment of atherosclerotic plaque in ApoE-/- mice.

BackgroundAtherosclerotic vulnerable plaque is the leading cause of acute fatal cardiovascular events. Thus, early rapid identification and appropriate treatment of atherosclerotic plaque maybe can prevent fatal cardiovascular events. However, few non–invasive molecular imaging techniques are currently available for the simultaneous detection and targeted treatment of atherosclerotic plaques. We hypothesized that diagnostic ultrasound (DU) combined with cyclic Arg-Gly-Asp-modified microbubbles (MBR) could provide targeted imaging and dissolution of activated platelets to identify advanced atherosclerotic plaques and improve plaque instability.MethodsThree mouse models, apolipoprotein E-deficient mice on a hypercholesterolemic diet (HCD) or normal chow diet and wild-type mice on an HCD were used. The most appropriate ultrasonic mechanical index (MI) was determined based on the expression of GP IIb/IIIa in sham, DU alone and DUMBR-treated groups at MI values of 0.5, 1.5, and 1.9. The video intensity (VI) values, activated platelets and plaque instability were analyzed by ultrasound molecular imaging, scanning electron microscopy and histopathological methods.ResultsWe found that the VI values of ultrasound molecular imaging of MBR were positively correlated with plaque GP IIb/IIIa expression, vulnerability index and necrotic center / fiber cap ratio. 24 h after treatment at different MIs, compared with those of the other groups, both the VI values and GP IIb/IIIa expression were significantly reduced in MI 1.5 and MI 1.9 DUMBR-treated groups. The plaque vulnerability index and necrotic center / fiber cap ratio were significantly decreased in MI 1.5-treated group, which may be due to targeted dissolution of activated platelets, with a reduction in von Willebrand factor expression.ConclusionDUMBR targeting GP IIb/IIIa receptors could rapidly detect advanced atherosclerotic plaques and simultaneously give targeted therapy by dissolving activated and aggregated platelets. This technology may represent a novel approach for the simultaneous identification and treatment of atherosclerotic plaques.

The Mechanism Underlying the Regulation of LncRNA-ASLNC18810 Involved in the Abnormal Function of Vascular Endothelial Cell in Atherosclerosis: Its Function as a microRNA (miRNA) Sponge for miR-559.

Abnormal function of endothelial cells (ECs) is an important reason for vascular endothelial remodeling and atherosclerotic plaque formation in patients with atherosclerosis (AS). Here, we report for the first time that the vascular ECs with apoptosis resistance phenotype (ARECs) exist in peripheral blood of AS patients. Our research data showed that the switch of regulation modes between HIF-1α and Bax operated by lncRNA-ASLNC18810 is the direct cause for the formation of ARECs. When ASLNC18810 is low or missing, HIF-1α indirectly negatively regulates the Bax in post-transcription through HIF-1α/miR-559/Bax pathway which makes ECs acquire apoptosis resistance and form ARECs. The functional experiments results showed that ASLNC18810 could effectively eliminate the anti-apoptotic properties of ARECs by blocking the HIF-1α/miR559/Bax pathway and maintaining HIF-1α/Bax pathway. In a word, our study shows that ASLNC18810 has full potential to become a biological target for the prevention and treatment of atherosclerotic plaques by regulating ARECs. ASLNC18810 was significantly upregulated in ECs compared to ARECs. With high level of ASLNC18810 in ECs, ASLNC18810 binds to miR-559 as a miRNA sponge and suppresses the inhibition effect of miR-559 on Bax protein, this direct positive transcriptional regulation between HIF-1α and Bax endows the apoptotic property in ECs induced by Ox-LDL. However, with low expression of ASLNC18810 in ARECs, the post-transcriptional regulation of Bax by miR-559 dominates and the indirect negative regulation between HIF-1α and Bax endows the anti-apoptotic property of ARECs. To sum up, low ASLNC18810 expression-mediated switching of HIF-1α/Bax pathway to HIF-1α/miR-559/Bax pathway is the internal reason for ECs to obtain apoptosis resistance and the formation of ARECs under the ox-LDL induction.

Collagenase-Cleavable Peptide Amphiphile Micelles as a Novel Theranostic Strategy in Atherosclerosis.

Atherosclerosis is an inflammatory disease characterized by plaques that can cause sudden myocardial infarction upon rupture. Such rupture-prone plaques have thin fibrous caps due to collagenase degradation, and a noninvasive diagnostic tool and targeted therapy that can identify and treat vulnerable plaques and may inhibit the onset of acute cardiac events. Toward this goal, monocyte-binding, collagenase-inhibiting, and gadolinium-modified peptide amphiphile micelles (MCG PAMs) are developed. Monocyte chemoattractant protein-1 (MCP-1) binds to C-C chemokine receptor-2 expressed on pathological cell types present within plaques. Through the peptide binding motif of MCP-1, MCG PAMs bind to monocytes and vascular smooth muscle cells in vitro. Moreover, using magnetic resonance imaging, MCG PAMs show enhanced targeting and successful detection of plaques in diseased mice in vivo and act as contrast agents for molecular imaging. Through the collagenase-cleaving peptide sequence of collagen [VPMS-MRGG], MCG PAMs can compete for collagenases that degrade the fibrous cap of plaques, providing therapy. MCG PAM-treated mice show increased fibrous cap thickness by 61% and 113% histologically compared to nontargeting micelle- or PBS-treated mice (p = 0.0075 and 0.001, respectively). Overall, this novel multimodal nanoparticle offers new theranostic opportunities for noninvasive diagnosis and treatment of atherosclerotic plaques.

Treatment of atherosclerotic plaque: perspectives on theranostics.

Atherosclerosis, a progressive condition characterised by the build-up of plaque due to the accumulation of low-density lipoprotein and fibrous substances in the damaged arteries, is the major underlying pathology of most cardiovascular diseases. Despite the evidence of the efficacy of the present treatments for atherosclerosis, the complex and poorly understood underlying mechanisms of atherosclerosis development and progression have prevented them from reaching their full potential. Novel alternative treatments like usage of nanomedicines and theranostics are gaining attention of the researchers worldwide. This review will briefly discuss the current medications for the disease and explore potential future developments based on theranostics nanomaterials that may help resolve atherosclerotic cardiovascular disease. Various drugs can slow the effects of atherosclerosis. They include hyperlipidaemia medications, anti-platelet drugs, hypertension and hyperglycaemia medications. Most of the theranostic agents developed for atherosclerosis have shown the feasibility of rapid and noninvasive diagnosis, as well as effective and specific treatment in animal models. However, there are still some limitation exist in their structure design, stability, targeting efficacy, toxicity and production, which should be optimized in order to develop clinically acceptable nanoparticle based theronostics for atherosclerosis. Current medications for atherosclerosis and potential theranostic nanomaterials developed for the disease are discussed in the current review. Further investigations remain to be carried out to achieve clinical translation of theranostic agents for atherosclerosis.

Research progress of combined statins and clopidogrel on atherosclerotic plaques

Statins and antiplatelet drugs are the two cornerstones for the treatment of cerebrovascular diseases.This two drugs play a vital role in reducing platelet reactivity and inhibiting inflammation.Statins can effectively delay the progression of atherosclerosis, reduce plaque volume and reduce the incidence of cerebrovascular diseases through multiple pathways.Clopidogrel is currently used primarily for anti-platelet aggregation.Some studies indicate that clopidogrel is also involved in the process of atherosclerosis, but the mechanism is not clear.The anti-atherosclerosis effect of clopidogrel is often neglected, when statins are combined with clopidogrel.This article reviews the progress in the treatment of atherosclerotic plaque by statin combined with clopidogrel. Key words: Atherosclerosis; Statins; Clopidogrel; Cerebrovascular disease; Plaques

Development of new antiatherosclerotic and antithrombotic drugs utilizing F11 receptor (F11R/JAM-A) peptides.

Peptides with enhanced resistance to proteolysis, based on the amino acid sequence of the F11 receptor molecule (F11R, aka JAM-A/Junctional adhesion molecule-A), were designed, prepared, and examined as potential candidates for the development of anti-atherosclerotic and anti-thrombotic therapeutic drugs. A sequence at the N-terminal of F11R together with another sequence located in the first Ig-loop of this protein, were identified to form a steric active-site operating in the F11R-dependent adhesion between cells that express F11R molecules on their external surface. In silico modeling of the complex between two polypeptide chains with the sequences positioned in the active-site was used to generate peptide-candidates designed to inhibit homophilic interactions between surface-located F11R molecules. The two lead F11R peptides were modified with D-Arg and D-Lys at selective sites, for attaining higher stability to proteolysis in vivo. Using molecular docking experiments we tested different conformational states and the putative binding affinity between two selected D-Arg and D-Lys-modified F11R peptides and the proposed binding pocket. The inhibitory effects of the F11R peptide 2HN-(dK)-SVT-(dR)-EDTGTYTC-CONH2 on antibody-induced platelet aggregation and on the adhesion of platelets to cytokine-inflammed endothelial cells are reported in detail, and the results point out the significant potential utilization of F11R peptides for the prevention and treatment of atherosclerotic plaques and associated thrombotic events.

Atheroma and coronary bifurcations: before and after stenting

First generation drug-eluting stents (DES) have significantly improved the treatment options for patients with symptomatic coronary artery disease by decreasing rates of restenosis after percutaneous coronary revascularisation procedures. However, early enthusiasm was tempered by reports of late stent thrombosis, primarily in "off-label" use. In particular, the treatment of atherosclerotic plaques at coronary bifurcations has been challenging for interventional cardiologists regardless of the stent choice due to the underlying nature of the atherosclerotic disease and the use of multiple stents. In this article we illustrate the location and severity of plaque and investigate the healing following both bare metal stents (BMS) and drug-eluting stents (DES) at bifurcations using post-mortem specimens. The presented data will demonstrate that neointimal growth following stent implantation correlate to flow conditions, as there is less underlying atherosclerotic disease at high shear regions and subsequently less neointimal growth is observed in these regions versus low shear regions. The occurrence of late stent thrombosis in DES is also shown to be associated with greater presence of uncovered stent struts at the high shear region, which is likely due to local flow mechanics.

Gene delivery of soluble vascular endothelial growth factor receptor-1 (sFlt-1) inhibits intra-plaque angiogenesis and suppresses development of atherosclerotic plaque

Intra-plaque angiogenesis plays an important role in the development of atherosclerotic plaque. Vascular endothelial growth factor (VEGF) is a major initiating factor in this pathologic progress. One selective and specific inhibitor of VEGF is soluble VEGF receptor-1 (sFlt-1). The anti-angiogenic utilization of sFlt-1 in treatment of atherosclerotic plaque has not been fully confirmed yet. Our study was designed to construct eukaryotic expression recombinant pEGFP-N1-sFlt-1, evaluate sFlt-1 recombinant's effects on endothelial cells proliferation and tube formation in vitro, and investigate effects of local high-expressed sFlt-1 on atherosclerotic plaque in vivo. Rabbit models of atherosclerotic plaque were established by high-lipid diet combined with injury induced by balloon catheter on iliac artery intima. Animals were divided into four groups randomly: control group (C), atherosclerotic plaque group (AP), atherosclerotic plaque with blank vector pEGFP-N1 transfection group (APV), and atherosclerotic plaque with pEGFP-N1-sFlt-1 transfection group (APsFlt-1). The local expression of sFlt-1 protein in target artery was detected by western blotting. The plaque area (PA), plaque circumference (PC), and maximum plaque thickness (MPT) were measured via HE staining. Degree of intra-plaque angiogenesis was evaluated by CD34+ cells immunohistochemistry. As results, we observed that pEGFP-N1-sFlt-1 transfection suppressed the HUVECs proliferation and ability of tube formation, against the effect of VEGF. We obtained higher local expression of sFlt-1 protein in Group APsFlt-1 than that in other groups (P<0.05). PA, PC, and MPT of plaque in group APsFlt-1 were significantly decreased when compared with other groups (P<0.05). Amount of annulations surrounded by CD34-positive cells was significantly decreased in pEGFP-N1-sFlt-1 transfection group, which represented decreased level of intra-plaque neovessels formation. The present study confirmed that local gene delivery of sFlt-1 can suppress plaque formation, as one of possible mechanisms, via inhibitive effect on intra atherosclerotic plaque angiogenesis, which hints at the clinical utility of sFlt-1 in atherosclerosis therapy.

Evaluation of recombinant endostatin in the treatment of atherosclerotic plaques and neovascularization in rabbits

Atherosclerotic plaques and neovascularization play an important role in the course of coronary atherosclerosis. This study evaluated the effect of recombinant endostatin on experimental atherosclerotic plaques and neovascularization in rabbits. Eighteen healthy male rabbits were divided into three groups: control group, atherosclerotic model group, and recombinant endostatin treated group. The atherosclerotic model was established via a high-cholesterol diet after balloon catheter injury. The subject weights, serum total cholesterol, creatine kinase-myocardial band fraction (CKMB), and matrix metalloproteinase-2 (MMP-2) were measured. Six weeks after treatment, the aortic roots were taken for pathological assay. The thickness ratio of the intima to media was measured by hematoxylin and eosin (HE) staining, and the number of neovessels was measured by immunohistochemistry via monoclonal antibody CD31 staining. The weight, plasma total cholesterol, and CKMB were not significantly different between the atherosclerotic model group and the recombinant endostatin treated group, but much higher than those of the control group (P<0.05). The thickness ratio of the intima to media in the recombinant endostatin treated group was distinctly less than that in the atherosclerotic model group (P<0.05). The number of neovessels decreased dramatically (P<0.05) and the content of MMP-2 decreased slightly without statistical difference (P>0.05) in the recombinant endostatin treated group, compared to the atherosclerotic model group. Recombinant endostatin is able to inhibit the growth of neovascularization in the atherosclerotic plaque and the development of plaque.

Erratum to “A novel device, flow maintaining stent delivery system, for treatment of atherosclerotic plaque in coronary arteries [abstract]” (Cardiovasc Radiat Med 2004;5:198–9)

Erratum to “A novel device, flow maintaining stent delivery system, for treatment of atherosclerotic plaque in coronary arteries [abstract]” (Cardiovasc Radiat Med 2004;5:198–9)

The promise of nanotechnology for heart, lung and blood diseases

Nanotechnology offers a broad range of opportunities for improving the diagnosis and therapy for heart, lung and blood diseases, and drug delivery represents an area of particular promise. For cardiovascular disease, the treatment of atherosclerotic plaque and prevention of restenosis following stent placement offer attractive targets for nanotechnology. In lung disease, nanotechnology may provide novel treatments for a broad range of intractable pulmonary diseases, including bacterial biofilms, fungal infections, and tuberculosis. For haematopoietic diseases, targeted delivery of drugs to lymphocytes may represent a strategy for reducing systemic cytotoxicity. This editorial discusses some of the more promising targets for nanotechnology-based treatment of heart, lung and blood diseases.

Novel photopoint photodynamic therapy for the treatment of atherosclerotic plaques

Novel photopoint photodynamic therapy for the treatment of atherosclerotic plaques

Toxicity in vital fluorescence microscopy: effect of dimethylsulfoxide, Rhodamine-123, and DiI-Low density lipoprotein on fibroblast growth in vitro

Fluorescence microscopy performed on living cells is a valuable technique for elucidating patterns of cell growth in vitro over artificial biomaterials such as vascular grafts, and for in vivo studies such as identification and treatment of atherosclerotic plaques. Two fluorescent dyes of particular value for vital fluorescence studies are Rhodamine-123 and 3,3'-dioctadecylindocarbocyanine-labeled low density lipoprotein (DiI-LDL). We examined the toxicity of these two dyes and of dimethylsulfoxide (DMSO), a solvent used in Rhodamine-123 studies, on the growth of MRC5 human fetal fibroblasts in monolayer culture. Two parameters of cell growth were quantitated: Cell number (a measure of proliferation), and cell area (a measure of cell spreading), based on microscopic images obtained at the start and end of a 48-h growth period after brief exposure (0.5 h) to test solutions. We found that the recommended solvent for solubilization of Rhodamine-123, DMSO, caused cessation of cell proliferation and actual reduction in the area covered by adherent fibroblasts at concentrations of as low as 0.1% (vol:vol). Rhodamine-123 made up from an aqueous stock solution modestly retarded proliferation and spreading, and there was no significant effect of DiI-LDL on these parameters over prolonged periods of exposure (up to 24 h) in culture. These results demonstrate that the most toxic substance for growing fibroblasts was the solvent DMSO. We conclude that both the solvent vehicle and fluorescent dye should be carefully examined for potential toxicity before such dyes are used for vital fluorescence studies of living cells.