[show abstract][hide abstract] ABSTRACT: Oxidized low-density lipoprotein (oxLDL) plays a key role in the formation of atherosclerotic plaques. However, its localization in human coronary arterial wall is not well understood. The present study was performed to visualize deposition sites and patterns of native oxLDL and their relation to plaque morphology in human coronary artery.
Evans blue dye (EB) elicits a violet fluorescence by excitation at 345-nm and emission at 420-nm, and a reddish-brown fluorescence by excitation at 470-nm and emission at 515-nm characteristic of oxLDL only. Therefore, native oxLDL in excised human coronary artery were investigated by color fluorescent microscopy (CFM) using EB as a biomarker.
(1) By luminal surface scan with CFM, the % incidence of oxLDL in 38 normal segments, 41 white plaques and 32 yellow plaques that were classified by conventional angioscopy, was respectively 26, 44 and 94, indicating significantly (p<0.05) higher incidence in the latter than the former two groups. Distribution pattern was classified as patchy, diffuse and web-like. Web-like pattern was observed only in yellow plaques with necrotic core. (2) By transected surface scan, oxLDL deposited within superficial layer in normal segments and diffusely within both superficial and deep layers in white and yellow plaques. In yellow plaques with necrotic core, oxLDL deposited not only in the marginal zone of the necrotic core but also in the fibrous cap.
Taken into consideration of the well-known process of coronary plaque growth, the results suggest that oxLDL begins to deposit in human coronary artery wall before plaque formation and increasingly deposits with plaque growth, exhibiting different deposition sites and patterns depending on morphological changes.
PLoS ONE 01/2013; 8(2):e55188. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Apolipoprotein B-100 (ApoB-100) is an important risk factor for coronary artery disease. However, its localization in human coronary plaques is not well understood. The present study was performed to visualize ApoB-100 in human coronary artery wall. Deposition of native ApoB-100 in excised human coronary plaques and normal segments classified by conventional angioscopy was investigated by color fluorescent angioscopy (CFA) and microscopy (CFM) using Nile blue dye (NB) which elicits a golden fluorescence characteristic of ApoB-100 as a biomarker. By CFA, the % incidence of ApoB-100 was 20 in 40 normal segments, 38 in 42 white, and 11 in 35 yellow plaques (P < 0.05 versus white plaques). There was no significant difference in detection sensitivity between CFA and luminal surface scan by CFM. By CFM transected surface scan, ApoB-100 deposited in superficial, deep, and/or in both layers. Deposition in both layers was frequently observed in white plaques and yellow plaques without necrotic core (NC), less frequently in normal segments, and rarely in yellow plaques with NC. (1) Taking into consideration the well known process of plaque growth, the results suggest that ApoB-100 begins to deposit before plaque formation, increasingly deposits with plaque growth, and disappears after necrotic core formation. (2) CFA is feasible for imaging of ApoB-100 in human coronary artery wall.
International Heart Journal 01/2013; 54(2):68-74. · 1.23 Impact Factor
[show abstract][hide abstract] ABSTRACT: Coronary intimal hyperplasia occurs at the site of spasm in patients with vasospastic angina. The migration of vascular smooth muscle cells (VSMCs) from the media has been proposed as a potential mechanism; however, this has not been confirmed with supportive evidence.
To determine which cell types participate in spasm-induced coronary intimal hyperplasia.
Morphological changes in spastic coronary artery segments in beagles were examined using electron microscopy and immunohistochemical staining of cell markers at 1 h, 3 h and 6 h, and two and four weeks after spasm provocation.
Small smooth muscle-like cells (SMLCs) were observed in the media of nonspastic coronary segments using electron microscopy. These cells attached side-to-side to large, known VSMCs. At 1 h to 6 h after spasm provocation, SMLCs separated from VSMCs, changed to an amoebic configuration and migrated through cleaved junctions or disrupted portions of the internal elastic lamina into the subendothelial space. The SMLCs expressed alpha-smooth muscle actin and N-cadherin, but not smooth muscle myosin heavy chain-1 and β-actin, suggesting that they were myofibroblasts and not a synthetic phenotype of VSMCs. Intimal hyperplasia was observed in all preparations at two and four weeks after spasm provocation. Furthermore, alpha-smooth muscle actin-positive SMLCs, often amoebic in configuration, were observed in the hyperplastic intima.
On coronary spasm provocation, SMLCs (ie, possible myofibroblasts) resident in the media migrate as a spearhead into the intima and play a role in coronary intimal hyperplasia.
Experimental and clinical cardiology 01/2013; 18(1):e65-e70. · 1.10 Impact Factor
[show abstract][hide abstract] ABSTRACT: It was previously thought that arteriogenesis and venogenesis are induced not only by proliferation of vessel-resident smooth muscle cells (SMCs) and endothelial cells (ECs) but also by migration of their precursors. However, it is not well understood through what route(s) the precursors migrate into the existing vessels.We examined through what route or routes circulating mononuclear cells expressing β-actin (β-MNCs), which we identified in canine coronary vessels, migrate into coronary vessel walls and cause arteriogenesis and venogenesis at 1, 2, 4 and 8 weeks after induction of myocardial infarction.The following changes were observed: (1) The β-MNCs migrated via coronary microvessels to the interstitial space at one week; (2) β-MNCs traversed the adventitia into the media and settled in parallel with pre-existing smooth muscle cells (SMCs) in arterioles and arteries and lost β-actin and acquired α-smooth muscle actin (α-SMA) to become mature SMCs at 2-4 weeks; (3) at the same time, other β-MNCs migrated across the adventitia and media into the intima and settled in parallel with pre-existing endothelial cells (ECs) and lost β-actin, while acquiring CD(31), to become mature ECs, resulting in arteriogenesis; (4) Similarly, β-MNCs migrated into venular and venous walls and became SMCs or ECs, resulting in venogenesis.β-MNCs in the interstitial space expressed CD(34) but not other major vascular cell markers.β-MNCs, possibly a vascular progenitor, migrate not from the lumen but across the adventitia into the media or intima of coronary vessels and transit to SMCs or ECs, and participate in arteriogenesis and venogenesis in ischemic myocardium.
International Heart Journal 01/2012; 53(1):54-63. · 1.23 Impact Factor
[show abstract][hide abstract] ABSTRACT: Coronary microvascular hyperplasia is a cause of microvessel angina, although the underlying cellular mechanisms remain unclear. We examined how mononuclear cells expressing β-actin (β-MNCs), which were identified in coronary vessels, induce coronary microvascular hyperplasia.The presence of β-MNCs in coronary hyperplastic arterial (HAM) and venous microvessels (HVM) was examined by endomyocardial biopsy in 25 patients with suspected microvessel angina. β-MNCs were identified in 14 HAMs obtained from 11 patients. Basic fibroblast growth factor and heparin sulfate were injected into the infarcted myocardium to induce HAM and HVM in 28 beagles, and then we examined the role of β-MNCs in the onset of HAM and HVM. The following changes were observed after infarction induction in beagles: (a) migration of β-MNCs from the existing microvessels into the interstitial space at 1-2 weeks; (b) those traversing the adventitia into the media, but not intima, of microvessels; (c) their transformation to smooth muscle cells (SMCs) and/or connective tissues (collagen and elastin fibers); (d) and medial hyperplasia without intimal hyperplasia. Medial hyperplasia was classified into SMC-proliferative and both SMC- and connective tissue-proliferative types. β-MNCs expressed CD(34) but did not express other major vessel-related cell markers.β-MNCs are a vascular progenitor, and migrate out of the adventitia into media, and participate in the etiology of coronary microvascular medial hyperplasia.
International Heart Journal 01/2012; 53(1):43-53. · 1.23 Impact Factor
[show abstract][hide abstract] ABSTRACT: Low-density lipoprotein (LDL) is an important risk factor for coronary artery disease. However, its localization in human coronary plaques is not well understood. The present study was performed to visualize LDL in human coronary artery wall.
(1) The fluorescence characteristic of LDL was investigated by color fluorescent microscopy (CFM) with excitation at 470-nm and emission at 515-nm using Nile blue dye (NB) as a biomarker. (2) Native LDL in 40 normal segments, 42 white plaques and 35 yellow plaques (20 with necrotic core) of human coronary arteries was investigated by color fluorescent angioscopy (CFA) and CFM.
(1) NB elicited a brown, golden and red fluorescence characteristic of LDL, apolipoprotein B-100, and lysophosphatidylcholine/triglyceride, respectively. (2) The % incidence of LDL in normal segments, white, and yellow plaques was 25, 38 and 14 by CFA and 42, 42 and 14 by CFM scan of their luminal surface, respectively, indicating lower incidence (p<0.05) of LDL in yellow plaques than white plaques, and no significant differences in detection sensitivity between CFA and CFM. By CFM transected surface scan, LDL deposited more frequently and more diffusely in white plaques and yellow plaques without necrotic core (NC) than normal segments and yellow plaques with NC. LDL was localized to fibrous cap in yellow plaques with NC. Co-deposition of LDL with other lipid components was observed frequently in white plaques and yellow plaques without NC.
(1) Taken into consideration of the well-known process of coronary plaque growth, the results of the present study suggest that LDL begins to deposit before plaque formation; increasingly deposits with plaque growth, often co-depositing with other lipid components; and disappears after necrotic core formation. (2) CFA is feasible for visualization of LDL in human coronary artery wall.
PLoS ONE 01/2012; 7(11):e50678. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: We found that 3,4-diaminopyridine (3,4-DAP), a voltage-gated potassium channel (K(V)) inhibitor, elicits pH-sensitive periodic contractions (PCs) of coronary smooth muscles. Underlying mechanisms of PCs, however, remained to be elucidated. The present study was performed to examine the roles of ion channels in the genesis of PCs. To determine the electromechanical changes of smooth muscles, isolated coronary arterial rings from beagles were suspended in organ chambers filled with Krebs-Henseleit solution, and 10(-2) M 3,4-DAP was added to elicit PCs. 3,4-DAP caused periodic spike-and-plateau depolarization accompanied by contraction. PCs were not produced when the CaCl(2) concentration in the chamber was ≤ 0.3 × 10(-3) or ≥ 10(-2) M. PCs were eliminated by a CaCl(2) concentration ≥ 5 × 10(-3) M or by lowering pH below 7.20 with HCl and recovered by the addition of iberiotoxin or charybdotoxin, which inhibit large-conductance calcium-activated potassium channels (K(Ca)), or by elevating pH above 7.35 with NaOH. PCs, as well as the spike-and-plateau depolarization, were eliminated by nifedipine, which inhibits L-type voltage-gated calcium channels (Ca(V)). Influx of Ca(2+) through L-type Ca(V), which was opened because closing of K(Ca), secondary to 3,4-DAP-induced closing of K(V), resulted in contraction; the intracellular Ca(2+) increased by this influx opened K(Ca), leading to closure of Ca(V) and consequent cessation of Ca(2+) influx with resultant relaxation. These processes were repeated spontaneously to cause PCs. H(+) and OH(-) were considered to act as the opener and closer of K(Ca), respectively.
Journal of Pharmacology and Experimental Therapeutics 06/2011; 338(3):974-83. · 3.89 Impact Factor
[show abstract][hide abstract] ABSTRACT: Although there are a number of studies on vasospastic angina, the structural changes at the cellular level that occur in the coronary arterial wall during spasm are not well known. Coronary spasm was induced by brushing the coronary adventitia in nine anesthetized beagles, and structural changes in the spastic coronary segments were examined by light and electron microscopy, making comparisons with the adjacent nonspastic segments. The % diameter stenosis of the spastic segments as measured angiographically was 79.4±12% (mean±SD). Light microscopic changes in the spastic and nonspastic segments were as follows: medial thickness 1,512 vs. 392 μm (P<0.0001) and % diameter and % area stenoses of spastic segment 81.0% and 96.5%, respectively, indicating that spasm was induced by medial thickening. Circular smooth muscle cells (SMCs) in the media were arranged in parallel with the internal (IEL) and external (EEL) elastic lamina in nonspastic segments but radially rearranged in spastic segments. SMCs were classified by their patterns of connection to IEL into six types by electron microscopy. Of these, three contracted and pulled the IEL toward the EEL, causing folding of the IEL and waving of EEL resulting in thickening of the media and narrowing of the lumen. We conclude that coronary spasm was elicited by radial rearrangement of the medial SMCs due to their own contraction and resultant medial thickening and folding of IEL, creating a piston effect to narrow the lumen, i.e., spasm.
[show abstract][hide abstract] ABSTRACT: Coronary microvessels play a direct and critical role in determining the extent and severity of myocardial ischemia and cardiac function. However, because direct observation has never been performed in vivo, the functional properties of the individual microvesssels in patients with coronary artery disease remain unknown. Subendocardial coronary microvessels were observed by cardioscopy in 149 successive patients with coronary artery disease (81 with stable angina and 68 with old myocardial infarction). Twenty-four arterial microvessels (AMs) and 27 venous microvessels (VMs) were observed in the left ventricular subendocardium. All 12 AMs and 13 of 14 VMs that were located in normokinetic-to-hypokinetic left ventricular wall segments were filled with blood during diastole and were collapsed during systole. In contrast, 8 of 12 AMs and 9 of 13 VMs that were located in akinetic-to-dyskinetic wall segments were filled with blood during systole and were collapsed during diastole. There were no significant correlations between the timing of blood filling and the severity of coronary stenosis and collateral development. In patients with coronary artery disease, the timing of blood filling of AMs and VMs was dependent on the regional left ventricular contractile state; during diastole when contraction was preserved and during systole when it was not. It remains to be elucidated whether and how blood filling is disturbed in other categories of heart disease.
International Heart Journal 01/2011; 52(5):274-9. · 1.23 Impact Factor
[show abstract][hide abstract] ABSTRACT: It is controversial as to whether or not nitroglycerin (NTG) increases subendocardial myocardial blood flow (SMBF), and if it does, whether arterial or venous blood flow is increased in patients with coronary artery disease. This study was performed to examine NTG-induced changes in SMBF.Changes in SMBF induced by NTG (200 µg, i.v.) were examined by cardioscopy in 58 left ventricular wall segments of 58 patients with coronary artery disease. NTG-induced red and purple endocardial colors were defined as increased arterial and venous SMBF, respectively. Endocardial color before NTG administration was classified into brown, light brown, pale and white. Endomyocardial biopsy of the observed portion and (201)Tl scintigraphy were performed in 40 of these patients immediately after cardioscopy and several days after cardioscopy, respectively.Upon administration of NTG, SMBF increased in 48 of 58 wall segments; arterial SMBF in 34 and venous SMBF in 12 wall segments; arterial SMBF in all 24 brown to light brown segments; venous SMBF, arterial SMBF and no change in 12, 10 and 5 of pale segments, respectively; and no change in all 10 white wall segments. (201)Tl-scintigraphy and endomyocardial biopsy revealed that brown, light brown, pale and white endocardial color represented no ischemia, mild ischemia, severe ischemia and fibrosis, respectively.NTG caused an increase in either arterial or venous SMBF depending on control endocardial color, wall motion and severity of coronary stenosis.
International Heart Journal 01/2011; 52(6):331-7. · 1.23 Impact Factor