Geographical miss and restenosis during catheter-based intracoronary beta-radiation for de novo lesions

Three-dimensional vessel analyses provide more accurate length estimations than the gold standard QCA

OBJECTIVES

The aim of this study was to compare lesion dimensions as determined by a three-dimensional quantitative coronary angiographic (QCA) system to that of a validated two-dimensional QCA system.

BACKGROUND

In an era of drug-eluting stents, device sizing has become an important clinical application of online QCA. The CardiOp-B system integrates two standard angiographic projections to provide a three-dimensional reconstruction of the arterial segment of interest.

METHODS

Phase 1 - 47 stenoses from consecutive coronary angiograms were assessed in two projections with both systems providing two data sets for the CMS-Medis system and a single data set for CardiOp-B. Phase 2--a perspex phantom with a known lesion length, was analyzed at increasing degrees of foreshortening with acceptance criteria set at 5% from the absolute value.

RESULTS

Phase 1 demonstrated an adequate correlation between the CardiOp-B and Medis systems when minimal luminal diameter was measured in the optimal view (1.32 +/- 0.47 mm vs 1.42 +/- 0.49 mm respectively; r = 0.82). A stronger correlation was noted when length was measured (25.27 +/- 10.76 mm and 21.32 +/- 8.08 mm, respectively; r = 0.95); however CardiOp-B provided a consistently longer length (P < 0.0001). On phantom length measurements the mean accuracy result for the CardiOp-B system was -1.3%. This compared favorably with the two-dimensional system where all measures performed at greater than 20 degrees of for shortening were beyond the 5% criteria from the known length.

CONCLUSIONS

Three-dimensional QCA provides accurate and precise vessel diameter assessments. Length assessments are consistently longer than two-dimensional measures and are significantly less affected by foreshortened projections.

Sustained release of multiple growth factors from injectable polymeric system as a novel therapeutic approach towards angiogenesis

Purpose

The aim was to investigate that a bio-degradable alginate and poly lactide-co-glycolide (PLG) system capable of delivering growth factors sequentially would be superior to single growth factor delivery in promoting neovascularization and improving perfusion.

Methods

Three groups of apoE null mice underwent unilateral hindlimb ischemia surgery and received ischemic limb intramuscular injections of alginate (Blank), alginate containing VEGF₁₆₅ (VEGF), or alginate containing VEGF₁₆₅ combined with PLG microspheres containing PDGF-BB (VEGF/PDGF). Vascularity in the ischemic hindlimb was assessed by morphologic and immunohistochemical end-points, while changes in blood flow were assessed by Laser Doppler Perfusion Index. Muscle VEGF and PDGF content was assessed at multiple time points.

Results

In the VEGF/PDGF group, local tissue VEGF and PDGF levels peaked at week 2 and 4, respectively, with detectable PDGF levels at week 6. At week 6, mean vessel mean diameter was significantly greater in the VEGF/PDGF group compared to the VEGF or Blank groups with evidence of well-formed smooth muscle-lined arterioles.

Conclusions

Sequential delivery of VEGF and PDGF using an injectable, biodegradable platform resulted in stable and sustained improvements in perfusion. This sustained, control-released, injectable alginate polymer system is a promising approach for multiple growth factor delivery in clinical application.

SBD.4 stimulates regenerative processes in vitro, and wound healing in genetically diabetic mice and in human skin/severe-combined immunodeficiency mouse chimera

In search of novel angiostimulators, we performed a high-throughput screening of medicinal plants beneficial for blood circulation. From the panel of positive hits, Angelica sinensis was selected for further investigation. Purified down to a low-molecular-weight fraction and characterized by high-performance liquid chromatography-mass spectrometry, the material, named SBD.4A, revealed a particularly strong wound healing activity in the diabetic mouse wound-healing model, and in the human/severe combined immunodeficiency mouse chimera wound-healing model. In both models, SBD.4A compared favorably with the Food and Drug Administration-approved wound-healing drug becaplermin, suggesting that this botanical product could be a valuable treatment for difficult-to-heal wounds. Further high-performance liquid chromatography fractionation of SBD.4A yielded a hydrophilic fraction, which strongly stimulated endothelial cell proliferation, tridimensional endothelial cell network formation, as well as the proliferation of human dermal fibroblasts and type I collagen secretion. Because angiogenesis and fibroblast proliferation are essential for wound healing, we propose that this liquid chromatography-mass spectrometry-defined hydrophilic fraction is at least partially responsible for the wound-healing activity of SBD.4A.

Docosahexaenoic acid induces apoptosis in proliferating human endothelial cells

n-3 polyunsaturated fatty acids (PUFAs) have been shown to exert beneficial effects in the prevention of cardiovascular disease, inflammation, and on tumor growth. To investigate effects of PUFAs on proliferation and apoptosis in endothelial cells, we tested the n-3 PUFA docosahexaenoic acid (DHA) and the n-6 PUFA arachidonic acid (AA) in human umbilical vein endothelial cells (HUVEC). The mitochondrial membrane potential (MMP) and the production of reactive oxygen species were examined by flow cytometry. Phosphorylation of p53 or p38 MAP kinase, and total levels of p53 were measured by Western blot. DNA binding activity of p53 was analyzed with a TransAM transcription factor assay kit. Tube formation was assessed on Matrigel. In proliferating HUVEC, but not in confluent cells, DHA reduced cell viability and induced apoptosis, as demonstrated by increases in membrane leakage (propidium iodide (PI) staining), Annexin-V binding, sub G(1) phase in the cell cycle, and TUNEL-positive cells. AA had no effect on these parameters. In addition to a reduced MMP and increased reactive oxygen species, phosphorylation of p38 and p53 (serine 15) and impaired DNA binding of p53 were observed. There was no change in total levels of p53. The p38 inhibitor SB203580 had no effect on Annexin V binding. DHA also attenuated HUVEC tube formation. Taken together, DHA induces apoptosis in proliferating, but not in resting HUVEC, potentially via the phosphorylation of p53, resulting in decreased p53 DNA binding. The results suggest that anti-angiogenic effects of DHA may be due to induction of apoptosis in proliferating endothelial cells.

Inhibition of endothelial proliferation by the somatostatin analogue SOM230

OBJECTIVE

Somatostatin (SST) modulates exocrine and endocrine secretion, proliferation and apoptosis via five G protein-linked receptors (SSTRs 1-5). Long-acting SST analogues such as Octreotide, and the new analogue SOM230, have been developed for the treatment of neuroendocrine tumours. Octreotide has previously been reported to inhibit endothelial proliferation. We wished to determine if SOM230 is a more potent inhibitor of endothelial cell proliferation than Octreotide.

DESIGN

We have determined the expression of SSTRs in proliferating human umbilical vein endothelial cells (HUVECs) in vitro, and determined their response to the somatostatin analogues SOM230 and Octreotide, following vascular endothelial growth factor (VEGF) stimulation.

MEASUREMENTS

Quantitative RT-PCR and western blotting were used to determine the expression of SSTRs 1-5 in proliferating HUVECs. These cells were grown in media containing 200 pg/ml VEGF and treated with 10(-11) to 10(-6) M Octreotide or SOM230. The WST-1 assay was then used to determine the effects of these analogues on HUVEC proliferation.

RESULTS

Using quantitative RT-PCR and western blotting, HUVECs were found to express SSTRs 1, 2 and 5. SSTRs 3 and 4 were not detected. Using the WST-1 assay, SOM230 was found to significantly inhibit proliferation by up to 46.0% +/- 9.4% (10(-6)-10(-7) M; P < 0.05), whereas in parallel studies Octreotide failed to inhibit HUVEC proliferation.

CONCLUSIONS

The pan SST analogue SOM230 inhibits proliferation of HUVECs, which are unaffected by Octreotide. SOM230 may thus represent a suitable candidate drug for antiangiogenic therapy.

Embryonic Cell Lines with Endothelial Potential: An In Vitro System for Studying Endothelial Differentiation

Objective— Endothelial differentiation is a fundamental process in angiogenesis and vasculogenesis with implications in development, normal physiology, and pathology. To better understand this process, an in vitro cellular system that recapitulates endothelial differentiation and is amenable to experimental manipulations is required.

Methods and Results— Embryonic cell lines that differentiate exclusively into endothelial cells were derived from early mouse embryos using empirical but reproducible culture techniques without viral or chemical transformation. The cells were not pluripotent and expressed reduced levels of Oct 4 and Rex-1 . They were non-tumorigenic with a population doubling time of ≈15 hours. When plated on matrigel, they readily differentiated to form patent tubular structures with diameters of 30 to 150 μm. The differentiated cells endocytosed acetylated low-density lipoprotein (LDL) and began to express endothelial-specific markers such as CD34, CD31, Flk-1, TIE2, P-selectin, Sca-1, and thy-1. They also expressed genes essential for differentiation and maintenance of endothelial lineages, eg, Flk-1, vascular endothelial growth factor (VEGF), and angiopoietin-1. When transplanted into animal models, these cells incorporated into host vasculature.

Conclusions— These cell lines can undergo in vitro and in vivo endothelial differentiation that recapitulated known endothelial differentiation pathways. Therefore, they are ideal for establishing an in vitro cellular system to study endothelial differentiation.

Angiopoietin/tie-2 as mediators of angiogenesis: a role in congestive heart failure?

Angiogenic factors, in particular vascular endothelial growth factor (VEGF) and the angiopoietins, Ang-1 and -2, have recently generated significant interest, especially in oncology. The process of angiogenesis is also thought to occur in response to ischaemic conditions, which lie at the core of cardiovascular disease states such as coronary artery disease and congestive heart failure. However, current data do not conclusively show evidence of angiogenesis per se in these conditions, despite (for example) the presence of high levels of VEGF and Ang-2. High levels of these angiogenic factors in heart disease also have not translated into clinically significant new vessel formation, as in accelerated cancer growth or proliferative retinopathy. Indeed, we would hypothesize that these angiogenic markers--especially the angiopoietins--do not necessarily translate into new vessel formation in congestive heart failure (CHF), but may well reflect disturbances of endothelial integrity in CHF.