Endothelial cell responses to castor oil-based polyurethane substrates functionalized by direct laser ablation.

Surface-induced thrombosis and lack of endothelialization are major drawbacks that hamper the widespread application of polyurethanes for the fabrication of implantable cardiovascular devices. Endothelialization of the blood-contacting surfaces of these devices may avoid thrombus formation and may be implemented by strategies that introduce micro and submicron patterns that favor adhesion and growth of endothelial cells. In this study, we used laser radiation to directly introduce topographical patterns in the low micrometer range on castor oil-based polyurethane, which is currently employed to fabricate cardiovascular devices. We have investigated cell adhesion, proliferation, morphology and alignment in response to these topographies. Reported results show that line-like and pillar-like patterns improved adhesion and proliferation rate of cultured endothelial cells. The line-like pattern with 1 µm groove periodicity was the most efficient to enhance cell adhesion and induced marked polarization and alignment. Our study suggests the viability of using laser radiation to functionalize PU-based implants by the introduction of specific microtopography to facilitate the development of a functional endothelium on target surfaces.

Histopathologic and Histomorphometric Analysis of Irradiation Injury in Bone and the Surrounding Soft Tissues of the Jaws.

PURPOSE: Surgery of irradiated tissue has an increased complication rate because of the development of hypovascular, hypocellular, and hypoxic tissue. This study was undertaken to perform histopathologic and histomorphometric analyses of irradiation tissue injury in bone and the surrounding soft tissues. MATERIAL AND METHODS: The histopathologic findings of 40 human mandibular bones and the surrounding soft tissue specimens obtained from different patients who underwent surgical procedures for treatment of osteoradionecrosis of the jaws were reviewed. RESULTS: Histopathologic examination showed 7 processes in the following order of appearance: hyperemia, endarteritis, thrombosis, cell loss, hypovascularity, increase of fat in the bone marrow cavity, and fibrosis. Histomorphometric analysis showed significant hypocellularity (P = .007), hypovascularity (P < .001), and fibrosis (P < .001) in irradiated specimens compared with control specimens. CONCLUSION: These results showed that radiation injuries affect the bone and surrounding soft tissues. However, the irradiation-induced injuries, such as cellular loss (hypocellularity) and fibrosis, were more expressive in bone tissue than in the surrounding soft tissues.

Effects of Different Therapeutic Ultrasound Waveforms on Endothelial Function in Healthy Volunteers: A Randomized Clinical Trial.

The purpose of this study was to determine the effects of different therapeutic 1-MHz ultrasound waveforms on endothelial function before and after cyclooxygenase (COX) inhibition. Forty-two healthy volunteers aged 27.2 ± 3.8 y underwent interventions and an evaluation for endothelial function (n = 15; with COX inhibition, n = 15; duration of the vasodilator effect, n = 12) by technique flow-mediated dilation. Continuous ultrasound therapy (0.4 W/cm(2 SATA)), pulsed ultrasound therapy (20% duty cycle, 0.08 W/cm(2 SATA)) or placebo (equipment power off) was randomly applied over the brachial artery for 5 min. COX inhibition (aspirin) was carried out 30 min before treatments. In relation to the placebo, flow-mediated dilation increased by 4.8% using continuous ultrasound and by 3.4% using pulsed ultrasound. After COX, flow-mediated dilation was enhanced by 2.1% by continuous ultrasound and 2.6% by pulsed ultrasound. This vasodilation persisted for 20 min. Continuous and pulsed therapeutic 1-MHz ultrasound waveforms improved endothelial function in humans, which provided them with anti-inflammatory vascular effects.

Unique extracellular matrix heparan sulfate from the bivalve Nodipecten nodosus (Linnaeus, 1758) safely inhibits arterial thrombosis after photochemically induced endothelial lesion.

Heparin-like glycans with diverse disaccharide composition and high anticoagulant activity have been described in several families of marine mollusks. The present work focused on the structural characterization of a new heparan sulfate (HS)-like polymer isolated from the mollusk Nodipecten nodosus (Linnaeus, 1758) and on its anticoagulant and antithrombotic properties. Total glycans were extracted from the mollusk and fractionated by ethanol precipitation. The main component (>90%) was identified as HS-like glycosaminoglycan, representing approximately 4.6 mg g(-1) of dry tissue. The mollusk HS resists degradation with heparinase I but is cleaved by nitrous acid. Analysis of the mollusk glycan by one-dimensional (1)H, two-dimensional correlated spectroscopy, and heteronuclear single quantum coherence nuclear magnetic resonance revealed characteristic signals of glucuronic acid and glucosamine residues. Signals corresponding to anomeric protons of nonsulfated, 3- or 2-sulfated glucuronic acid as well as N-sulfated and/or 6-sulfated glucosamine were also observed. The mollusk HS has an anticoagulant activity of 36 IU mg(-1), 5-fold lower than porcine heparin (180 IU mg(-1)), as measured by the activated partial thromboplastin time assay. It also inhibits factor Xa (IC(50) = 0.835 microg ml(-1)) and thrombin (IC(50) = 9.3 microg ml(-1)) in the presence of antithrombin. In vivo assays demonstrated that at the dose of 1 mg kg(-1), the mollusk HS inhibited thrombus growth in photochemically injured arteries. No bleeding effect, factor XIIa-mediated kallikrein activity, or toxic effect on fibroblast cells was induced by the invertebrate HS at the antithrombotic dose.

Abnormal endothelium-dependent responses in early radiation nephropathy.

While arterial hypertension and renal dysfunction are well recognized complications of renal irradiation, the mechanisms that trigger the development of these complications are unknown. Recently, it was reported that the endothelium is a major target in radiation injury. Because dysfunction of the endothelial cells may lead or contribute to the development of hypertension and renal dysfunction in radiation nephropathy, we tested the hypothesis that endothelium-dependent vasodilation is impaired in radiated kidneys prior to the onset of hypertension. To test this hypothesis, we used Long-Evans rats that had undergone left nephrectomy (3 weeks earlier) and irradiation (3000 r's) to the right kidney 8 days earlier (mean blood pressures in the irradiated rats were not different than in the controls). We then measured the changes in renal blood flow (RBF) induced by endothelium-dependent (acetylcholine and bradykinin) and -independent (nitroprusside, norepinephrine, and angiotensin II) vasoactive agents. We found that the increases in RBF induced by the endothelium-dependent but not independent vasodilators were markedly impaired in the irradiated kidneys. Blocking nitric oxide synthesis with nitro L-arginine methyl ester in sham rats mimicked the blunted responsiveness of the irradiated rats, whereas indomethacin (an inhibitor of prostaglandin synthesis) had no effect on either sham or irradiated rats. Finally, the RBF responses to the endothelium-independent vasoconstrictors, norepinephrine and angiotensin II, were not altered in the irradiated kidneys. These results suggest that renal irradiation causes endothelial dysfunction (prior to the onset of hypertension) but spares the vascular smooth muscle cells.

Cellular effects of the pulsed tunable dye laser at 577 nanometers on human endothelial cells, fibroblasts, and erythrocytes: an in vitro study.

The 577-nm flashlamp-pumped tunable dye laser pulsed at 450 microseconds is rapidly becoming the treatment of choice for removal of portwine stains and other vascular ectasias. In this study, we examined the mechanisms of vessel destruction by determining the effects of laser irradiation on three types of primary target cells--erythrocytes, endothelial cells, and fibroblasts. Human endothelial cells and fibroblasts in microwell plates were irradiated at various energy densities with the laser, after which several aspects of cellular biology were determined, including 1) viability of cells by trypan blue exclusion test; 2) cell proliferation by [3H]thymidine incorporation; and 3) rate of protein synthesis using [3H]leucine incorporation as a marker. In endothelial cell cultures, both [3H]thymidine and [3H]leucine incorporations were inhibited at energy levels of 5-12 J/cm2 (P less than 0.01). In fibroblast cultures, cell proliferation was similarly inhibited, while supratherapeutic energy density (greater than or equal to 12 J/cm2) was required for inhibition of protein synthesis. The laser energy in the range of 5-8.5 J/cm2 had no effect on cell viability. Erythrocytes as target cells for laser energy demonstrated rapid, dose-dependent lysis, as determined by release of free hemoglobin into culture medium. Addition of erythrocytes into a coculture with endothelial cells abolished the direct inhibitory effect noted in cultures when endothelial cells were present alone. The results of the latter experiment imply that erythrocytes are the primary target cell absorbing the laser energy at 577 nm. However, direct laser effects on endothelial cells may also contribute to the mechanisms of ablation of the vascular ectasias by the tunable dye laser at 577 nm.