nitinol and Inflammation

Because first-generation stent-grafts did not meet initial expectations, a recently designed nitinol-expanded polytetrafluoroethylene (ePTFE) stent-graft was tested for treatment of abdominal aortic aneurysms (AAAs) in a prospective clinical study. The primary study endpoints were technical success and safety.. A nitinol-ePTFE self-expandable stent-graft (Excluder) was used to treat 72 patients with AAAs. The median follow-up period was 21.5 months +/- 13 (range, 1-46 mo).. Primary technical success in accurate placement of the device was achieved in 70 of 72 patients (97%). Complete exclusion of the aneurysm from arterial flow was achieved in 57 of 72 patients (79.2%). Three type I leaks were observed during implantation and were immediately corrected with a proximal cuff prosthesis in two patients. Fourteen of 72 patients (19.4%) had a type II leak. Major complications were observed in three patients (4.1%), including one death in the early postinterventional period (one of 72, 1.4%). At 3 months, aneurysms were excluded in 70 of 71 patients (98.6%), and at 12 months, aneurysms were occluded in 29 of 30 patients (96.7%). The maximum diameter of the aneurysm decreased from 55 mm +/- 11 (median +/- SD) before intervention to 53 mm +/- 13 at 6 and 12 months. None of the patients showed aneurysm growth.. This newly designed stent-graft proved to be effective and safe for treatment of AAAs.

Topics: Aged; Aged, 80 and over; Alloys; Aortic Aneurysm, Abdominal; Arterial Occlusive Diseases; Blood Vessel Prosthesis Implantation; C-Reactive Protein; Coated Materials, Biocompatible; Combined Modality Therapy; Endpoint Determination; Equipment Safety; Female; Follow-Up Studies; Humans; Iliac Artery; Inflammation; Length of Stay; Leukocyte Count; Male; Middle Aged; Polytetrafluoroethylene; Postoperative Complications; Prospective Studies; Prosthesis Design; Radiography, Interventional; Stents; Survival Analysis; Time Factors; Treatment Outcome; Vascular Resistance

Zilver PTX nitinol self-expanding drug-eluting stent with paclitaxel coating is effective for treatment of superficial femoral artery (SFA) disease. However, as with any stent, it induces a measure of vascular inflammatory response. The current clinical trial (NCT02734836) aimed to assess vascular patency, remodeling, and inflammatory markers with intravascular optical coherence tomography (OCT) in patients with SFA disease treated with Zilver PTX stents.. Serial OCT examinations were performed in 13 patients at baseline and 12-month follow-up. Variables evaluated included neointimal area, luminal narrowing, thrombus area, stent expansion as well as measures of inflammation including, peri-strut low-intensity area (PLIA), macrophage arc, neovascularization, stent strut apposition and coverage.. Percentage of malapposed struts decreased from 10.3 ± 7.9% post-intervention to 1.1 ± 2.2% at 12-month follow-up, but one patient showed late-acquired stent malapposition (LASM). The percent of uncovered struts at follow-up was 3.0 ± 4.5%. Average expansion of stent cross-sectional area from baseline to follow-up was 35 ± 19%. The average neointimal area was 7.8 ± 3.8 mm. At 12-month follow-up, OCT analysis of Zilver PTX stent shows outward remodeling and minimal neointimal growth, but evidence of inflammation including PLIA, neovessels, thrombus and macrophages.. Thirteen patients with PAD had paclitaxel-coated stents implanted in their SFAs and were then imaged with OCT at baseline and 12-month follow-up. OCT proxy metrics of inflammation were quantified.

Topics: Aged; Aged, 80 and over; Alloys; Angioplasty, Balloon; Cardiovascular Agents; Drug-Eluting Stents; Female; Femoral Artery; Humans; Inflammation; Male; Middle Aged; Neointima; Paclitaxel; Peripheral Arterial Disease; Predictive Value of Tests; Prospective Studies; Prosthesis Design; Risk Factors; Self Expandable Metallic Stents; Time Factors; Tomography, Optical Coherence; Treatment Outcome; Vascular Patency; Vascular Remodeling

Braiding of Nitinol micro wires is an established technology for the manufacturing of fine-meshed neurovascular implants for tortuous vessel geometries. Electropolishing of wires before the braiding process has the potential to improve the in vitro behaviour in terms of thrombogenicity and endothelial cell proliferation. In this study, we present the first in vitro investigation of braided electropolished/blue oxide Nitinol samples in a blood flow loop, showing a significantly lower activation of the coagulation pathway (represented by the TAT III marker) and a tendency towards reduced platelet adhesion. Furthermore, we applied the same surface treatment on flat disks and measured protein adhesion as well as endothelial cell proliferation. We compared our results to non-electropolished samples with a native oxide surface. While platelet deposition was reduced on electropolished/blue oxide surface, a significant increase of endothelial cell seeding was observed. Investigation of inflammatory marker expression in endothelial cells provided divergent results depending on the marker tested, demanding closer investigation. Surface analysis using Auger electron spectroscopy revealed a thin layer mainly consisting of titanium oxynitride or titanium oxide + titanium nitride as a potential cause of the improved biological performance. Translated to the clinical field of intracranial aneurysm treatment, the improved biocompatibility has the potential to increase both safety (low thrombogenicity) and effectiveness (aneurysm neck reconstruction).

Topics: Adsorption; Alloys; Aneurysm; Blood Coagulation; Blood Platelets; Blood Vessels; Cell Adhesion; Cell Proliferation; Coated Materials, Biocompatible; Elasticity; Electrochemistry; Endothelial Cells; Humans; Inflammation; Materials Testing; Nickel; Oxides; Patient Safety; Platelet Adhesiveness; Prostheses and Implants; Surface Properties; Titanium

This study was conducted to determine whether a nitinol stent coated with doxycycline prevents tracheal inflammation and fibrosis in a rabbit.. A nitinol stent coated with doxycycline was designed by us. Twelve rabbits were divided into three groups: normal, control (nondoxycycline-coated stent), and doxycycline-coated stent group. The stents were inserted into the tracheal lumen through the oral cavity. Tracheal granulation was evaluated and graded by laryngoscopy. Histological examinations evaluated the inflammatory response and fibrosis. Real-time polymerase chain reaction (PCR) and Western blot assessed the changes to the extracellular matrix (ECM).. Endoscopic findings showed that the nitinol stent coated with doxycycline resulted in lesser granulation tissue in the trachea than the noncoated stent. Histologic examination further revealed that the doxycycline-coated stent was associated with decreased inflammatory cells and reduced fibrosis, compared to the noncoated stent. In PCR and Western blot, the doxycycline-coated stent showed lower expression of ECM components inducing fibrosis.. A nitinol stent coated with doxycycline showed favorable effects in reducing tracheal inflammation and fibrosis in a rabbit model. Further research is required to study the beneficial effects of local application of doxycycline for prevention of tracheal stenosis.. NA. Laryngoscope, 128:1558-1563, 2018.

Topics: Adjuvants, Immunologic; Alloys; Animals; Anti-Bacterial Agents; Disease Models, Animal; Doxycycline; Fibrosis; Inflammation; Laryngoscopy; Rabbits; RNA, Messenger; Stents; Trachea; Tracheal Stenosis; Transforming Growth Factor beta1; Wound Healing

Topics: Alloys; Aortic Aneurysm; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Endovascular Procedures; Humans; Hypersensitivity; Inflammation; Polyesters; Prosthesis Design; Risk Factors; Stents; Syndrome; Treatment Outcome

The popularity of vascular stents continues to increase for a variety of applications, including coronary, lower limb, renal, carotid, and neurovascular disorders. However, their clinical effectiveness is hindered by numerous postdeployment complications, which may stimulate inflammatory and fibrotic reactions. The purpose of this study was to evaluate the vessel inflammatory response via in vivo imaging in a mouse stent implantation model. Corroded and noncorroded self-expanding miniature nitinol stents were implanted in mice abdominal aortas, and novel in vivo imaging techniques were used to assess trafficking and accumulation of fluorescent donor monocytes as well as cellular proliferation at the implantation site. Monocytes were quantitatively tracked in vivo and found to rapidly clear from circulation within hours after injection. Differences were found between the test groups with respect to the numbers of recruited monocytes and the intensity of the resulting fluorescent signal. Image analysis also revealed a subtle increase in matrix metalloproteinase activity in corroded compared with the normal stented aortas. In conclusion, this study has been successful in developing a murine stent inflammation model and applying novel in vivo imaging tools and methods to monitor the complex biological processes of the host vascular wall response.

Topics: Alloys; Animals; Aorta, Abdominal; Cell Separation; Coronary Vessels; Corrosion; Disease Models, Animal; Fluorescence; Inflammation; Male; Matrix Metalloproteinases; Metals; Mice; Monitoring, Physiologic; Monocytes; Stents

In this study, we describe the synthesis of an upright nanotubular coating with discrete, exposed nanotubes on top of superelastic Nitinol via anodization and characterization of the surface elemental composition and nickel release rates. We demonstrate, for the first time, that this coating could improve re-endothelialization by increasing the cell spreading and migration of primary human aortic endothelial cells on Nitinol. We also show the potential for reducing neointimal hyperplasia by decreasing the proliferation and expression of collagen I and MMP-2 in primary human aortic smooth muscle cells (HASMC). Furthermore, we did not observe the nanotubular surface to induce inflammation through ICAM-1 expression in HASMC as compared to the flat control. This coating could be used to improve Nitinol stents by reducing restenosis rates and, given the extensive use of Nitinol in other implantable devices, act as a generalized coating strategy for other medical devices.

Topics: Alloys; Aorta; Biocompatible Materials; Cell Movement; Cell Proliferation; Collagen Type I; Coronary Restenosis; Endothelial Cells; Endothelium, Vascular; Flow Cytometry; Humans; Inflammation; Intercellular Adhesion Molecule-1; Matrix Metalloproteinase 2; Microscopy, Electron, Scanning; Microscopy, Fluorescence; Myocytes, Smooth Muscle; Nanotechnology; Nanotubes; Stents; Surface Properties

Despite substantial research in the past few decades, only slight progress has been made toward developing biocompatible, tissue-engineered scaffolds for heart valve leaflets that can withstand the dynamic pressure inside the heart. Recent progress on the development of hybrid scaffolds, which are composed of a thin metal mesh enclosed by multi-layered tissue, appear to be promising for heart valve engineering. This approach retains all the advantages of biological scaffolds while developing a strong extracellular matrix backbone to withstand dynamic loading. This study aims to test the inflammatory response of hybrid tissue-engineered leaflets based on characterizing the activation of macrophage cells cultured on the surfaces of the tissue construct. The results indicate that integration of biological layers around a metal mesh core-regardless of its type-may reduce the evoked inflammatory responses by THP-1 monocyte-like cells. This observation implies that masking a metal implant within a tissue construct prior to implantation can hide it from the immune system and may improve the implant's biocompatibility.

Topics: Alloys; Aorta; Biocompatible Materials; Cell Line; Collagen Type I; Endothelial Cells; Fibroblasts; Heart Valves; Humans; Inflammation; Macrophages; Myocytes, Smooth Muscle; Stainless Steel; Tissue Engineering; Tissue Scaffolds; Tumor Necrosis Factor-alpha; Umbilical Cord

Gastrointestinal anastomosis is a crucial step in many operative procedures, and responsible for a major portion of early and late post-operative complications. In order to improve on the results of current tools to perform an anastomosis, such as sutures and staplers, new concepts are being developed. One of these concepts is compression anastomosis. Compression anastomosis has been tried in the past but did not become popular mostly because of technical reasons. Recently, trials to accomplish compression anastomosis using Nitinol devices were conducted. Two devices were made and tested in the past three years: a side-to-side device and an end-to-end device. The common principle in both devices is the compression of two bowel loops through the constant pressure of a Nitinol device, thus producing a dual process of necrosis and healing until the lumens of both bowels fuse, and the device falls into the lumen and is excreted. Both devices have been tested in animals and humans, with encouraging results. In animals, the anastomoses were shown to demonstrate minimal inflammation and no foreign body reaction, with perfect healing of the mucosa. The side-to-side device was tested in over 500 human patients, and the end-to-end device is currently used in a large, multi-centric human trial.

Topics: Alloys; Anastomosis, Surgical; Animals; Clinical Trials as Topic; Digestive System Surgical Procedures; Elasticity; Equipment Design; Foreign-Body Reaction; Humans; Inflammation; Postoperative Complications; Pressure; Suture Techniques

This investigation was undertaken to simulate in an animal model the particles released from a porous nitinol interbody fusion device and to evaluate its consequences on the dura mater, spinal cord and nerve roots, lymph nodes (abdominal para-aortic), and organs (kidneys, spleen, pancreas, liver, and lungs). Our objective was to evaluate the compatibility of the nitinol particles with the dura mater in comparison with titanium alloy. In spite of the great use of metallic devices in spine surgery, the proximity of the spinal cord to the devices raised concerns about the effect of the metal debris that might be released onto the neural tissue. Forty-five New Zealand white female rabbits were divided into three groups: nitinol (treated: N = 4 per implantation period), titanium (treated: N = 4 per implantation period), and sham rabbits (control: N = 1 per observation period). The nitinol and titanium alloy particles were implanted in the spinal canal on the dura mater at the lumbar level L2-L3. The rabbits were sacrificed at 1, 4, 12, 26, and 52 weeks. Histologic sections from the regional lymph nodes, organs, from remote and implantation sites, were analyzed for any abnormalities and inflammation. Regardless of the implantation time, both nitinol and titanium particles remained at the implantation site and clung to the spinal cord lining soft tissue of the dura mater. The inflammation was limited to the epidural space around the particles and then reduced from acute to mild chronic during the follow-up. The dura mater, sub-dural space, nerve roots, and the spinal cord were free of reaction. No particles or abnormalities were found either in the lymph nodes or in the organs. In contact with the dura, the nitinol elicits an inflammatory response similar to that of titanium. The tolerance of nitinol by a sensitive tissue such as the dura mater during the span of 1 year of implantation demonstrated the safety of nitinol and its potential use as an intervertebral fusion device.

Topics: Alloys; Animals; Dura Mater; Female; Inflammation; Joint Prosthesis; Lymph Nodes; Materials Testing; Rabbits; Spinal Cord; Spinal Fusion; Titanium

Three recently developed stent-grafts and the Wallstent were compared directly in an ovine animal model with regard to performance and biocompatibility.. Three stent-grafts, the Hemobahn (polytetrafluoroethylene [ePTFE]/nitinol), Wallgraft (polyester/Ni-Co-Ti-steel alloy), and Jostent peripheral stent-graft (balloon-expandable ePTFE/stainless steel), and the Wallstent (Ni-Co-Ti-steel alloy), were implanted in sheep iliac arteries (one type of each stent or stent-graft per animal, n = 8). Pre- and postimplantation luminal diameters were measured for each prosthesis and implantation site. Angiography, intravascular ultrasonography (IVUS), and histomorphometric, histologic, and scanning electron microscopic analyses were performed at 3 months.. Early lumen gain, late lumen loss, and patent vessel diameter at angiography were not significantly different. Two stent-grafts had significantly more neointima formation (Hemobahn, 9.88 mm(2) +/- 0.94; Wallgraft, 14.98 mm(2) +/- 0.90) than the other stent-graft (Jostent, 6.52 mm(2) +/- 0.46) and the Wallstent (5.24 mm(2) +/- 0.62; P <.01). Patent lumen area was not significantly different (Hemobahn, 42.57 mm(2) +/- 1.41; Jostent, 39.76 mm(2) +/- 2.04; Wallgraft, 40.22 mm(2) +/- 1.04; Wallstent, 41.64 mm(2) +/- 1.59; P =.57). The Hemobahn had significantly more inflammatory reaction (inflammation score of 0.83 +/- 0.03) than the Jostent (0.58 +/- 0.03), Wallgraft (0.55 +/- 0.04), or Wallstent (0.16 +/- 0.01). Angiography and IVUS demonstrated absence of anastomotic neointima formation. Endothelialization was incomplete and immature for all prostheses.. The stent-grafts caused a greater degree of neointima formation and inflammatory vessel wall reaction than the bare stent. However, these changes did not interfere with patent lumen areas and occurred in the absence of excessive anastomotic neointima formation.

Topics: Alloys; Animals; Biocompatible Materials; Blood Vessel Prosthesis; Female; Iliac Artery; Inflammation; Microscopy, Electron, Scanning; Polyesters; Polytetrafluoroethylene; Radiography; Sheep; Stainless Steel; Stents; Tunica Intima

Topics: Alloys; Angiography, Digital Subtraction; Angioplasty, Balloon; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Constriction, Pathologic; Female; Humans; Iliac Artery; Inflammation; Middle Aged; Polyethylene Terephthalates; Recurrence; Stents; Syndrome; Ureter; Ureteral Obstruction

To evaluate with magnetic resonance (MR) imaging the inflammatory perigraft response after implantation of Dacron-covered and noncovered arterial endovascular prostheses in sheep.. Four prosthesis types--two Dacron-covered nitinol stent-grafts (plain and heparin-coated) and two noncovered nitinol stents (Memotherm and Cragg)--were each inserted into the external iliac arteries of eight sheep. MR imaging before and after gadolinium enhancement was performed 5-8 days and 1 month after implantation (before the animals were killed). Macroscopic and microscopic examinations of the vessels were performed, and findings were correlated with those on MR images.. Severe inflammatory perigraft responses to the heparin-coated Dacron-covered stent-grafts were found; MR images demonstrated contrast enhancement and edema. Macroscopic examination showed marked vascular wall thickening and adhesions around the Dacron fabric; microscopic examination showed a pronounced inflammatory foreign-body response. There was a moderate inflammatory response to the plain Dacron-covered stent-grafts and almost no response to noncovered stents.. In sheep, MR imaging findings of perigraft soft-tissue edema and contrast enhancement correlated well with histopathologic findings of severe perigraft inflammation due to heparin-coated Dacron-covered stent-grafts.

Topics: Alloys; Animals; Blood Vessel Prosthesis; Foreign-Body Reaction; Heparin; Iliac Artery; Inflammation; Magnetic Resonance Imaging; Polyethylene Terephthalates; Sheep; Stents