Biomedical subjects

Niels D Martin

Publications and source records attributed to Niels D Martin.

4 recordsLinked to original sources

PubMed2005

In vivo behavior of decellularized vein allograft.

BACKGROUND: We are investigating decellularized vein allograft as a scaffold to engineer a non-synthetic, small-diameter vascular graft. This study examines the in vivo behavior of this scaffolding after implantation into the arterial circulation. MATERIALS AND METHODS: Canine animals underwent bilateral carotid interposition grafting using jugular vein implanted as either: 1) fresh autograft, 2) fresh allograft, or 3) decellularized allograft. Decellularization was achieved using sodium dodecyl sulfate. Grafts were examined with duplex ultrasound biweekly to determine luminal diameter, thrombosis, stenosis, or anastomotic breakdown. After perfusion fixation at 2 or 8 weeks, grafts underwent histological, morphometric, and immunohistochemical examination. RESULTS: All animals survived without neurological or hemorrhagic complication. No deterioration of graft integrity (rupture, aneurysm) was observed in any group. Luminal narrowing was observed in both allograft groups, but secondary to different pathology. Fresh allografts had significant mononuclear cell infiltrate, intimal hyperplasia, and intramural hemorrhage consistent with rejection. Conversely, decellularized allografts had minimal evidence of rejection but instead had a compact fibrin layer formed along their lumen. This fibrin layer was absent in the peri-anastomotic regions where endothelium had migrated from the native artery. By 8 weeks, decellularized grafts had repopulated with cells staining positive for smooth muscle alpha-actin. CONCLUSIONS: After 8 weeks of arterial flow, decellularized vein allograft exhibits satisfactory strength, reduced antigenicity compared to fresh allograft, and supports cellular repopulation. These characteristics make it satisfactory for further tissue engineering; combined with luminal vascular cell seeding, it may prove useful as a small-diameter arterial bypass graft.

Animals↗

PubMed2005

Endovascular repair of carotid artery aneurysms following carotid endarterectomy.

Aneurysm of the carotid artery following endarterectomy is a rare entity that historically has required reoperation. Endovascular deployment of a covered stent can theoretically exclude an aneurysm while minimizing the risks seen with reoperation. Herein, we review the scientific literature on this evolving technique and report an additional case involving successful treatment of an aneurysm that developed following remote endarterectomy.

Aged↗

PubMed2004

Decellularized vein as a potential scaffold for vascular tissue engineering.

PURPOSE: Current strategies to create small-diameter vascular grafts involve seeding biocompatible, compliant scaffolds with autologous vascular cells. Our purpose was to study the composition and strength of decellularized vein to determine its potential as a vascular tissue-engineering scaffold. METHODS: Intact human greater saphenous vein specimens were decellularized by using sodium dodecyl sulfate (SDS). Residual cellular and extracellular matrix composition was studied with light and electron microscopy as well as immunohistochemistry. Burst and suture-holding strength was measured in vitro by insufflation and pull-through techniques. To assess initial handling and durability of decellularized vein in vivo, a canine model was developed wherein decellularized canine jugular veins were implanted as carotid interposition grafts in recipient animals. After two weeks of arterial perfusion, these grafts were studied with duplex imaging and histologic methods. RESULTS: Human saphenous vein decellularized by using SDS was devoid of endothelial cells and >94% of the cells resident within the vein wall. Collagen morphology appeared unchanged, and elastin staining decreased only slightly. Basement membrane collagen type IV remained intact. Compared with fresh vein, decellularized vein had similar in vitro burst (2480 +/- 460 mm Hg vs 2380 +/- 620 mm Hg; P >.05) and suture-holding (185 +/- 30 gm vs 178 +/- 66 gm; P >.05) strength. Decellularized canine vein functioned well in vivo without dilation, anastomotic complication, or rupture over 2 weeks of arterial perfusion. CONCLUSIONS: Vein rendered acellular with SDS has well-preserved extracellular matrix, basement membrane structure, and strength sufficient for vascular grafting. These properties suggest proof of concept for its use as a scaffold for further vascular tissue engineering. CLINICAL RELEVANCE: The following research examines the creation of a new small-diameter bypass graft. It is clinically relevant to patients who need distal arterial bypass, coronary artery bypass, or hemodialysis access, but who do not have adequate autologous vein for their surgeries. Future investigations will involve further tissue engineering of this vascular scaffold (eg, autologous endothelial seeding of its lumen) and testing the clinical usefulness of the completed graft.

Antigens, Surface↗

PubMed2004

Combination treatment of venous thoracic outlet syndrome: open surgical decompression and intraoperative angioplasty.

OBJECTIVE: Residual subclavian vein stenosis after thoracic outlet decompression in patients with venous thoracic outlet syndrome is often treated with postoperative percutaneous angioplasty (PTA). However, interval recurrent thrombosis before postoperative angioplasty is performed can be a vexing problem. Therefore we initiated a prospective trial at 2 referral institutions to evaluate the safety and efficacy of combined thoracic outlet decompression with intraoperative PTA performed in 1 stage. METHODS: Over 3 years 25 consecutive patients (16 women, 9 men; median age, 30 years) underwent treatment for venous thoracic outlet syndrome with a standard protocol at 2 institutions. Twenty-one patients (84%) underwent preoperative thrombolysis to treat axillosubclavian vein thrombosis. First-rib resection was performed through combined supraclavicular and infraclavicular incisions. Intraoperative venography and subclavian vein PTA were performed through a percutaneous basilic vein approach. Postoperative anticoagulation therapy was not used routinely. Venous duplex ultrasound scanning was performed postoperatively and at 1, 6, and 12 months. RESULTS: Intraoperative venography enabled identification of residual subclavian vein stenosis in 16 patients (64%), and all underwent intraoperative PTA with 100% technical success. Postoperative duplex scans documented subclavian vein patency in 23 patients (92%). Complications included subclavian vein recurrent thrombosis in 2 patients (8%), and both underwent percutaneous mechanical thrombectomy, with restoration of patency in 1 patient. One-year primary and secondary patency rates were 92% and 96%, respectively, at life-table analysis. CONCLUSIONS: Residual subclavian vein stenosis after operative thoracic outlet decompression is common in patients with venous thoracic outlet syndrome. Combination treatment with surgical thoracic outlet decompression and intraoperative PTA is a safe and effective means for identifying and treating residual subclavian vein stenosis. Moreover, intraoperative PTA may reduce the incidence of postoperative recurrent thrombosis and eliminate the need for venous stent placement or open venous repair.

Adult↗