Ferromagnetic Bare Metal Stent for Endothelial Cell Capture and Retention

Uthamaraj, Susheil; Tefft, Brandon J.; Hlinomaz, Ota; Sandhu, Gurpreet S.; Dragomir-Daescu, Dan

doi:10.3791/53100

Cited by 7 publications

(12 citation statements)

References 23 publications

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“…Compared to the austenitic stainless steel grades, the 2205 grade exhibits approximately 25% higher ultimate tensile strength, 135% higher yield strength, 60% lower ultimate tensile strain, and superior corrosion resistance [25, 26]. The 2205 grade is also somewhat more difficult to machine, but high quality stents can be manufactured using standard tube drilling and grinding followed by laser cutting of the strut pattern [12]. …”

Section: Discussionmentioning

confidence: 99%

“…Stent-grafts were fabricated by coating stents made from magnetic 2205 duplex stainless steel (2205 SS) or non-magnetic 316L stainless steel (316L SS) [12] with electrospun polyurethane nanofibers as previously described [13]. Briefly, a 15% polyurethane in dimethylacetamide (DMA) solution (DSM Biomedical, Exton, PA) was loaded into a 5 mL glass syringe and a blunt needle was attached.…”

Section: Methodsmentioning

confidence: 99%

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Magnetizable stent-grafts enable endothelial cell capture

Tefft

Uthamaraj

Harburn

et al. 2017

Journal of Magnetism and Magnetic Materials

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Emerging nanotechnologies have enabled the use of magnetic forces to guide the movement of magnetically-labeled cells, drugs, and other therapeutic agents. Endothelial cells labeled with superparamagnetic iron oxide nanoparticles (SPION) have previously been captured on the surface of magnetizable 2205 duplex stainless steel stents in a porcine coronary implantation model. Recently, we have coated these stents with electrospun polyurethane nanofibers to fabricate prototype stent-grafts. Facilitated endothelialization may help improve the healing of arteries treated with stent-grafts, reduce the risk of thrombosis and restenosis, and enable small-caliber applications. When placed in a SPION-labeled endothelial cell suspension in the presence of an external magnetic field, magnetized stent-grafts successfully captured cells to the surface regions adjacent to the stent struts. Implantation within the coronary circulation of pigs (n=13) followed immediately by SPION-labeled autologous endothelial cell delivery resulted in widely patent devices with a thin, uniform neointima and no signs of thrombosis or inflammation at 7 days. Furthermore, the magnetized stent-grafts successfully captured and retained SPION-labeled endothelial cells to select regions adjacent to stent struts and between stent struts, whereas the non-magnetized control stent-grafts did not. Early results with these prototype devices are encouraging and further refinements will be necessary in order to achieve more uniform cell capture and complete endothelialization. Once optimized, this approach may lead to more rapid and complete healing of vascular stent-grafts with a concomitant improvement in long-term device performance.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Magnetizable stent-grafts enable endothelial cell capture

Tefft

Uthamaraj

Harburn

et al. 2017

Journal of Magnetism and Magnetic Materials

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“…Stent-grafts currently available are limited in their ability to maintain a low profile and flexibility for deployment. Bare metal stents developed by our group in our previous studies have proven to assist in rapid healing of the stented artery 24,26 . Various polymers have been electrospun by other groups and polyurethane has been proven biostable and biocompatible.…”

Section: Discussionmentioning

confidence: 99%

“…3. Slide the balloon expandable stainless steel stent 26 onto the electrospun tube to a desired location. It may be necessary to slightly expand the stent so it slips on without damaging the electrospun tube.…”

Section: Electrospinning a Stent-graftmentioning

confidence: 99%

Fabrication of Small Caliber Stent-grafts Using Electrospinning and Balloon Expandable Bare Metal Stents

Uthamaraj

Tefft

Jana

et al. 2016

JoVE

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Stent-grafts are widely used for the treatment of various conditions such as aortic lesions, aneurysms, emboli due to coronary intervention procedures and perforations in vasculature. Such stent-grafts are manufactured by covering a stent with a polymer membrane. An ideal stentgraft should have a biocompatible stent covered by a porous, thromboresistant, and biocompatible polymer membrane which mimics the extracellular matrix thereby promoting injury site healing. The goal of this protocol is to manufacture a small caliber stent-graft by encapsulating a balloon expandable stent within two layers of electrospun polyurethane nanofibers. Electrospinning of polyurethane has been shown to assist in healing by mimicking native extracellular matrix, thereby promoting endothelialization. Electrospinning polyurethane nanofibers on a slowly rotating mandrel enabled us to precisely control the thickness of the nanofibrous membrane, which is essential to achieve a small caliber balloon expandable stent-graft. Mechanical validation by crimping and expansion of the stent-graft has shown that the nanofibrous polyurethane membrane is sufficiently flexible to crimp and expand while staying patent without showing any signs of tearing or delamination. Furthermore, stent-grafts fabricated using the methods described here are capable of being implanted using a coronary intervention procedure using standard size guide catheters. Video LinkThe video component of this article can be found at

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“…Pislaru et al tried this approach using stainless steel interspaced with for synthetic vascular grafts Others, such as Uthamaraj et al, used stainless steel stents rendered ferromagnetic to capture IO-labeled endothelial cells. 19 Stainless steel, however, is not biodegradable and thus require long-term drug therapy with antibiotics or antiplatelet therapy. to minimize complications.…”

Section: Introductionmentioning

confidence: 99%

Magnetically Coated Bioabsorbable Stents for Renormalization of Arterial Vessel Walls after Stent Implantation

Lee¹,

Han²,

Song³

et al. 2017

Nano Lett.

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The insertion of a stent in diseased arteries is a common endovascular procedure that can be compromised by the development of short- and long-term inflammatory responses leading to restenosis and thrombosis, respectively. While treatment with drugs, either systemic or localized, has decreased the incidence of restenosis and thrombosis these complications persist and are associated with a high mortality in those that present with stent thrombosis. We reasoned that if stents could be made to undergo accelerated endothelialization in the deployed region, then such an approach would further decrease the occurrence of stent thrombosis and restenosis thereby improving clinical outcomes. Toward that objective, the first step necessitated efficient capture of progenitor stem cells, which eventually would become the new endothelium. To achieve this objective, we engineered intrinsic ferromagnetism within nonmagnetizable, biodegradable magnesium (Mg) bare metal stents. Mg stents were coated with biodegradable polylactide (PLA) polymer embedding magnetizable iron-platinum (FePt) alloy nanoparticles, nanomagnetic particles, Mags, which increased the surface area and hence magnetization of the stent.Mags uniformly distributed on stents enabled capture, under flow, up to 50 mL/min, of systemically injected iron-oxide-labeled (IO-labeled) progenitor stem cells. Critical parameters enhancing capture efficiency were optimized, and we demonstrated the generality of the approach by showing that Mag-coated stents can capture different cell types. Our work is a potential paradigm shift in engineering stents because implants are rendered as tissue in the body, and this "natural stealthiness" reduces or eliminates issues associated with pro-inflammatory immune responses postimplantation.

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Ferromagnetic Bare Metal Stent for Endothelial Cell Capture and Retention

Cited by 7 publications

References 23 publications

Magnetizable stent-grafts enable endothelial cell capture

Magnetizable stent-grafts enable endothelial cell capture

Fabrication of Small Caliber Stent-grafts Using Electrospinning and Balloon Expandable Bare Metal Stents

Magnetically Coated Bioabsorbable Stents for Renormalization of Arterial Vessel Walls after Stent Implantation

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