Papers by Alexander Seifalian
Journal of …, 2006
Surface properties have been found to be one of the key parameters which cause degradation and of... more Surface properties have been found to be one of the key parameters which cause degradation and of thrombogenicity in all polymers used in biomedical devices, thus signifying the importance and the necessity for quantitative and accurate characterization of the polymer surface itself as used in the construction of the device. The characterization techniques employed generally involve thermal and spectroscopic measurements, in which class the electrochemical investigations and scanning probe microscopies can also be included. Current hypotheses on the correlations that exist between surface parameters and hemocompatibility and degradation of polymers are examined herein, but concentrating on the field of clinically utilized polymeric materials as used within medical devices themselves. Furthermore, this review provides a brief but complete synopsis of these techniques and other emerging ones, which have proven useful in the analysis of the surface properties of polymeric materials as used in the construction of cardiovascular devices. Statements and examples are given as to how specific information can be acquired from these differing methodologies and how it aids in the design and development of new polymers for usage in biomedical device construction.
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Clinical and Experimental Rheumatology 26 1134 1145, 2008
Patients with systemic lupus erythematosus (SLE) have an increased vascular morbidity and mortali... more Patients with systemic lupus erythematosus (SLE) have an increased vascular morbidity and mortality. Several established vascular risk factors are more prevalent in this population but cannot fully explain the reported excess atherosclerotic burden. Emerging vascular risk factors may also contribute to the increased vascular risk in these patients although the evidence is limited and often conflicting. SLE-specific risk factors also play a role in the pathogenesis of atherosclerosis.Given the multifactorial aetiology of vascular disease in SLE, an integrated index of risk could be useful in the management of these patients. Arterial stiffness possibly represents such an index and accumulating data suggest an increased prevalence of arterial stiffness in SLE. Many factors play a role in the loss of arterial elasticity in this population, including both emerging and established vascular risk factors. Arterial stiffness may emerge as a useful index for risk stratification in SLE and has the potential to guide therapeutic decisions in these patients.
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Nano Reviews, 2010
Over the years, biological imaging has seen many advances, allowing scientists to unfold many of ... more Over the years, biological imaging has seen many advances, allowing scientists to unfold many of the mysteries surrounding biological processes. The ideal imaging resolution would be in nanometres, as most biological processes occur at this scale. Nanotechnology has made this possible with functionalised nanoparticles that can bind to specific targets and trace processes at the cellular and molecular level. Quantum dots (QDs) or semiconductor nanocrystals are luminescent particles that have the potential to be the next generation fluorophores. This paper is an overview of the basics of QDs and their role as fluorescent probes for various biological imaging applications. Their potential clinical applications and the limitations that need to be overcome have also been discussed.
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In British Journal of Surgery John Wiley Sons Ltd, Sep 1, 2004
Direct ischaemic preconditioning of the liver reduces ischaemia-reperfusion injury (IRI). Remote ... more Direct ischaemic preconditioning of the liver reduces ischaemia-reperfusion injury (IRI). Remote ischaemic preconditioning (RIPC) of a limb has been shown to reduce IRI to the heart. This study determined the effect of brief remote ischaemia to the limb in reducing early liver warm IRI. Twenty-eight male rabbits were allocated to four groups: sham operated, RIPC alone, IRI alone, and RIPC plus IRI. RIPC was induced in the leg with a tourniquet, before liver IRI, by three alternate cycles of 10 min ischaemia followed by 10 min reperfusion. Liver IRI was produced by total inflow occlusion for 25 min. Markers of liver injury and systemic and hepatic haemodynamics were measured for 2 h after reperfusion. At 2 h, IRI alone was associated with increased serum levels of aminotransferases, and reduced mean arterial blood pressure, hepatic blood flow and peripheral oxygen saturation. There was significant improvement in these variables in animals that had RIPC before liver IRI, and hepatic venous nitrate/nitrite levels were also significantly higher. In this experimental model RIPC appeared to reduce liver IRI.
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International wound journal, 2016
The potential use of stem cell-based therapies for the repair and regeneration of various tissues... more The potential use of stem cell-based therapies for the repair and regeneration of various tissues and organs offers a paradigm shift in plastic and reconstructive surgery. The use of either embryonic stem cells (ESC) or induced pluripotent stem cells (iPSC) in clinical situations is limited because of regulations and ethical considerations even though these cells are theoretically highly beneficial. Adult mesenchymal stem cells appear to be an ideal stem cell population for practical regenerative medicine. Among these cells, adipose-derived stem cells (ADSC) have the potential to differentiate the mesenchymal, ectodermal and endodermal lineages and are easy to harvest. Additionally, adipose tissue yields a high number of ADSC per volume of tissue. Based on this background knowledge, the purpose of this review is to summarise and describe the proliferation and differentiation capacities of ADSC together with current preclinical data regarding the use of ADSC as regenerative tools in ...
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Journal of Biomedical Materials Research, Aug 1, 2002
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In British Journal of Surgery, 2000
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Journal of Gastrointestinal and Liver Diseases Jgld, Mar 1, 2008
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Clinical Hemorheology and Microcirculation, Feb 1, 2005
Small-diameter prosthetic cardiovascular bypass grafts have high occlusion rates. Thrombogenicity... more Small-diameter prosthetic cardiovascular bypass grafts have high occlusion rates. Thrombogenicity caused by the lack of endothelial cells (ECs) on the luminal surface of the grafts is one of the main reasons for its occlusion. One strategy to improve the clinical performance of cardiovascular prosthetic grafts has been to seed its luminal surface with a monolayer of the patient's own ECs. In this strategy a "two stage" seeding procedure is utilized whereby cells obtained from a vein are amplified in cell culture, then seeded onto a fibrin-arginine-glycine-aspartate (RGD) tripeptide-enriched expanded polytetrafluoroethylene (ePTFE) graft in a rotating bioreactor for one week, after which it is surgically implanted. This achieves patency rates approaching those of vein grafts. The disadvantage of two stage seeding is that it requires culture facilities, a large amount of RGD, which is expensive and is confined to elective cases because of the delay between cell cultivation, seeding, and graft implantation. A single stage seeding using freshly extracted ECs that is transplanted onto the graft at the same time frame of the bypass operation without the need for cell cultivation would be an ideal answer for the disadvantages of two stage seeding. Animal trials have been successful but human trials of single stage seeding have been disappointing. It has been hypothesized that extracted ECs are scarce, furthermore, they are washed off the graft surface once exposed to blood flow. This review examines the various techniques/technologies to improve endothelial cell extraction from various sources and retention onto the luminal surface of prosthetic cardiovascular grafts in order to develop a clinically applicable strategy for single stage seeding.
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Journal of Vascular Surgery, 2002
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Biomaterials, 2016
Polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) is a versatile nano... more Polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) is a versatile nanocomposite biomaterial with growing applications as a bioscaffold for tissue engineering. Integration of synthetic implants with host tissue can be problematic but could be improved by topographical modifications. We describe optimization of POSS-PCU by dispersion of porogens (sodium bicarbonate (NaHCO3), sodium chloride (NaCl) and sucrose) onto the material surface, with the principle aim of increasing surface porosity, thus providing additional opportunities for improved cellular and vascular ingrowth. We assess the effect of the porogens on the material's mechanical strength, surface chemistry, wettability and cytocompatibilty. Surface porosity was characterized by scanning electron microscopy (SEM). There was no alteration in surface chemistry and wettability and only modest changes in mechanical properties were detected. The size of porogens correlated well with the porosity of the construct produced and larger porogens improved interconnectivity of spaces within constructs. Using primary human bronchial epithelial cells (HBECs) we demonstrate moderate in vitro cytocompatibility for all surface modifications; however, larger pores resulted in cellular aggregation. These cells were able to differentiate on POSS-PCU scaffolds. Implantation of the scaffold in vivo demonstrated that larger pore sizes favor cellular integration and vascular ingrowth. These experiments demonstrate that surface modification with large porogens can improve POSS-PCU nanocomposite scaffold integration and suggest the need to strike a balance between the non-porous surfaces required for epithelial coverage and the porous structure required for integration and vascularization of synthetic scaffolds in future construct design.
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Current Medicinal Chemistry, 2014
Intracranial aneurysms are present in 1-5% of population and can be described as &amp... more Intracranial aneurysms are present in 1-5% of population and can be described as "ticking time bombs" that can go off at any time and cause serious harms including permanent disability and death. There are two routinely practiced treatment options for this disease; endovascular coiling and surgical clipping. In recent years other promising methods, such as stent-assisted coiling, flow diverting devices and Onyx embolic agent, have also been developed and tested. The studies reviewed here suggest endovascular coiling to be the most commonly chosen treatment method and that there are reservations on using the newly developed techniques, despite studies suggesting their safety and effectiveness. Therefore, it is now becoming clear that a competent management system, in which treatment methods are chosen to best fit the characterisation of the patient and the aneurysm, should be developed in order to effectively diagnose and treat intracranial aneurysms. One way to develop such a system could be through the advancements of nanotechnology and smart materials. Neurosurgery, like many other areas of the medical field, is moving towards adopting the exciting and rapidly developing technologies based on nanomaterials as the nano-approach to detect and treat intracranial aneurysms could offer surgical opportunities that were more invasive or out of rich at the microneurosurgery level.
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F1000posters, Oct 2, 2012
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Carbon, 2010
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J Gastroenterol Hepatol, 2010
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Nano Reviews, Mar 12, 2013
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European Journal of Vascular and Endovascular Surgery the Official Journal of the European Society For Vascular Surgery, Apr 1, 2003
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In Faseb Journal Federation Amer Soc Exp Biol, Mar 14, 2003
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Papers by Alexander Seifalian