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1.
Eur J Med Res ; 26(1): 121, 2021 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-34641963

RESUMO

BACKGROUND: Percutaneous coronary interventions (PCI) of bifurcation stenoses are both complex and challenging. Stenting strategies share that the stents' side cells must be carefully explored and appropriately prepared using balloons or stents. So far, stent manufacturers have not provided any information regarding side-branch expansion capacity of their stent platforms. AIMS: Given that drug-eluting stent (DES) information regarding their mechanical capacity of side-branch expansion is not available, we aimed to evaluate contemporary DES (Orsiro, BIOTRONIK AG; Xience Sierra, Abbott Vascular; Resolute Integrity, Medtronic; Promus Premier Select, Boston Scientific; Supraflex Cruz, Sahajan and Medical Technologies) by their side-branch expansion behavior using in vitro bench testing. METHODS: In this in vitro study, we analyzed five commercially available DES (diameter 3.0 mm), measuring their side-branch expansion following inflation of different high-pressure non-compliant (NC) balloons (balloon diameter: 2.00-4.00 mm), thereby revealing the morphological characteristics of their side-branch expansion capacities. RESULTS: We demonstrated that all tested contemporary DES platforms could withstand large single-cell deformations, up to 4.0 mm. As seen in our side-branch experiments, DES designs consisting of only two connectors between strut rings did not only result in huge cell areas, but also in larger cell diameters following side-branch expansion compared with DES designs using three or more connectors. Furthermore, the stent cell diameter attained was below the balloon diameter at normal pressure. CONCLUSIONS: We recommend that the expansion capacity of side-branches should be considered in stent selection for bifurcation interventions.

2.
Int J Mol Sci ; 22(17)2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34502107

RESUMO

Skin regeneration is a quite complex process. Epidermal differentiation alone takes about 30 days and is highly regulated. Wounds, especially chronic wounds, affect 2% to 3% of the elderly population and comprise a heterogeneous group of diseases. The prevailing reasons to develop skin wounds include venous and/or arterial circulatory disorders, diabetes, or constant pressure to the skin (decubitus). The hallmarks of modern wound treatment include debridement of dead tissue, disinfection, wound dressings that keep the wound moist but still allow air exchange, and compression bandages. Despite all these efforts there is still a huge treatment resistance and wounds will not heal. This calls for new and more efficient treatment options in combination with novel biocompatible skin scaffolds. Cold atmospheric pressure plasma (CAP) is such an innovative addition to the treatment armamentarium. In one CAP application, antimicrobial effects, wound acidification, enhanced microcirculations and cell stimulation can be achieved. It is evident that CAP treatment, in combination with novel bioengineered, biocompatible and biodegradable electrospun scaffolds, has the potential of fostering wound healing by promoting remodeling and epithelialization along such temporarily applied skin replacement scaffolds.

3.
Int J Mol Sci ; 22(12)2021 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-34199303

RESUMO

The main purpose of new stent technologies is to overcome unfavorable material-related incompatibilities by producing bio- and hemo-compatible polymers with anti-inflammatory and anti-thrombogenic properties. In this context, wettability is an important surface property, which has a major impact on the biological response of blood cells. However, the influence of local hemodynamic changes also influences blood cell activation. Therefore, we investigated biodegradable polymers with different wettability to identify possible aspects for a better prediction of blood compatibility. We applied shear rates of 100 s-1 and 1500 s-1 and assessed platelet and monocyte activation as well as the formation of CD62P+ monocyte-bound platelets via flow cytometry. Aggregation of circulating platelets induced by collagen was assessed by light transmission aggregometry. Via live cell imaging, leukocytes were tracked on biomaterial surfaces to assess their average velocity. Monocyte adhesion on biomaterials was determined by fluorescence microscopy. In response to low shear rates of 100 s-1, activation of circulating platelets and monocytes as well as the formation of CD62P+ monocyte-bound platelets corresponded to the wettability of the underlying material with the most favorable conditions on more hydrophilic surfaces. Under high shear rates, however, blood compatibility cannot only be predicted by the concept of wettability. We assume that the mechanisms of blood cell-polymer interactions do not allow for a rule-of-thumb prediction of the blood compatibility of a material, which makes extensive in vitro testing mandatory.


Assuntos
Plaquetas/citologia , Comunicação Celular/efeitos dos fármacos , Monócitos/citologia , Monócitos/efeitos dos fármacos , Poliésteres/farmacologia , Plaquetas/efeitos dos fármacos , Adesão Celular/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Humanos , Agregação Plaquetária/efeitos dos fármacos , Água , Molhabilidade
4.
Biomedicines ; 9(4)2021 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-33810541

RESUMO

The use of additive manufacturing (AM) technologies is a relatively young research area in modern medicine. This technology offers a fast and effective way of producing implants, tissues, or entire organs individually adapted to the needs of a patient. Today, a large number of different 3D printing technologies with individual application areas are available. This review is intended to provide a general overview of these various printing technologies and their function for medical use. For this purpose, the design and functionality of the different applications are presented and their individual strengths and weaknesses are explained. Where possible, previous studies using the respective technologies in the field of tissue engineering are briefly summarized.

5.
Biomed Mater ; 16(1): 015022, 2020 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-33022660

RESUMO

An ongoing challenge in drug delivery systems for a variety of medical applications, including cardiovascular diseases, is the delivery of multiple drugs to address numerous phases of a treatment or healing process. Therefore, an extended dual drug delivery system (DDDS) based on our previously reported cardiac DDDS was generated. Here we use the polymer poly(L-lactide) (PLLA) as drug carrier with the cytostatic drug Paclitaxel (PTX) and the endothelial cell proliferation enhancing growth factor, human vascular endothelial growth factor (VEGF), to overcome typical in-stent restenosis complications. We succeeded in using one solution to generate two separate DDDS via spray coating (film) and electrospinning (nonwoven) with the same content of PTX and the same post processing for VEGF immobilisation. Both processes are suitable as coating techniques for implants. The contact angle analysis revealed differences between films and nonwovens. Whereas, the morphological analysis demonstrated nearly no changes occurred after immobilisation of both drugs. Glass transition temperatures (Tg ) and degree of crystallinity (χ) show only minor changes. The amount of immobilised VEGF on nonwovens was over 300% higher compared to the films. Also, the nonwovens revealed a much faster and over three times higher PTX release over 70 d compared to the films. The almost equal physical properties of nonwovens and films allow the comparison of both DDDS independently of their fabrication process. Both films and nonwovens have significantly increased in vitro cell viability for human umbilical vein endothelial cells (EA.hy926) with dual loaded PTX and VEGF compared to PTX-only loaded samples.

6.
Eur J Med Res ; 25(1): 28, 2020 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-32727596

RESUMO

BACKGROUND: Percutaneous coronary intervention is among the most common therapeutic interventions in cardiology. This procedure may, however, be associated with a rare, though life-threatening complication: acute coronary perforation (CP). CP is primarily treated using covered stents, which are made of bare metal stents with a polytetrafluoroethylene (PTFE) or polyurethane coating. These stents' major limitations include higher rates of thrombus formation and restenosis. Hence, there is a still unmet need for new stents regarding their design and composition. Or, to test new covered stent designs, the rabbit iliac artery has become the best-established animal model. This study sought to present a preclinical animal approach designed to test covered stents that are utilized following vessel perforation. METHODS: The animal experiments were performed using New Zealand white rabbits, each weighting 3.5-4.5 kg. The animal models described herein relied on the three most common clinical causes for CP, such as guidewire-induced, balloon catheter bursting, and device oversizing. Moreover, the sealing capacity of covered stent grafts was assessed for each of these models by means of angiography. RESULTS: We herein report a rabbit iliac artery perforation model using three different types of vessel perforation that closely mimic the clinical setting, such as guidewire-induced, balloon catheter rupture, and device oversizing. Using the same rabbit iliac perforation model, we additionally assessed the sealing capacity of a covered stent graft for each model. CONCLUSIONS: The novel rabbit iliac artery perforation models, as described in this report, represent promising animal testing approaches. While their setting is very similar to the real-life context encountered in humans, all three models are based on an animal model that is ideally suited for evaluating the sealing capacity and performance of new medical devices for humans.


Assuntos
Doença das Coronárias/terapia , Modelos Animais de Doenças , Traumatismos Cardíacos/prevenção & controle , Intervenção Coronária Percutânea/efeitos adversos , Stents , Animais , Traumatismos Cardíacos/etiologia , Coelhos
7.
Macromol Biosci ; 20(9): e2000152, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32686889

RESUMO

In this work ion functionalized hydrogels as potent drug delivery systems are presented. The ion functionalization of the hydrogel enables the retention of ionic drug molecules and thus a reduction of burst release effects. Timolol maleate in combination with polymerized anionic 3-sulfopropylmethacrylate potassium and ibuprofen combined with cationic poly-[2-(methacryloyloxy)ethyl] trimethylammonium chloride are investigated in respect to their drug release profile. The results are showing an ion exchange depending release behavior instead of a diffusion-controlled drug release as it is known from common drug delivery systems. Furthermore, the suitability of such hydrogels for standard methods for sterilization is investigated.

8.
PLoS One ; 15(4): e0231421, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32310981

RESUMO

Polymers are commonly used in medical device manufacturing, e.g. for drug delivery systems, bone substitutes and stent coatings. Especially hydrogels exhibit very promising properties in this field. Hence, the development of new hydrogel systems for customized application is of great interest, especially regarding the swelling behavior and mechanical properties as well as the biocompatibility. The aim of this work was the preparation and investigation of various polyelectrolyte and poly-ionic liquid based hydrogels accessible by radical polymerization. The obtained polymers were covalently crosslinked with N,N'-methylenebisacrylamide (MBAA) or different lengths of poly(ethyleneglycol)diacrylate (PEGDA). The effect of different crosslinker-to-monomer ratios has been examined. In addition to the compression curves and the maximum degree of swelling, the biocompatibility with L929 mouse fibroblasts of these materials was determined in direct cell seeding experiments and the outcome for the different hydrogels was compared.


Assuntos
Materiais Biocompatíveis/química , Hidrogéis/química , Líquidos Iônicos/química , Acrilamidas/química , Animais , Materiais Biocompatíveis/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Força Compressiva , Hidrogéis/farmacologia , Camundongos , Polietilenoglicóis/química
9.
Pharmaceutics ; 11(12)2019 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-31817900

RESUMO

Here, we present a new hybrid additive manufacturing (AM) process to create drug delivery systems (DDSs) with selectively incorporated drug depots. The matrix of a DDS was generated by stereolithography (SLA), whereas the drug depots were loaded using inkjet printing. The novel AM process combining SLA with inkjet printing was successfully implemented in an existing SLA test setup. In the first studies, poly(ethylene glycol) diacrylate-based specimens with integrated depots were generated. As test liquids, blue and pink ink solutions were used. Furthermore, bovine serum albumin labeled with Coomassie blue dye as a model drug was successfully placed in a depot inside a DDS. The new hybrid AM process makes it possible to place several drugs independently of each other within the matrix. This allows adjustment of the release profiles of the drugs depending on the size as well as the position of the depots in the DDS.

10.
Acta Biomater ; 94: 33-43, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31226481

RESUMO

Biomedical devices in the blood flow disturb the fine-tuned balance of pro- and anti-coagulant factors in blood and vessel wall. Numerous technologies have been suggested to reduce coagulant and inflammatory responses of the body towards the device material, ranging from camouflage effects to permanent activity and further to a responsive interaction with the host systems. However, not all types of modification are suitable for all types of medical products. This review has a focus on application-oriented considerations of hemocompatible surface fittings. Thus, passive versus bioactive modifications are discussed along with the control of protein adsorption, stability of the immobilization, and the type of bioactive substance, biological or synthetic. Further considerations are related to the target system, whether enzymes or cells should be addressed in arterial or venous system, or whether the blood vessel wall is addressed. Recent developments like feedback controlled or self-renewing systems for drug release or addressing cellular regulation pathways of blood platelets and endothelial cells are paradigms for a generation of blood contacting devices, which are hemocompatible by cooperation with the host system. STATEMENT OF SIGNIFICANCE: This paper is part 4 of a series of 4 reviews discussing the problem of biomaterial associated thrombogenicity. The objective was to highlight features of broad agreement and provide commentary on those aspects of the problem that were subject to dispute. We hope that future investigators will update these reviews as new scholarship resolves the uncertainties of today.


Assuntos
Materiais Biocompatíveis , Plaquetas/citologia , Células Endoteliais/metabolismo , Propriedades de Superfície , Adsorção , Animais , Coagulação Sanguínea , Proteínas Sanguíneas/metabolismo , Fibrinólise , Hemólise , Hemorreologia , Humanos , Teste de Materiais , Camundongos , Polímeros , Resistência ao Cisalhamento , Engenharia Tecidual
11.
J Mech Behav Biomed Mater ; 91: 174-181, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30583263

RESUMO

Resorbable magnesium scaffolds are used for the treatment of atherosclerotic coronary vascular disease and furthermore, for vascular restoration therapy. Recently, the first-in-man clinical studies with Magmaris showed promising results regarding the target lesion failure as well as vasomotion properties after 12 and 24 month. The consistency of in vivo degraded magnesium alloys in a cardiovascular environment is qualitatively described in literature, but only little has been disclosed about the actual change in mechanical properties and the behavior of the magnesium alloy degradation products. In the present study, uncoated magnesium scaffolds 3.0 × 20 mm were implanted in coronary arteries of two healthy Goetinnger mini-swine. The scaffolds were explanted to evaluate the mechanical properties of the degraded magnesium scaffolds after 180 days in vivo. Ex vivo sample preparation and test conditions were adapted to a customized compression test setup which was developed to investigate the micro-scale scaffold fragments (width 225 ±â€¯75 µm, thickness 150 µm). As reference bare undegraded magnesium scaffold fragments were tested. Mechanical parameters relating to force as a function of displacement were determined for both sample groups. The undegraded samples showed no fracturing at the maximum applied force of 8 N, whereas the in vivo degraded test samples showed forces of 0.411 ±â€¯0.197 N at the first fracturing and a maximum force of 0.956 ±â€¯0.525 N. The deformation work, calculated as area beneath the force-displacement curve, of the in vivo degraded test samples was reduced by approximately 87-88% compared to the undegraded samples (5.20 mN mm and 40.79 mN mm, both at 7.5% deformation). The indication for a complete loss of structural integrity through a reduction of mechanical properties after a certain degradation time increases the chance to restore vascular function and physiological vasomotion in the stented vessel compartment.


Assuntos
Implantes Absorvíveis , Magnésio/química , Magnésio/metabolismo , Fenômenos Mecânicos , Animais , Vasos Coronários , Teste de Materiais , Suínos
12.
Biomed Tech (Berl) ; 64(3): 251-262, 2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-29933242

RESUMO

Bioresorbable scaffolds (BRS) promise to be the treatment of choice for stenosed coronary vessels. But higher thrombosis risk found in current clinical studies limits the expectations. Three hemodynamic metrics are introduced to evaluate the thrombosis risk of coronary stents/scaffolds using transient computational fluid dynamics (CFD). The principal phenomena are platelet activation and effective diffusion (platelet shear number, PSN), convective platelet transport (platelet convection number, PCN) and platelet aggregation (platelet aggregation number, PAN) were taken into consideration. In the present study, two different stent designs (thick-strut vs. thin-strut design) positioned in small- and medium-sized vessels (reference vessel diameter, RVD=2.25 mm vs. 2.70 mm) were analyzed. In both vessel models, the thick-strut design induced higher PSN, PCN and PAN values than the thin-strut design (thick-strut vs. thin-strut: PSN=2.92/2.19 and 0.54/0.30; PCN=3.14/1.15 and 2.08/0.43; PAN: 14.76/8.19 and 20.03/10.18 for RVD=2.25 mm and 2.70 mm). PSN and PCN are increased by the reduction of the vessel size (PSN: RVD=2.25 mm vs. 2.70 mm=5.41 and 7.30; PCN: RVD=2.25 mm vs. 2.70 mm=1.51 and 2.67 for thick-strut and thin-strut designs). The results suggest that bulky stents implanted in small caliber vessels may substantially increase the thrombosis risk. Moreover, sensitivity analyses imply that PSN is mostly influenced by vessel size (lesion-related factor), whereas PCN and PAN sensitively respond to strut-thickness (device-related factor).


Assuntos
Doença da Artéria Coronariana/cirurgia , Vasos Coronários/cirurgia , Implantes Absorvíveis , Doença da Artéria Coronariana/fisiopatologia , Hemodinâmica , Humanos , Stents , Trombose , Resultado do Tratamento
13.
Klin Monbl Augenheilkd ; 235(12): 1360-1365, 2018 Dec.
Artigo em Alemão | MEDLINE | ID: mdl-30566996

RESUMO

PURPOSE: Evaluation of the long-term efficiency of MIGS implants is still challenging, due to the lack of standardized clinical studies of stand-alone procedures. Moreover, the different mechanisms of the various glaucoma drainage devices are not adequately considered. The current study focusses on the development of a method for oculopression to evaluate the efficiency of glaucoma drainage devices. METHODS: Explanted porcine eyes were subjected to pressure or weight load using three oculopressors with different modi operandi. The time-dependent intraocular pressure was measured using an anterior chamber maintainer. The Honan Balloon exerts variable pressure onto the eye via an air bellows, whereas the Taylor oculopressor applies a defined weight loading on the eye. A novel oculopressor with a weight loading of 60 g was developed and manufactured by means of 3-D-printing. RESULTS: The intraocular pressure changes observed during the experiments were similar for all tested oculopression devices, varying only in the absolute pressure values. The Honan Balloon was not suitable for the intended purpose, due to poor standardisation of the applied pressure. Oculopression using a defined weight appeared more suitable. The Taylor oculopressor, however, created intraocular pressure values of up to 203.3 ± 38.4 mmHg, which precludes its use with glaucoma patients. On the basis of these data, the new oculopression device was used in a preliminary trial with healthy human subjects, thereby preparing its use in a clinical trial. CONCLUSIONS: Oculopression represents a potentially suitable tool to analyse the efficiency of glaucoma drainage devices. Commercially available oculopression devices are not directly applicable for this task. Difficult handling, high intraocular pressure, and lack of standardisation complicate the use for glaucoma patients. These difficulties were overcome with the newly designed oculopressor that facilitates a well defined increase in intraocular pressure. The device is currently being used in a clinical study to evaluate the efficiency of MIGS implants.


Assuntos
Implantes para Drenagem de Glaucoma , Glaucoma , Animais , Câmara Anterior , Drenagem , Humanos , Pressão Intraocular , Suínos
14.
Biosci Rep ; 38(4)2018 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-30061178

RESUMO

To prevent implant failure due to fibrosis is a major objective in glaucoma research. The present study investigated the antifibrotic effects of paclitaxel (PTX), caffeic acid phenethyl ester (CAPE), and pirfenidone (PFD) coated microstent test specimens in a rat model. Test specimens based on a biodegradable blend of poly(4-hydroxybutyrate) biopolymer and atactic poly(3-hydroxybutyrate) (at.P(3HB)) were manufactured, equipped with local drug delivery (LDD) coatings, and implanted in the subcutaneous white fat depot. Postoperatively, test specimens were explanted and analyzed for residual drug content. Fat depots including the test specimens were histologically analyzed. In vitro drug release studies revealed an initial burst for LDD devices. In vivo, slow drug release of PTX was found, whereas it already completed 1 week postoperatively for CAPE and PFD LDD devices. Histological examinations revealed a massive cell infiltration in the periphery of the test specimens. Compact fibrotic capsules around the LDD devices were detectable at 4-36 weeks and least pronounced around PFD-coated specimens. Capsules stained positive for extracellular matrix (ECM) components. The presented model offers possibilities to investigate release kinetics and the antifibrotic potential of drugs in vivo as well as the identification of more effective agents for a novel generation of drug-eluting glaucoma microstents.


Assuntos
Ácidos Cafeicos/administração & dosagem , Sistemas de Liberação de Medicamentos/instrumentação , Stents Farmacológicos , Paclitaxel/administração & dosagem , Álcool Feniletílico/análogos & derivados , Piridonas/administração & dosagem , Animais , Ácidos Cafeicos/farmacocinética , Ácidos Cafeicos/uso terapêutico , Fibrose , Glaucoma/terapia , Masculino , Paclitaxel/farmacocinética , Paclitaxel/uso terapêutico , Álcool Feniletílico/administração & dosagem , Álcool Feniletílico/farmacocinética , Álcool Feniletílico/uso terapêutico , Piridonas/farmacocinética , Piridonas/uso terapêutico , Ratos , Ratos Wistar
15.
Electrophoresis ; 39(20): 2590-2597, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30025167

RESUMO

Simultaneous electrokinetic and hydrodynamic injection of rapamycin (sirolimus) with off-line and online sample preconcentration techniques and using MEKC has been studied. Compared to conventional hydrodynamic injection, a 168-fold improvement in the signal was obtained with a combination of simultaneous electrokinetic and hydrodynamic injectionand field enhanced sample injection in conjunction with a sweeping technique called sequential stacking featuring sweeping. However, the coupling of the developed electrophoretic method and solid-phase microextraction allowed the signal intensity to increase more than 231 times. In this approach, the injection of the sample at negative polarity (anode at the detector end) into the capillary and the MEKC separation was achieved within 5 min using an electrolyte (composed of 10 mM sodium tetraborate and 40 mM SDS) when ultraviolet (UV) detection was performed at 280 nm. Thus, by combining the application of the sequential stacking featuring sweeping supported by the solid-phase microextraction clean-up procedure, the detection limit (LOD) for rapamycin in a serum sample was significantly decreased, and was set at 25 ng/mL. The proposed combined simultaneous electrokinetic and hydrodynamic injection with field enhanced sample injection -sweeping technique following MEKC separation of sirolimus in human serum could be an effective tool in biomedical and clinical applications.


Assuntos
Cromatografia Capilar Eletrocinética Micelar/métodos , Sirolimo/sangue , Humanos , Limite de Detecção , Pressão , Microextração em Fase Sólida
16.
Drug Deliv Transl Res ; 8(3): 719-728, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29532357

RESUMO

The successive incorporation of several drugs into the polymeric bulk of implants mostly results in loss of considerable quantity of one drug, and/or the loss in quality of the coating and also in changes of drug release time points. A dual drug delivery system (DDDS) based on poly-L-lactide (PLLA) copolymers combining the effective inhibition of smooth muscle cell proliferation while simultaneously promoting re-endothelialization was successfully developed. To overcome possible antagonistic drug interactions and the limitation of the polymeric bulk material as release system for dual drugs, a novel concept which combines the bulk and surface drug immobilization for a DDDS was investigated. The advantage of this DDDS is that the bulk incorporation of fluorescein diacetate (FDAc) (model drug for paclitaxel (PTX)) via spray coating enhanced the subsequent cleavable surface coupling of vascular endothelial growth factor (VEGF) via the crosslinker bissulfosuccinimidyl suberate (BS3). In the presence of the embedded FDAc, the VEGF loading and release are about twice times higher than in absence. Furthermore, the DDDS combines the diffusion drug delivery (FDAc or PTX) and the chemical controlled drug release, VEGF via hydrolysable ester bonds, without loss in quantity and quality of the drug release curves. Additionally, the performed in vitro biocompatibility study showed the bimodal influences of PTX and VEGF on human endothelial EA.hy926 cells. In conclusion, it was possible to show the feasibility to develop a novel DDDS which has a high potential for the medical application due to the possible easy and short modification of a polymer-based PTX delivery system.


Assuntos
Antineoplásicos Fitogênicos/administração & dosagem , Sistemas de Liberação de Medicamentos , Proteínas Imobilizadas/administração & dosagem , Paclitaxel/administração & dosagem , Polímeros/administração & dosagem , Fator A de Crescimento do Endotélio Vascular/administração & dosagem , Antineoplásicos Fitogênicos/química , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Liberação Controlada de Fármacos , Células Endoteliais/efeitos dos fármacos , Fluoresceínas/administração & dosagem , Fluoresceínas/química , Humanos , Proteínas Imobilizadas/química , Paclitaxel/química , Polímeros/química , Propriedades de Superfície , Fator A de Crescimento do Endotélio Vascular/química
17.
Materials (Basel) ; 11(3)2018 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-29495462

RESUMO

Silicones are widely used in medical applications. In ophthalmology, glaucoma drainage devices are utilized if conservative therapies are not applicable or have failed. Long-term success of these devices is limited by failure to control intraocular pressure due to fibrous encapsulation. Therefore, different medical approved silicones were tested in vitro for cell adhesion, cell proliferation and viability of human Sclera (hSF) and human Tenon fibroblasts (hTF). The silicones were analysed also depending on the sample preparation according to the manufacturer's instructions. The surface quality was characterized with environmental scanning electron microscope (ESEM) and water contact angle measurements. All silicones showed homogeneous smooth and hydrophobic surfaces. Cell adhesion was significantly reduced on all silicones compared to the negative control. Proliferation index and cell viability were not influenced much. For development of a new glaucoma drainage device, the silicones Silbione LSR 4330 and Silbione LSR 4350, in this study, with low cell counts for hTF and low proliferation indices for hSF, and silicone Silastic MDX4-4210, with low cell counts for hSF and low proliferation indices for hTF, have shown the best results in vitro. Due to the high cell adhesion shown on Silicone LSR 40, 40,026, this material is unsuitable.

18.
Eur J Med Res ; 23(1): 2, 2018 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-29310720

RESUMO

BACKGROUND: Drug-eluting stents (DES) compared to bare metal stents (BMS) have shown superior clinical performance, but are considered less suitable in complex cases. Most studies do not distinguish between DES and BMS with respect to their mechanical performance. The objective was to obtain mechanical parameters for direct comparison of BMS and DES. METHODS: In vitro bench tests evaluated crimped stent profiles, crossability in stenosis models, elastic recoil, bending stiffness (crimped and expanded), and scaffolding properties. The study included five pairs of BMS and DES each with the same stent platforms (all n = 5; PRO-Kinetic Energy, Orsiro: BIOTRONIK AG, Bülach, Switzerland; MULTI-LINK 8, XIENCE Xpedition: Abbott Vascular, Temecula, CA; REBEL Monorail, Promus PREMIER, Boston Scientific, Marlborough, MA; Integrity, Resolute Integrity, Medtronic, Minneapolis, MN; Kaname, Ultimaster: Terumo Corporation, Tokyo, Japan). Statistical analysis used pooled variance t tests for pairwise comparison of BMS with DES. RESULTS: Crimped profiles in BMS groups ranged from 0.97 ± 0.01 mm (PRO-Kinetic Energy) to 1.13 ± 0.01 mm (Kaname) and in DES groups from 1.02 ± 0.01 mm (Orsiro) to 1.13 ± 0.01 mm (Ultimaster). Crossability was best for low profile stent systems. Elastic recoil ranged from 4.07 ± 0.22% (Orsiro) to 5.87 ± 0.54% (REBEL Monorail) including both BMS and DES. The bending stiffness of crimped and expanded stents showed no systematic differences between BMS and DES neither did the scaffolding. CONCLUSIONS: Based on in vitro measurements BMS appear superior to DES in some aspects of mechanical performance, yet the differences are small and not class uniform. The data provide assistance in selecting the optimal system for treatment and assessment of new generations of bioresorbable scaffolds. TRIAL REGISTRATION: not applicable.


Assuntos
Stents Farmacológicos/normas , Stents Metálicos Autoexpansíveis/normas , Stents Farmacológicos/efeitos adversos , Fenômenos Mecânicos , Stents Metálicos Autoexpansíveis/efeitos adversos
19.
Materials (Basel) ; 10(12)2017 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-29168794

RESUMO

Titanium is widely used as a bone implant material due to its biocompatibility and high resilience. Since its Young's modulus differs from bone tissue, the resulting "stress shielding" could lead to scaffold loosening. However, by using a scaffold-shaped geometry, the Young's modulus can be adjusted. Also, a porous geometry enables vascularisation and bone ingrowth inside the implant itself. Additionally, growth factors can improve these effects. In order to create a deposit and release system for these factors, the titanium scaffolds could be coated with degradable polymers. Therefore, in the present study, synthetic poly-ε-caprolactone (PCL) and the biopolymer poly(3-hydroxybutyrate) (P(3HB)) were tested for coating efficiency, cell adhesion, and biocompatibility to find a suitable coating material. The underlying scaffold was created from titanium by Selective Laser Melting (SLM) and coated with PCL or P(3HB) via dip coating. To test the biocompatibility, Live Cell Imaging (LCI) as well as vitality and proliferation assays were performed. In addition, cell adhesion forces were detected via Single Cell Force Spectroscopy, while the coating efficiency was observed using environmental scanning electron microscopy (ESEM) and energy-dispersive X-ray (EDX) analyses. Regarding the coating efficiency, PCL showed higher values in comparison to P(3HB). Vitality assays revealed decent vitality values for both polymers, while values for PCL were significantly lower than those for blank titanium. No significant differences could be observed between PCL and P(3HB) in proliferation and cell adhesion studies. Although LCI observations revealed decreasing values in cell number and populated area over time on both polymer-coated scaffolds, these outcomes could be explained by the possibility of coating diluent residues accumulating in the culture medium. Overall, both polymers fulfill the requirements regarding biocompatibility. Nonetheless, since only PCL coating ensured the maintenance of the porous implant structure, it is preferable to be used as a coating material for creating a deposit and release system for growth factors.

20.
Sci Rep ; 7(1): 15780, 2017 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-29150670

RESUMO

Local drug delivery systems (DDS) have become a favourable approach for the treatment of numerous diseases. Biomedical imaging techniques such as ultrahigh field magnetic resonance imaging (UHF-MRI) offer unique insight into DDS biodegradation in vivo. We describe the establishment of a 7 Tesla MRI routine for longitudinal in vivo examinations of a subconjunctival DDS for the treatment of glaucoma in a rabbit model. In initial in vitro examinations the T2-relaxation times of the polymeric DDS components were assessed. Imaging of enzymatically degraded depot samples in vitro did not reveal changes in sample morphology or T2-relaxation time. Ex vivo investigations with an enucleated porcine eye showed good correlation of anatomical MRI and histological data. In longitudinal in vivo studies in rabbits, we repeatedly scanned the depot in the same animal over the course of 5 months with an in-plane resolution of 130 µm at scan times of less than 30 minutes. The degradation was quantified using volumetric analysis showing a volume reduction of 82% between 3 and 21 weeks after depot implantation. We have thereby demonstrated the feasibility of our UHF-MRI protocol as a non-invasive imaging routine for qualitative and quantitative, longitudinal evaluation of biodegradable subconjunctival DDS.


Assuntos
Túnica Conjuntiva/patologia , Sistemas de Liberação de Medicamentos , Glaucoma/diagnóstico por imagem , Glaucoma/tratamento farmacológico , Imageamento por Ressonância Magnética , Animais , Túnica Conjuntiva/diagnóstico por imagem , Modelos Animais de Doenças , Feminino , Coelhos , Suínos
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