scholarly journals Polyisobutylene-Based Thermoplastic Elastomers for Manufacturing Polymeric Heart Valve Leaflets: In Vitro and In Vivo Results

2019 ◽  
Vol 9 (22) ◽  
pp. 4773 ◽  
Author(s):  
Evgeny Ovcharenko ◽  
Maria Rezvova ◽  
Pavel Nikishau ◽  
Sergei Kostjuk ◽  
Tatiana Glushkova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heart Valve ◽  
Heart Valves ◽  
Reference Sample ◽  
Sample Surface ◽  
Thermoplastic Elastomers ◽  
Water Contact ◽  
Promising Alternative

Superior polymers represent a promising alternative to mechanical and biological materials commonly used for manufacturing artificial heart valves. The study is aimed at assessing poly(styrene-block-isobutylene-block-styrene) (SIBS) properties and comparing them with polytetrafluoroethylene (Gore-texTM, a reference sample). Surface topography of both materials was evaluated with scanning electron microscopy and atomic force microscopy. The mechanical properties were measured under uniaxial tension. The water contact angle was estimated to evaluate hydrophilicity/hydrophobicity of the study samples. Materials’ hemocompatibility was evaluated using cell lines (Ea.hy 926), donor blood, and in vivo. SIBS possess a regular surface relief. It is hydrophobic and has lower strength as compared to Gore-texTM (3.51 MPa vs. 13.2/23.8 MPa). SIBS and Gore-texTM have similar hemocompatibility (hemolysis, adhesion, and platelet aggregation). The subcutaneous rat implantation reports that SIBS has a lower tendency towards calcification (0.39 mg/g) compared with Gore-texTM (1.29 mg/g). SIBS is a highly hemocompatible material with a promising potential for manufacturing heart valve leaflets, but its mechanical properties require further improvements. The possible options include the reinforcement with nanofillers and introductions of new chains in its structure.

CURRENT DEVELOPMENTS AND FUTURE CHALLENGES FOR THE CREATION OF AORTIC HEART VALVE

2008 ◽  
Vol 08 (01) ◽  
pp. 1-15 ◽  
Author(s):  
YOS S. MORSI ◽  
CYNTHIA S. WONG
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Characteristics ◽  
Polyglycolic Acid ◽  
Cellular Interactions ◽  
Trimethylene Carbonate ◽  
The Creation ◽  
Tissue Engineered Heart Valves

The concept of tissue-engineered heart valves offers an alternative to current heart valve replacements that is capable of addressing shortcomings such as life-long administration of anticoagulants, inadequate durability, and inability to grow. Since tissue engineering is a multifaceted area, studies conducted have focused on different aspects such as hemodynamics, cellular interactions and mechanisms, scaffold designs, and mechanical characteristics in the form of both in vitro and in vivo investigations. This review concentrates on the advancements of scaffold materials and manufacturing processes, and on cell–scaffold interactions. Aside from the commonly used materials, polyglycolic acid and polylactic acid, novel polymers such as hydrogels and trimethylene carbonate-based polymers are being developed to simulate the natural mechanical characteristics of heart valves. Electrospinning has been examined as a new manufacturing technique that has the potential to facilitate tissue formation via increased surface area. The type of cells utilized for seeding onto the scaffolds is another factor to take into consideration; currently, stem cells are of great interest because of their potential to differentiate into various types of cells. Although extensive studies have been conducted, the creation of a fully functional heart valve that is clinically applicable still requires further investigation due to the complexity and intricacies of the heart valve.

scholarly journals Recellularization of decellularized heart valves: Progress toward the tissue-engineered heart valve

2017 ◽  
Vol 8 ◽  
pp. 204173141772632 ◽  
Author(s):  
Mitchell C VeDepo ◽  
Michael S Detamore ◽  
Richard A Hopkins ◽  
Gabriel L Converse
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Conditioning ◽  
New Era ◽  
Processing Strategies ◽  
Tissue Engineered Heart Valve ◽  
Tissue Engineered Heart Valves

The tissue-engineered heart valve portends a new era in the field of valve replacement. Decellularized heart valves are of great interest as a scaffold for the tissue-engineered heart valve due to their naturally bioactive composition, clinical relevance as a stand-alone implant, and partial recellularization in vivo. However, a significant challenge remains in realizing the tissue-engineered heart valve: assuring consistent recellularization of the entire valve leaflets by phenotypically appropriate cells. Many creative strategies have pursued complete biological valve recellularization; however, identifying the optimal recellularization method, including in situ or in vitro recellularization and chemical and/or mechanical conditioning, has proven difficult. Furthermore, while many studies have focused on individual parameters for increasing valve interstitial recellularization, a general understanding of the interacting dynamics is likely necessary to achieve success. Therefore, the purpose of this review is to explore and compare the various processing strategies used for the decellularization and subsequent recellularization of tissue-engineered heart valves.

Crosslinking porcine aortic valve by radical polymerization for the preparation of BHVs with improved cytocompatibility, mild immune response, and reduced calcification

2021 ◽  
pp. 088532822098406
Author(s):  
Liangpeng Xu ◽  
Fan Yang ◽  
Yao Ge ◽  
Gaoyang Guo ◽  
Yunbing Wang
Keyword(s):  
Mechanical Properties ◽  
Immune Response ◽  
Aortic Valve ◽  
Radical Polymerization ◽  
Heart Valve ◽  
Heart Valves ◽  
Animal Experiments ◽  
Artificial Heart Valve ◽  
Valvular Stenosis

Over one million artificial heart valve transplantations are performed each year due to valvular stenosis or regurgitation. Among them, bioprosthetic heart valves (BHVs) are increasingly being used because of the absence of the need for lifelong anticoagulation. Almost all of the commercial BHVs are treated with Glutaraldehyde (GLUT). As GLUT-treated BHVs are prone to calcification and structural degradation, their durability is greatly reduced with a service life of only 12–15 years. The physiological structure and mechanical properties of the porcine aortic valve (PAV) are closer to that of a human heart valve, so in this study, PAV is used as the model to explore the comprehensive properties of the prepared BHVs by radical polymerization crosslinking method. We found that PAV treated by radical polymerization crosslinking method showed similar ECM stability and biaxial mechanical properties with GLUT-treated PAV. However, radical polymerization crosslinked PAV exhibited better cytocompatibility and endothelialization potential in vitro cell experiment as better anticalcification potential and reduced immune response than GLUT-treated PAV through subcutaneous animal experiments in rats. To conclude, a novel crosslinking method of non-glutaraldehyde fixation of xenogeneic tissues for the preparation of BHVs is expected.

scholarly journals Nanohydroxyapatite Effect on the Degradation, Osteoconduction and Mechanical Properties of Polymeric Bone Tissue Engineered Scaffolds

2016 ◽  
Vol 10 (1) ◽  
pp. 900-919 ◽  
Author(s):  
Shima Salmasi ◽  
Leila Nayyer ◽  
Alexander M. Seifalian ◽  
Gordon W. Blunn
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Bone Fractures ◽  
Synthetic Polymers ◽  
Patient Specific ◽  
Promising Alternative

BACKGROUNDStatistical reports show that every year around the world approximately 15 million bone fractures occur; of which up to 10% fail to heal completely and hence lead to complications of non-union healing. In the past, autografts or allografts were used as the “gold standard” of treating such defects. However, due to various limitations and risks associated with these sources of bone grafts, other avenues have been extensively investigated through which bone tissue engineering; in particular engineering of synthetic bone graft substitutes, has been recognised as a promising alternative to the traditional methods.METHODSA selective literature search was performed.RESULTSBone tissue engineering offers unlimited supply, eliminated risk of disease transmission and relatively low cost. It could also lead to patient specific design and manufacture of implants, prosthesis and bone related devices. A potentially promising building block for a suitable scaffold is synthetic nanohydroxyapatite incorporated into synthetic polymers. Incorporation of nanohydroxyapatite into synthetic polymers has shown promising bioactivity, osteoconductivity, mechanical properties and degradation profile compared to other techniques previously considered.CONCLUSIONScientific research, through extensive physiochemical characterisation,in vitroandin vivoassessment has brought together the optimum characteristics of nanohydroxyapatite and various types of synthetic polymers in order to develop nanocomposites of suitable nature for bone tissue engineering. The aim of the present article is to review and update various aspects involved in incorporation of synthetic nanohydroxyapatite into synthetic polymers, in terms of their potentials to promote bone growth and regenerationin vitro,in vivoand consequently in clinical applications.

scholarly journals Evaluation of the In Vitro Biocompatibility of PEDOT:Nafion Coatings

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2022
Author(s):  
Sonia Guzzo ◽  
Stefano Carli ◽  
Barbara Pavan ◽  
Alice Lunghi ◽  
Mauro Murgia ◽  
...  
Keyword(s):  
Neutral Red ◽  
In Vitro Cytotoxicity ◽  
Water Contact ◽  
Promising Alternative ◽  
Force Microscopy ◽  
In Vitro Biocompatibility ◽  
Angle Measurements ◽  
Organic Bioelectronics

Poly(3,4-ethylenedioxythiophene)-Nafion (PEDOT:Nafion) is emerging as a promising alternative to PEDOT-polystyrene sulfonate (PEDOT:PSS) in organic bioelectronics. However, the biocompatibility of PEDOT:Nafion has not been investigated to date, limiting its deployment toward in vivo applications such as neural recording and stimulation. In the present study, the in vitro cytotoxicity of PEDOT:Nafion coatings, obtained by a water-based PEDOT:Nafion formulation, was evaluated using a primary cell culture of rat fibroblasts. The surface of PEDOT:Nafion coating was characterized by Atomic Force Microscopy (AFM) and water contact angle measurements. Fibroblasts adhesion and morphology was investigated by scanning electron microscopy (SEM) and AFM measurements. Cell proliferation was assessed by fluorescence microscopy, while cell viability was quantified by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT), lactate dehydrogenase (LDH) and neutral red assays. The results showed that PEDOT:Nafion coatings obtained by the water dispersion were not cytotoxic, making the latter a reliable alternative to PEDOT:PSS dispersion, especially in terms of chronic in vivo applications.

Tissue Engineering of Pulmonary Heart Valves on Allogenic Acellular Matrix Conduits

Circulation ◽  
2000 ◽  
Vol 102 (suppl_3) ◽  
Author(s):  
Gustav Steinhoff ◽  
Ulrich Stock ◽  
Najibulla Karim ◽  
Heike Mertsching ◽  
Adine Timke ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Endothelial Cells ◽  
Heart Valve ◽  
Heart Valves ◽  
Sheep Model ◽  
Control Valves ◽  
Acellular Matrix ◽  
Valve Tissue

Background —Tissue engineering using in vitro–cultivated autologous vascular wall cells is a new approach to biological heart valve replacement. In the present study, we analyzed a new concept to process allogenic acellular matrix scaffolds of pulmonary heart valves after in vitro seeding with the use of autologous cells in a sheep model. Methods and Results —Allogenic heart valve conduits were acellularized by a 48-hour trypsin/EDTA incubation to extract endothelial cells and myofibroblasts. The acellularization procedure resulted in an almost complete removal of cells. After that procedure, a static reseeding of the upper surface of the valve was performed sequentially with autologous myofibroblasts for 6 days and endothelial cells for 2 days, resulting in a patchy cellular restitution on the valve surface. The in vivo function was tested in a sheep model of orthotopic pulmonary valve conduit transplantation. Three of 4 unseeded control valves and 5 of 6 tissue-engineered valves showed normal function up to 3 months. Unseeded allogenic acellular control valves showed partial degeneration (2 of 4 valves) and no interstitial valve tissue reconstitution. Tissue-engineered valves showed complete histological restitution of valve tissue and confluent endothelial surface coverage in all cases. Immunohistological analysis revealed cellular reconstitution of endothelial cells (von Willebrand factor), myofibroblasts (α-actin), and matrix synthesis (procollagen I). There were histological signs of inflammatory reactions to subvalvar muscle leading to calcifications, but these were not found in valve and pulmonary artery tissue. Conclusions —The in vitro tissue-engineering approach using acellular matrix conduits leads to the in vivo reconstitution of viable heart valve tissue.

scholarly journals Tissue Engineering Heart Valves – a Review of More than Two Decades into Preclinical and Clinical Testing for Obtaining the Next Generation of Heart Valve Substitutes

2021 ◽  
Vol 31 (3) ◽  
pp. 501-510
Author(s):  
Dan SIMIONESCU ◽  
◽  
Marius Mihai HARPA ◽  
Codrut OPRITA ◽  
Ionela MOVILEANU ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Heart Valve ◽  
Heart Valves ◽  
Research Work ◽  
Heart Valve Disease ◽  
Next Generation ◽  
Clinical Scenarios ◽  
Mechanical Prostheses

Well documented shortcomings of current heart valve substitutes – biological and mechanical prostheses make them imperfect choices for patients diagnosed with heart valve disease, in need for a cardiac valve replacement. Regenerative Medicine and Tissue Engineering represent the research grounds of the next generation of valvular prostheses – Tissue Engineering Heart Valves (TEHV). Mimicking the structure and function of the native valves, TEHVs are three dimensional structures obtained in laboratories encompassing scaffolds (natural and synthetic), cells (stem cells and differentiated cells) and bioreactors. The literature stipulates two major heart valve regeneration paradigms, differing in the manner of autologous cells repopulation of the scaffolds; in vitro, or in vivo, respectively. During the past two decades, multidisciplinary both in vitro and in vitro research work was performed and published. In vivo experience comprises preclinical tests in experimental animal model and cautious limited clinical translation in patients. Despite initial encouraging results, translation of their usage in large clinical scenarios represents the most important challenge that needs to be overcome. This review purpose is to outline the most remarkable preclinical and clinical results of TEHV evaluation along with the lessons learnt from all this experience.

A Thin Film Nitinol Heart Valve

2005 ◽  
Vol 127 (6) ◽  
pp. 915-918 ◽  
Author(s):  
Lenka L. Stepan ◽  
Daniel S. Levi ◽  
Gregory P. Carman
Keyword(s):  
Thin Film ◽  
Heart Valve ◽  
Heart Valves ◽  
Thrombus Formation ◽  
Prosthetic Heart Valve ◽  
Flow Loop ◽  
Niti Wire ◽  
Tissue Samples

In order to create a less thrombogenic heart valve with improved longevity, a prosthetic heart valve was developed using thin film nitinol (NiTi). A “butterfly” valve was constructed using a single, elliptical piece of thin film NiTi and a scaffold made from Teflon tubing and NiTi wire. Flow tests and pressure readings across the valve were performed in vitro in a pulsatile flow loop. Bio-corrosion experiments were conducted on untreated and passivated thin film nitinol. To determine the material’s in vivo biocompatibility, thin film nitinol was implanted in pigs using stents covered with thin film NiTi. Flow rates and pressure tracings across the valve were comparable to those through a commercially available 19 mm Perimount Edwards tissue valve. No signs of corrosion were present on thin film nitinol samples after immersion in Hank’s solution for one month. Finally, organ and tissue samples explanted from four pigs at 2, 3, 4, and 6 weeks after thin film NiTi implantation appeared without disease, and the thin film nitinol itself was without thrombus formation. Although long term testing is still necessary, thin film NiTi may be very well suited for use in artificial heart valves.

A Thin Film Nitinol Heart Valve

Aerospace ◽  
2004 ◽  
Author(s):  
Lenka Stepan ◽  
Daniel Levi ◽  
Gregory Carman
Keyword(s):  
Thin Film ◽  
Heart Valve ◽  
Heart Valves ◽  
Thrombus Formation ◽  
Prosthetic Heart Valve ◽  
Flow Loop ◽  
Niti Wire ◽  
Tissue Samples

In order to create a less thrombogenic heart valve with improved longevity, a prosthetic heart valve was developed using thin film nitinol (NiTi). A “butterfly” thin film NiTi valve was constructed using a single, elliptical piece of thin film NiTi and a scaffold made from Teflon tubing and NiTi wire. Flow tests and pressure readings across the valve were performed in vitro in a pulsatile flow loop. Biocorrosion experiments were conducted on untreated and passivated thin film nitinol. To determine the material’s in vivo biocompatibility, thin film nitinol was implanted in a pig using a stent covered with thin film NiTi. Flow rates and pressure tracings across the valve were comparable to those through a commercially available 19 mm Perimount Edwards tissue valve. No signs of corrosion were present on samples of thin film nitinol after immersion in Hank’s solution for 1 month. Finally, organs and tissue samples explanted from the pig 17 days after thin film NiTi implantation appeared without disease, and the thin film nitinol itself was without thrombus formation or endothelialization. Although long term testing will be needed, thin film NiTi may be very well suited for use in artificial heart valves.

scholarly journals Injectable non-leaching tissue-mimetic bottlebrush elastomers as an advanced platform for reconstructive surgery

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Erfan Dashtimoghadam ◽  
Farahnaz Fahimipour ◽  
Andrew N. Keith ◽  
Foad Vashahi ◽  
Pavel Popryadukhin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reconstructive Surgery ◽  
Biomedical Applications ◽  
The Body ◽  
Surrounding Tissue ◽  
Curing Time ◽  
Materials Used ◽  
Significant Health

AbstractCurrent materials used in biomedical devices do not match tissue’s mechanical properties and leach various chemicals into the body. These deficiencies pose significant health risks that are further exacerbated by invasive implantation procedures. Herein, we leverage the brush-like polymer architecture to design and administer minimally invasive injectable elastomers that cure in vivo into leachable-free implants with mechanical properties matching the surrounding tissue. This strategy allows tuning curing time from minutes to hours, which empowers a broad range of biomedical applications from rapid wound sealing to time-intensive reconstructive surgery. These injectable elastomers support in vitro cell proliferation, while also demonstrating in vivo implant integrity with a mild inflammatory response and minimal fibrotic encapsulation.

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