The Experts below are selected from a list of 68901 Experts worldwide ranked by ideXlab platform

Simon P Hoerstrup - One of the best experts on this subject based on the ideXlab platform.

  • human ipscs and genome editing technologies for precision Cardiovascular Tissue engineering
    Frontiers in Cell and Developmental Biology, 2021
    Co-Authors: Eric K N Gahwiler, Simon P Hoerstrup, Sarah E Motta, Marcy Martin, Bramasta Nugraha, Maximilian Y Emmert
    Abstract:

    Induced pluripotent stem cells (iPSCs) originate from the reprogramming of adult somatic cells using four Yamanaka transcription factors. Since their discovery, the stem cell (SC) field achieved significant milestones and opened several gateways in the area of disease modeling, drug discovery, and regenerative medicine. In parallel, the emergence of clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (CRISPR-Cas9) revolutionized the field of genome engineering, allowing the generation of genetically modified cell lines and achieving a precise genome recombination or random insertions/deletions, usefully translated for wider applications. Cardiovascular diseases represent a constantly increasing societal concern, with limited understanding of the underlying cellular and molecular mechanisms. The ability of iPSCs to differentiate into multiple cell types combined with CRISPR-Cas9 technology could enable the systematic investigation of pathophysiological mechanisms or drug screening for potential therapeutics. Furthermore, these technologies can provide a cellular platform for Cardiovascular Tissue engineering (TE) approaches by modulating the expression or inhibition of targeted proteins, thereby creating the possibility to engineer new cell lines and/or fine-tune biomimetic scaffolds. This review will focus on the application of iPSCs, CRISPR-Cas9, and a combination thereof to the field of Cardiovascular TE. In particular, the clinical translatability of such technologies will be discussed ranging from disease modeling to drug screening and TE applications.

  • Translational Challenges in Cardiovascular Tissue Engineering
    Journal of Cardiovascular Translational Research, 2017
    Co-Authors: Maximilian Y Emmert, Emanuela S. Fioretta, Simon P Hoerstrup
    Abstract:

    Valvular heart disease and congenital heart defects represent a major cause of death around the globe. Although current therapy strategies have rapidly evolved over the decades and are nowadays safe, effective, and applicable to many affected patients, the currently used artificial prostheses are still suboptimal. They do not promote regeneration, physiological remodeling, or growth (particularly important aspects for children) as their native counterparts. This results in the continuous degeneration and subsequent failure of these prostheses which is often associated with an increased morbidity and mortality as well as the need for multiple re-interventions. To overcome this problem, the concept of Tissue engineering (TE) has been repeatedly suggested as a potential technology to enable native-like Cardiovascular replacements with regenerative and growth capacities, suitable for young adults and children. However, despite promising data from pre-clinical and first clinical pilot trials, the translation and clinical relevance of such TE technologies is still very limited. The reasons that currently limit broad clinical adoption are multifaceted and comprise of scientific, clinical, logistical, technical, and regulatory challenges which need to be overcome. The aim of this review is to provide an overview about the translational problems and challenges in current TE approaches. It further suggests directions and potential solutions on how these issues may be efficiently addressed in the future to accelerate clinical translation. In addition, a particular focus is put on the current regulatory guidelines and the associated challenges for these promising TE technologies.

  • bioresorbable scaffolds for Cardiovascular Tissue engineering
    2014
    Co-Authors: Melanie Generali, Petra E Dijkman, Simon P Hoerstrup
    Abstract:

    Cardiovascular disease is a major cause of morbidity and mortality, especially in developed countries. Currently, when suitable autologous Tissue is lacking, mostly non-degradable synthetic material or fixated xenogeneic grafts (e.g. heart valves) are used to restore, repair, or replace the injured Cardiovascular Tissues. However, these materials are associated with several disadvantages, such as the significant risk of thromboembolism and calcification. Bioresorbable scaffolds for Tissue-engineered solutions are proposed to overcome the limitations of the current replacement materials as they provide temporary scaffolding for the in vitro, in situ, or in vivo formation of autologous Tissue. Thereby, it is pursued that the engineered Tissue mimics the composition and structure of the original Tissue and has the capacity of regeneration and growth. The initial scaffold should possess strong material properties as the Cardiovascular system requires an enormous strength, flexibility, and durability of the engineered structures, while on the other hand complete resorption of the scaffold material is aimed for. This review discusses the diversity of natural and synthetic bioresorbable materials that are currently investigated for their suitability as a scaffold for Cardiovascular Tissue engineering.

  • prenatally harvested cells for Cardiovascular Tissue engineering fabrication of autologous implants prior to birth
    Placenta, 2011
    Co-Authors: Benedikt Weber, Steffen M Zeisberger, Simon P Hoerstrup
    Abstract:

    Using the principal of Tissue engineering, several groups have demonstrated the feasibility of creating heart valves, blood vessels, and myocardial structures using autologous cells and biodegradable scaffold materials. In the current Cardiovascular clinical scenario, the main medical need for a Tissue engineering solution is in the field of pediatric applications treating congenital heart disease. In these young patients, the introduction of autologous viable and growing replacement structures, such as Tissue engineered heart valves and vessels, would substantially reduce today's severe therapeutic limitations, which are mainly due to the need for repeat reoperations to adapt the current artificial prostheses to somatic growth. Based on high resolution imaging techniques, an increasing number of defects are diagnosed already prior to birth around week 20. For interventions, cells should be obtained already during pregnancy to provide Tissue engineered implants either at birth or even prenatally. In our recent studies human fetal mesenchymal stem cells were isolated from routinely sampled prenatal amniotic fluid or chorionic villus specimens and expanded in vitro. Fresh and cryopreserved samples were used. After phenotyping and genotyping, cells were seeded onto synthetic biodegradable scaffolds and conditioned in a bioreactor. Leaflets were endothelialized with either amniotic fluid- or umbilical cord blood-derived endothelial progenitor cells and conditioned. Resulting Tissues were analyzed by histology, immunohistochemistry, biochemistry (amounts of extracellular matrix, DNA), mechanical testing, and scanning electron microscopy (SEM) and were compared with native neonatal heart valve leaflets. Genotyping confirmed their fetal origin, and fresh versus cryopreserved cells showed comparable myofibroblast-like phenotypes. Neo-Tissues exhibited organization, cell phenotypes, extracellular matrix production, and DNA content comparable to their native counterparts. Leaflet surfaces were covered with functional endothelia. SEM showed morphologically cellular distribution throughout the polymer and smooth surfaces. Mechanical profiles approximated those of native heart valves. These in vitro studies demonstrated the principal feasibility of using various human cell types isolated from fetal sources for Cardiovascular Tissue engineering. Umbilical cord blood-, amniotic fluid- and chorionic villi-derived cells have shown promising potential for the clinical realization of this congenital Tissue engineering approach. Based on these results, future research must aim at further investigation as well as preclinical evaluation of prenatally harvested stem- or progenitor cells with regard to their potential for clinical use.

  • umbilical cord cells as a source of Cardiovascular Tissue engineering
    Stem Cell Reviews and Reports, 2006
    Co-Authors: Christian Breymann, Dorthe Schmidt, Simon P Hoerstrup
    Abstract:

    There is increasing scientific evidence that human umbilical cord cells are a valuable source of adult stem cells that can be used for various implications including regenerative medicine and Tissue engineering. The review describes the role of progenitor cells (mesenchymal, endothelial, prenatal) for the use in Cardiovascular Tissue engineering, i.e., the formation of large vessels and heart valves from umbilical cord cells. Currently used replacements in Cardiovascular surgery are made of foreign materials with well known drawbacks such as thrombo-embolic complications, infection, loss of functional and biological properties, and others. Especially in the field of replacements in congenital cardiac defects, there would be a need of materials which have the advantage of optimal biological and mechanical properties. In the case of human umbilical cord cells, autologous cells can be used by minimally invasive procedures. The cells have excellent growth capacities and form a neo-matrix with excellent mechanical properties. For optimal growth and modeling, scaffolds are required with high biocompatibility and biodegradability, which allow cell attachment, ingrowth, and organization. Nutrients and waste must be easily transported and cells should be in entire contact with host's body. Finally, regenerated materials can be fully incorporated and the scaffold is completely replaced. Besides these cell and scaffold requirements, feto-maternal conditions and risk factors concerning deriving stem cells are of major interest. There are still many open questions concerning whether and how maternal conditions such as infection (viral or bacterial) or gestational age of the newborn influence stem cell harvesting and quality. If these cells will be used for the construction of replacement materials, it is clear that very strict criteria and protocols be introduced enabling the promising step from isolated cells to a therapeutic device such as a new heart valve. It is hoped that it will be only a question of time until human umbilical cord cells will be used frequently as the source of Cardiovascular Tissues among others in the clinical setting of treating congenital heart defects.

Gregor Zund - One of the best experts on this subject based on the ideXlab platform.

  • human umbilical cord cells for Cardiovascular Tissue engineering a comparative study
    European Journal of Cardio-Thoracic Surgery, 2004
    Co-Authors: Alexander Kadner, Gregor Zund, Marko Turina, Christian Breymann, Gregor Kadner, Christine F Maurus, Sidika Yakarisik, Simon P Hoerstrup
    Abstract:

    Objective: Tissue engineering of viable, autologous Cardiovascular replacements with the potential to grow, repair and remodel represents an attractive approach to overcome the shortcomings of available replacements for the repair of congenital cardiac defects. Currently, vascular myofibroblast cells represent an established cell source for Cardiovascular Tissue engineering. Cell isolation requires the invasive harvesting of venous or arterial vessel segments prior to scaffold seeding, a technique which may not be preferable, especially in pediatric patients. This study evaluates cells isolated from human umbilical cord artery, umbilical cord vein and whole cord as alternative autologous cell sources for Cardiovascular Tissue engineering. Methods: Cells were isolated from human umbilical cord artery (UCA), umbilical cord vein (UCV), whole umbilical cord (UCC) and saphenous vein segments (VC), and were expanded in culture. All three expanded cell groups were seeded on bioabsorbable copolymer strips and grown in vitro for 28 days. Isolated cells were characterized by flow cytometry, histology, immunohistochemistry, proliferation assays and compared to VC. Morphological analysis of the seeded polymer strips included histology, immunohistochemistry, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and uniaxial stress testing. Results: UCA, UCV and UCC demonstrated excellent cell growth properties comparable to VC. Following isolation, all three cell groups showed myofibroblast-like morphology and characteristics by staining positive for a-smooth muscle actin (ASMA) and vimentin. Histology and immunohistochemistry of seeded polymers showed good Tissue and extracellular matrix formation containing collagen I, III and elastin. TEM showed viable myofibroblasts and the deposition of collagen fibrils and progessive growing Tissue formation, with a confluent surface, was observed in SEM. No difference was found among the mechanical properties of UCA, UCV, UCC and VC Tissue engineered constructs. Conclusions: Tissue engineering of Cardiovascular constructs by using UCA, UCV and UCC is feasible in an in vitro environment. Cell growth, morphology, characteristics and Tissue formation were comparable between UCA, UCV, UCC and VC. UCC represent an attractive, readily available autologous cell source for Cardiovascular Tissue engineering offering the additional benefits of utilizing juvenile cells and avoiding the invasive harvesting of intact vascular structures. q 2004 Elsevier B.V. All rights reserved.

  • human umbilical cord cells a new cell source for Cardiovascular Tissue engineering
    The Annals of Thoracic Surgery, 2002
    Co-Authors: Alexander Kadner, Gregor Zund, Simon P Hoerstrup, Jay Tracy, Christian Breymann, Hristine C F Maurus, Serguei Melnitchouk, Gregor Kadner, M Turina
    Abstract:

    Abstract Background Tissue engineering of viable, autologous Cardiovascular constructs with the potential to grow, repair, and remodel represents a promising new concept for cardiac surgery, especially for pediatric patients. Currently, vascular myofibroblast cells (VC) represent an established cell source for Cardiovascular Tissue engineering. Cell isolation requires the invasive harvesting of venous or arterial vessel segments before scaffold seeding, a technique that may not be preferable, particularly in pediatric patients. In this study, we investigated the feasibility of using umbilical cord cells (UCC) as an alternative autologous cell source for Cardiovascular Tissue engineering. Methods Human UCC were isolated from umbilical cord segments and expanded in culture. The cells were sequentially seeded on bioabsorbable copolymer patches ( n = 5) and grown in vitro in laminar flow for 14 days. The UCC were characterized by flow cytometry (FACS), histology, immunohistochemistry, and proliferation assays and were compared to saphenous vein–derived VC. Morphologic analysis of the UCC-seeded copolymer patches included histology and both transmission and scanning electron microscopy. Characterization of the extracellular matrix was performed by immunohistochemistry and quantitative extracellular matrix protein assays. The Tissue-engineered UCC patches were biomechanically evaluated using uniaxial stress testing and were compared to native Tissue. Results We found that isolated UCC show a fibroblast-like morphology and superior cell growth compared to VC. Phenotype analysis revealed positive signals for α-smooth muscle actin (ASMA), desmin, and vimentin. Histology and immunohistochemistry of seeded polymers showed layered Tissue formation containing collagen I, III, and glycoaminoglycans. Transmission electron microscopy showed viable myofibroblasts and the deposition of collagen fibrils. A confluent Tissue surface was observed during scanning electron microscopy. Glycoaminoglycan content did not reach values of native Tissue, whereas cell content was increased. The biomechanical properties of the Tissue-engineered constructs approached native Tissue values. Conclusions Tissue engineering of Cardiovascular constructs using UCC is feasible in an in vitro environment. The UCC demonstrated excellent growth properties and Tissue formation with mechanical properties approaching native Tissue. It appears that UCC represent a promising alternative autologous cell source for Cardiovascular Tissue engineering, offering the additional benefits of using juvenile cells and avoiding the invasive harvesting of intact vascular structures.

  • a new source for Cardiovascular Tissue engineering human bone marrow stromal cells
    European Journal of Cardio-Thoracic Surgery, 2002
    Co-Authors: Alexander Kadner, Gregor Zund, Simon P Hoerstrup, Jurg Grunenfelder, Serguei Melnitchouk, Christine F Maurus, Karim Eid, Marko Turina
    Abstract:

    Objective: Vascular-derived cells represent an established cell source for Tissue engineering of Cardiovascular constructs. Previously, cell isolation was performed by harvesting of vascular structures prior to scaffold seeding. Marrow stromal cells (MSC) demonstrate the ability to differentiate into multiple mesenchymal cell lineages and would offer an alternative cell source for Tissue engineering involving a less invasive harvesting technique. We studied the feasibility of using MSC as an alternative cell source for Cardiovascular Tissue engineering. Methods: Human MSC were isolated from bone marrow and expanded in culture. Subsequently MSC were seeded on bioabsorbable polymers and grown in vitro. Cultivated cells and seeded polymers were studied for cell characterization and Tissue formation including extracellular matrix production. Applied methods comprised flow cytometry, histology, immunohistochemistry, transmission (TEM) and scanning electron microscopy (SEM), and biochemical assays. Results: Isolated MSC demonstrated fibroblast-like morphology. Phenotype analysis revealed positive signals for alpha-smooth muscle actin and vimentin. Histology and SEM of seeded polymers showed layered Tissue formation. TEM demonstrated formation of extracellular matrix with deposition of collagen fibrils. Matrix protein analysis showed production of collagen I and III. In comparison to vascular-derived cell constructs quantitative analysis demonstrated comparable amounts of extracellular matrix proteins in the Tissue engineered constructs. Conclusions: Isolated MSC demonstrated myofibroblast-like characteristics. Tissue formation on bioabsorbable scaffolds was feasible with extracellular matrix production comparable to vascular-cell derived Tissue engineered constructs. It appears that MSC represent a promising cell source for Cardiovascular Tissue engineering. q 2002 Elsevier Science B.V. All rights reserved.

  • optimal cell source for Cardiovascular Tissue engineering venous vs aortic human myofibroblasts
    Thoracic and Cardiovascular Surgeon, 2001
    Co-Authors: A M Schnell, Gregor Zund, Simon P Hoerstrup, Stefan A Kolb, Ralf Sodian, Jeroen Visjager, Jurg Grunenfelder, A Suter, Marko Turina
    Abstract:

    Presented at: 30. Annual meeting of the German Society for Thoracic and Cardiovascular Surgery in Leipzig, February 18 - 21, 2001 Arterial vascular cells have been successfully utilized for Tissue engineering in human Cardiovascular structures, such as heart valves. The present study evaluates saphenous vein-derived myofibroblasts as an alternative, easy-to-access cell source for human Cardiovascular Tissue engineering. Biodegradable polyurethane scaffolds were seeded with human vascular myofibroblasts. Group A consisted of scaffolds seeded with cells from ascending aortic Tissue; in group B, saphenous vein-derived cells were used. Analysis included histology, electron microscopy, mechanical testing, and biochemical assays for cell proliferation (DNA) and extracellular matrix (collagen). DNA content was comparable in both groups. Collagen and stress at maximum load was significantly higher in group B. Morphology showed viable, layered cellular Tissue in all samples, with collagen fibrils most pronounced in group B. In conclusion, saphenous vein myofibroblasts cultured on biodegradable scaffolds showed excellent in vitro Tissue generation. Collagen formation and mechanical properties were superior to aortic Tissue derived constructs. Therefore, the easy-to-access vein cells represent a promising alternative cell source for Cardiovascular Tissue engineering.

  • fibrin gel advantages of a new scaffold in Cardiovascular Tissue engineering
    European Journal of Cardio-Thoracic Surgery, 2001
    Co-Authors: Stefan Jockenhoevel, Gregor Zund, Simon P Hoerstrup, K Chalabi, J S Sachweh, L Demircan, B J Messmer, Marko I Turina
    Abstract:

    Objective: The field of Tissue engineering deals with the creation of Tissue structures based on patient cells. The scaffold plays a central role in the creation of 3-D structures in Cardiovascular Tissue engineering like small vessels or heart valve prosthesis. An ideal scaffold should have Tissue-like mechanical properties and a complete immunologic integrity. As an alternative scaffold the use of fibrin gel was investigated. Methods: Preliminary, the degradation of the fibrin gel was controlled by the supplementation of aprotinin to the culture medium. To prevent Tissue from shrinking a mechanical fixation of the gel with 3-D microstructure culture plates and a chemical fixation with poly-l-lysine in different fixation techniques were studied. The thickness of the gel layer was changed from 1 to 3 mm. The Tissue development was analysed by light, transmission and scanning electron microscopy. Collagen production was detected by the measurement of hydroxyproline. Injection molding techniques were designed for the formation of complex 3-D Tissue structures. Results: The best Tissue development was observed at an aprotinin concentration of 20 mg per cc culture medium. The chemical border fixation of the gel by poly-l-lysine showed the best Tissue development. Up to a thickness of 3 mm no nutrition problems were observed in the light and transmission electron microscopy. The molding of a simplified valve conduit was possible by the newly developed molding technique. Conclusion: Fibrin gel combines a number of important properties of an ideal scaffold. It can be produced as a complete autologous scaffold. It is moldable and degradation is controllable by the use of aprotinin. q 2001 Elsevier Science B.V. All rights reserved.

Stefan Jockenhoevel - One of the best experts on this subject based on the ideXlab platform.

  • hybrid elastin like recombinamer fibrin gels physical characterization and in vitro evaluation for Cardiovascular Tissue engineering applications
    Biomaterials Science, 2016
    Co-Authors: Israel Gonzalez De Torre, Stefan Jockenhoevel, Miriam Weber, Luis G Quintanilla, Matilde Alonso, Jose Carlos Rodriguez Cabello, Petra Mela
    Abstract:

    In the field of Tissue engineering, the properties of the scaffolds are of crucial importance for the success of the application. Hybrid materials combine the properties of the different components that constitute them. In this study hybrid gels of Elastin-Like Recombinamer (ELR) and fibrin were prepared with a range of polymer concentrations and ELR-to-fibrin ratios. The correlation between SEM micrographs, porosities, swelling ratios and rheological properties was discussed and a poroelastic mechanism was suggested to explain the mechanical behavior of the hybrid gels. Applicability as scaffold materials for Cardiovascular Tissue engineering was shown by the realization of cell-laden matrixes which supported the synthesis of collagens as revealed by immunohistochemical analysis. As a proof of concept, a Tissue-engineered heart valve was fabricated by injection moulding and cultivated in a bioreactor for 3 weeks under dynamic conditions. Tissue analysis revealed the production of collagen I and III, fundamental proteins for Cardiovascular constructs.

  • Tranexamic Acid—An Alternative to Aprotinin in Fibrin-Based Cardiovascular Tissue Engineering
    2015
    Co-Authors: Auc Eva Cholewinski, Stefan Jockenhoevel, Maren Dietrich, Thomas C Flanagan, Thomas Schmitz-rode, Ph. D
    Abstract:

    Recent clinical trials have led to the worldwide suspension of aprotinin, the most commonly used antifibrinolytic agent in fibrin-based Tissue engineering. For future clinical applications of fibrin-based scaffolds, a suitable, alternative fibrinolysis inhibitor must be identified. The present study aimed to evaluate tranexamic acid (trans-4-aminomethyl-cyclohexane-1-carboxylic acid [t-AMCA]) as an alternative fibrinolysis inhibitor to aprotinin for Cardiovascular Tissue engineering applications. The effects of various concentrations of t-AMCA (30–160 mg=mL) and aprotinin on fibrin gel-lysis were spectrophotometrically quantified in vitro. Cytotoxic effects of t-AMCA and aprotinin on carotid artery–derived cells, in addition to their influence on fibrin gel mechanical strength, were examined. Further, the influence of t-AMCA versus aprotinin on three-dimensional fibrin-based constructs was analyzed using light microscopy, scanning electron microscopy, and transmission electron microscopy. The results demonstrated that neither t-AMCA (30–160 mg=mL) nor aprotinin elicited cytotoxic effects on cultured cells. Although aprotinin showed reduced fibrinolysis in the presence of plasmin compared to t-AMCA, no significant difference was obtained under standard culture conditions. Additionally, t-AMCA had no negative influence on the mechanical stability of fibrin gels, which also demonstrated excellent cell morphology, Tissue development, and ultrastructure. The results from the present study demonstrate that t-AMCA may be a suitable alternative to aprotinin for controlling the in vitro degradation rate of fibrin-based Tissue-engineered constructs

  • carbon nanotubes reinforced chitosan films mechanical properties and cell response of a novel biomaterial for Cardiovascular Tissue engineering
    Journal of Materials Science: Materials in Medicine, 2013
    Co-Authors: A Kroustalli, A E Zisimopoulou, Sabine Koch, Lisanne Rongen, Despina Deligianni, S Diamantouros, G Athanassiou, M Kokozidou, D Mavrilas, Stefan Jockenhoevel
    Abstract:

    Carbon nanotubes have been proposed as fillers to reinforce polymeric biomaterials for the strengthening of their structural integrity to achieve better biomechanical properties. In this study, a new polymeric composite material was introduced by incorporating various low concentrations of multiwalled carbon nanotubes (MWCNTs) into chitosan (CS), aiming at achieving a novel composite biomaterial with superior mechanical and biological properties compared to neat CS, in order to be used in Cardiovascular Tissue engineering applications. Both mechanical and biological characteristics in contact with the two relevant cell types (endothelial cells and vascular myofibroblasts) were studied. Regarding the mechanical behavior of MWCNT reinforced CS (MWCNT/CS), 5 and 10 % concentrations of MWCNTs enhanced the mechanical behavior of CS, with that of 5 % exhibiting a superior mechanical strength compared to 10 % concentration and neat CS. Regarding biological properties, MWCNT/CS best supported proliferation of endothelial and myofibroblast cells, MWCNTs and MWCNT/CS caused no apoptosis and were not toxic of the examined cell types. Conclusively, the new material could be suitable for Tissue engineering (TE) and particularly for Cardiovascular TE applications.

  • Cardiovascular Tissue engineering based on fibrin gel scaffolds
    2011
    Co-Authors: Stefan Jockenhoevel, Thomas C Flanagan
    Abstract:

    Cardiovascular disease is a major cause of death in the Western World. Novel drugs and innovative devices have enhanced the quality of life for patients with Cardiovascular disease, but such treatments are not without limitations and complications. The major constraint with these current treatments is the inability for growth, repair and remodeling of the structure. The emergence of Tissue engineering as an alternative therapy for Cardiovascular disease has generated an intensity of research into the development of many components of the Cardiovascular system, including heart valves, small-calibre vascular grafts and biological stent materials. The composition of the biomaterial used as a support for the developing Cardiovascular structure is a key mediator of cell behaviour and function in the Tissue, and the ideal scaffold biomaterial for development of a successful end-product continues to be a matter of debate. Fibrin, a major structural protein involved in wound healing, represents an ideal scaffold for the rapid synthesis of autologous Tissue-engineered Cardiovascular grafts, as its primary scaffold constituents (fibrinogen and thrombin) can be isolated directly from a blood sample of the patient requiring the graft. Fibrin gel scaffolds offer immediate high cell seeding efficiency and homogenous cell distribution by gelation entrapment, and have a degradation rate that can be controlled by protease inhibitors, e.g. tranexamic acid or aprotinin. Fibrin is also known to stimulate the secretion of reinforcing extracellular matrix (ECM) proteins by seeded cells. The potential to control the fibrin polymerisation process also offers the opportunity to produce complex 3-D structures, like heart valve prostheses and to embed porous, textile or metal (stent) structures. This book chapter reviews the properties of fibrin that make it an ideal scaffold candidate for applications in the area of Cardiovascular Tissue engineering, and documents the successful development of fibrin-based heart valves, vascular grafts and biostents for clinical application.

  • tranexamic acid an alternative to aprotinin in fibrin based Cardiovascular Tissue engineering
    Tissue Engineering Part A, 2009
    Co-Authors: Eva Cholewinski, Maren Dietrich, Thomas C Flanagan, Thomas Schmitzrode, Stefan Jockenhoevel
    Abstract:

    Recent clinical trials have led to the worldwide suspension of aprotinin, the most commonly used antifibrinolytic agent in fibrin-based Tissue engineering. For future clinical applications of fibrin-based scaffolds, a suitable, alternative fibrinolysis inhibitor must be identified. The present study aimed to evaluate tranexamic acid (trans-4-aminomethyl-cyclohexane-1-carboxylic acid [t-AMCA]) as an alternative fibrinolysis inhibitor to aprotinin for Cardiovascular Tissue engineering applications. The effects of various concentrations of t-AMCA (30-160 microg/mL) and aprotinin on fibrin gel-lysis were spectrophotometrically quantified in vitro. Cytotoxic effects of t-AMCA and aprotinin on carotid artery-derived cells, in addition to their influence on fibrin gel mechanical strength, were examined. Further, the influence of t-AMCA versus aprotinin on three-dimensional fibrin-based constructs was analyzed using light microscopy, scanning electron microscopy, and transmission electron microscopy. The results demonstrated that neither t-AMCA (30-160 microg/mL) nor aprotinin elicited cytotoxic effects on cultured cells. Although aprotinin showed reduced fibrinolysis in the presence of plasmin compared to t-AMCA, no significant difference was obtained under standard culture conditions. Additionally, t-AMCA had no negative influence on the mechanical stability of fibrin gels, which also demonstrated excellent cell morphology, Tissue development, and ultrastructure. The results from the present study demonstrate that t-AMCA may be a suitable alternative to aprotinin for controlling the in vitro degradation rate of fibrin-based Tissue-engineered constructs.

Katja Schenkelayland - One of the best experts on this subject based on the ideXlab platform.

  • non invasive functional molecular phenotyping of human smooth muscle cells utilized in Cardiovascular Tissue engineering
    Acta Biomaterialia, 2019
    Co-Authors: Julia Marzi, Katja Schenkelayland, Eva M Brauchle, Marsha W Rolle
    Abstract:

    Abstract Smooth muscle cell (SMC) diversity and plasticity are limiting factors in their characterization and application in Cardiovascular Tissue engineering. This work aimed to evaluate the potential of Raman microspectroscopy and Raman imaging to distinguish SMCs of different Tissue origins and phenotypes. Cultured human SMCs isolated from different vascular and non-vascular Tissues as well as fixed human SMC-containing Tissues were analyzed. In addition, Raman spectra and images of Tissue-engineered SMC constructs were acquired. Routine techniques such as qPCR, histochemistry, histological and immunocytological staining were performed for comparative gene and protein expression analysis. We identified that SMCs of different Tissue origins exhibited unique spectral information that allowed a separation of all groups of origin by multivariate data analysis (MVA). We were further able to non-invasively monitor phenotypic switching in cultured SMCs and assess the impact of different culture conditions on extracellular matrix remodeling in the Tissue-engineered ring constructs. Interestingly, we identified that the Raman signature of the human SMC-based ring constructs was similar to the one obtained from native aortic Tissue. We conclude that Raman microspectroscopic methods are promising tools to characterize cells and define cellular and extracellular matrix components on a molecular level. In this study, in situ measurements were marker-independent, fast, and identified cellular differences that were not detectable by established routine techniques. Perspectively, Raman microspectroscopy and MVA in combination with artificial intelligence can be suitable for automated quality monitoring of (stem) cell and cell-based Tissue engineering products. Statement of Significance The accessibility of autologous blood vessels for surgery is limited. Tissue engineering (TE) aims to develop functional vascular replacements; however, no commercially available TE vascular graft (TEVG) exists to date. One limiting factor is the availability of a well-characterized and safe cell source. Smooth muscle cells (SMCs) are generally used for TEVGs. To engineer a TEVG, proliferating SMCs of the synthesizing phenotype are essential, whereas functional, sustainable TEVGs require SMCs of the contractile phenotype. SMC diversity and plasticity are therefore limiting factors, also for their quality monitoring and application in TE. In this study, Raman microspectroscopy and imaging combined with machine learning tools allowed the non-destructive, marker-independent characterization of SMCs, smooth muscle Tissues and TE SMC-constructs. The spectral information was specific enough to distinguish for the first time the phenotypic switching in SMCs in real-time, and monitor the impact of culture conditions on ECM remodeling in the TE SMC-constructs.

  • three dimensional electrospun ecm based hybrid scaffolds for Cardiovascular Tissue engineering
    Biomaterials, 2008
    Co-Authors: Sepideh Heydarkhanhagvall, Katja Schenkelayland, Ramin E Beygui, Andrew P Dhanasopon, Fady Rofail, Hunter Smith, Benjamin M Wu, Richard J Shemin, William R Maclellan
    Abstract:

    Electrospinning using natural proteins or synthetic polymers is a promising technique for the fabrication of fibrous scaffolds for various Tissue engineering applications. However, one limitation of scaffolds electrospun from natural proteins is the need to cross-link with glutaraldehyde for stability, which has been postulated to lead to many complications in vivo including graft failure. In this study, we determined the characteristics of hybrid scaffolds composed of natural proteins including collagen and elastin, as well as gelatin, and the synthetic polymer poly(ɛ-caprolactone) (PCL), so to avoid chemical cross-linking. Fiber size increased proportionally with increasing protein and polymer concentrations, whereas pore size decreased. Electrospun gelatin/PCL scaffolds showed a higher tensile strength when compared to collagen/elastin/PCL constructs. To determine the effects of pore size on cell attachment and migration, both hybrid scaffolds were seeded with adipose-derived stem cells. Scanning electron microscopy and nuclei staining of cell-seeded scaffolds demonstrated the complete cell attachment to the surfaces of both hybrid scaffolds, although cell migration into the scaffold was predominantly seen in the gelatin/PCL hybrid. The combination of natural proteins and synthetic polymers to create electrospun fibrous structures resulted in scaffolds with favorable mechanical and biological properties.

  • three dimensional electrospun ecm based hybrid scaffolds for Cardiovascular Tissue engineering
    Biomaterials, 2008
    Co-Authors: Sepideh Heydarkhanhagvall, Katja Schenkelayland, Ramin E Beygui, Andrew P Dhanasopon, Fady Rofail, Hunter Smith, Richard J Shemin, William R Maclellan
    Abstract:

    Electrospinning using natural proteins or synthetic polymers is a promising technique for the fabrication of fibrous scaffolds for various Tissue engineering applications. However, one limitation of scaffolds electrospun from natural proteins is the need to cross-link with glutaraldehyde for stability, which has been postulated to lead to many complications in vivo including graft failure. In this study, we determined the characteristics of hybrid scaffolds composed of natural proteins including collagen and elastin, as well as gelatin, and the synthetic polymer poly(epsilon-caprolactone) (PCL), so to avoid chemical cross-linking. Fiber size increased proportionally with increasing protein and polymer concentrations, whereas pore size decreased. Electrospun gelatin/PCL scaffolds showed a higher tensile strength when compared to collagen/elastin/PCL constructs. To determine the effects of pore size on cell attachment and migration, both hybrid scaffolds were seeded with adipose-derived stem cells. Scanning electron microscopy and nuclei staining of cell-seeded scaffolds demonstrated the complete cell attachment to the surfaces of both hybrid scaffolds, although cell migration into the scaffold was predominantly seen in the gelatin/PCL hybrid. The combination of natural proteins and synthetic polymers to create electrospun fibrous structures resulted in scaffolds with favorable mechanical and biological properties.

  • human adipose stem cells a potential cell source for Cardiovascular Tissue engineering
    Cells Tissues Organs, 2008
    Co-Authors: Sepideh Heydarkhanhagvall, Katja Schenkelayland, Jin Q Yang, Sanaz Heydarkhan, Patricia A Zuk, Robb W Maclellan, Ramin E Beygui
    Abstract:

    Background/Aims: A crucial step in providing clinically relevant applications of Cardiovascular Tissue engineering involves the identification of a suitable cell source. The objecti

William R Maclellan - One of the best experts on this subject based on the ideXlab platform.

  • three dimensional electrospun ecm based hybrid scaffolds for Cardiovascular Tissue engineering
    Biomaterials, 2008
    Co-Authors: Sepideh Heydarkhanhagvall, Katja Schenkelayland, Ramin E Beygui, Andrew P Dhanasopon, Fady Rofail, Hunter Smith, Benjamin M Wu, Richard J Shemin, William R Maclellan
    Abstract:

    Electrospinning using natural proteins or synthetic polymers is a promising technique for the fabrication of fibrous scaffolds for various Tissue engineering applications. However, one limitation of scaffolds electrospun from natural proteins is the need to cross-link with glutaraldehyde for stability, which has been postulated to lead to many complications in vivo including graft failure. In this study, we determined the characteristics of hybrid scaffolds composed of natural proteins including collagen and elastin, as well as gelatin, and the synthetic polymer poly(ɛ-caprolactone) (PCL), so to avoid chemical cross-linking. Fiber size increased proportionally with increasing protein and polymer concentrations, whereas pore size decreased. Electrospun gelatin/PCL scaffolds showed a higher tensile strength when compared to collagen/elastin/PCL constructs. To determine the effects of pore size on cell attachment and migration, both hybrid scaffolds were seeded with adipose-derived stem cells. Scanning electron microscopy and nuclei staining of cell-seeded scaffolds demonstrated the complete cell attachment to the surfaces of both hybrid scaffolds, although cell migration into the scaffold was predominantly seen in the gelatin/PCL hybrid. The combination of natural proteins and synthetic polymers to create electrospun fibrous structures resulted in scaffolds with favorable mechanical and biological properties.

  • three dimensional electrospun ecm based hybrid scaffolds for Cardiovascular Tissue engineering
    Biomaterials, 2008
    Co-Authors: Sepideh Heydarkhanhagvall, Katja Schenkelayland, Ramin E Beygui, Andrew P Dhanasopon, Fady Rofail, Hunter Smith, Richard J Shemin, William R Maclellan
    Abstract:

    Electrospinning using natural proteins or synthetic polymers is a promising technique for the fabrication of fibrous scaffolds for various Tissue engineering applications. However, one limitation of scaffolds electrospun from natural proteins is the need to cross-link with glutaraldehyde for stability, which has been postulated to lead to many complications in vivo including graft failure. In this study, we determined the characteristics of hybrid scaffolds composed of natural proteins including collagen and elastin, as well as gelatin, and the synthetic polymer poly(epsilon-caprolactone) (PCL), so to avoid chemical cross-linking. Fiber size increased proportionally with increasing protein and polymer concentrations, whereas pore size decreased. Electrospun gelatin/PCL scaffolds showed a higher tensile strength when compared to collagen/elastin/PCL constructs. To determine the effects of pore size on cell attachment and migration, both hybrid scaffolds were seeded with adipose-derived stem cells. Scanning electron microscopy and nuclei staining of cell-seeded scaffolds demonstrated the complete cell attachment to the surfaces of both hybrid scaffolds, although cell migration into the scaffold was predominantly seen in the gelatin/PCL hybrid. The combination of natural proteins and synthetic polymers to create electrospun fibrous structures resulted in scaffolds with favorable mechanical and biological properties.