The Experts below are selected from a list of 3243 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.

Ngan F Huang - One of the best experts on this subject based on the ideXlab platform.

  • extracellular matrix based biomaterials for Cardiovascular Tissue Engineering
    Journal of Cardiovascular Development and Disease, 2021
    Co-Authors: Astha Khanna, Maedeh Zamani, Ngan F Huang
    Abstract:

    Regenerative medicine and Tissue Engineering strategies have made remarkable progress in remodeling, replacing, and regenerating damaged Cardiovascular Tissues. The design of three-dimensional (3D) scaffolds with appropriate biochemical and mechanical characteristics is critical for Engineering Tissue-engineered replacements. The extracellular matrix (ECM) is a dynamic scaffolding structure characterized by Tissue-specific biochemical, biophysical, and mechanical properties that modulates cellular behavior and activates highly regulated signaling pathways. In light of technological advancements, biomaterial-based scaffolds have been developed that better mimic physiological ECM properties, provide signaling cues that modulate cellular behavior, and form functional Tissues and organs. In this review, we summarize the in vitro, pre-clinical, and clinical research models that have been employed in the design of ECM-based biomaterials for Cardiovascular regenerative medicine. We highlight the research advancements in the incorporation of ECM components into biomaterial-based scaffolds, the Engineering of increasingly complex structures using biofabrication and spatial patterning techniques, the regulation of ECMs on vascular differentiation and function, and the translation of ECM-based scaffolds for vascular graft applications. Finally, we discuss the challenges, future perspectives, and directions in the design of next-generation ECM-based biomaterials for Cardiovascular Tissue Engineering and clinical translation.

  • big bottlenecks in Cardiovascular Tissue Engineering
    Communications biology, 2018
    Co-Authors: Ngan F Huang, Vahid Serpooshan, Viola B Morris, Nazish Sayed, Gaspard Pardon, Oscar J Abilez, Karina H Nakayama
    Abstract:

    Although Tissue Engineering using human-induced pluripotent stem cells is a promising approach for treatment of Cardiovascular diseases, some limiting factors include the survival, electrical integration, maturity, scalability, and immune response of three-dimensional (3D) engineered Tissues. Here we discuss these important roadblocks facing the Tissue Engineering field and suggest potential approaches to overcome these challenges.

  • regulation of the microenvironment for cardiac Tissue Engineering
    Regenerative Medicine, 2017
    Co-Authors: Ngan F Huang, Maureen Wanjare
    Abstract:

    The microenvironment of myocardium plays an important role in the fate and function of cardiomyocytes (CMs). Cardiovascular Tissue Engineering strategies commonly utilize stem cell sources in conjunction with microenvironmental cues that often include biochemical, electrical, spatial and biomechanical factors. Microenvironmental stimulation of CMs, in addition to the incorporation of intercellular interactions from non-CMs, results in the generation of engineered cardiac constructs. Current studies suggest that use of these factors when Engineering cardiac constructs improve cardiac function when implanted in vivo. In this review, we summarize the approaches to modulate biochemical, electrical, biomechanical and spatial factors to induce CM differentiation and their subsequent organization for cardiac Tissue Engineering application.

  • role of extracellular matrix signaling cues in modulating cell fate commitment for Cardiovascular Tissue Engineering
    Advanced Healthcare Materials, 2014
    Co-Authors: Ngan F Huang, Karina H Nakayama, Luqia Hou
    Abstract:

    It is generally agreed that engineered Cardiovascular Tissues require cellular interactions with the local milieu. Within the microenvironment, the extracellular matrix (ECM) is an important support structure that provides dynamic signaling cues in part through its chemical, physical, and mechanical properties. In response to ECM factors, cells activate biochemical and mechanotransduction pathways that modulate their survival, growth, migration, differentiation, and function. This Review describes the role of ECM chemical composition, spatial patterning, and mechanical stimulation in the specification of Cardiovascular lineages, with a focus on stem cell differentiation, direct transdifferentiation, and endothelial-to-mesenchymal transition. The translational application of ECMs is discussed in the context of Cardiovascular Tissue Engineering and regenerative medicine.

  • chemical and physical regulation of stem cells and progenitor cells potential for Cardiovascular Tissue Engineering
    Tissue Engineering, 2007
    Co-Authors: Ngan F Huang, Randall J Lee
    Abstract:

    The field of Cardiovascular Tissue Engineering has experienced tremendous advances in the past several decades, but the clinical reality of engineered heart Tissue and vascular conduits remains immature. Stem cells and progenitor cells are promising cell sources for Engineering functional Cardiovascular Tissues. To realize the therapeutic potential of stem cells and progenitor cells, we need to understand how microenvironmental cues modulate and guide stem cell differentiation and organization. This review describes the current understanding of the chemical and physical regulation of embryonic and adult stem cells for potential applications in Cardiovascular repair, focusing on cardiac therapies after myocardial infarction and the Engineering of vascular conduits

Carlijn Carlijn Bouten - One of the best experts on this subject based on the ideXlab platform.

  • Porous scaffolds using dual electrospinning for in situ Cardiovascular Tissue Engineering
    2017
    Co-Authors: Sh Shraddha Thakkar, Anita Anita Driessen-mol, Fpt Frank Baaijens, Carlijn Carlijn Bouten
    Abstract:

    In situ Cardiovascular Tissue Engineering is emerging as a promising approach for replacing diseased or damaged components of the Cardiovascular system by the use of biodegradable synthetic grafts. Functional porous scaffolds are implanted to create in vivo complex Tissues that are functionally similar to their native counterparts. A biodegradable starter matrix permits cell infiltration and Tissue formation at the site of implantation, while maintaining Tissue mechanical and biological function. This chapter elaborates on the fabrication of porous scaffolds via the electrospinning technique, including advantages, as well as limitations of various approaches, like single-nozzle, dual-nozzle, and coaxial-nozzle electrospinning. 442The added value of dual-nozzle electrospinning technique is highlighted, where scaffold porosity is enhanced by selectively removing one of the polymers while the other polymer maintains mechanical stability. Further, optimization techniques for modifying the porosity of electrospun scaffolds are described along with their influence on the graft’s mechanical properties and biodegradation rate.

  • matrix production and organization by endothelial colony forming cells in mechanically strained engineered Tissue constructs
    PLOS ONE, 2013
    Co-Authors: Nicky De Jonge, Fpt Frank Baaijens, Emanuela S. Fioretta, Dimitri E P Muylaert, Joost O Fledderus, Marianne C Verhaar, Carlijn Carlijn Bouten
    Abstract:

    Aims: Tissue Engineering is an innovative method to restore Cardiovascular Tissue function by implanting either an in vitro cultured Tissue or a degradable, mechanically functional scaffold that gradually transforms into a living neo-Tissue by recruiting Tissue forming cells at the site of implantation. Circulating endothelial colony forming cells (ECFCs) are capable of differentiating into endothelial cells as well as a mesenchymal ECM-producing phenotype, undergoing Endothelial-toMesenchymal-transition (EndoMT). We investigated the potential of ECFCs to produce and organize ECM under the influence of static and cyclic mechanical strain, as well as stimulation with transforming growth factor b1 (TGFb1). Methods and Results: A fibrin-based 3D Tissue model was used to simulate neo-Tissue formation. Extracellular matrix organization was monitored using confocal laser-scanning microscopy. ECFCs produced collagen and also elastin, but did not form an organized matrix, except when cultured with TGFb1 under static strain. Here, collagen was aligned more parallel to the strain direction, similar to Human Vena Saphena Cell-seeded controls. Priming ECFC with TGFb1 before exposing them to strain led to more homogenous matrix production. Conclusions: Biochemical and mechanical cues can induce extracellular matrix formation by ECFCs in Tissue models that mimic early Tissue formation. Our findings suggest that priming with bioactives may be required to optimize neo-Tissue development with ECFCs and has important consequences for the timing of stimuli applied to scaffold designs for both in vitro and in situ Cardiovascular Tissue Engineering. The results obtained with ECFCs differ from those obtained with other cell sources, such as vena saphena-derived myofibroblasts, underlining the need for experimental models like ours to test novel cell sources for Cardiovascular Tissue Engineering.

  • sequential use of human derived medium supplements favours Cardiovascular Tissue Engineering
    Journal of Cellular and Molecular Medicine, 2012
    Co-Authors: Paul Riem W Vis, Jolanda Kluin, Joost P G Sluijter, Sarita R Soekhradjsoechit, Lex A Van Herwerden, Carlijn Carlijn Bouten
    Abstract:

    For clinical application of Tissue Engineering strategies, the use of animal-derived serum in culture medium is not recommended, because it can evoke immune responses in patients. We previously observed that human platelet-lysate (PL) is favourable for cell expansion, but generates weaker Tissue as compared to culture in foetal bovine serum (FBS). We investigated if human serum (HS) is a better human supplement to increase Tissue strength. Cells were isolated from venous grafts of 10 patients and expanded in media supplemented with PL or HS, to determine proliferation rates and expression of genes related to collagen production and maturation. Zymography was used to assess protease expression. Collagen contraction assays were used as a two-dimensional (2D) model for matrix contraction. As a prove of principle, 3D Tissue culture and tensile testing was performed for two patients, to determine Tissue strength. Cell proliferation was lower in HS-supplemented medium than in PL medium. The HS cells produced less active matrix metallo-proteinase 2 (MMP2) and showed increased matrix contraction as indicated by gel contraction assays and 3D-Tissue culture. Tensile testing showed increased strength for Tissues cultured in HS when compared to PL. This effect was more pronounced if cells were sequentially cultured in PL, followed by Tissue culture in HS. These data suggest that sequential use of PL and HS as substitutes for FBS in culture medium for Cardiovascular Tissue Engineering results in improved cell proliferation and Tissue mechanical properties, as compared to use of PL or HS apart.

  • a mesofluidics based test platform for systematic development of scaffolds for in situ Cardiovascular Tissue Engineering
    Tissue Engineering Part C-methods, 2012
    Co-Authors: Aipm Anthal Smits, Carlijn Carlijn Bouten, Anita Anita Driessenmol, Fpt Frank Baaijens
    Abstract:

    Recently, in situ Tissue Engineering has emerged as a new approach to obtain autologous, living replacement Tissues with off-the-shelf availability. The method is based on the use of an instructive biodegradable scaffold that is capable of repopulation with host cells in situ and subsequent Tissue formation. This approach imposes high demands on scaffold properties. For Cardiovascular grafts, the repopulation with endogenous cells from the circulation is further hypothesized to be influenced by the hemodynamic environment of the scaffold. To systematically study the effect of scaffold properties on the response of circulating cells, we aimed to develop a mesofluidics-based in vitro test platform that enables on-stage investigation of the interaction of circulating cells with three-dimensional (3D) synthetic scaffolds under physiologic hemodynamic conditions. The test platform consists of a custom-developed cross-flow chamber that houses small-scale 3D scaffolds. The cross-flow chamber is incorporated into a flow-loop to drive a cell suspension along the scaffold with physiological wall shear stress and perfusion pressure. The fluidics system is validated numerically and experimentally using a computational fluid dynamics model and real-time microbead tracing studies, demonstrating a fully developed flow profile with a homogeneous shear stress distribution over the scaffold. Wall shear stresses and pressure can be controlled independently, well within the target physiological range (0-8 Pa and 0-100 mmHg, respectively). Bench-top evaluation is performed using electrospun poly(ɛ-caprolactone) scaffolds with varying fiber diameter, exposed to a suspension of human peripheral blood mononuclear cells in pulsatile flow for 72 h. Cell adhesion and infiltration are monitored using time-lapsed confocal laser scanning microscopy. In conclusion, we have successfully developed a mesofluidics platform to study cell-scaffold interactions under hemodynamic conditions in vitro. This platform not only enables us to systematically screen and develop potential scaffolds for future in situ Cardiovascular Tissue Engineering approaches, but also acts as a tool to further elucidate processes as observed in vivo.

  • platelet lysate as an autologous alternative for fetal bovine serum in Cardiovascular Tissue Engineering
    Tissue Engineering Part A, 2010
    Co-Authors: Carlijn Carlijn Bouten, Gerard Pasterkamp, Joost P G Sluijter, Lex A Van Herwerden, Jolanda Kluin
    Abstract:

    There is an ongoing search for alternative Tissue culture sera to engineer autologous Tissues, since use of fetal bovine serum (FBS) is limited under Good Tissue Practice guidelines. We compared FBS with human platelet-lysate (PL) in media for in vitro cell culture. A threefold increase in duplication rate was found when human, saphenous vein-derived myofibroblasts were cultured in PL, whereas expression of marker proteins (α-smooth muscle actin, vimentin, desmin, and nonmuscle myosin heavy chain) was similar. Heat shock protein 47 mRNA expression was increased in PL cells, and type III collagen fibers were seen on PL-cell monolayers but not on cells cultured in FBS. These results imply a more efficient collagen fiber production. We also found higher levels of proteins involved in Tissue repair and collagen remodeling, which could explain increased production of proteases and protease inhibitors by PL cells. Our findings indicate that PL is beneficial due to the increased duplication rate, in addition to ...

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

  • harnessing topographical biochemical cues to enhance elastogenesis by paediatric cells for Cardiovascular Tissue Engineering applications
    Biochemical and Biophysical Research Communications, 2019
    Co-Authors: Ian Woods, Stefan Jockenhoevel, Alexander Black, Thomas C Flanagan
    Abstract:

    The development of Tissue-engineered vascular grafts (TEVGs) with a biomimetic extracellular matrix (ECM) structure, including a mature elastic network, remains a key challenge for the production of grafts with long-term functionality. The aim of this study was to investigate the influence of aligned nanofiber substrates on ECM protein synthesis by neonatal smooth muscle cells (SMCs), and to examine the combined effects of this topographical cue in conjunction with transforming growth factor beta-1 (TGF-β1) - a biochemical elastogenic promoter. Glass coverslips were coated in electrospun fibrinogen nanofibers (average diameter < 500 nm) with either a randomly-orientated or aligned topography. Human umbilical artery smooth muscle cells (hUASMCs) were cultured on the electrospun substrates for 7 and 14 days, with or without a 2 ng/ml TGF-β1 supplement. The ECM structure was analysed using immunohistochemistry and the quantity of secreted elastin in the cell layer was measured using a dye-binding assay. Aligned fiber substrates induced a directed orientation of both the seeded cells and cell-synthesized ECM fibers. Cells cultured on aligned fibers exhibited a significant increase in the expression of phenotypic contractile proteins, as well as increases in the secreted elastin content of the cell layer, compared to cells cultured on randomly-orientated substrates. TGF-β1 supplementation was shown to synergistically increase secreted elastin from cells cultured on aligned fiber substrates (p < 0.05). Aligned nanofiber scaffolds can be used to direct cellular orientation, elastin-related protein synthesis and cell phenotype, and consequently there is potential for their application in the development of TEVGs as part of a multi-pronged strategy to promote elastic fiber formation.

  • 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.

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.