Abstracts: Suppl. 2 to Vol. 15 (October 27–31, 2012)

Interactive CardioVascular and Thoracic Surgery Basic Science Postgraduate Course: Session 1 Sunday, 28 October 2012 AW N 001 SPRAY- AND LASER-ASSISTED BIOMATERIAL PROCESSING FOR INTRAOPERATIVE TABLE-SIDE AUTOLOGOUS HEART VALVE TISSUE ENGINEERING C. Klopsch1, R. Gaebel1, A. Kaminski1, B. Chichkov2, S. Jockenhoevel3, G. Steinhoff1 1 Reference and Translation Center for Cardiac Stem Cell Therapy, Department of Cardiac Surgery, University of Rostock, Rostock, Germany; 2 Laser Zentrum Hannover, Hannover, Germany; 3Department of Tissue Engineering and Textile Implants, Applied Medical Engineering, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany WI TH DR Objectives: At present, intensive investigation aims at the creation of optimal valvular prostheses. We introduced and tested two advanced cellplus-matrix seeding technologies, spray-assisted bioprocessing (SaBP) and laser-assisted bioprocessing (LaBP), for intraoperative table-side autologous tissue engineering (TE) of bioresorbable artificial grafts. Methods: Three-leaflet valves were manufactured following TE of electrospun poly ε-caprolactone (PCL) tissue equivalents. For SaBP, human mesenchymal stem cells (HMSC), umbilical cord vein endothelial cells (HUVEC) and fibrin were simultaneously spray-administered on PCL substrates. For LaBP, HUVEC and HMSC were separately laser-printed in stripes followed by fibrin sealing. Tissue equivalents were monitored in vitro under static and dynamic conditions in bioreactors. Results: SaBP and LaBP resulted in TE of grafts with homogenous cell distribution and accurate cell pattern, respectively. Engineered valves demonstrated immediate sufficient performance, complete cell coating, proliferation, engraftment, HUVEC-mediated invasion, HMSC differentiation and extracellular matrix deposition. SaBP revealed higher efficiency with at least a 12-fold shorter processing time than the applied LaBP setup. LaBP realized coating with higher cell density and minimal cell-to-scaffold distance. Fibrin and PCL stability remain issues for improvement. Conclusions: The introduced TE technologies resulted in complete valvular cell-plus-matrix coating and excellent engraftment. SaBP seems to have more potential for table-side TE than LaBP in terms of procedural duration and ease of implementation. On the other hand, LaBP might accelerate engraftment with precise patterns. 002 IMPROVED MYOCARDIAL ENGRAFTMENT OF INDUCED PLURIPOTENT CELLDERIVED CARDIOMYOCYTES BY CO-TRANSPLANTATION WITH MESENCHYMAL STEM CELLS Y. Choi1, K. Neef1, V. Lenerz2, T. Saric2, O.J. Liakopoulos1, C. Stamm3, T. Wittwer1, T. Wahlers1 1 Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany; 2Institute of Neurophysiology, University of Cologne, Cologne, Germany; 3Department of Cardiothoracic Surgery, German Heart Institute Berlin, Berlin, Germany Objectives: Cardiomyocytes generated from induced pluripotent cells (iPSCM) hold great promise as a sustainable and patient-specific source of cells with the potential for the regeneration of infarcted myocardium. Since myocardial engrafting of iPS-CM is poor, the goal of this study was to investigate the efficacy of the co-transplantation approach, applying iPS-CM in combination with mesenchymal stem cells (MSC). Methods: Directed in vitro differentiation was used to generate iPS-CM from a cardiac-specific selectable iPS cell line. The purity and quality of iPS-CM were confirmed by fluorescence-activated cell sorting (FACS) and immunocytochemistry. MSC were isolated from bone marrow and specificity was confirmed by in vitro differentiation and FACS. 5x105 iPS-CM, MSC, or a combination of both, were transplanted after cryo-infarct induction in C57BL/6 mice. A clinical 3T MRI scanner was used for the assessment of left ventricular function over four weeks. Immuno-histochemical analyses were performed to track the transplanted cells individually and to determine myocardial integration and functional maturation. Results: iPS-CM were successfully generated and cellular identity of iPS-CM was confirmed by immune-cytochemistry (α-actinin, troponinT). MSC were validated for expression of CD44 (64.1±4.1%) and Sca-1 (98.1±0.9%) and in vitro adipo-/chondro- and osteogenic differentiation. After transplantations, left-ventricular function improved significantly after four weeks (sham 43.5 ±4.7%; iPS 52.5±4.9%; MSC 45.0±6.2%; iPS+MSC 52.3±6.0%; P<0.05). Immunohistochemical analyses (α-actinin and connexion 43) revealed functional integration and structural maturation of iPS-CM. Conclusions: For the first time, a complete myocardial integration of iPS-CM after co-transplantation with MSC could be demonstrated, resulting in improved recovery of left ventricular function. This approach opens up a completely new perspective for cardiac cell therapy. 003 A NOVEL NATIVE-DERIVED CORONARY ARTERY MODEL H. Aubin, A. Kranz, J. Huelsmann, A. Lichtenberg, P. Akhyari Department of Cardiovascular Surgery, Heinrich Heine Düsseldorf, Düsseldorf, Germany University Objectives: Rising epidemiologic numbers of cardiovascular disease and donor organ shortage increase the need for alternative therapies for endstage heart failure. Although tissue-engineering approaches have led to significant progress in the quest to find a viable substitute for the injured myocardium, the vascularization of such bio-artificial constructs still remains a major challenge. Therefore, the objective of this study is to create a standardized native-derived coronary artery model in order to study the re-endothelialization and endothelial function of tissue-engineered cardiac constructs. Methods: Whole rat hearts were decellularized preserving macro- and microscopic architecture as well as bio-molecular integrity, as previously described. Decellularized hearts were then dissected, creating two coronary artery tissue flaps adherent to the aorta ascendens along the left coronary artery and right coronary artery, respectively. Coronary arteries were seeded with cells by retrograde aortic perfusion while the circumjacent tissue was surface seeded. Results: The coronary artery system remained patent after decellularization. Retrograde aortic perfusion allows for selective seeding of the coronary artery system, leading to cell adherence to the basal membrane, without cell migration into the adjacent tissue. Surface seeding of the coronary artery tissue flaps allows for additional controlled co-culture of different cell types. On top, lucid tissue morphology allows for live cell-tracking. Conclusions: This novel native-derived coronary artery model offers a patent coronary vascular architecture with preserved cardiac extra-cellular matrix, therefore mimicking nature’s input to the highest possible degree. This offers the possibility to study re-endothelialization and endothelial function of different donor cell types and interaction with cardiac cells in a standardized in vitro model. Sun (...truncated)