To improve the predictive capability of pre-clinical models and reduce the use of animal models in drug discovery and disease modelling, advanced in vitro models are being developed. These... Show moreTo improve the predictive capability of pre-clinical models and reduce the use of animal models in drug discovery and disease modelling, advanced in vitro models are being developed. These microphysiological systems (MPS) or “Organs-on-Chip” (OoC) are being developed to include all aspects of the human physiology to improve the in vitro cellular response. OoCs combined with differentiated human induced pluripotent stem cells (hiPSC) allow the use of cells with patient specific genotypes and aid the development of personalized and precision medicine.In this thesis, the development of tractable models of the vasculature is described. These models allow for the combination of hiPSC-derived vascular and tissue specific cells with haemodynamics to recapitulate essential stimuli of blood vessels. Show less
Bobylev, D.; Horke, A.; Avsar, M.; Cvitkovic, T.; Boethig, D.; Hazekamp, M.; ... ; Sarikouch, S. 2023
For decades, bovine jugular vein conduits (BJV) and classic cryopreserved homografts have been the two most widely used options for pulmonary valve replacement (PVR) in congenital heart disease.... Show moreFor decades, bovine jugular vein conduits (BJV) and classic cryopreserved homografts have been the two most widely used options for pulmonary valve replacement (PVR) in congenital heart disease. More recently, decellularized pulmonary homografts (DPH) have provided an alternative avenue for PVR. Matched comparison of patients who received DPH for PVR with patients who received bovine jugular vein conduits (BJV) considering patient age group, type of heart defect, and previous procedures. 319 DPH patients were matched to 319 BJV patients; the mean age of BJV patients was 15.3 (SD 9.5) years versus 19.1 (12.4) years in DPH patients (p = 0.001). The mean conduit diameter was 24.5 (3.5) mm for DPH and 20.3 (2.5) mm for BJV (p < 0.001). There was no difference in survival rates between the two groups after 10 years (97.0 vs. 98.1%, p = 0.45). The rate of freedom from endocarditis was significantly lower for BJV patients (87.1 vs. 96.5%, p = 0.006). Freedom from explantation was significantly lower for BJV at 10 years (81.7 vs. 95.5%, p = 0.001) as well as freedom from any significant degeneration at 10 years (39.6 vs. 65.4%, p < 0.001). 140 Patients, matched for age, heart defect type, prior procedures, and conduit sizes of 20-22 mm (+/- 2 mm), were compared separately; mean age BJV 8.7 (4.9) and DPH 9.5 (7.3) years (p = n.s.). DPH showed 20% higher freedom from explantation and degeneration in this subgroup (p = 0.232). Decellularized pulmonary homografts exhibit superior 10-year results to bovine jugular vein conduits in PVR. Show less
Due to the steep rise of the prevalence of osteoarthritis in the world's population in recent years, it has been of great interest to search for the best way to relieve symptoms and consequences of... Show moreDue to the steep rise of the prevalence of osteoarthritis in the world's population in recent years, it has been of great interest to search for the best way to relieve symptoms and consequences of OA like pain and inflammation. For that reason, the tissue engineering using a porous tri-layer scaffold is a great alternative for patients with this illness.In this way, it was designed, developed and improved a novel chitosan/collagen-based tri-layer porous scaffold with similar chemical composition and structure to the articular cartilage. One of these layers included hydroxyapatite, to promote the integration of growing tissue next to subchondral bone.The biomaterial was physic-chemical characterized, in vitro and in vivo tested obtaining promising results. Later, the scaffold was crosslinked to promote rheological properties that bear the knee cyclic charges while walking. The anti-inflammatory effect was enhanced by the incorporation of a TNF-α blocking drug, which was released in a controlled manner from the material in the damaged tissue over time. The scaffold was non-cytotoxic against chondrocytes and osteoblasts, had great rheological properties and promoted the growth of new cartilage tissue after four weeks after grafted into the osteoarthritic mice knee. Show less
Bobylev, D.; Horke, A.; Boethig, D.; Hazekamp, M.; Meyns, B.; Rega, F.; ... ; Sarikouch, S. 2022
OBJECTIVES: Early results from the prospective ESPOIR Trial have indicated excellent results for pulmonary valve replacement using decellularized pulmonary homografts (DPH).METHODS: A 5-year... Show moreOBJECTIVES: Early results from the prospective ESPOIR Trial have indicated excellent results for pulmonary valve replacement using decellularized pulmonary homografts (DPH).METHODS: A 5-year analysis of ESPOIR Trial patients was performed to provide an insight into the midterm DPH performance. ESPOIR Trial and Registry patients were matched with cryopreserved homografts (CH) patients considering patient age, type of heart defect and previous procedures to present the overall experience with DPH.RESULTS: A total of 121 patients (59 female) were prospectively enrolled (8/2014-12/2016), median age 16.5 years (interquartile range 11.2-29.8), and median DPH diameter 24 mm. One death (73 year-old) occurred during a median follow-up of 5.9 years (5.4-6.4), in addition to 2 perioperative deaths resulting in an overall mortality rate of 2.5%. One case of endocarditis in 637 patient-years was noticed, resulting in an incidence of 0.15% per patient-year. At 5 years, the mean peak gradient was 19.9 mmHg (9.9), mean regurgitation 0.9 (0.6, grade 0-3) and freedom from explantation/any reintervention 97.5% (1.5). The combined DPH cohort, n = 319, comprising both Trial and Registry data, showed significantly better freedom from explantation for DPH 95.5% (standard deviation 1.7) than CH 83.0% (2.8) (P < 0.001) and less structural valve degeneration at 10 years when matched to 319 CH patients [DPH 65.5% (standard deviation 4.4) and CH 47.3% (3.7), P = 0.11].CONCLUSIONS: The 5-year data of the prospective ESPOIR Trial show excellent performance for DPH and low rates of adverse events. ESPOIR Registry data up to 15 years, including a matched comparison with CH, demonstrated statistically significant better freedom from explantation. Show less
Velden, J. van der; Asselbergs, F.W.; Bakkers, J.; Batkai, S.; Bertrand, L.; Bezzina, C.R.; ... ; Thum, T. 2022
Cardiovascular diseases represent a major cause of morbidity and mortality, necessitating research to improve diagnostics, and to discover and test novel preventive and curative therapies. All of... Show moreCardiovascular diseases represent a major cause of morbidity and mortality, necessitating research to improve diagnostics, and to discover and test novel preventive and curative therapies. All of which warrant experimental models that recapitulate human disease. The translation of basic science results to clinical practice is a challenging task. In particular for complex conditions such as cardiovascular diseases, which often result from multiple risk factors and co-morbidities. This difficulty might lead some individuals to question the value of animal research, citing the translational 'valley of death', which largely reflects the fact that studies in rodents are difficult to translate to humans. This is also influenced by the fact that new, human-derived in vitro models can recapitulate aspects of disease processes. However, it would be a mistake to think that animal models cannot provide a vital step in the translational pathway as they do provide important pathophysiological insights into disease mechanisms particularly on a organ and systemic level. While stem cell-derived human models have the potential to become key in testing toxicity and effectiveness of new drugs, we need to be realistic, and carefully validate all new human-like disease models. In this position paper, we highlight recent advances in trying to reduce the number of animals for cardiovascular research ranging from stem cell-derived models to in situ modelling of heart properties, bioinformatic models based on large datasets, and improved current animal models, which show clinically relevant characteristics observed in patients with a cardiovascular disease. We aim to provide a guide to help researchers in their experimental design to translate bench findings to clinical routine taking the replacement, reduction and refinement (3R) as a guiding concept. Show less
Corneal transplantation still represents the elected method for the treatment of corneal endothelial pathologies. However, the worldwide shortage of donor corneas induced the exploration of... Show moreCorneal transplantation still represents the elected method for the treatment of corneal endothelial pathologies. However, the worldwide shortage of donor corneas induced the exploration of approaches to use the donor tissue more efficiently or to be more independent from donor tissue. This thesis will illustrate the improvements of new strategies for cell-based corneal endothelial regeneration, alternative to corneal endothelial surgical transplantation, by bridging the gap between in vitro experiments and clinical models. In the studies described, we first address the establishment of a GMP-compliant protocol for in vitro hCEC culture for clinical application and then we focus on endothelial cell sheet transplantation, describing both in vitro and in vivo applications of expanded CEC-carriers constructs made by biocompatible materials. Show less
Horke, A.; Tudorache, I.; Laufer, G.; Andreas, M.; Pomar, J.L.; Pereda, D.; ... ; Sarikouch, S. 2020
OBJECTIVES: Decellularized aortic homografts (DAH) may provide an additional aortic valve replacement option for young patients due to their potential to overcome the high early failure rate of... Show moreOBJECTIVES: Decellularized aortic homografts (DAH) may provide an additional aortic valve replacement option for young patients due to their potential to overcome the high early failure rate of conventional allogenic and xenogenic aortic valve prostheses.METHODS: A prospective, European Union-funded, single-arm, multicentre, safety study was conducted in 8 centres evaluating non-cryopreserved DAH for aortic valve replacement.RESULTS: One hundred and forty-four patients (99 male) were prospectively enrolled between October 2015 and October 2018, mean age 33.6 +/- 20.8 years; 45% had undergone previous cardiac operations. Mean implanted DAH diameter 22.6 +/- 2.4 mm and mean durations for the operation, cardiopulmonary bypass and cross-clamp were 341 +/- 140, 174 +/- 80 and 126 +/- 43 min, respectively. There were 2 early deaths (1 LCA thrombus on day 3 and 1 ventricular arrhythmia 5 h postop) and 1 late death due to endocarditis 4 months postoperatively, resulting in a total mortality of 2.08%. One pacemaker implantation was necessary and 1 DAH was successfully repaired after 6 weeks for early regurgitation following subcoronary implantation. All other DAH were implanted as a free-standing root. After a mean follow-up of 1.54 +/- 0.81 years, the primary efficacy end points peak gradient (mean 11.8 +/- 7.5 mmHg) and regurgitation (mean 0.42 +/- 0.49, grade 0-3) were excellent. At 2.5 years, freedom from explantation/endocarditis/bleeding/stroke was 98.4 +/- 1.1%/99.4 +/- 0.6%/99.1 +/- 0.9%/99.2 +/- 0.8%, respectively, with results almost identical to those in an age-matched Ross operation cohort of 212 patients (mean age 34 years) despite DAH patients having undergone >2x more previous procedures.CONCLUSIONS: The initial results of the prospective multicentre ARISE trial show DAH to be safe for aortic valve replacement with excellent haemodynamics in the short follow-up period. Show less
The general introduction in Chapter 1 of this thesis provides an overview of the emerging field of regenerative medicine, and its different areas of technology. Contemporary approaches to heart... Show moreThe general introduction in Chapter 1 of this thesis provides an overview of the emerging field of regenerative medicine, and its different areas of technology. Contemporary approaches to heart valve repair and replacement by mechanical and biological prosthesis, as well as their limitations are discussed. Furthermore, the novel approach of (stem)cell-based therapy in ischemic heart disease and a variety of potential cell types are described. In Part I of the thesis different methods to produce completely acellular porcine and rat aortic valve scaffolds for the purpose of creating a biological substitute that can restore, maintain, or improve normal function. In addition, the in vivo behavior of these valves was studied in a rat model. Subsequently, Part II of the thesis studied the in vivo behavior and functional improvement after transplantation of different human cell types in an animal model of acute myocardial infarction. Furthermore, the feasibility of combining cell therapy with gene-therapy was studied in this same model. Finally, in Part III different methods for cardiac phenotyping in mice were assessed and compared. Show less
