Introduction: T he fields of Regenerative Medicine (RM) and Tissue Engineering (TE) aim for the ide-al valvular substitute that overcomes the well-known shortcomings of current prosthesis – limited lifespan for the biological prostheses and permanent anticoa-gulant therapy for mechanical ones. In this project, a Living Tissue Engineered Heart Valve (L-TEHV) is manufactured based on RM principles using scaffolds, stem cells and bioreactors.
Methods: T his study has Ethics Committee of UM-SFT Târgu Mureș approval. Ovine and porcine Aor-tic (n=37) and Pulmonary (n=18) valves underwent a cell removal protocol (decellularization), resulting in acellular scaffolds. Cell absence was proved with nucle-ar stains (4 ‘,6-diamidino-2-phenylindol and haema-toxylin-eosin) and DNA extraction. Adipose Derived Stem Cells were harvested from sheep (n=6), cultured and differentiated towards heart valve specific cells (endothelial and fibroblasts) then used to internally and externally repopulate the scaffolds. Using a biore-actor at 70 bpm, pulmonary (20/5mmHg) and aortic (120/80mmHg) conditions were recreated for L-TEHV preconditioning. By ultrasound (US), valve functiona-lity in the bioreactor was assessed. In vivo performance is currently being tested by orthotopic surgical implan-tation in a sheep animal model with periodic transtho-racic US and histology at explantation.
Results: Extraction showed above 90% nucleic material reduction. Six ADSCs cultures were obtained resulting in over 108 million cells. Five cultures underwent di-fferentiation towards endothelial and fibroblast lines followed by cryopreservation. Good hemodynamics of the L-TEHV was shown in the bioreactor and no regur-gitation or stenosis at the ultrasound. Until now 2 L-TEVH were implanted in sheep, 1 Aortic (for 2 hours) and 1 Pulmonary (more than 6 months of follow-up). Animal somatic development was normal. Transthora-cic US describes normal valvular function.
Conclusions: L-TEHV, the new generation of valvular prostheses, obtained in the lab could solve clinicians di-lemma when choosing a valular substitute for a patient. Using xenogeneic origin for the scaffolds, availability in various sizes and shapes is high. Cells originating from the same patient give the characteristics of non immu-nogenicity, non trombogenicity and growth capacity. Results seem promising but extension of the study in terms of follow-up and study group is mandatory.
Acknowledgement: T his work was supported by a grant from the Competitiveness Operational Program-me2014-2020, Tissue engineering technologies for cardiac valve regeneration, valve-regen, idP_37_673, Mysmis code: 103431, contract50/05.09.2016.