Stem cell-based transcatheter aortic valve implantation: first experiences in a pre-clinical model.
OBJECTIVE
This study sought to investigate the combination of transcatheter aortic valve implantation and a novel concept of stem cell-based, tissue-engineered heart valves (TEHV) comprising minimally invasive techniques for both cell harvest and valve delivery.


BACKGROUND
TAVI represents an emerging technology for the treatment of aortic valve disease. The used bioprostheses are inherently prone to calcific degeneration and recent evidence suggests even accelerated degeneration resulting from structural damage due to the crimping procedures. An autologous, living heart valve prosthesis with regeneration and repair capacities would overcome such limitations.


METHODS
Within a 1-step intervention, trileaflet TEHV, generated from biodegradable synthetic scaffolds, were integrated into self-expanding nitinol stents, seeded with autologous bone marrow mononuclear cells, crimped and transapically delivered into adult sheep (n = 12). Planned follow-up was 4 h (Group A, n = 4), 48 h (Group B, n = 5) or 1 and 2 weeks (Group C, n = 3). TEHV functionality was assessed by fluoroscopy, echocardiography, and computed tomography. Post-mortem analysis was performed using histology, extracellular matrix analysis, and electron microscopy.


RESULTS
Transapical implantation of TEHV was successful in all animals (n = 12). Follow-up was complete in all animals of Group A, three-fifths of Group B, and two-thirds of Group C (1 week, n = 1; 2 weeks, n = 1). Fluoroscopy and echocardiography displayed TEHV functionality demonstrating adequate leaflet mobility and coaptation. TEHV showed intact leaflet structures with well-defined cusps without signs of thrombus formation or structural damage. Histology and extracellular matrix displayed a high cellularity indicative for an early cellular remodeling and in-growth after 2 weeks.


CONCLUSIONS
We demonstrate the principal feasibility of a transcatheter, stem cell-based TEHV implantation into the aortic valve position within a 1-step intervention. Its long-term functionality proven, a stem cell-based TEHV approach may represent a next-generation heart valve concept.
Swiss Center for Regenerative Medicine, University and University Hospital Zurich, Zurich, Switzerland.
Maximilian Y
MY
Emmert
Benedikt
B
Weber
Petra
P
Wolint
Luc
L
Behr
Sebastien
S
Sammut
Thomas
T
Frauenfelder
Laura
L
Frese
Jacques
J
Scherman
Chad E
CE
Brokopp
Christian
C
Templin
Jürg
J
Grünenfelder
Gregor
G
Zünd
Volkmar
V
Falk
Simon P
SP
Hoerstrup
D000818:Animals; D001021:Aortic Valve / Q000601:surgery*; D001705:Bioprosthesis; D006328:Cardiac Catheterization; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D023421:Models, Animal; D012756:Sheep; D033581:Stem Cell Transplantation