Abstract 3445: Prenatally Fabricated Autologous Human Living Heart Valves based on Fetal Amniotic Fluid-Derived Progenitors as Single Cell Source
Introduction: Here, a novel concept providing prenatally tissue engineered human autologous heart valves based on routinely obtained fetal amniotic fluid progenitors as single cell source is introduced.
Methods: Fetal human amniotic progenitors were isolated from routinely sampled amniotic fluid and sorted by CD133 magnetic beads. After expansion and differentiation, cell phenotypes of CD133- and CD133+ cells were analyzed by immunohistochemistry. Plasticity of TNF-α stimulated and unstimulated CD 133+ cells was detected by flowcytometry using antibodies against tissue factor (TF) and thrombomodulin (TM). After characterization, CD 133-derived cells were seeded onto heart valve leaflet scaffolds (n= 12) fabricated from rapidly biodegradable polymers and conditioned in a pulse duplicator system and subsequently coated with CD 133+ derived cells. After in vitro maturation under biomimetic conditions, neo-tissues were analyzed by histology, immunohistochemistry and scanning electron microscopy (SEM). Extracellular matrix (ECM) elements and cell numbers were quantified biochemically. Mechanical properties were assessed by tensile testing.
Results: CD 133- derived cells demonstrated characteristics of mesenchymal progenitors. Differentiated CD133+ cells showed features of functional endothelial cells in flowcytometry by CD31 and TM expression and reciprocal up-and down regulation of TF and TM under TNF-α stimulation. Engineered heart valve tissues demonstrated endothelialized layered tissue formation with production of ECM-elements (GAG 80%, HYP 5%, cell numbers 100% of native values). SEM showed intact endothelial surfaces. Young‘s modulus were 25% of those of native values.
Conclusions: The use of amniotic fluid as single cell source is a promising, low-risk approach enabling the prenatal fabrication of heart valves ready to use at birth. These living replacements with the potential of growth, remodeling and regeneration may realize the early repair of congenital malformations.