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DOI: 10.1055/s-0029-1247016
Human tissue-engineered heart valves based on umbilical cord blood cells
Objective: Tissue engineering of autologous heart valves with the potential to grow represents a promising concept. Currently we are exploring the impact of umbilical cord blood-derived cells as single cell source for tissue engineering of heart valves.
Methods: Cord blood-derived endothelial progenitor cells (EPC) were obtained from the mononuclear cell fractions. After expansion and differentiation cell phenotypes of CD133+ cells were analyzed by immunohistochemistry and cryopreserved. After 12 weeks the blood-derived myofibroblasts were seeded onto heart valve scaffolds (n=8) fabricated from a biodegradable polymer and subsequently coated with blood-derived endothelial cells. Afterwards, the heart valve constructs were grown in a pulse duplicator system. After in-vitro maturation, analysis of all heart valves included histology, immunohistochemistry, electron microscopy, fluorescence imaging, biochemical and biomechanical examination.
Results: Differentiated CD133+ cells remained viable after cryopreservation and showed a myofibroblast-like morphology that stained positive for a-actin and fibroblastspecific marker as well as functional endothelial cells staining positive for CD31, VWF and VE-cadherin. The tissue engineered heart valves showed endothelialized layered tissue formation including connective tissue between the inside and the outside of the scaffold. Immunohistochemistry was positive for collagen, desmin, laminin, a-actin, CD31, VWF and VE-cadherin. The notion of an intact endothelial phenotype was substantiated by fluorescence imaging studies of cellular NO production and Ca2+ signaling. Biochemical examination showed extracellular matrix formation (77±9% collagen, 85±61% glycosaminoglycans and 67±17% elastin compared to human pulmonary leaflet tissue).
Conclusion: This study demonstrates in vitro generation of viable human heart valves based on umbilical cord blood-derived cells.