Tissue-engineered heart valves. Autologous valve leaflet replacement study in a lamb model

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Cardiovascular Research

Background:

• Previous success in creating and implanting tissue-engineered valve leaflets in the pulmonary position.
• This study aimed to trace seeded cells and evaluate construct evolution using a Di-1 cell-labeling method.

Purpose of the Study:

• To trace the fate of cultured cells seeded onto biodegradable polymer scaffolds.
• To examine the biochemical, biomechanical, and histological changes in tissue-engineered valve leaflets over time.
• To assess the in vivo performance of autologous cell-seeded polymer constructs.

Main Methods:

• Isolation and labeling of endothelial cells and fibroblasts from ovine arteries.
• Seeding of a polyglycolic acid scaffold with fibroblasts, followed by endothelial cells.
• Implantation of cell-seeded and acellular polymer constructs into the pulmonary valve position in animals.
• Histological, biochemical (collagen content), and biomechanical evaluation of explanted leaflets.

Main Results:

• Tissue-engineered leaflets with autologous cells persisted, unlike acellular controls which degraded within 8 weeks.
• Progressive increase in collagen content and presence of elastin fibers and endothelial cells (Factor VIII positive) were observed.
• Cell-labeling experiments confirmed the persistence of seeded cells within the implanted leaflets.

Conclusions:

• Autologous cells successfully generated a functional matrix on the polymer scaffold within the physiological environment.
• Tissue-engineered heart valve leaflets demonstrate potential for in vivo regeneration and long-term integration.