Cells, scaffolds and bioreactors for tissue engineered heart valves: a journey from basic concepts to contemporary developmental innovations

摘要

The development of viable and functional tissue-engineered heart valves (TEHVs) is a challenge that, for almost two decades, the scientificcommunity has been committed to face to create life-lasting prosthetic devices for treating heart valve diseases. One of the main drawbacks oftissue-based commercial substitutes, xenografts and homografts, is their lack of viability, and hence failure to grow, repair, and remodel. Inadults, the average bioprostheses life span is around 13 years, followed by structural valve degeneration, such as calcification; in pediatric,mechanical valves are commonly used instead of biological substitutes, as in young patients, the mobilization of calcium, due to bone remodeling,accelerates the calcification process. Moreover, neither mechanical nor bioprostheses are able to follow children’s body growth. Cell seeding andrepopulation of acellular heart valve scaffolds, biological and polymeric, appears as a promising way to create a living valve. Biomechanicalstimuli have significant impact on cell behavior including in vitro differentiation, and physiological hemodynamic conditioning has been found topromote new tissue development. These concepts have led scientists to design bioreactors to mimic the in vivo environment of heart valves. Manydifferent types of somatic and stem cells have been tested for colonizing both the surface and the core of the valve matrix but controversialresults have been achieved so far.