CARDIAC TISSUE ENGINEERING: EX VIVO CONSTRUCTION OF FULL THICKNESS SEEDED SCAFFOLDS VIA PERFUSION BIOREACTOR, ELECTRICAL STIMULATION, AND CYCLIC MECHANICAL LOAD

Cardiac tissue engineering aims to achieve functional tissue constructs that can restore the structure and function of injured myocardium. However, the successful reseeding of tissue-engineered constructs with regenerative cells remains a substantial obstacle in achieving a functional tissue. Particularly, when dealing with complex thick constructs, such as decellularized porcine cardiac ECM (pcECM), the development of supporting technologies enabling the repopulation of scaffolds is highly challenging. As such, any bioreactor system intended to perfuse the pcECM should necessarily provide mechanical and electrical stimuli, which have shown to support cell growth, and tissue functionality.

A bi-functional apparatus providing mechanical and electrical stimuli was incorporated into a perfusion-bioreactor, to support the cultivation of mesenchymal stem cells, reseeded onto decellularized pcECM. An inflated balloon placed under the tissue, mimicking the circulatory beating, produces the required mechanical pressure. The electrical action-potential of the left ventricle is simulated using an electrical output device attached to electrodes designed to create an alternating electrical field. To achieve precise balance between the two rhythms, a computer-controlled input/output device collects data and synchronizes both stimuli while monitoring parameters such as pH, temperature etc.

This system has been applied for culturing pcECM scaffolds with regenerative cells and assessing the effect of the various stimuli on cell growth. The application of either perfusion or electrical stimuli alone has demonstrated a significant improvement in cell viability and growth. Moreover, the perfusion enabled the support of cell growth in depth of more than 1000 micron from the scaffold`s surface. Finally, a further increase in cell viability and growth was obtained when applying a gradual elevation of perfusion rates, combined with increasing rhythm of mechanical and electrical stimulations.