Myocardial tissue engineering: toward a bioartificial pump
Regenerative therapies, including cell injection and bioengineered tissue transplantation, have the potential to treat severe heart failure. Direct implantation of isolated skeletal myoblasts and bone-marrow-derived cells has already been clinically performed and research on fabricating three-dimensional (3-D) cardiac grafts using tissue engineering technologies has also now been initiated. In contrast to conventional scaffold-based methods, we have proposed cell sheet-based tissue engineering, which involves stacking confluently cultured cell sheets to construct 3-D cell-dense tissues. Upon layering, individual cardiac cell sheets integrate to form a single, continuous, cell-dense tissue that resembles native cardiac tissue. The transplantation of layered cardiac cell sheets is able to repair damaged hearts. As the next step, we have attempted to promote neovascularization within bioengineered myocardial tissues to overcome the longstanding limitations of engineered tissue thickness. Finally, as a possible advanced therapy, we are now trying to fabricate functional myocardial tubes that may have a potential for circulatory support. Cell sheet-based tissue engineering technologies therefore show an enormous promise as a novel approach in the field of myocardial tissue engineering.