| Approximately every minute, someone will die of a coronary event. Myocardial infarction patients experience the loss of cardiomyocytes, which cannot regenerate. The goal of cell therapy then becomes to regenerate this tissue. Although there has been limited success using intracoronary injections, cardiac patches made of cellular sheets of cardiomyocytes and other cells offer advantages, such as a targeted delivery. However, although current cardiac patches do improve heart function, the fibers in the patch are misaligned, which may lead to maladaptive remodeling. We can increase the integrity of the cardiac patch by mechanically conditioning individual cellular sheets of cardiomyocytes, thereby increasing the biochemical secretion of cardiac proteins and extracellular matrix (ECM). Additionally, we can induce cellular alignment to increase electrical pacing.;Current technology will allow for stretching or nondamaging detachment of cellular sheets, but not both. We have modified a silicone membrane with poly (N-isopropylacrylamide-co-acrylic acid) (P(NIPAAm-co-AAc)) copolymers to create a bioreactor that can mechanically condition cells and subsequently detach those cells with cell-cell and cell-matrix junctions intact. P(NIPAAm-co-AAc) is a copolymer that allows for cell attachment at 37°C, and spontaneous cell detachment at room temperature, thereby bypassing the need for enzymatic treatments that would damage the synthesized ECM. Using this bioreactor, we have been able to condition sheets of cardiomyocytes and other cells (e.g., NIH3T3 cells) at the native conditions to induce secretion of cardiac proteins and ECM so that we can influence the cellular sheets to have the natural mechanical properties of heart tissue. We also demonstrate that we can detach those sheets without damage so that they can be layered to form a cellular patch for regenerating tissue following myocardial infarction. |
