Generating cells for lung tissue engineering

Abstract

Decellularization of essential organs such as the lung has become an integral part of regenerative medicine. As the availability of donors is very low reseeding of these decellularized organs with a patient's own cells is a potential therapy for those desperately in need. This way, the risks associated with allogeneic immune rejection are avoided. Some research groups have been successful in reseeding the lung with allogeneic differentiated cells. However, the barrier to presently overcome is to seed with stem cells and ensure these cells differentiate to all the desired cell types of the lung. Another obstacle is obtaining the desired number of cells for recellularization of large organs such as the lung. Scale-up methods using stirred vessel bioreactors with conditions similar to the physiological environment are a desirable alternative to conventional cell culture. In this study, I demonstrate large-scale cell culture in stirred flask bioreactors by facing the challenges of scale-up from 2D to 3D suspension culture. I also show the existence of exosomes in decellularized pig and mouse lung and identify the miRNAs (miRNAs) contained within them. MicroRNAs are becoming increasingly popular research tools as they are known to regulate many essential processes. Exosomes are enriched with miRNAs and can be shuttled between cells, thereby affecting target cell behavior. I utilized the exosomes from decellularized lungs in directed differentiation of induced pluripotent stem cells (iPSCs) to the definitive endoderm (DE) lineage and compared it with conventional differentiation methods. The exosomes had a profound effect on the morphology of the cells which will lead to further studies on exosome-directed differentiation procedures.