The first goal of these studies was to characterize the contents that remain after removal of cells using a decellularization process to obtain the natural templates of the kidney or lung. These studies are important because attempts to recellularize donor tissues that may have elements that remain after the decellularization process could result in an immune response post-transplantation. These studies also focused on whether techniques to recellularize the natural templates of these tissues with human embryonic stem cells would result in comparable outcomes or would differ based on the tissue of origin. Results showed that elements remain within the scaffolds that could have an impact on transplant efficiency, and that recellularization of the tissues resulted in structures that were specific to either the kidney or to the lung.