Over 100,000 individuals in the United States currently await kidney transplantation, while 400,000 individuals live with end-stage kidney disease requiring hemodialysis. The creation of a transplantable graft to permanently replace kidney function would address donor organ shortage and the morbidity associated with immunosuppression. Such a bioengineered graft must have the kidney’s architecture and function, and permit perfusion, filtration, secretion, absorption, and drainage of urine. We decellularized rat, porcine, and human kidneys by detergent perfusion, yielding acellular scaffolds with vascular, cortical and medullary architecture, collecting system and ureters. To regenerate functional tissue, we seeded rat kidney scaffolds with epithelial and endothelial cells, then perfused these cell-seeded constructs in a whole organ bioreactor. The resulting grafts produced rudimentary urine in vitro when perfused via their intrinsic vascular bed. When transplanted in orthotopic position in rat, the grafts were perfused by the recipient’s circulation, and produced urine via the ureteral conduit in vivo.

Fibrocytes are an indicator for disease activity of IPF and might be useful as a clinical marker for disease progression. This study suggests that quantification of circulating fibrocytes may allow prediction of early mortality in patients with IPF.

Rationale More than 25 million individuals suffer from heart failure worldwide, with nearly 4,000 patients currently awaiting heart transplantation in the United States. Donor organ shortage and allograft rejection remain major limitations with only about 2,500 hearts transplanted each year. As a theoretical alternative to allotransplantation, patient-derived bioartificial myocardium could provide functional support and ultimately impact the treatment of heart failure. Objective The objective of this study is to translate previous work to human scale and clinically relevant cells, for the bioengineering of functional myocardial tissue based on the combination of human cardiac matrix and human iPS-derived cardiac myocytes. Methods and Results To provide a clinically relevant tissue scaffold, we translated perfusion-decellularization to human scale and obtained biocompatible human acellular cardiac scaffolds with preserved extracellular matrix composition, architecture, and perfusable coronary vasculature. We then repopulated this native human cardiac matrix with cardiac myocytes derived from non-transgenic human induced pluripotent stem cells (iPSCs) and generated tissues of increasing three-dimensional complexity. We maintained such cardiac tissue constructs in culture for 120 days to demonstrate definitive sarcomeric structure, cell and matrix deformation, contractile force, and electrical conduction. To show that functional myocardial tissue of human scale can be built on this platform, we then partially recellularized human whole heart scaffolds with human iPSC-derived cardiac myocytes. Under biomimetic culture, the seeded constructs developed force-generating human myocardial tissue, showed electrical conductivity, left ventricular pressure development, and metabolic function. Conclusions Native cardiac extracellular matrix scaffolds maintain matrix components and structure to support the seeding and engraftment of human iPS-derived cardiac myocytes, and enable the bioengineering of functional human myocardial-like tissue of multiple complexities.