Methods for decellularizing organs and tissues in vitro and in vivo are provided, as are methods of maintaining organ and tissue frameworks and methods of recellularizing organs and tissues, thereby providing an approach to needed organs or tissues.

The invention relates to a liver microtissue, preferably, the liver microtissue having the largest dimension between 500 and 700 μm, and the liver microtissue expressing CYP3A4 monooxygenase with an activity of at least 75,000 RLU per million cells and producing at least 18 ag of urea per million cells per 24 hours. The invention also relates to a method for producing the liver microtissue from pluripotent stem cells, and uses of the liver microtissue in treatment and/or prevention of liver failure.

The disclosure provides a method of using blood or fractions thereof, e.g., serum, obtained from a mammal subjected to liver surgery, for example, obtained following a partial hepatectomy, to increase the engraftment, proliferation and/or functionality of cells on a biocompatible scaffold.

Described are methods, cell growth substrates, and devices that are useful in preparing cell-containing graft materials for administration to patients. Tubular passages can be defined in cell growth substrates to promote distribution of cells into the substrates. Also described are methods and devices for preparing cell-seeded graft compositions, methods and devices for preconditioning cell growth substrates prior to application of cells, and cell seeded grafts having novel substrates, and uses thereof.

Compositions and methods of transplanting cells by grafting strategies into solid organs (especially internal organs) are provided. These methods and compositions can be used to repair diseased organs or to establish models of disease states in experimental hosts. The method involves attachment onto the surface of a tissue or organ, a patch graft, a “bandaid-like” covering, containing epithelial cells with supporting early lineage stage mesenchymal cells. The cells are incorporated into soft gel-forming biomaterials prepared under serum-free, defined conditions comprised of nutrients, lipids, vitamins, and regulatory signals that collectively support stemness of the donor cells. The graft is covered with a biodegradable, biocompatible, bioresorbable backing used to affix the graft to the target site. The cells in the graft migrate into and throughout the tissue such that within a couple of weeks they are uniformly dispersed within the recipient (host) tissue. The mechanisms by which engraftment and integration of donor cells into the organ or tissue involve multiple membrane-associated and secreted forms of MMPs.

Compositions and methods of transplanting cells by grafting strategies into solid organs (especially internal organs) are provided. These methods and compositions can be used to repair diseased organs or to establish models of disease states in experimental hosts. The method involves attachment onto the surface of a tissue or organ, a patch graft, a “bandaid-like” covering, containing epithelial cells with supporting early lineage stage mesenchymal cells. The cells are incorporated into soft gel-forming biomaterials prepared under serum-free, defined conditions comprised of nutrients, lipids, vitamins, and regulatory signals that collectively support stemness of the donor cells. The graft is covered with a biodegradable, biocompatible, bioresorbable backing used to affix the graft to the target site. The cells in the graft migrate into and throughout the tissue such that within a couple of weeks they are uniformly dispersed within the recipient (host) tissue. The mechanisms by which engraftment and integration of donor cells into the organ or tissue involve multiple membrane-associated and secreted forms of MMPs.

The present invention discloses an automated device for tissue and organ engineering. The device comprises a main chamber for performing decellularization, tissue sterilization, and recellularization and a set of solution and medium chambers, which provide solutions and medium for the decellularization and recellularization processes, respectively, in a continuous closed circuit. The device further comprises a sterilizing system for self-sterilization of the automated device. The device further comprises a user interface to input steps of protocols for tissue or organ engineering. The device further comprises a controller configured to control valves and pumps, which control and direct the flow of solutions and medium based on the steps of protocols, thereby automating the processes of decellularization, tissue sterilization, recellularization and self-sterilization. All parts of the device are installed in one single body in a fully integrated manner, in one example, which makes the device ready to use. The device minimizes the user intervention and enhances sterility, reproducibility, and efficiency.

The disclosure provides a method of using blood or fractions thereof, e.g., serum, obtained from a mammal subjected to liver surgery, for example, obtained following a partial hepatectomy, to increase the engraftment, proliferation and/or functionality of cells on a biocompatible scaffold.

Engineered human tissue seed constructs are provided that are suitable for implantation in subjects. Methods of making and using the engineered tissue seed constructs are provided.

Disclosed herein are recellularized livers prepared from decellularized liver extracellular matrices. Also disclosed herein are kits and systems comprising a recellularized liver as described herein. Also disclosed herein are methods of recellularizing livers from decellularized liver extracellular matrices.