method involves obtaining a donor organ, removing the cells and MHC antigens from the donor organ, and colonizing it with stem cells obtained from the patient. This method does not create an entire organ from stem cells, and it still requires a donor to provide the decellularized graft. However, the first surgery done with this method was successful and the patient has shown no signs of rejection since. The current debate with this method is whether the decellularized graft was only used to provide the shape of the organ, or whether it provided benefits from it being a donor graft. Current research is being done to find ways to use adult stem cells for neo-organs without using decellularized donor organs for structural support. Decellularization Researchers have begun to focus on decellularization for organ transplants since it reduces the chance of rejection to almost none. This process was used in the first successful stem-cell based organ transplant by removing the cells and MHC antigens from the donor organ. There are different ways to remove the cells from the organ which can include physical, chemical, and enzymatic treatments. This method is especially useful when trying to create a neo-heart because the heart needs to be created in a way where the structure remains. Since the stem cells used are currently not able to maintain a shape, researchers have started to look more into decellularization of existing organs to be able to perform successful transplant procedures without the problem of rejection. While this method may assist with the problem of rejection, donors are still needed to provide this structure to patients. 3-D Bioprinting The process of creating a 3-D organ with stem cells is thought to not be possible without the structural support of a donor organ. However, new studies are being conducted that discuss research on the process of 3-D bioprinting organs. The process of 3-D Bioprinting includes combining cells and growth factors to create a bioink, then using that bioink to print individual layers of tissue. Research is being done to find ways to use the formulated bioink to print organs that have the same structural support of donor organs without the need for donors. While currently there have not been experimental success with printing structural organs, there has been success with using bioink for printing tissue layers. A method for creating gelatin based vascularized bone equivalents has shown to be