In the 2005 sci-fi film The Island, humanity had found a way to live forever. They would grow clones and harvest their organs. In the real world, however, humanity came up with a much less diabolical way of doing this. In the real world, humanity would grow individual organs. No clone attached.
The secret to replacing organs was with stem cells. Stem cells were the mother of all cells. They could become any cell in the body. Each cell had the complete genetic code of the entire body inside it. There was a problem. As cells matured, they would turn off certain genes and become a certain cell. Embryonic stem cells could still turn into any cell. There was a problem with that, too. Embryonic stem cells were controversial. An embryo had to be sacrificed in order to get the stem cells. The solution was Induced Pluripotent Stem Cells. This worked by turning stem cells into embryonic stem cells. To avoid cancer, one of the genes used in the process had to be eliminated before the stem cell was transplanted. After that was achieved, IPS cells were used to cure many diseases such as cancer, diabetes, Parkinson's, Huntington's, etc. Soon, they would be used to grow organs.
Tech Level: 10-11
In July 2011, the first transplant of a cloned organ occurred. A 36-year old man suffering from cancer in the trachea received a new trachea. This used a nanotech scaffold made of flexible polymer that was then covered in stem cells. The transplant was a success. There was no chance of rejection. Transplants became far quicker and more accessible. There was no need for a human donor in the simplest of organ transplants. As the decade continued, more complex organs were created in the same way. By 2020, scientists finally discovered how every part of the heart worked. This eliminated the need for external donors. The new heart would be a genetic match to the old, like a clone. Transplants were now even more successful. Other complex organs were also being cloned like the lungs, the liver, the kidneys, the spleen, the stomach, the pancreas, and even the entire reproductive system. The cost of healthcare was reduced. Internal organ became a thing of the past. Not only that, but new cryoprotectants were made to protect organs from ice crystal damage. By 2030, it was possible to create full clones.