https://blogs.scientificamerican.com/observations/we-need-to-make-organ-transplantation-easier/ > It’s been four years since I donated my kidney in a so-called “paired exchange,” allowing my friend Tinh to receive the kidney she needed. > I met Tinh during nursing school in September of 2012. We quickly became friends, spending grueling hours in our university’s library, preparing ourselves for our future nursing careers.