  The shortage of transplant organs is a major worldwide public health problem.  According to the US Department of Health and Human Services Organ Procurement and Transplantation Network, there are approximately 123,000 patients on transplant waiting lists in the US and around 300,000 patients waiting for an organ transplant in China (The Economist 2014). In the US in 2014, the overall median waiting time for a kidney transplant was over three and a half years (National Kidney Foundation 2014).  The situation is similar in the UK (Department of Health 2014). Furthermore, waiting list sizes do not even fully reflect the actual level of need because doctors are sometimes reluctant even to list patients who they feel do not stand a realistic chance of getting an organ in time. (see Other Internet Resources section below).