Doctors say advances in technology and immunology, as well as the kindness of strangers, have improved the numbers for those in need of kidney donors. Kidney transplants are often complicated procedures. Due to difficulties matching blood types and accounting for changes in antibodies, it can be difficult to find a donor kidney that won\'t be rejected by the recipient\'s body. Thanks to donor chains, which link hundreds if not thousands of individuals in need of kidneys to willing donors, fewer transplant patients wither away at the bottom of waiting lists. Donor chains, or domino chains, were first implemented in 2005 at Johns Hopkins to increase the number of patients helped by living donors. In 2010, such models resulted in 429 transplants, The New York Times reported. Computer models suggest if more Americans knew about such chains, an additional 2,000 to 4,000 transplants could be achieved a year. In recent years, Good Samaritan donors are more widely accepted at hospitals, where they were previously turned away because they were thought to be unreliable. Thanks to such donors, donor chains have expanded to help more people in need. The increase in transplants could also take patients off of dialysis sooner, a costly and time consuming procedure upon which only half of patients survive more than three years.