Megan Barrowclough donated a kidney to her childhood best friend Regina Bence at Mayo Clinic. ROCHESTER, Minn. — More than 90,000 people are on the waiting list for a kidney in the U.S. Unfortunately, less than a third of those waiting for a kidney transplant can expect to get one this year. This comes as rates of chronic kidney disease, which can lead to kidney failure, continue to climb across the globe. But there is…