The primary hypothesis of this proposal is that chronic kidney disease (CKD) and treatment with calcineurin inhibitors (CNIs) are each associated with the release of endothelial microparticles into the plasma. These injury-associated microparticles have a different molecular/protein composition than those released from endothelial cells in healthy patients, and their abundance correlates with vascular injury. To test this hypothesis the investigators propose a 3 arm case-controlled study including normal controls, individuals with stage III and IV CKD not receiving CNI therapy, and individuals with stage III and IV CKD post kidney transplantation receiving a CNI. The goal of this study is to measure the amount of microparticles in patients with kidney disease who have had a kidney transplant. Another goal of this study is to see if the measurements of microparticles are related to poor function of the vessels (endothelial dysfunction).