We present an Agency called UCTx designed to model the tasks performed by a Transplant Coordination Unit (UCTx) inside a Hospital. The aim of this work is to show how a multi-agent approach allows us to describe and implement the model, and how UCTx is capable of dealing with an Agent Mediated Institution for the Exchange of Human Tissues among Hospitals for Transplantation. Also UCTx will act as the representative of the hospital in the transactions. As an example we present the use of this Agency in the case of Cornea Transplantation.