This trial is testing whether infusing special cells called mesenchymal stromal stem cells (MSCs) can help kidney transplant patients need fewer strong anti-rejection drugs. The study focuses on people who received a kidney from a living donor. MSCs might help control the immune system to protect the new kidney better. Mesenchymal stem cells (MSCs) have been studied for their potential to improve kidney transplant outcomes through their immunomodulatory, reparative, and regenerative properties.