Neurological endpoints of this study included evaluation of the number and severity of adverse events after cell grafting, and the efficacy in the improvement of motor responses, as assessed on the UPDRS part I (mentation, behavior and mood), part II (motor activities of the daily living), part III (motor performance), and part IV (complications of therapy), as well as the modified Höehn and Yahr Scale, and the modified Schwab and England Activities of the Daily Living Scale. Patients were clinically evaluated with these scales at screening (as baseline, before surgery), and then after the procedure at six and 12 months. At every visit, patients were asked to discontinue antiparkinsonian medications at least 12 hours before the UPDRS assessment (for practical purposes, "OFF" state was defined as overnight drug withdrawal) in order to be rated in their "OFF" state and then, UPDRS "ON" medication evaluations were performed 1 hour after receiving their usual dose of levodopa. Each patient received the same preoperative levodopa dose for each assessment. Adverse events, including those reported by the patients spontaneously and those observed during the evaluations were recorded. After obtaining signed informed consent from all patients that completed the study, all "OFF" and "ON" UPDRS evaluations, were videotaped.