Background: Patients who are in a minimally consciousness state (MCS) have often remained in the MCS for a long time. At the moment, the only chance for these patients seems to be the development of regenerative medicine based on stem cells as the studies on laboratory animals have demonstrated promising results. The favourable outcomes of these experiments insentivize to check the safety of using similar tests in humans. The aim of this study was to evaluate the safety of intrathecal administration of autologous bone marrow derived-mesenchymal stem cells (BM-MSCs) in patients with minimally conscious state. Methods: The study involved 28 patients diagnosed with persistent consciousness disorder who had completed an intensive care unit therapy at University Clinical Hospital in Olsztyn, Poland. The patients were referred for an in-patient care and admitted to hospital in a regular mode without prior verification of the diagnosis. All patients were evaluated according to a uniform test protocol. Diagnostics included a neurological, internal, cardiological and ENT examinations as well as anesthesiological, and rehabilitation assessment, and logopedic and psychological tests. The next stage of the experiment covered 9 selected MCS patients. This stage aimed at establishing a colony of autologous stem cells derived from the bone marrow and then three intrathecal administrations of stem cells at 2 month intervals. All the patients underwent a thorough virological examination before the stem cell cultures were started. The BM-MSC transplantation procedure safety assessment relied on a thorough analysis of the immediate and delayed adverse events. The immediate adverse events comprised an allergic reaction, respiratory failure, local complications (hematoma, local infection), and paralysis. Among the delayed adverse events an intraspinal tumor formation, permanent loss of sensation and paralysis, unrelated to the progress of the disease, were determined. During the hospitalization, a daily assessment procedure of the patient's condition was adhered to and the data recorded in the patient's medical chart. Findings: No severe side effects were documented during the procedure. of the patients demonstrated any symptoms of infection. In 2 patients, an increased psychomotor activity was observed, more increased when placed on the side from which the bone marrow had been collected. In one patient it was necessary to repeat the bone marrow collection due to the detection of bacteria in the stem cell culture. Out of the 9 patients, 3 were administered 3 intrathecal doses. In 2 patients, there were 2 intrathecal stem cell administrations completed, and in 1 patient, after the first administration, the subsequent doses were abandoned. Moreover, in a group of 6 patients, who had undergone 3 administrations, 1 patient had to have the treatment postponed due to an upper respiratory tract infection. In 1 patient, after two intrathecal administrations of stem cells without any evidence of adverse effects, the third dose could not have been given on account of a necessary urological treatment in another medical center. Thus, this patient had to be excluded from the experiment. In 1 patient, an epileptic status occurred after the first injection of stem cells. Due to the unclear coincidence of the epileptic status with the administration of stem cells, any subsequent administrations were abandoned. Interpretation: The study showed more difficulties occurring in patients with consciousness disorders than in patients treated for other diseases. Moreover, data collected based on a small and changeable group of patient require to be confirmed in a study encompassing a larger group of patients. However, in the course of any further research, the risks of this treatment should be borne in mind and proper precautions employed. Funding Statement: This work was supported by the National Centre for Research and Development (No: STRATEGMED I/234261/2/2014). Declaration of Interests: The authors state: None to declare. Ethics Approval Statement: The study was approved by the Bioethical Committee of the Faculty of Medicine, University of Warmia and Mazury in Olsztyn, Poland (ethical approval No. 7/2013 of February 2013, and No. 46/2013 of December 2013). The study was carried out in accordance with the provisions of the Declaration of Helsinki.
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