Adjunctive Allogeneic Mesenchymal Stem Cells for Treatment-resistant Bipolar Depression

This clinical trial is a randomized, double-blind, placebo-controlled study aiming to study the efficacy and side effects of MSCs adjunctive to TAU compared to a normal saline solution in patients with TRBD. Relevant patients with bipolar depression will be addressed in order to establish whether they are willing to be screened for the study. The patients must be assigned a patient number and sign the consent form after receiving oral and written information about the study prior to undergoing any study procedures. MSCs will be infused as a single dose up to one week after the inclusion of the patient. The treatment trial lasts eight weeks. Of note, the investigators will assess patients also at week 26 with a neurocognitive and clinical battery. It will not be allowed changes in psychiatric medication during this period. If a patient or the treating clinician decides that the patient could receive better treatment outside of the study, the patient may leave the study at all times, as specified in the informed consent. Patients were not allowed to take nonsteroidal or steroidal anti-inflammatory medications during the study. Medications for hypertension, diabetes, hypothyroidism, allergies, infections, or other medical conditions were allowed as dictated by the patients' treating physicians. The investigators defined refractory bipolar depression as depression that failed to respond to two trials (during lifetime) with antidepressants and/or mood stabilizer with proven efficacy in bipolar depression (lithium, lamotrigine, quetiapine, lurasidone, olanzapine) in adequate doses for at least 6 weeks or until cessation of treatment due to side effects (Schoeyen et al., 2015). After the initial injection, patients will continue maintenance treatment with their current psychiatrist. During this time, they will not receive additional injections but will receive treatment as usual per their clinician's choice. Patients will remain on stable psychiatric medications during this period. If patients need to change medications, they will be removed from the study protocol.