Cell-based therapies are considered as promising strategies for spinal cord regeneration. However, a combinatorial cell therapeutic approach seems more beneficial as it can target various aspects of the injury. Here, we assessed the safety and feasibility of autologous mucosal Olfactory Ensheathing Cell (OEC) and bone marrow Mesenchymal Stem Cell (MSC) co-transplantation in patients with chronic, complete (American Spinal Injury Association (ASIA) classification A) Spinal Cord Injury (SCI). Three patients with the traumatic SCI of the thoracic level were enrolled. They received autologous OEC and MSC combination through the lumbar puncture. All adverse events and possible functional outcomes were documented performing pre- and post-operative general clinical examination, Magnetic Resonance Imaging (MRI), neurological assessment based on the International Standard of Neurological Classification for SCI (ISNCSCI), and functional evaluation using Spinal Cord Independence Measure version III (SCIM III). No serious safety issue was recorded during the two years of follow-up. MRI findings remained unchanged with no neoplastic tissue formation. ASIA impairment scale improved from A to B in one of the participants. SCIM III evaluation also showed some degrees of progress in this patient's quality of life. The two other patients had negligible or no improvement in their sensory scores without any changes in the ASIA impairment scale and SCIM III scores. No motor recovery was observed in any of the participants. Overall, this two-year trial was not associated with any adverse findings, which may suggest the safety of autologous OEC and bone marrow MSC combination for the treatment of human SCI.This study was registered at the Iranian Registry of Clinical Trials (IRCT registration number: IRCT20160110025930N2/ registration date: 2018-09-29).