Objective: Multiple sclerosis (MS) is the most ubiquitous autoimmune disease affecting the central nervous system (CNS). Many efforts have been done to stop demyelination process and even reverse it. In this study we are going to use the combination of oligodendrocyte progenitor cells (OPC) and bone marrow-derived neural stem cells (BM-NSC) to utilize their useful interactions and enhance remyelination. Material and Methods: Forty 120g rats with no previous neurological disorders (we assess them with BBB scoring system) are divided into 4 groups: "Combination cell transplantation", "Only OPC transplantation", “Only BM-NSC transplantation" and “NO cell transplantation (Control)". First we perform bone marrow aspiration and culture cells with specific protocols to obtain the desired cells. Next, we induce MS animal model (EAE: Experimental Autoimmune Encephalomyelitis) in all rats and after about 3 weeks they are ready for cell transplantation. We will assess the rats in 0, 1, 2, 3, 4 weeks after transplantation. Results: OPCs are generally considered responsible for the major part of spontaneous remyelination. On the other hand, BM-NSCs provide a feasible and practical way to achieve remyelination, neuroprotection and in situ immunomodulation in CNS autoimmune diseases. According to these facts, by combining these two cell types, we will assess their interaction in vivo and desire to obtain better results. Conclusion: MS is an excellent candidate for cell therapy because of three factors more or less unique to it: 1. MS pathophysiology is primarily directed against oligodendrocytes and/or myelin, and that axons are relatively spared until the late stages of disease. 2. Cell-based therapies are an approach that enhances or supplements spontaneous myelin repair. 3. Cell therapy can achieves successful remyelination and has been variously demonstrated to restore normal nervous conduction and/or function. Five major cell types have been used for MS cell therapy. The oligodendrocyte lineage, Schwann cells, embryonic stem cells (ESCs), adult neural stem cells (aNSCs) and bone marrow-derived neural stem cells (BM-NSCs). The migration of Schwann cells transplanted into CNS and Schwann cell-mediated remyelination are inhibited by astrocytes, also there are significant practical and ethical concerns about ESCs. aNSCs have major advantages but they are relatively inaccessible for clinical application. On the other hand, OPCs are generally considered responsible for the major part of spontaneous remyelination and BM-NSCs are morphologically and physiologically indistinguishable from aNSCs, so these two cell types are the best candidates for MS cell therapy, but it needs more evaluations to roul out any undesired reactions in vivo.