**6. Limitations in mesenchymal stem cell delivery**

MSC type, dosage, delivery method, and timing of therapy are current obstacles in spinal cord injury cell therapy that limit its translation to clinical practice. Bone marrow stromal cells, bone marrow mononuclear cells, and neural stem/progenitor cells are just some examples of the cell types currently under study for this purpose, with no clear best candidate yet. Cell dosage needs further research since the appropriate therapeutic dose is still unclear. Dosage standardization is required to build a homogenized body of literature that allows for an appropriate comparison of delivery methods. The most appropriate delivery method is still debated since all poses unique benefits. Innovative methods such as subpial delivery and stem cellderived nanovesicle are promising new alternatives that will be added to the battery of delivery techniques [87, 88].
