Table 1.
Overview of the main stem cell types currently being investigated in both pre-clinical and clinical studies for the treatment of spinal cord injuries
| Type of trial | Cell type | SCI treatment approach | Main results | References |
|---|---|---|---|---|
| Pre-Clinical | ESCs | Human ESC-derived oligodendrocyte progenitor cells (OPCs), mice ESC in rodent model of acute, subacute, chronic SCI and SCI-myelin-deficient shiverer (shi/shi) mutant mice, SCI rat-chemical demyelination model. | Implanted cells differentiated into oligodendrocytes; improved remyelination of host axons; functional improvement. | [32,37,39–41] |
| NSCs | Mice, foetal neural precursor cells engineered to express BMP inhibitor, rat neural precursor cells neutralizating ciliary neurotrophic factor (CNTF), human foetal NSCs (neurospheres) in rodent model of acute, subacute, chronic SCI and SCI - myelin-deficient shiverer (shi/shi) mutant mice, spinal cord-injured NOD-scid mice, SCI-ischaemia. | Implanted cells differentiated into neurons (cholinergic, GABA-ergic), oligodendrocytes, low astrocytes; increased number of regenerated CST fibres both at the lesion and at caudal sites; improved remyelination, trunk stability, suppression of spasticity and rigidity; functional improvement. | [14,46,51,49,50,54] | |
| SCs | Autologous, syngeneic, allogeneic or xenogeneic transplantation of adult, new-born, skin-derived, bone-marrow derived or SC precursors in rodent model of acute, subacute and chronic SCI. Combinatorial therapies. | Improved axonal regeneration and remyelination; functional improvement; limited integration of SC into the host tissue. | [22,59–62] | |
| OECs | Allogeneic OEC implantation, and chondroitinase addition, olfactory-ensheathing glia grafts and SC bridges with chondroitinase in rodent models of acute, subacute and chronic SCI. Combinatorial therapies. | Improved axonal regeneration and remyelination; increased serotonergic axons in the bridge and beyond; significant correlation with functional improvement. | [62,69] | |
| MSCs | Autologous, syngeneic, allogeneic or xenogeneic MSC transplantation in rodent, large animals and primate models of acute, subacute and chronic SCI. Combinatorial therapies. | Reduced lesion volume, anti-apoptotic effect, enhanced axonal regeneration and remyelination; functional improvement. | [13,18,22,72,73] | |
| Clinical | ESCs | Human ESC-derived oligodendrocyte progenitor cells (OPCs) GRNOPC1 in complete T3-T9 subacute SCI. | Safety of the therapy. No adverse or beneficial effect. | Geron News Release, CA, US, November 14, 2011 |
| NSCs | Human foetal derived neural progenitor (HuCNS-SC) in SCI Injury. Phase I/II. | Safety of the therapy. No adverse or beneficial effect. | [55] | |
| SCs | Autologous intramedullar SC transplantation into chronic SCI. | Safety of the therapy. No adverse or beneficial effect. | [168] | |
| OECs | Autologous olfactory ensheathing cell transplantation in human SCI: a pilot clinical study; a Phase I and a 3-year clinical trial (Phase I/IIa). | Feasibility and safety. | [66–68] | |
| MSCs | Autologous bone marrow mononuclear cells or ex vivo expanded autologous MSCs transplantation. Combination with granulocyte–macrophage colony-stimulating factor. Phase I/II. | Safety of the therapy. Modest functional improvement in acute and sub-acute patients, mild improvement in chronic patients. | [12,78–84] |
ESCs – embryonic stem cells; NSCs – neural stem cells; SCs – Schwann cells; OECs – olfactory ensheathing cells and MSCs – mesenchymal stem cells.