Allogeneic Neural Stem/Progenitor Cells Derived From Embryonic Stem Cells Promote Functional Recovery After Transplantation Into Injured Spinal Cord of Nonhuman Primates

Abstract

Previous studies have demonstrated that neural stem/progenitor cells (NS/PCs) promote functional recovery in rodent animal models of spinal cord injury (SCI). Because distinct differences exist in the neuroanatomy and immunological responses between rodents and primates, it is critical to determine the effectiveness and safety of allografted embryonic stem cell (ESC)-derived NS/PCs (ESC-NS/PCs) in a nonhuman primate SCI model. In the present study, common marmoset ESC-NS/PCs were grafted into the lesion epicenter 14 days after contusive SCI in adult marmosets (transplantation group). In the control group, phosphate-buffered saline was injected instead of cells. In the presence of a low-dose of tacrolimus, several grafted cells survived without tumorigenicity and differentiated into neurons, astrocytes, or oligodendrocytes. Significant differences were found in the transverse areas of luxol fast blue-positive myelin sheaths, neurofilament-positive axons, corticospinal tract fibers, and platelet endothelial cell adhesion molecule-1-positive vessels at the lesion epicenter between the transplantation and control groups. Immunoelectron microscopic examination demonstrated that the grafted ESC-NS/PC-derived oligodendrocytes contributed to the remyelination of demyelinated axons. In addition, some grafted neurons formed synaptic connections with host cells, and some transplanted neurons were myelinated by host cells. Eventually, motor functional recovery significantly improved in the transplantation group compared with the control group. In addition, a mixedlymphocyte reaction assay indicated that ESC-NS/PCs modulated the allogeneic immune rejection. Taken together, our results indicate that allogeneic transplantation of ESC-NS/PCs from a nonhuman primate promoted functional recovery after SCI without tumorigenicity. STEM CELLS TRANSLATIONAL MEDICINE 2015;4:708-719 SIGNIFICANCEThis study demonstrates that allogeneic embryonic stem cell (ESC)-derived neural stem/progenitor cells (NS/PCs) promoted functional recovery after transplantation into the injured spinal cord in nonhuman primates. ESC-NS/PCs were chosen because ESC-NS/PCs are one of the controls for induced pluripotent stem cell-derived NS/PCs and because ESC derivatives are possible candidates for clinical use. This translational research using an allograft model of a nonhuman primate is critical for clinical application of grafting NS/PCs derived from various allogeneic pluripotent stem cells, especially induced pluripotent stem cells, into injured spinal cord at the subacute phase.

Prolonged human neural stem cell maturation supports recovery in injured rodent CNS

“…When implanted into sites of spinal cord injury (SCI), rat-and human-derived multipotent neural progenitor cells, human embryonic stem cell-derived (ESC-derived) NSCs, and human induced pluripotent stem cell-derived (iPSC-derived) NSCs all extend very large numbers of axons over long distances and form synapses with host neurons (4,5) that in some cases support functional improvement (4,(8)(9)(10). These findings suggest the potential for human translation; indeed, NSC clinical trials for SCI have begun, and more are planned (ClinicalTrials.gov).…”

Applications of induced pluripotent stem cell technologies in spinal cord injury

“…To decide the time window of cell transplantation therapy for primates at subacute phase, we transplanted NPCs derived from common marmoset embryonic stem cells 14 days after SCI in a marmoset model, and demonstrated that the injected cells preferentially differentiated into neurons and oligodendrocytes, promoted neuronal interaction and myelination, and contributed to motor functional recovery (Iwai et al . ). These results suggest that NPC transplantation is effective in a primate model of SCI, lending more support to the feasibility of delayed injection of human NPCs in human SCI.…”

“…; Iwai et al . ). Therefore, it is suitable to establish a cell bank and stock hiPSC‐NPCs in order to provide cells for use in allogenic transplantation (Okano and Yamanaka ).…”

Microfluidic systems for stem cell-based neural tissue engineering

“…On the other hand, essential elements of cell sources must be considered to develop the cell/tissue replacement and promote the outcome efficiency. First they must be allogeneic to reduce the unwanted immune-responses 37 , further they should represent higher surviving rate to promote the clinical applications 38 . Also the cell sources must be able to be prepared by standard methods to control the expression of undesired phenotype and risk of dyskinesia 39 .…”

“…The discovery of the unique properties of these stem cells, their self-renewing ability, and their responsiveness to particular stimulations by undergoing differentiation to different specific cell types, paved the way for a revolution in regenerative medicine 41 . For example Iwai et al 37 , demonstrated that ESC obtained from allogeneic sources could be used to generate neurons and to from synaptic connections in a non-human primate. Kassmer et al 42 reported new type of PSCs known as very small embryonic-like cells that have potential ability to generate all cell types including the neurons.…”