LOTUS overexpression via ex vivo gene transduction further promotes recovery of motor function following human iPSC-NS/PC transplantation for contusive spinal cord injury.
ABSTRACT: Functional recovery is still limited mainly due to several mechanisms, such as the activation of Nogo receptor-1 (NgR1) signaling, when human induced pluripotent stem cell-derived neural stem/progenitor cells (hiPSC-NS/PC) are transplanted for subacute spinal cord injury (SCI). We previously reported the neuroprotective and regenerative benefits of overexpression of lateral olfactory tract usher substance (LOTUS), an endogenous NgR1 antagonist, in the injured spinal cord using transgenic mice. Here, we evaluate the effects of lentiviral transduction of LOTUS gene into hiPSC-NS/PCs before transplantation in a mouse model of subacute SCI. The transduced LOTUS contributes to neurite extension, suppression of apoptosis, and secretion of neurotrophic factors in vitro. In vivo, the hiPSC-NS/PCs enhance the survival of grafted cells and enhance axonal extension of the transplanted cells, resulting in significant restoration of motor function following SCI. Therefore, the gene transduction of LOTUS in hiPSC-NS/PCs could be a promising adjunct for transplantation therapy for SCI.
Project description:Our previous work reported functional recovery after transplantation of mouse and human induced pluripotent stem cell-derived neural stem/progenitor cells (hiPSC-NS/PCs) into rodent models of spinal cord injury (SCI). Although hiPSC-NS/PCs proved useful for the treatment of SCI, the tumorigenicity of the transplanted cells must be resolved before they can be used in clinical applications. The current study sought to determine the feasibility of ablation of the tumors formed after hiPSC-NS/PC transplantation through immunoregulation. Tumorigenic hiPSC-NS/PCs were transplanted into the intact spinal cords of immunocompetent BALB/cA mice with or without immunosuppressant treatment. In vivo bioluminescence imaging was used to evaluate the chronological survival and growth of the transplanted cells. The graft survival rate was 0% in the group without immunosuppressants versus 100% in the group with immunosuppressants. Most of the mice that received immunosuppressants exhibited hind-limb paralysis owing to tumor growth at 3 months after iPSC-NS/PC transplantation. Histological analysis showed that the tumors shared certain characteristics with low-grade gliomas rather than with teratomas. After confirming the progression of the tumors in immunosuppressed mice, the immunosuppressant agents were discontinued, resulting in the complete rejection of iPSC-NS/PC-derived masses within 42 days after drug cessation. In accordance with the tumor rejection, hind-limb motor function was recovered in all of the mice. Moreover, infiltration of microglia and lymphocytes was observed during the course of tumor rejection, along with apoptosis of iPSC-NS/PC-generated cells. Thus, immune rejection can be used as a fail-safe system against potential tumorigenicity after transplantation of iPSC-NS/PCs to treat SCI.
Project description:Neural stem/progenitor cells (NS/PCs) derived from human induced pluripotent stem cells (hiPSCs) are considered to be a promising cell source for cell-based interventions that target CNS disorders. We previously reported that transplanting certain hiPSC-NS/PCs in the spinal cord results in tumor-like overgrowth of hiPSC-NS/PCs and subsequent deterioration of motor function. Remnant immature cells should be removed or induced into more mature cell types to avoid adverse effects of hiPSC-NS/PC transplantation. Because Notch signaling plays a role in maintaining NS/PCs, we evaluated the effects of ?-secretase inhibitor (GSI) and found that pretreating hiPSC-NS/PCs with GSI promoted neuronal differentiation and maturation in vitro, and GSI pretreatment also reduced the overgrowth of transplanted hiPSC-NS/PCs and inhibited the deterioration of motor function in vivo. These results indicate that pretreatment with hiPSC-NS/PCs decreases the proliferative capacity of transplanted hiPSC-NS/PCs, triggers neuronal commitment, and improves the safety of hiPSC-based approaches in regenerative medicine.
Project description:Tumorigenesis is an important problem that needs to be addressed in the field of human stem/progenitor cell transplantation for the treatment of subacute spinal cord injury (SCI). When certain "tumorigenic" cell lines are transplanted into the spinal cord of SCI mice model, there is initial improvement of motor function, followed by abrupt deterioration secondary to the effect of tumor growth. A significant proportion of the transplanted cells remains undifferentiated after transplantation and is thought to increase the risk of tumorigenesis. In this study, using lentiviral vectors, we introduced the herpes simplex virus type 1 thymidine kinase (HSVtk) gene into a human induced pluripotent stem cell-derived neural stem/progenitor cell (hiPSC-NS/PC) line that is known to undergo tumorigenic transformation. Such approach enables selective ablation of the immature proliferating cells and thereby prevents subsequent tumor formation. In vitro, the HSVtk system successfully ablated the immature proliferative neural cells while preserving mature postmitotic neuronal cells. Similar results were observed in vivo following transplantation into the injured spinal cords of immune-deficient (nonobese diabetic-severe combined immune-deficient) mice. Ablation of the proliferating cells exerted a protective effect on the motor function which was regained after transplantation, simultaneously defending the spinal cord from the harmful tumor growth. These results suggest a potentially promising role of suicide genes in opposing tumorigenesis during stem cell therapy. This system allows both preventing and treating tumorigenesis following hiPSC-NS/PC transplantation without sacrificing the improved motor function. Stem Cells Translational Medicine 2019;8:260&270.
Project description:Transplantation of human-induced pluripotent stem cell-derived neural stem/progenitor cells (hiPSC-NS/PCs) is a promising treatment for a variety of neuropathological conditions. Although previous reports have indicated the effectiveness of hiPSC-NS/PCs transplantation into the injured spinal cord of rodents and nonhuman primates, long-term observation of hiPSC-NS/PCs post-transplantation suggested some "unsafe" differentiation-resistant properties, resulting in disordered overgrowth. These findings suggest that, even if "safe" NS/PCs are transplanted into the human central nervous system (CNS), the dynamics of cellular differentiation of stem cells should be noninvasively tracked to ensure safety. Positron emission tomography (PET) provides molecular-functional information and helps to detect specific disease conditions. The current study was conducted to visualize Nestin (an NS/PC marker)-positive undifferentiated neural cells in the CNS of immune-deficient (nonobese diabetic-severe combined immune-deficient) mice after hiPSC-NS/PCs transplantation with PET, using 18?kDa translocator protein (TSPO) ligands as labels. TSPO was recently found to be expressed in rodent NS/PCs, and its expression decreased with the progression of neuronal differentiation. We hypothesized that TSPO would also be present in hiPSC-NS/PCs and expressed strongly in residual immature neural cells after transplantation. The results showed high levels of TSPO expression in immature hiPSC-NS/PCs-derived cells, and decreased TSPO expression as neural differentiation progressed in vitro. Furthermore, PET with [<sup>18</sup> F] FEDAC (a TSPO radioligand) was able to visualize the remnant undifferentiated hiPSC-NS/PCs-derived cells consisting of TSPO and Nestin<sup>+</sup> cells in vivo. These findings suggest that PET with [<sup>18</sup> F] FEDAC could play a key role in the safe clinical application of CNS repair in regenerative medicine.
Project description:Treatment involving regenerative medicine for chronic spinal cord injury (SCI) is difficult due to phase-dependent changes in the intraspinal environment. We previously reported that treatment with a gamma-secretase inhibitor (GSI), which inhibits Notch signaling, promotes the differentiation into mature neurons in human induced pluripotent stem cell-derived neural stem/progenitor cell (hiPSC-NS/PC) transplantation for subacute SCI. Here, we evaluated the efficacy of GSI-treated hiPSC-NS/PC transplantation in treating chronic SCI, which resulted in significantly enhanced axonal regrowth, remyelination, inhibitory synapse formation with the host neural circuitry, and reticulo spinal tract fiber formation. Interestingly, inhibiting Notch signaling with GSI caused phosphorylation of p38 MAPK, which is a key molecule required to promote axonal regeneration. These favorable outcomes contributed to motor function improvement. Therefore, treating cells with GSI provides a beneficial effect after transplantation, even in the chronic phase following SCI.
Project description:Most studies targeting chronic spinal cord injury (SCI) have concluded that neural stem/progenitor cell (NS/PC) transplantation exerts only a subclinical recovery; this in contrast to its remarkable effect on acute and subacute SCI. To determine whether the addition of rehabilitative intervention enhances the effect of NS/PC transplantation for chronic SCI, we used thoracic SCI mouse models to compare manifestations secondary to both transplantation and treadmill training, and the two therapies combined, with a control group. Significant locomotor recovery in comparison with the control group was only achieved in the combined therapy group. Further investigation revealed that NS/PC transplantation improved spinal conductivity and central pattern generator activity, and that treadmill training promoted the appropriate inhibitory motor control. The combined therapy enhanced these independent effects of each single therapy, and facilitated neuronal differentiation of transplanted cells and maturation of central pattern generator activity synergistically. Our data suggest that rehabilitative treatment represents a therapeutic option for locomotor recovery after NS/PC transplantation, even in chronic SCI.
Project description:Spinal cord injury (SCI) frequently provokes serious detrimental outcomes because neuronal regeneration is limited in the central nervous system (CNS). Thus, the creation of a permissive environment for transplantation therapy with neural stem/progenitor cells (NS/PCs) is a promising strategy to replace lost neuronal cells, promote repair, and stimulate functional plasticity after SCI. Macrophages are important SCI-associated inflammatory cells and a major source of secreted factors that modify the lesion milieu. Here, we used conditional medium (CM) from bone marrow-derived M1 or M2 polarized macrophages to culture murine NS/PCs. The NS/PCs showed enhanced astrocytic versus neuronal/oligodendrocytic differentiation in the presence of M1- versus M2-CM. Similarly, cotransplantation of NS/PCs with M1 and M2 macrophages into intact or injured murine spinal cord increased the number of engrafted NS/PC-derived astrocytes and neurons/oligodendrocytes, respectively. Furthermore, when cotransplantated with M2 macrophages, the NS/PC-derived neurons integrated into the local circuitry and enhanced locomotor recovery following SCI. Interesting, engrafted M1 macrophages promoted long-distance rostral migration of NS/PC-derived cells in a chemokine (C-X-C motif) receptor 4 (CXCR4)-dependent manner, while engrafted M2 macrophages resulted in limited cell migration of NS/PC-derived cells. Altogether, these findings suggest that the cotransplantation of NS/PCs together with polarized macrophages could constitute a promising therapeutic approach for SCI repair.
Project description:Transplantation of neural stem/progenitor cells (NS/PCs) derived from human induced pluripotent stem cells (hiPSCs) is considered to be a promising therapy for spinal cord injury (SCI) and will soon be translated to the clinical phase. However, how grafted neuronal activity influences functional recovery has not been fully elucidated. Here, we show the locomotor functional changes caused by inhibiting the neuronal activity of grafted cells using a designer receptor exclusively activated by designer drugs (DREADD). In vitro analyses of inhibitory DREADD (hM4Di)-expressing cells demonstrated the precise inhibition of neuronal activity via administration of clozapine N-oxide. This inhibition led to a significant decrease in locomotor function in SCI mice with cell transplantation, which was exclusively observed following the maturation of grafted neurons. Furthermore, trans-synaptic tracing revealed the integration of graft neurons into the host motor circuitry. These results highlight the significance of engrafting functionally competent neurons by hiPSC-NS/PC transplantation for sufficient recovery from SCI.
Project description:<h4>Background</h4>Spinal cord injury (SCI) is a common disease that results in motor and sensory disorders and even lifelong paralysis. The transplantation of stem cells, such as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), mesenchymal stem cells (MSCs), or subsequently generated stem/progenitor cells, is predicted to be a promising treatment for SCI. In this study, we aimed to investigate effect of human iPSC-derived neural stem cells (hiPSC-NSCs) and umbilical cord-derived MSCs (huMSCs) in a mouse model of acute SCI.<h4>Methods</h4>Acute SCI mice model were established and were randomly treated as phosphate-buffered saline (PBS) (control group), repaired with 1?×?10<sup>5</sup> hiPSC-NSCs (NSC group), and 1?×?10<sup>5</sup> huMSCs (MSC group), respectively, in a total of 54 mice (n?=?18 each). Hind limb motor function was evaluated in open-field tests using the Basso Mouse Scale (BMS) at days post-operation (dpo) 1, 3, 5, and 7 after spinal cord injury, and weekly thereafter. Spinal cord and serum samples were harvested at dpo 7, 14, and 21. Haematoxylin-eosin (H&E) staining and Masson staining were used to evaluate the morphological changes and fibrosis area. The differentiation of the transplanted cells in vivo was evaluated with immunohistochemical staining.<h4>Results</h4>The hiPSC-NSC-treated group presented a significantly smaller glial fibrillary acidic protein (GFAP) positive area than MSC-treated mice at all time points. Additionally, MSC-transplanted mice had a similar GFAP+ area to mice receiving PBS. At dpo 14, the immunostained hiPSC-NSCs were positive for SRY-related high-mobility-group (HMG)-box protein-2 (SOX2). Furthermore, the transplanted hiPSC-NSCs differentiated into GFAP-positive astrocytes and beta-III tubulin-positive neurons, whereas the transplanted huMSCs differentiated into GFAP-positive astrocytes. In addition, hiPSC-NSC transplantation reduced fibrosis formation and the inflammation level. Compared with the control or huMSC transplanted group, the group with transplantation of hiPSC-NSCs exhibited significantly improved behaviours, particularly limb coordination.<h4>Conclusions</h4>HiPSC-NSCs promote functional recovery in mice with acute SCI by replacing missing neurons and attenuating fibrosis, glial scar formation, and inflammation.
Project description:Nogo receptor-1 (NgR1) and its ligands inhibit neuronal plasticity and limit functional recovery after brain damage such as ischemic stroke. We have previously shown that lateral olfactory tract usher substance (LOTUS) antagonizes NgR1-mediated signaling. Here, we investigated whether LOTUS enhances neuronal plasticity and functional recovery after brain focal ischemia in adult mice. Focal ischemic infarcts were induced in wild-type and LOTUS-overexpressing transgenic mice via middle cerebral artery occlusion. Endogenous LOTUS expression was increased in brain and cervical spinal cord of the contralateral side of ischemia in the chronic phase after brain ischemia. LOTUS overexpression accelerated midline-crossing axonal sprouting from the contralateral side to the ipsilateral side of ischemia in the medullar reticular formation and gray matter of denervated cervical spinal cord. Importantly, LOTUS overexpression improved neurological score highly correlated with laterality ratio of corticoreticular fibers of the medulla oblongata, indicating that LOTUS overexpression may overcome the inhibitory environment induced by NgR1 signaling for damaged motor pathway reconstruction after ischemic stroke. Thus, our data suggest that LOTUS overexpression accelerates neuronal plasticity in the brainstem and cervical spinal cord after stroke and LOTUS administration is useful for future therapeutic strategies.