Modulation by DREADD reveals the therapeutic effect of human iPSC-derived neuronal activity on functional recovery after spinal cord injury

Abstract

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.

3Dimaging of supraspinal inputs to the thoracic and lumbar spinal cord mapped by retrograde tracing and light‐sheet microscopy

“…Our previous works reported that the grafted cells migrated rostrally and caudally in mice (Ishii et al, 2006; Ito et al, 2021; Kawai et al, 2021; Kitagawa et al, 2022) and marmoset (Iwanami et al, 2005), which increased the connection between grafted cell‐derived neurons and host spared interneurons and fibers around lesion area. Although the tendency of circuit formation between grafted cells and rostral thoracic‐projection or lumbar‐projection supraspinal neurons as well as which way contributes more function recovery needs to be further studied, this work provided a kind of anatomical distribution pattern of supraspinal inputs to rostral and caudal spinal segments, which mapped the relative location of CSNs and RNs projecting to T9‐vertebral (rostral) and T13‐vertebral level (caudal).…”

A non-invasive system to monitor in vivo neural graft activity after spinal cord injury

“…Instead, a consecutive hM3Dq stimulation of the CST may achieve simultaneous amelioration of circuit/behavioural activities enhancing synaptic activity 45 , 46 . Furthermore, inactivating CST function by CST-DREADDs would better help provide evidence of the host-to-graft connectivity 47 .…”

Transplantation of Human Induced Pluripotent Stem Cell-Derived Neural Progenitor Cells Promotes Forelimb Functional Recovery after Cervical Spinal Cord Injury

“…Connection mapping using trans-synaptic rabies viruses, especially the monosynaptic modified rabies viruses, could provide useful insights about the integration and functional connection of graft-derived neurons [ 41 , 42 ]. In addition, deactivation/activation of grafted neurons using chemo-genetic or optogenetic approaches could be very helpful to determine the contribution of grafted neurons in functional recovery [ 43 , 44 ]. It will be very interesting to determine whether different neuronal phenotypes differentiated from grafted NPCs could play varying roles in restoring functional recovery.…”