Motoneurons Derived from Induced Pluripotent Stem Cells Develop Mature Phenotypes Typical of Endogenous Spinal Motoneurons

Abstract

Induced pluripotent cell-derived motoneurons (iPSCMNs) are sought for use in cell replacement therapies and treatment strategies for motoneuron diseases such as amyotrophic lateral sclerosis (ALS). However, much remains unknown about the physiological properties of iPSCMNs and how they compare with endogenous spinal motoneurons or embryonic stem cell-derived motoneurons (ESCMNs). In the present study, we first used a proteomic approach and compared protein expression profiles between iPSCMNs and ESCMNs to show that Ͻ4% of the proteins identified were differentially regulated. Like ESCs, we found that mouse iPSCs treated with retinoic acid and a smoothened agonist differentiated into motoneurons expressing the LIM homeodomain protein Lhx3. When transplanted into the neural tube of developing chick embryos, iPSCMNs selectively targeted muscles normally innervated by Lhx3 motoneurons. In vitro studies showed that iPSCMNs form anatomically mature and functional neuromuscular junctions (NMJs) when cocultured with chick myofibers for several weeks. Electrophysiologically, iPSCMNs developed passive membrane and firing characteristic typical of postnatal motoneurons after several weeks in culture. Finally, iPSCMNs grafted into transected mouse tibial nerve projected axons to denervated gastrocnemius muscle fibers, where they formed functional NMJs, restored contractile force. and attenuated denervation atrophy. Together, iPSCMNs possess many of the same cellular and physiological characteristics as ESCMNs and endogenous spinal motoneurons. These results further justify using iPSCMNs as a source of motoneurons for cell replacement therapies and to study motoneuron diseases such as ALS.

Modeling ALS with motor neurons derived from human induced pluripotent stem cells

“…It is clear that filling in cellular interactions critical for MN function will make studies on hPSC-MNs more relevant to their physiology and pathology in vivo , and may enhance maturation in vitro . Indeed, mouse ESC-derived MNs are capable of maturing and forming functional neuromuscular junctions when transplanted into chick spinal cords 77 and mouse sciatic nerve, 78 . Non-MN cell types involved in the neuromuscular circuit such as astrocytes, Schwann cells and myofibers play heavily on LMN function and may increase LMN maturity during development.…”

“…Electrophysiological recordings from putative NMJs in vitro also show generally poor NMJ-induced myofibril activation. Interestingly, recent studies on xenogeneic co-culture of mouse iPSC-derived MNs and primary chick myoblasts show more typical endplate morphology and electrical function in vitro 77 .…”

Transplantation of Embryonic Spinal Cord Derived Cells Helps to Prevent Muscle Atrophy after Peripheral Nerve Injury

“…So far, mostly neural progenitor and embryonic stem cells have shown to act through direct neuronal replacement while other cells, such as stem cells from adipose tissue, hair, skin, bone marrow and amniotic fluid, seem to be beneficial for their regeneration supportive effect through the production of neurotrophic factors, extracellular matrix components, through growth cone guidance and remyelination [30,35,36,38,39,40,41,45]. Promising cells are also iPSCs that have shown the ability to differentiate into motoneurons in vitro [57,58,59] and to form functional connections with reinnervated muscle in vivo [26]. Embryonic fetal cells are safer compared to IPSCs because there is no danger of virus activation or cancer development due to induced pluripotency [60,61,62,63,64,65].…”

Modeling ALS and FTD with iPSC-derived neurons

“…Several studies in rodents and in chicks have provided proof-of-principle evidence that iPSC-derived neurons can indeed be transplanted into cerebral cortex or spinal cord, and demonstrate functional integration into the existing neural circuits (Espuny-Camacho et al, 2013; Sareen et al, 2014; Toma et al, 2015). Given the available technology to correct the genetic mutations, it is possible that patient-specific iPSC-derived neurons might be able to reduce immune response and improve the chance of graft survival.…”