Muscular dystrophies are a group of genetic muscle disorders that cause progressive muscle weakness and degeneration. Within this group, Duchenne muscular dystrophy (DMD) is the most common and one ...of the most severe. DMD is an X chromosome linked disease that occurs to 1 in 3500 to 1 in 5000 boys. The cause of DMD is a mutation in the dystrophin gene, whose encoded protein provides both structural support and cell signaling capabilities. So far, there are very limited therapeutic options available and there is no cure for this disease. In this review, we discuss the existing cell therapy research, especially stem cell-based, which utilize myoblasts, satellite cells, bone marrow cells, mesoangioblasts and CD133+ cells. Finally, we focus on human pluripotent stem cells (hPSCs) which hold great potential in treating DMD. hPSCs can be used for autologous transplantation after being specified to a myogenic lineage. Over the last few years, there has been a rapid development of isolation, as well as differentiation, techniques in order to achieve effective transplantation results of myogenic cells specified from hPSCs. In this review, we summarize the current methods of hPSCs myogenic commitment/differentiation, and describe the current status of hPSC-derived myogenic cell transplantation.
•Myogenic progenitor cells could provide a source for cell therapy for DMD to regenerate and replace the diseased tissue•An orchestration of signaling molecules directing the lineage determination sets the basis for PSC differentiation in vitro•There is a need to develop more cell therapy options (e.g iPSC) for DMD due to limited success of current ones•The review describes the most recent studies of hiPSC muscle lineage specification and the potential of their application
The equivalence of human induced pluripotent stem cells (hiPSCs) and human embryonic stem cells (hESCs) remains controversial. Here we use genetically matched hESC and hiPSC lines to assess the ...contribution of cellular origin (hESC vs. hiPSC), the Sendai virus (SeV) reprogramming method and genetic background to transcriptional and DNA methylation patterns while controlling for cell line clonality and sex. We find that transcriptional and epigenetic variation originating from genetic background dominates over variation due to cellular origin or SeV infection. Moreover, the 49 differentially expressed genes we detect between genetically matched hESCs and hiPSCs neither predict functional outcome nor distinguish an independently derived, larger set of unmatched hESC and hiPSC lines. We conclude that hESCs and hiPSCs are molecularly and functionally equivalent and cannot be distinguished by a consistent gene expression signature. Our data further imply that genetic background variation is a major confounding factor for transcriptional and epigenetic comparisons of pluripotent cell lines, explaining some of the previously observed differences between genetically unmatched hESCs and hiPSCs.
Human pluripotent stem cell (hPSC)-derived neural crest (NC) cells present a valuable tool for modeling aspects of human NC development, including cell fate specification, multipotency and cell ...migration. hPSC-derived NC cells are also suitable for modeling human disease and as a renewable cell source for applications in regenerative medicine. Here we provide protocols for the step-wise differentiation of human embryonic stem cells (hESCs) or human induced pluripotent stem cells (hiPSCs) into neuroectodermal and NC cells using either the MS5 coculture system or a novel defined culture method based on pharmacological inhibition of bone morphogenetic protein and transforming growth factor-beta signaling pathways. Furthermore, we present protocols for the purification and propagation of hPSC-NC cells using flow cytometry and defined in vitro culture conditions. Our protocol has been validated in multiple independent hESC and hiPSC lines. The average time required for generating purified hPSC-NC precursors using this protocol is 2-5 weeks.
Melanocytes are pigment-producing cells of neural crest (NC) origin that are responsible for protecting the skin against UV irradiation. Pluripotent stem cell (PSC) technology offers a promising ...approach for studying human melanocyte development and disease. Here, we report that timed exposure to activators of WNT, BMP, and EDN3 signaling triggers the sequential induction of NC and melanocyte precursor fates under dual-SMAD-inhibition conditions. Using a SOX10::GFP human embryonic stem cell (hESC) reporter line, we demonstrate that the temporal onset of WNT activation is particularly critical for human NC induction. Subsequent maturation of hESC-derived melanocytes yields pure populations that match the molecular and functional properties of adult melanocytes. Melanocytes from Hermansky-Pudlak syndrome and Chediak-Higashi syndrome patient-specific induced PSCs (iPSCs) faithfully reproduce the ultrastructural features of disease-associated pigmentation defects. Our data define a highly specific requirement for WNT signaling during NC induction and enable the generation of pure populations of human iPSC-derived melanocytes for faithful modeling of pigmentation disorders.
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► Narrow window of WNT activation efficiently induces neural crest from hESCs ► BMP and EDN3 bias NC fate toward KIT+ melanocyte lineage ► Melanocytes are functional and recreate different human pigmentation levels ► Melanocytes from patient-specific iPSCs model ultrastructural disease features
Melanocytes are pigment-producing cells of neural crest origin that are responsible for protecting the skin against UV irradiation. Here, Studer and colleagues use pluripotent stem cell (PSC) technology to model human melanocyte development and disease. They describe conditions for the sequential derivation of neural crest, melanoblast progenitors, and mature and functional melanocytes from human embryonic stem cells. They further demonstrate that their system can be used with induced-PSC-derived melanocytes to faithfully recapitulate pigmentation defects associated with Hermansky-Pudlak syndrome and Chediak-Higashi syndrome.
Vertebrate neural crest development depends on pluripotent, migratory precursor cells. Although avian and murine neural crest stem (NCS) cells have been identified, the isolation of human NCS cells ...has remained elusive. Here we report the derivation of NCS cells from human embryonic stem cells at the neural rosette stage. We show that NCS cells plated at clonal density give rise to multiple neural crest lineages. The human NCS cells can be propagated in vitro and directed toward peripheral nervous system lineages (peripheral neurons, Schwann cells) and mesenchymal lineages (smooth muscle, adipogenic, osteogenic and chondrogenic cells). Transplantation of human NCS cells into the developing chick embryo and adult mouse hosts demonstrates survival, migration and differentiation compatible with neural crest identity. The availability of unlimited numbers of human NCS cells offers new opportunities for studies of neural crest development and for efforts to model and treat neural crest-related disorders.
The cerebral cortex contains layers of neurons sequentially generated by distinct lineage-related progenitors. At the onset of corticogenesis, the first-born progenitors are apical progenitors (APs), ...whose asymmetric division gives birth directly to neurons. Later, they switch to indirect neurogenesis by generating intermediate progenitors (IPs), which give rise to projection neurons of all cortical layers. While a direct lineage relationship between APs and IPs has been established, the molecular mechanism that controls their transition remains elusive. Here we show that interfering with codon translation speed triggers ER stress and the unfolded protein response (UPR), further impairing the generation of IPs and leading to microcephaly. Moreover, we demonstrate that a progressive downregulation of UPR in cortical progenitors acts as a physiological signal to amplify IPs and promotes indirect neurogenesis. Thus, our findings reveal a contribution of UPR to cell fate acquisition during mammalian brain development.
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•The UPR is a homeostat regulating the specification of cortical stem cells•Elp3 loss in cortical stem cells triggers UPR by decreasing codon translation rates•Gradual UPR suppression promotes the switch from direct to indirect neurogenesis
Laguesse, Creppe et al. demonstrate that the unfolded protein response (UPR) contributes to neurogenesis in the developing cerebral cortex. Depletion of the Elongator complex component Elp3 triggers the UPR through interference with codon translation speed. UPR activation impairs the balance between direct and indirect neurogenesis, leading to premature neuron generation.
Amyotrophic lateral sclerosis (ALS) is a devastating disorder in which motor neurons degenerate, the causes of which remain unclear. In particular, the basis for selective vulnerability of spinal ...motor neurons (sMNs) and resistance of ocular motor neurons to degeneration in ALS has yet to be elucidated. Here, we applied comparative multi-omics analysis of human induced pluripotent stem cell-derived sMNs and ocular motor neurons to identify shared metabolic perturbations in inherited and sporadic ALS sMNs, revealing dysregulation in lipid metabolism and its related genes. Targeted metabolomics studies confirmed such findings in sMNs of 17 ALS (SOD1, C9ORF72, TDP43 (TARDBP) and sporadic) human induced pluripotent stem cell lines, identifying elevated levels of arachidonic acid. Pharmacological reduction of arachidonic acid levels was sufficient to reverse ALS-related phenotypes in both human sMNs and in vivo in Drosophila and SOD1
mouse models. Collectively, these findings pinpoint a catalytic step of lipid metabolism as a potential therapeutic target for ALS.
•Animal models can be poor mimics of healthy and diseased skeletal muscle phenotypes.•Engineered muscle tissues offer alternative systems to study dystrophic pathology.•Engineered muscle maturation ...is required to ensure models mimic in vivo physiology.•This review covers strategies for promoting engineered muscle development.•The effect such models could have muscular dystrophy therapies is also discussed.
Engineered in vitro models using human cells, particularly patient-derived induced pluripotent stem cells (iPSCs), offer a potential solution to issues associated with the use of animals for studying disease pathology and drug efficacy. Given the prevalence of muscle diseases in human populations, an engineered tissue model of human skeletal muscle could provide a biologically accurate platform to study basic muscle physiology, disease progression, and drug efficacy and/or toxicity. Such platforms could be used as phenotypic drug screens to identify compounds capable of alleviating or reversing congenital myopathies, such as Duchene muscular dystrophy (DMD). Here, we review current skeletal muscle modeling technologies with a specific focus on efforts to generate biomimetic systems for investigating the pathophysiology of dystrophic muscle.
This review covers current state-of-the-art skeletal muscle engineering technologies, and discusses the relevance of these models in furthering our understanding of muscular dystrophy and advancing the drug development process.
Familial dysautonomia (FD) is a debilitating disorder that affects derivatives of the neural crest (NC). For unknown reasons, people with FD show marked differences in disease severity despite ...carrying an identical, homozygous point mutation in IKBKAP, encoding IκB kinase complex-associated protein. Here we present disease-related phenotypes in human pluripotent stem cells (PSCs) that capture FD severity. Cells from individuals with severe but not mild disease show impaired specification of NC derivatives, including autonomic and sensory neurons. In contrast, cells from individuals with severe and mild FD show defects in peripheral neuron survival, indicating that neurodegeneration is the main culprit for cases of mild FD. Although genetic repair of the FD-associated mutation reversed early developmental NC defects, sensory neuron specification was not restored, indicating that other factors may contribute to disease severity. Whole-exome sequencing identified candidate modifier genes for individuals with severe FD. Our study demonstrates that PSC-based modeling is sensitive in recapitulating disease severity, which presents an important step toward personalized medicine.
Varicella-zoster virus (VZV) maintains lifelong latency in neurons following initial infection and can subsequently be reactivated to result in herpes zoster or severe neurological manifestations ...such as encephalitis. Mechanisms of VZV neuropathogenesis have been challenging to study due to the strict human tropism of the virus. Although neuronal entry mediators of other herpesviruses, including herpes simplex virus, have been identified, little is known regarding how VZV enters neurons. Here, we utilize a human stem cell-based neuronal model to characterize cellular factors that mediate entry. Through transcriptional profiling of infected cells, we identify the cell adhesion molecule nectin-1 as a candidate mediator of VZV entry. Nectin-1 is highly expressed in the cell bodies and axons of neurons. Either knockdown of endogenous nectin-1 or incubation with soluble forms of nectin-1 produced in mammalian cells results in a marked decrease in infectivity of neurons. Notably, while addition of soluble nectin-1 during viral infection inhibits infectivity, addition after infection has no effect on infectivity. Ectopic expression of human nectin-1 in a cell line resistant to productive VZV infection confers susceptibility to infection. In summary, we have identified nectin-1 as a neuronal entry mediator of VZV.
Varicella-zoster virus (VZV) causes chickenpox, gains access to neurons during primary infection where it resides lifelong, and can later be reactivated. Reactivation is associated with shingles and postherpetic neuralgia, as well as with severe neurologic complications, including vasculitis and encephalitis. Although the varicella vaccine substantially decreases morbidity and mortality associated with primary infection, the vaccine cannot prevent the development of neuronal latency, and vaccinated populations are still at risk for reactivation. Furthermore, immunocompromised individuals are at higher risk for VZV reactivation and associated complications. Little is known regarding how VZV enters neurons. Here, we identify nectin-1 as an entry mediator of VZV in human neurons. Identification of nectin-1 as a neuronal VZV entry mediator could lead to improved treatments and preventative measures to reduce VZV related morbidity and mortality.
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