Correction: Aberrant iPSC-derived human astrocytes in Alzheimer's disease

Insights into Human-Induced Pluripotent Stem Cell-Derived Astrocytes in Neurodegenerative Disorders

Most neurodegenerative disorders have complex and still unresolved pathology characterized by progressive neuronal damage and death. Astrocytes, the most-abundant non-neuronal cell population in the central nervous system, play a vital role in these processes. They are involved in various functions in the brain, such as the regulation of synapse formation, neuroinflammation, and lactate and glutamate levels. The development of human-induced pluripotent stem cells (iPSCs) reformed the research in neurodegenerative disorders allowing for the generation of disease-relevant neuronal and non-neuronal cell types that can help in disease modeling, drug screening, and, possibly, cell transplantation strategies. In the last 14 years, the differentiation of human iPSCs into astrocytes allowed for the opportunity to explore the contribution of astrocytes to neurodegenerative diseases. This review discusses the development protocols and applications of human iPSC-derived astrocytes in the most common neurodegenerative conditions.

Ceftriaxone regulates glutamate production and vesicular assembly in presynaptic terminals through GLT-1 in APP/PS1 mice

Perturbations in the glutamate-glutamine cycle and glutamate release from presynaptic terminals have been involved in the development of cognitive deficits in Alzheimer's disease (AD) patients and mouse models. Glutamate transporter-1 (GLT-1) removes glutamate from the synaptic cleft and transports it into astrocytes, where it is used as substrate for the glutamate-glutamine cycle. Ceftriaxone has been reported to improve cognitive deficits in AD mice by increasing GLT-1 expression, glutamate transformation to glutamine, and glutamine efflux from astrocytes. However, the impact of ceftriaxone on glutamine metabolism in neurons is unknown. The present study aimed to investigate whether ceftriaxone regulated the production and vesicular assembly of glutamate in the presynaptic terminals of neurons and to determine GLT-1 involvement in this process. We used the amyloid precursor protein (APP)/presenilin-1 (PS1) AD mouse model and GLT-1 knockdown APP/PS1 (GLT-1^+/-/APP/PS1) mice. The expression levels of sodium-coupled neutral amino-acid transporter 1 (SNAT1) and vesicular glutamate transporters 1 and 2 (VGLUT1/2) were analyzed by immunofluorescence and immunohistochemistry staining as well as by Western blotting. Glutaminase activity was assayed by fluorometry. Ceftriaxone treatment significantly increased SNAT1 expression and glutaminase activity in neurons in APP/PS1 mice. Similarly, VGLUT1/2 levels were increased in the presynaptic terminals of APP/PS1 mice treated with ceftriaxone. The deletion of one GLT-1 allele in APP/PS1 mice prevented the ceftriaxone-induced upregulation of SNAT1 and VGLUT1/2 expression, indicating that GLT-1 played an important role in ceftriaxone effect. Based on the role of SNAT1, glutaminase, and VGLUT1/2 in the glutamate-glutamine cycle in neurons, the present results suggested that ceftriaxone improved the production and vesicular assembly of glutamate as a neurotransmitter in presynaptic terminals by acting on GLT-1 in APP/PS1 mice.

The application of patient-derived induced pluripotent stem cells for modeling and treatment of Alzheimer’s disease

Alzheimer’s disease (AD) is the most prevalent age-related neurodegenerative disease which is mainly caused by aggregated protein plaques in degenerating neurons of the brain. These aggregated protein plaques are mainly consisting of amyloid β (Aβ) fibrils and neurofibrillary tangles (NFTs) of phosphorylated tau protein. Even though the transgenic murine models can recapitulate some of the AD phenotypes, they are not the human cell models of AD. Recent breakthrough in somatic cell reprogramming made it available to use induced pluripotent stem cells (iPSCs) for patientspecific disease modeling and autologous transplantation therapy. Human iPSCs provide alternative ways to obtain specific human brain cells of AD patients to study the molecular mechanisms and therapeutic approaches for familial and sporadic forms of AD. After differentiation into neuronal cells, iPSCs have enabled the investigation of the complex aetiology and timescale over which AD develops in human brain. Here, we first go over the pathological process of and transgenic models of AD. Then we discuss the application of iPSC for disease model and cell transplantation. At last the challenges and future applications of iPSCs for AD will be summarized to propose cell-based approaches for the treatment of this devastating disorder.