Delineating the Neuropathology of Lysosomal Storage Diseases Using Patient-Derived Induced Pluripotent Stem Cells.

Lysosomal storage diseases (LSDs) are inherited metabolic diseases caused by deficiency of lysosomal enzymes, essential for the normal development of the brain and other organs. Approximately two-thirds of the patients suffering from LSD exhibit neurological deficits and impose an escalating challenge to the medical and scientific field. The advent of induced pluripotent stem cell (iPSC) technology has aided researchers in efficiently generating functional neuronal and non-neuronal cells through directed differentiation protocols, as well as in decoding the cellular, subcellular, and molecular defects associated with LSDs using two-dimensional cultures and cerebral organoid models. This review highlights the information assembled from patient-derived iPSCs on neurodevelopmental and neuropathological defects identified in LSDs. Multiple studies have identified neural progenitor cell migration and differentiation defects, substrate accumulation, axon growth and myelination defects, impaired calcium homeostasis, and altered electrophysiological properties, using patient-derived iPSCs. In addition, these studies have also uncovered defective lysosomes, mitochondria, endoplasmic reticulum, Golgi complex, autophagy and vesicle trafficking and signaling pathways, oxidative stress, neuroinflammation, blood-brain barrier dysfunction, neurodegeneration, gliosis, and altered transcriptomes in LSDs. The review also discusses the therapeutic applications such as drug discovery, repurposing of drugs, synergistic effects of drugs, targeted molecular therapies, gene therapy, and transplantation applications of mutation-corrected lines identified using patient-derived iPSCs for different LSDs.

Patient-derived iPSC modeling of rare neurodevelopmental disorders: Molecular pathophysiology and prospective therapies.

The pathological alterations that manifest during the early embryonic development due to inherited and acquired factors trigger various neurodevelopmental disorders (NDDs). Besides major NDDs, there are several rare NDDs, exhibiting specific characteristics and varying levels of severity triggered due to genetic and epigenetic anomalies. The rarity of subjects, paucity of neural tissues for detailed analysis, and the unavailability of disease-specific animal models have hampered detailed comprehension of rare NDDs, imposing heightened challenge to the medical and scientific community until a decade ago. The generation of functional neurons and glia through directed differentiation protocols for patient-derived iPSCs, CRISPR/Cas9 technology, and 3D brain organoid models have provided an excellent opportunity and vibrant resource for decoding the etiology of brain development for rare NDDs caused due to monogenic as well as polygenic disorders. The present review identifies cellular and molecular phenotypes demonstrated from patient-derived iPSCs and possible therapeutic opportunities identified for these disorders. New insights to reinforce the existing knowledge of the pathophysiology of these disorders and prospective therapeutic applications are discussed.

Constraint Induced Movement Therapy as a Rehabilitative Strategy for Ischemic Stroke-Linking Neural Plasticity with Restoration of Skilled Movements.

BACKGROUND: Stroke leads to devastating impact on health as well as quality of life making it one of the leading causes of disability. Restoring the functions of upper extremities after ischemic (ISC) stroke is one of the challenges for rehabilitation. Lack of trained professionals and accessibility to rehabilitation centers are limited in many counties. Constraint induced movement therapy (CIMT) has been practiced in regaining the functional activity following stroke. CIMT can be practiced with minimum clinical set up which makes it cost effective. However, the neural plasticity mechanism underlying the recovery with CIMT is not well understood. METHODS: In the current study, we sought to investigate the extent to which CIMT helps in ameliorating neurological deficits in rat model of ISC stroke, induced by Endothelin-1 (ET-1). As well as to understand the cortical plasticity with Golgi-Cox staining and interhemispheric interaction with biotinylated dextran amine (BDA) following CIMT. Neurological deficits were identified within 24 hours of ET-1 infusion. RESULTS: CIMT restored the impaired skilled movements after ISC stroke and improved the quality of fine movements. Golgi-Cox staining showed significant decrease in dendritic arborization in the injured motor cortex following ISC stroke. CIMT was efficient in reversing this effect as indicated by increased dendritic arborization especially in layer III pyramidal neurons. Also, the stroke induced asymmetry in dendritic length across both hemispheres was found to be reduced with CIMT. BDA tracing showed a re-establishment of the axonal connections between the hemispheres after CIMT. CONCLUSIONS: Implications of CIMT can be one of the promising and low cost rehabilitative technique for the individuals with upper limb movement deficits.

Electrophysiological characterization of Nsc-34 cell line using Microelectrode Array.

Neurons communicate with each other through intricate network to evolve higher brain functions. The electrical activity of the neurons plays a crucial role in shaping the connectivity. With motor neurons being vulnerable to neurodegenerative diseases, understanding the electrophysiological properties of motor neurons is the need of the hour, in order to comprehend the impairment of connectivity in these diseases. NSC-34 cell line serves as an excellent model to study the properties of motor neurons as they express Choline acetyltransferase (ChAT). Although NSC-34 cell lines have been used to study the effect of various toxicological, neurotrophic and neuroprotective agents, the electrical activity of these cells has not been elucidated. In the current study, we have characterized the electrophysiological properties of NSC-34 cell lines using Micro-Electrode Array (MEA) as a tool. Based on the spike waveform, firing frequency, auto- and cross-correlogram analysis, we demonstrate that NSC-34 cell culture has >2 distinct types of neuronal population: principal excitatory neurons, putative interneurons and unclassified neurons. The presence of interneurons in the NSC-34 culture was characterized by increased expression of GAD-67 markers. Thus, finding an understanding of the electrophysiological properties of different population of neurons in NSC-34 cell line, will have multiple applications in the treatment of neurological disorders.

A study on fear memory retrieval and REM sleep in maternal separation and isolation stressed rats.

As rapid brain development occurs during the neonatal period, environmental manipulation during this period may have a significant impact on sleep and memory functions. Moreover, rapid eye movement (REM) sleep plays an important role in integrating new information with the previously stored emotional experience. Hence, the impact of early maternal separation and isolation stress (MS) during the stress hyporesponsive period (SHRP) on fear memory retention and sleep in rats were studied. The neonatal rats were subjected to maternal separation and isolation stress during postnatal days 5-7 (6h daily/3d). Polysomnographic recordings and differential fear conditioning was carried out in two different sets of rats aged 2 months. The neuronal replay during REM sleep was analyzed using different parameters. MS rats showed increased time in REM stage and total sleep period also increased. MS rats showed fear generalization with increased fear memory retention than normal control (NC). The detailed analysis of the local field potentials across different time periods of REM sleep showed increased theta oscillations in the hippocampus, amygdala and cortical circuits. Our findings suggest that stress during SHRP has sensitized the hippocampus-amygdala-cortical loops which could be due to increased release of corticosterone that generally occurs during REM sleep. These rats when subjected to fear conditioning exhibit increased fear memory and increased fear generalization. The development of helplessness, anxiety and sleep changes in human patients, thus, could be related to the reduced thermal, tactile and social stimulation during SHRP on brain plasticity and fear memory functions.