The impact of VPS35 D620N mutation on alternative autophagy and its reversal by estrogen in Parkinson's disease.

VPS35 plays a key role in neurodegenerative processes in Alzheimer's disease and Parkinson's disease (PD). Many genetic studies have shown a close relationship between autophagy and PD pathophysiology, and specifically, the PD-causing D620N mutation in VPS35 has been shown to impair autophagy. However, the molecular mechanisms underlying neuronal cell death and impaired autophagy in PD are debated. Notably, increasing evidence suggests that Rab9-dependent "alternative" autophagy, which is driven by a different molecular mechanism that driving ATG5-dependent "conventional" autophagy, also contributes to neurodegenerative process. In this study, we investigated the relationship between alternative autophagy and VPS35 D620N mutant-related PD pathogenesis. We isolated iPSCs from the blood mononuclear cell population of two PD patients carrying the VPS35 D620N mutant. In addition, we used CRISPR-Cas9 to generate SH-SY5Y cells carrying the D620N variant of VPS35. We first revealed that the number of autophagic vacuoles was significantly decreased in ATG5-knockout Mouse Embryonic Fibroblast or ATG5-knockdown patient-derived dopaminergic neurons carrying the VPS35 D620N mutant compared with that of the wild type VPS35 control cells. Furthermore, estrogen, which activates alternative autophagy pathways, increased the number of autophagic vacuoles in ATG5-knockdown VPS35 D620N mutant dopaminergic neurons. Estrogen induces Rab9 phosphorylation, mediated through Ulk1 phosphorylation, ultimately regulating alternative autophagy. Moreover, estrogen reduced the apoptosis rate of VPS35 D620N neurons, and this effect of estrogen was diminished under alternative autophagy knockdown conditions. In conclusion, alternative autophagy might be important for maintaining neuronal homeostasis and may be associated with the neuroprotective effect of estrogen in PD with VPS35 D620N.

Effect of sedatives or anesthetics on the measurement of resting brain function in common marmosets.

Common marmosets are promising laboratory animals for the study of higher brain functions. Although there are many opportunities to use sedatives and anesthetics in resting brain function measurements in marmosets, their effects on the resting-state network remain unclear. In this study, the effects of sedatives or anesthetics such as midazolam, dexmedetomidine, co-administration of isoflurane and dexmedetomidine, propofol, alfaxalone, isoflurane, and sevoflurane on the resting brain function in common marmosets were evaluated using independent component analysis, dual regression analysis, and graph-theoretic analysis; and the sedatives or anesthetics suitable for the evaluation of resting brain function were investigated. The results show that network preservation tendency under light sedative with midazolam and dexmedetomidine is similar regardless of the type of target receptor. Moreover, alfaxalone, isoflurane, and sevoflurane have similar effects on resting state brain function, but only propofol exhibits different tendencies, as resting brain function is more preserved than it is following the administration of the other anesthetics. Co-administration of isoflurane and dexmedetomidine shows middle effect between sedatives and anesthetics.

The Japan Monkey Centre Primates Brain Imaging Repository of high-resolution postmortem magnetic resonance imaging: The second phase of the archive of digital records.

A comparison of neuroanatomical features of the brain between humans and our evolutionary relatives, nonhuman primates, is key to understanding the human brain system and the neural basis of mental and neurological disorders. Although most comparative MRI studies of human and nonhuman primate brains have been based on brains of primates that had been used as subjects in experiments, it is essential to investigate various species of nonhuman primates in order to elucidate and interpret the diversity of neuroanatomy features among humans and nonhuman primates. To develop a research platform for this purpose, it is necessary to harmonize the scientific contributions of studies with the standards of animal ethics, animal welfare, and the conservation of brain information for long-term continuation of the field. In previous research, we first developed a gated data-repository of anatomical images obtained using 9.4-T ex vivo MRI of postmortem brain samples from 12 nonhuman primate species, and which are stored at the Japan Monkey Centre. In the present study, as a second phase, we released a collection of T2-weighted images and diffusion tensor images obtained in nine species: white-throated capuchin, Bolivian squirrel monkey, stump-tailed macaque, Tibet monkey, Sykes' monkey, Assamese macaque, pig-tailed macaque, crested macaque, and chimpanzee. Our image repository should facilitate scientific discoveries in the field of comparative neuroscience. This repository can also promote animal ethics and animal welfare in experiments with nonhuman primate models by optimizing methods for in vivo and ex vivo MRI scanning of brains and supporting veterinary neuroradiological education. In addition, the repository is expected to contribute to conservation, preserving information about the brains of various primates, including endangered species, in a permanent digital form.

Generation of induced pluripotent stem cell (iPSC) from NY-ESO-I-specific cytotoxic T cells isolated from the melanoma patient with minor HLAs: The practical pilot study for the adoptive immunotherapy for melanoma using iPSC technology.

Melanoma is one of the most severe skin cancers, derived from melanocytes. Among various therapies for melanoma, adoptive immunotherapy using tumor-infiltrating lymphocytes/chimeric antigen receptor-T cells (TCs) is advanced in recent years; however, the efficacy is still limited, and major challenges remain in terms of safety and cell supply. To solve the issues of adoptive immunotherapy, we utilized induced pluripotent stem cells (iPSCs), which have an unlimited proliferative ability and various differentiation capability. First, we monoclonally isolated CD8+ TCs specifically reactive with NY-ESO-1, one of tumor antigens, from the melanoma patient's monocytes after stimulated with NY-ESO-1 peptide by manual procedure, and cultured NY-ESO-1-specific TCs until proliferated and formed colonies. iPSCs were consequently generated from colony-forming TCs by exogenous expression of reprogramming factors using Sendai virus vector. After the RAG2 gene in TC-derived iPSCs (T-iPSCs) was knocked out for preventing T-cell receptor (TCR) rearrangement, T-iPSCs were re-differentiated into rejuvenated cytotoxic TCs. We confirmed that TCR of T-iPSC-derived TC was maintained as the same of original TCs. In conclusion, T-iPSCs have a potential to be an unlimited cell source for providing cytotoxic TCs. Our study could be a "touchstone" to develop iPSC-based adoptive immunotherapy for the treatment of melanoma for the future clinical use.

Controlled release of adeno-associated virus from alginate hydrogel microbeads with enhanced sensitivity to ultrasound.

Adeno-associated virus (AAV)-based gene therapy holds promise as a fundamental treatment for genetic disorders. For clinical applications, it is necessary to control AAV release timing to avoid an immune response to AAV. Here we propose an ultrasound (US)-triggered on-demand AAV release system using alginate hydrogel microbeads (AHMs) with a release enhancer. By using a centrifuge-based microdroplet shooting device, the AHMs encapsulating AAV with tungsten microparticles (W-MPs) are fabricated. Since W-MPs work as release enhancers, the AHMs have high sensitivity to the US with localized variation in acoustic impedance for improving the release of AAV. Furthermore, AHMs were coated with poly-l-lysine (PLL) to adjust the release of AAV. By applying US to the AAV encapsulating AHMs with W-MPs, the AAV was released on demand, and gene transfection to cells by AAV was confirmed without loss of AAV activity. This proposed US-triggered AAV release system expands methodological possibilities in gene therapy.

Embryonic kidney function in a chronic renal failure model in rodents.

BACKGROUND: Rapid advancements have been made in alternative treatments for renal diseases. Our goal for renal regeneration is to establish a kidney graft derived from human embryonic tissues. In this study, we investigated the effects of host renal failure on the structure and activity of transplanted embryonic kidney and bladder, and found that diuretics effectively induced urine production in the transplanted kidney. METHODS: Uremic conditions were reproduced using a 5/6 renal infarction rat model. An embryonic kidney plus bladder (embryonic day 15) was isolated from a pregnant Lewis rat and transplanted into the para-aortic area of a 5/6 renal-infarcted Lewis rat. Following growth, the embryonic bladder was successfully anastomosed to the host ureter. RESULTS: We assessed graft function in terms of survival rates and found no differences between normal (n = 5) and renal failure (n = 8) groups (median survival: 70.5 vs 74.5 h; p = 0.331) in terms of survival, indicating that the grafts prolonged rat survival, even under renal failure conditions. Furosemide (n = 9) significantly increased urine volume compared with saline-treated controls (n = 7; p < 0.05), confirming that the grafts were functional. We also demonstrated the possibilities of an in vivo imaging system for determining the viability of transplanted embryonic kidney with bladder. CONCLUSION: The results of this study demonstrate that transplanted embryonic kidney and bladder can grow and function effectively, even under uremic conditions.

Alternative role of HuD splicing variants in neuronal differentiation.

HuD is a neuronal RNA-binding protein that plays an important role in neuronal differentiation of the nervous system. HuD has been reported to have three RNA recognition motifs (RRMs) and three splice variants (SVs) that differ in their amino acid sequences between RRM2 and RRM3. This study investigates whether these SVs have specific roles in neuronal differentiation. In primary neural epithelial cells under differentiating conditions, HuD splice variant 1 (HuD-sv1), which is a general form, and HuD-sv2 were expressed at all tested times, whereas HuD-sv4 was transiently expressed at the beginning of differentiation, indicating that HuD-sv4 might play a role compared different from that of HuD-sv1. Indeed, HuD-sv4 did not promote neuronal differentiation in epithelial cells, whereas HuD-sv1 did promote neuronal differentiation. HuD-sv4 overexpression showed less neurite-inducing activity than HuD-sv1 in mouse neuroblastoma N1E-115 cells; however, HuD-sv4 showed stronger growth-arresting activity. HuD-sv1 was localized only in the cytoplasm, whereas HuD-sv4 was localized in both the cytoplasm and the nuclei. The Hu protein has been reported to be involved in translation and alternative splicing in the cytoplasm and nuclei, respectively. Consistent with this observation, HuD-sv1 showed translational activity on p21, which plays a role in growth arrest and neuronal differentiation, whereas HuD-sv4 did not. By contrast, HuD-sv4 showed stronger pre-mRNA splicing activity than did HuD-sv1 on Clasp2, which participates in cell division. Therefore, HuD SVs might play a role in controlling the timing of proliferation/differentiation switching by controlling the translation and alternative splicing of target genes.

Structural MRI analysis of age-related changes and sex differences in marmoset brain volume.

The field of aging biology, which aims to extend healthy lifespans and prevent age-related diseases, has turned its focus to the Callithrix jacchus (common marmoset) to understand the aging process better. This study utilized magnetic resonance imaging (MRI) to non-invasively analyze the brains of 216 marmosets, investigating age-related changes in brain structure; the relationship between body weight and brain volume; and potential differences between males and females. The key findings revealed that, similar to humans, Callithrix jacchus experiences a reduction in total intracranial volume, cortex, subcortex, thalamus, and cingulate volumes as they age, highlighting site-dependent changes in brain tissue. Notably, the study also uncovered sex differences in cerebellar volume. These insights into the structural connectivity and volumetric changes in the marmoset brain throughout aging contribute to accumulating valuable knowledge in the field, promising to inform future aging research and interventions for enhancing healthspan.

Sox21 promotes hippocampal adult neurogenesis via the transcriptional repression of the Hes5 gene.

Despite the importance of the production of new neurons in the adult hippocampus, the transcription network governing this process remains poorly understood. The High Mobility Group (HMG)-box transcription factor, Sox2, and the cell surface activated transcriptional regulator, Notch, play important roles in CNS stem cells. Here, we demonstrate that another member of the SoxB (Sox1/Sox2/Sox3) transcription factor family, Sox21, is also a critical regulator of adult neurogenesis in mouse hippocampus. Loss of Sox21 impaired transition of progenitor cells from type 2a to type 2b, thereby reducing subsequent production of new neurons in the adult dentate gyrus. Analysis of the Sox21 binding sites in neural stem/progenitor cells indicated that the Notch-responsive gene, Hes5, was a target of Sox21. Sox21 repressed Hes5 gene expression at the transcriptional level. Simultaneous overexpression of Hes5 and Sox21 revealed that Hes5 was a downstream effector of Sox21 at the point where the Notch and Sox pathways intersect to control the number of neurons in the adult hippocampus. Therefore, Sox21 controls hippocampal adult neurogenesis via transcriptional repression of the Hes5 gene.

Xenotransplanted embryonic kidney provides a niche for endogenous mesenchymal stem cell differentiation into erythropoietin-producing tissue.

Recent findings have demonstrated that stem cells can differentiate into mature tissue when supplied with a niche containing factors identical to those in the normal developmental program. A niche for the development of an organ can be provided by xenotransplantation of a similar developing organ. However, this process has many technical, safety, and ethical concerns. Here, we established xenotransplantation models that control endogenous mesenchymal stem cell (MSC) differentiation into mature erythropoietin (EPO)-producing tissue in a niche provided by a developing xenometanephros. Transplantation of rat metanephroi into mouse omentum, and similarly pig metanephroi into cat omentum, led to the recruitment of host cells and EPO production. EPO-expressing cells were not differentiated from integrating vessels because they did not coexpress endothelial markers (Tie-2 and VE-cadherin). Instead, EPO-expressing cells were shown to be derived from circulating host cells, as shown by enhanced green fluorescent protein (EGFP) expression in the grown transplants of chimeric mice bearing bone marrow from a transgenic mouse expressing EGFP under the control of the EPO promoter. These results suggest that donor cell recruitment and differentiation in a xenotransplanted developing organ may be consistent between species. The cells responsible for EPO expression were identified as MSCs by injecting human bone marrow-derived MSCs and endothelial progenitor cells into NOD/SCID mice. Furthermore, using metanephroi from transgenic ER-E2F1 suicide-inducible mice, the xenotissue component could be eliminated, leaving autologous EPO-producing tissue. Our findings may alleviate adverse effects due to long-lasting immunosuppression and help mitigate ethical concerns.

A Novel Rat Model of Embolic Cerebral Ischemia Using a Cell-Implantable Radiopaque Hydrogel Microfiber.

The failure of neuroprotective treatment-related clinical trials, including stem cell therapies, may be partially due to a lack of suitable animal models. We have developed a stem cell-implantable radiopaque hydrogel microfiber that can survive for a long time in vivo. The microfiber is made of barium alginate hydrogel containing zirconium dioxide, fabricated in a dual coaxial laminar flow microfluidic device. We aimed to develop a novel focal stroke model using this microfiber. Using male Sprague-Dawley rats (n=14), a catheter (inner diameter, 0.42 mm; outer diameter, 0.55 mm) was navigated from the caudal ventral artery to the left internal carotid artery using digital subtraction angiography. A radiopaque hydrogel microfiber (diameter, 0.4 mm; length, 1 mm) was advanced through the catheter by slow injection of heparinized physiological saline to establish local occlusion. Both 9.4-T magnetic resonance imaging at 3 and 6 h and 2% 2,3,5-triphenyl tetrazolium chloride staining at 24 h after stroke model creation were performed. Neurological deficit score and body temperature were measured. The anterior cerebral artery-middle cerebral artery bifurcation was selectively embolized in all rats. Median operating time was 4 min (interquartile range [IQR], 3-8 min). Mean infarct volume was 388 mm3 (IQR, 354-420 mm3) at 24 h after occlusion. No infarction of the thalamus or hypothalamus was seen. Body temperature did not change significantly over time (P = 0.204). However, neurological deficit scores before and at 3, 6, and 24 h after model creation differed significantly (P < 0.001). We present a novel rat model of focal infarct restricted to the middle cerebral artery territory using a radiopaque hydrogel microfiber positioned under fluoroscopic guidance. By comparing the use of stem cell-containing versus non-containing fibers in this stroke model, it would be possible to determine the efficacy of "pure" cell transplantation in treating stroke.

Specific vulnerability of iPSC-derived motor neurons with TDP-43 gene mutation to oxidative stress.

Amyotrophic lateral sclerosis (ALS) is a disease that affects motor neurons and has a poor prognosis. We focused on TAR DNA-binding protein 43 kDa (TDP-43), which is a common component of neuronal inclusions in many ALS patients. To analyze the contribution of TDP-43 mutations to ALS in human cells, we first introduced TDP-43 mutations into healthy human iPSCs using CRISPR/Cas9 gene editing technology, induced the differentiation of these cells into motor and sensory neurons, and analyzed factors that are assumed to be altered in or associated with ALS (cell morphology, TDP-43 localization and aggregate formation, cell death, TDP-43 splicing function, etc.). We aimed to clarify the pathological alterations caused solely by TDP-43 mutation, i.e., the changes in human iPSC-derived neurons with TDP-43 mutation compared with those with the same genetic background except TDP-43 mutation. Oxidative stress induced by hydrogen peroxide administration caused the death of TDP-43 mutant-expressing motor neurons but not in sensory neurons, indicating the specific vulnerability of human iPSC-derived motor neurons with TDP-43 mutation to oxidative stress. In our model, we observed aggregate formation in a small fraction of TDP-43 mutant-expressing motor neurons, suggesting that aggregate formation seems to be related to ALS pathology but not the direct cause of cell death. This study provides basic knowledge for elucidating the pathogenesis of ALS and developing treatments for the disease.

Developmental changes in brain activity of heterozygous Scn1a knockout rats.

Introduction: Dravet syndrome (DS) is an infantile-onset developmental and epileptic encephalopathy characterized by an age-dependent evolution of drug-resistant seizures and poor developmental outcomes. Functional impairment of gamma-aminobutyric acid (GABA)ergic interneurons due to loss-of-function mutation of SCN1A is currently considered the main pathogenesis. In this study, to better understand the age-dependent changes in the pathogenesis of DS, we characterized the activity of different brain regions in Scn1a knockout rats at each developmental stage. Methods: We established an Scn1a knockout rat model and examined brain activity from postnatal day (P) 15 to 38 using a manganese-enhanced magnetic resonance imaging technique (MEMRI). Results: Scn1a heterozygous knockout (Scn1a +/-) rats showed a reduced expression of voltage-gated sodium channel alpha subunit 1 protein in the brain and heat-induced seizures. Neural activity was significantly higher in widespread brain regions of Scn1a +/- rats than in wild-type rats from P19 to P22, but this difference did not persist thereafter. Bumetanide, a Na+-K+-2Cl- cotransporter 1 inhibitor, mitigated hyperactivity to the wild-type level, although no change was observed in the fourth postnatal week. Bumetanide also increased heat-induced seizure thresholds of Scn1a +/- rats at P21. Conclusions: In Scn1a +/- rats, neural activity in widespread brain regions increased during the third postnatal week, corresponding to approximately 6 months of age in humans, when seizures most commonly develop in DS. In addition to impairment of GABAergic interneurons, the effects of bumetanide suggest a possible contribution of immature type A gamma-aminobutyric acid receptor signaling to transient hyperactivity and seizure susceptibility during the early stage of DS. This hypothesis should be addressed in the future. MEMRI is a potential technique for visualizing changes in basal brain activity in developmental and epileptic encephalopathies.

Interactive effect of orthostatic hypotension on gray matter atrophy associated with hyposmia and RBD in de novo Parkinson's disease.

BACKGROUND: Orthostatic hypotension (OH) is a potential modifiable risk factor for cognitive impairment in patients with Parkinson's disease (PD). Although other risk factors for dementia, hyposmia and REM sleep behavior disorder (RBD), are closely associated with autonomic dysfunction in PD, little is known about how these risk factors influence cognitive function and cerebral pathology. OBJECTIVE: We investigated how these three factors contribute to gray matter atrophy by considering the interaction of OH with hyposmia and RBD. METHODS: We analyzed cortical thickness, subcortical gray matter volume, and cognitive measures from 78 patients with de novo PD who underwent the head-up tilt test for the diagnosis of OH. RESULTS: Whole-brain analyses with Monte Carlo corrections revealed that hyposmia was associated with decreased cortical thickness in a marginal branch of the cingulate sulcus among patients with OH, and cortical thickness in this area correlated with cognitive functioning only in patients with OH. Subcortical gray matter volume analysis indicated that severe RBD was associated with decreased volume in the left hippocampus and bilateral amygdala among patients with OH. CONCLUSION: Even in early PD, OH exerts effects on gray matter atrophy and cognitive dysfunction by interacting with RBD and hyposmia. OH might exacerbate cerebral pathology induced by hyposmia or RBD.

Multi-modal brain magnetic resonance imaging database covering marmosets with a wide age range.

Magnetic resonance imaging (MRI) is a non-invasive neuroimaging technique that is useful for identifying normal developmental and aging processes and for data sharing. Marmosets have a relatively shorter life expectancy than other primates, including humans, because they grow and age faster. Therefore, the common marmoset model is effective in aging research. The current study investigated the aging process of the marmoset brain and provided an open MRI database of marmosets across a wide age range. The Brain/MINDS Marmoset Brain MRI Dataset contains brain MRI information from 216 marmosets ranging in age from 1 and 10 years. At the time of its release, it is the largest public dataset in the world. It also includes multi-contrast MRI images. In addition, 91 of 216 animals have corresponding high-resolution ex vivo MRI datasets. Our MRI database, available at the Brain/MINDS Data Portal, might help to understand the effects of various factors, such as age, sex, body size, and fixation, on the brain. It can also contribute to and accelerate brain science studies worldwide.

Conditions for quantitative evaluation of injured spinal cord by in vivo diffusion tensor imaging and tractography: preclinical longitudinal study in common marmosets.

Conventional magnetic resonance imaging (MRI) can detect hemorrhage, edema, syrinx, and spinal cord atrophy, but not axonal disruption after spinal cord injury (SCI). We previously demonstrated that diffusion tensor tractography (DTT) could depict axonal disruption after hemisection SCI in common marmosets. In the present study, to determine the relationship between DTT results and functional recovery after contusive SCI, we performed longitudinal DTT, behavioral, and histological analyses before and after contusive SCI in common marmosets. By comparing the tract fiber estimate depicted by DTT with neuronal fibers labeled with RT97 and SMI-31, anti-neurofilament antibodies, we determined the optimal fractional anisotropy (FA) threshold for fiber tracking to be 0.40. The ratio of the number of tract fiber estimates at the lesion site to the number before SCI, determined by DTT, was significantly correlated with the functional recovery after SCI. Moreover, comparison of the longitudinal pre- and post-SCI FA and axial diffusivity (λ(‖)) values revealed that they decreased after injury at the sites caudal to the lesion epicenter in the corticospinal tract and rostral to the lesion epicenter in the dorsal column. The FA values, then, showed partial recovery in the dorsal column. FA-value-oriented color DTT was used to represent axonal sparing or regeneration of the different tracts. These findings indicated that DTT analysis might be a versatile non-invasive tool for evaluating the axonal disruption after SCI.

Bioluminescent system for dynamic imaging of cell and animal behavior.

The current utility of bioluminescence imaging is constrained by a low photon yield that limits temporal sensitivity. Here, we describe an imaging method that uses a chemiluminescent/fluorescent protein, ffLuc-cp156, which consists of a yellow variant of Aequorea GFP and firefly luciferase. We report an improvement in photon yield by over three orders of magnitude over current bioluminescent systems. We imaged cellular movement at high resolution including neuronal growth cones and microglial cell protrusions. Transgenic ffLuc-cp156 mice enabled video-rate bioluminescence imaging of freely moving animals, which may provide a reliable assay for drug distribution in behaving animals for pre-clinical studies.

Molecular signatures to define spermatogenic cells in common marmoset (Callithrix jacchus).

Germ cell development is a fundamental process required to produce offspring. The developmental program of spermatogenesis has been assumed to be similar among mammals. However, recent studies have revealed differences in the molecular properties of primate germ cells compared with the well-characterized mouse germ cells. This may prevent simple application of rodent insights into higher primates. Therefore, thorough investigation of primate germ cells is necessary, as this may lead to the development of more appropriate animal models. The aim of this study is to define molecular signatures of spermatogenic cells in the common marmoset, Callithrix jacchus. Interestingly, NANOG, PRDM1, DPPA3 (STELLA), IFITM3, and ZP1 transcripts, but no POU5F1 (OCT4), were detected in adult marmoset testis. Conversely, mouse testis expressed Pou5f1 but not Nanog, Prdm1, Dppa3, Ifitm3, and Zp1. Other previously described mouse germ cell markers were conserved in marmoset and mouse testes. Intriguingly, marmoset spermatogenic cells underwent dynamic protein expression in a developmental stage-specific manner; DDX4 (VASA) protein was present in gonocytes, diminished in spermatogonial cells, and reexpressed in spermatocytes. To investigate epigenetic differences between adult marmoset and mice, DNA methylation analyses identified unique epigenetic profiles to marmoset and mice. Marmoset NANOG and POU5F1 promoters in spermatogenic cells exhibited a methylation status opposite to that in mice, while the DDX4 and LEFTY1 loci, as well as imprinted genes, displayed an evolutionarily conserved methylation pattern. Marmosets have great advantages as models for human reproductive biology and are also valuable as experimental nonhuman primates; thus, the current study provides an important platform for primate reproductive biology, including possible applications to humans.

Significance of remyelination by neural stem/progenitor cells transplanted into the injured spinal cord.

Previous reports of functional recovery from spinal cord injury (SCI) in rodents and monkeys after the delayed transplantation of neural stem/progenitor cells (NS/PCs) have raised hopes that stem cell therapy could be used to treat SCI in humans. More research is needed, however, to understand the mechanism of functional recovery. Oligodendrocytes derived from grafted NS/PCs remyelinate spared axons in the injured spinal cord. Here, we studied the extent of this remyelination's contribution to functional recovery following contusive SCI in mice. To isolate the effect of remyelination from other possible regenerative benefits of the grafted cells, NS/PCs obtained from myelin-deficient shiverer mutant mice (shi-NS/PCs) were used in this work alongside wild-type NS/PCs (wt-NS/PCs). shi-NS/PCs behaved like wt-NS/PCs in vitro and in vivo, with the exception of their myelinating potential. shi-NS/PC-derived oligodendrocytes did not express myelin basic protein in vitro and formed much thinner myelin sheaths in vivo compared with wt-NS/PC-derived oligodendrocytes. The transplantation of shi-NS/PCs promoted some locomotor and electrophysiological functional recovery but significantly less than that afforded by wt-NS/PCs. These findings establish the biological importance of remyelination by graft-derived cells for functional recovery after the transplantation of NS/PCs into the injured spinal cord.

The disruption of Sox21-mediated hair shaft cuticle differentiation causes cyclic alopecia in mice.

Hair is maintained through a cyclic process that includes periodic regeneration of hair follicles in a stem cell-dependent manner. Little is known, however, about the cellular and molecular mechanisms that regulate the layered differentiation of the hair follicle. We have established a mutant mouse with a cyclic alopecia phenotype resulting from the targeted disruption of Sox21, a gene that encodes a HMG-box protein. These mice exhibit progressive hair loss after morphogenesis of the first hair follicle and become completely nude in appearance, but then show hair regrowth. Sox21 is expressed in the cuticle layer and the progenitor cells of the hair shaft in both mouse and human. The lack of this gene results in a loss of the interlocking structures required for anchoring the hair shaft in the hair follicle. Furthermore, the expression of genes encoding the keratins and keratin binding proteins in the hair shaft cuticle are also specifically down-regulated in the Sox21-null mouse. These results indicate that Sox21 is a master regulator of hair shaft cuticle differentiation and shed light on the possible causes of human hair disorders.