Project description:There is emerging evidence that astrocytes exhibit molecular and cellular heterogeneity; however, whether distinct subpopulations perform these diverse roles remains poorly defined. Previous studies used Aldhl1l1 as a bulk astrocyte marker. Here we show that the Lunatic Fringe-GFP (Lfng-GFP) bacteria artificial chromosome mouse line specifically labels astrocyte populations within lamina III and IV of the dorsal spinal cord. We compared the transcriptional profile of Lfng-GFP+ astrocytes with Aldh1l1-GFP astrocytes to identify what is unique about the astrocyte population.
Project description:Human astrocytes have reported to reprogram into neurons, but they have yet to be induced to three-dimensional (3D) neural tissue for neural organogenesis. Here, we demonstrate a remarkable strategy for 3D organoid generation by direct reprogramming human astrocytes. By combining overexpression OCT4, suppression p53 and small molecules CHIR99021, SB431542, RepSox and Y27632, termed as Op53-CSBRY, we successfully reprogramed human astrocytes into neural ectodermal cells and further induced human 3D-brain organoid. Those organoids can be finally induced into spinal cord organoids by activating FGF, SHH and BMP signaling. The grafts of Human astrocyte derived spinal cord organoids (hADSC-Organs) can survived, differentiated into spinal cord neurons, migrated long distance, formed synaptic connectivity with host neurons, bridged complete injury spinal cord tissue in mice. This method indicates that human astrocytes could be directly triggered neural organogenesis, and may hold a great promising to support local astrocytes in situ organogenesis after brain damages, such as stroke and spinal cord injury.
Project description:We conducted snRNAseq of mouse astrocytes after traumatic spinal cord injury (SCI). These data reveal transcriptomic similarities and differences among astrocytes in healthy spinal cord and after spinal cord injury.
Project description:Spinal cord injury (SCI) is a common but devastating trauma of the central nerve system. In this study, we reprogrammed cultured spinal-cord reactive astrocytes into neurons by Neurod1 expression. The mechanism of programmed conversion from astrocytes to neurons has not been clarified yet. Thus, we used label-free proteomics to identify differentially expressed proteins in Neurod1 over-expressed astrocytes and control group. A total of 1952 proteins were identified, including 92 significantly changed proteins. Among these proteins, 8 proteins were identified as candidates involving in the process of the reprogramming, based on their biological function and fold change in the bioinformatic analysis. Our study revealed that that Neurod1 can directly reprogram cultured spinal-cord reactive astrocytes into neurons, and several proteins that could play a significant role during the neuronal reprogramming were discovered.
Project description:The goal of this study is to determine gene expression changes in the adult zebrafish spinal cord at 2 weeks after complete transection.
Project description:Adult zebrafish have the ability to recover from spinal cord injury and exhibit re-growth of descending axons from the brainstem to the spinal cord. We performed gene expression analysis using microarray to find damage-induced genes after spinal cord injury, which shows that Sox11b mRNA is up-regulated at 11 days after injury. However, the functional relevance of Sox11b for regeneration is not known. Here, we report that the up-regulation of Sox11b mRNA after spinal cord injury is mainly localized in ependymal cells lining the central canal and in newly differentiating neuronal precursors or immature neurons. Using an in vivo morpholino-based gene knockout approach, we demonstrate that Sox11b is essential for locomotor recovery after spinal cord injury. In the injured spinal cord, expression of the neural stem cell associated gene, Nestin, and the proneural gene Ascl1a (Mash1a), which are involved in the self-renewal and cell fate specification of endogenous neural stem cells, respectively, is regulated by Sox11b. Our data indicate that Sox11b promotes neuronal determination of endogenous stem cells and regenerative neurogenesis after spinal cord injury in the adult zebrafish. Enhancing Sox11b expression to promote proliferation and neurogenic determination of endogenous neural stem cells after injury may be a promising strategy in restorative therapy after spinal cord injury in mammals. Spinal cord injury or control sham injury was performed on adult zebrafish. After 4, 12, or 264 hrs, a 5 mm segment of spinal cord was dissected and processed (as a pool from 5 animals) in three replicate groups for each time point and treatment.
Project description:Astrocytes play many important functions in response to spinal cord injury (SCI) in an activated manner, including clearance of necrotic tissue, formation of protective barrier, maintenance of microenvironment balance, interaction with immune cells, and formation of the glial scar. More and more studies have shown that the astrocytes are heterogeneous, such as inflammatory astrocyte 1 (A1) and neuroprotective astrocyte 2 (A2) types. However, the subtypes of astrocyte resulting from SCI have not been clearly defined. In this study, using single-cell RNA sequencing, we constructed the transcriptomic profile of astrocytes from uninjured spinal cord tissue and nearby the lesion epicenter at 0.5, 1, 3, 7, 14, 60, and 90 days after mouse hemisection spinal cord tissue. Our analysis uncovered six transcriptionally distinct astrocyte states, including Atp1b2+, S100a4+, Gpr84+, C3+/G0s2+, GFAP+/Tm4sf1+, and Gss+/Cryab+ astrocytes. We used these new signatures combined with canonical astrocyte markers to determine the distribution of morphological and physiologically distinct for each astrocyte population at injured sites by immunofluorescence staining. Then we identified the dynamic evolution process of each astrocyte subtype following SCI. Finally, we also revealed the evolution of highly expressed genes in these astrocyte subtypes at different phases of SCI. Together, we provided six astrocyte subtypes at single-cell resolution following SCI. These data not only contribute to understanding the heterogeneity of astrocytes during SCI but also help to find new astrocyte subtypes as a target for SCI repair.
Project description:Neonatal spinal cord tissues exhibit remarkable regenerative capabilities than adult tissues after injury, but the role of extracellular matrix (ECM) in this process has remained elusive. Here we found that early developmental spinal cord had higher levels of ECM proteins associated with neural development and axon growth, but fewer inhibitory proteoglycans compared to adult spinal cord. Decellularized spinal cord ECM from neonatal (DNSCM) and adult (DASCM) rabbits preserved these differences. DNSCM promoted proliferation, migration, and neuronal differentiation of neural progenitor cells (NPCs), and facilitated axonal outgrowth and regeneration of spinal cord organoids than DASCM. Pleiotrophin (PTN) and Tenascin (TNC) in DNSCM were identified as contributors to these abilities. Furthermore, DNSCM demonstrated superior performance as a delivery vehicle for NPCs and organoids in rats with spinal cord injury (SCI). It suggests that ECM cues from early development stages might significantly contribute to the prominent regeneration ability in spinal cord.
Project description:Neural stem cells (NSCs) can be isolated from different regions of the central nervous system. There has been controversy whether regional differences amongst stem and progenitor cells are cell intrinsic and whether these differences are maintained during expansion in culture. The identification of inherent regional differences has important implications for the use of these cells in neural repair. Here, we compared neural stem cells derived from the spinal cord and embryonic cortex. We found that while cultured cortical and spinal cord derived neural stem cells respond similarly to mitogens and are equally neuronogenic, they retain and maintain through multiple passages gene expression patterns indicative of the region from which they were isolated. Further microarray analysis identified 229 genes that were differentially expressed between cortical and spinal cord derived neurospheres. Experiment Overall Design: Cortex and and spinal cords were isolated from embryonic day 14 cd1 mice and cultured ad neurospheres for 2 passages in EGF and bFGF. 3 independent sets of cultures serve as biological replicates with a dye flip control for each hybridization, for a total of 6 arrays.
Project description:Neonatal spinal cord tissues exhibit remarkable regenerative capabilities as compared to adult spinal cord tissues after injury, but the role of extracellular matrix (ECM) in this process has remained elusive. Here, we found that early developmental spinal cord had higher levels of ECMproteins associated with neural development and axon growth, but fewer inhibitory proteoglycans, compared to those of adult spinal cord. Decellularized spinal cord ECM from neonatal (DNSCM) and adult (DASCM) rabbits preserved these differences. DNSCM promoted proliferation, migration, and neuronal differentiation of neural progenitor cells (NPCs) and facilitated axonal outgrowth and regeneration of spinal cord organoids more effectively than DASCM. Pleiotrophin (PTN) and Tenascin (TNC) inDNSCMwere identified as contributors tothese abilities. Furthermore,DNSCMdemonstrated superior performance as a delivery vehicle forNPCs and organoids in spinal cord injury (SCI)models. This suggests that ECMcues from early development stages might significantly contribute to the prominent regeneration ability in spinal cord.