Dissecting reactive astrocyte responses: lineage tracing and morphology-based clustering.

Brain damage triggers diverse cellular and molecular events, with astrocytes playing a crucial role in activating local neuroprotective and reparative signaling within damaged neuronal circuits. Here, we investigated reactive astrocytes using a multidimensional approach to categorize their responses into different subtypes based on morphology. This approach utilized the StarTrack lineage tracer, single-cell imaging reconstruction and multivariate data analysis.

Inflammatory Response and Defects on Myelin Integrity in the Olfactory System of K18hACE2 Mice Infected with SARS-CoV-2.

Viruses, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), use respiratory epithelial cells as an entry point for infection. Within the nasal cavity, the olfactory epithelium (OE) is particularly sensitive to infections which may lead to olfactory dysfunction. In patients suffering from coronavirus disease 2019, deficits in olfaction have been characterized as a distinctive symptom.

Microglia Maintain Homeostatic Conditions in the Developing Rostral Migratory Stream.

Microglia invade the neuroblast migratory corridor of the rostral migratory stream (RMS) early in development. The early postnatal RMS does not yet have the dense astrocyte and vascular scaffold that helps propel forward migrating neuroblasts, which led us to consider whether microglia help regulate conditions permissive to neuroblast migration in the RMS. GFP-labeled microglia in mice assemble primarily along the outer borders of the RMS during the first postnatal week, where they exhibit predominantly an ameboid morphology and associate with migrating neuroblasts.

α-Synuclein Pathology and Reduced Neurogenesis in the Olfactory System Affect Olfaction in a Mouse Model of Parkinson's Disease.

Parkinson's disease (PD) is characterized by multiple symptoms including olfactory dysfunction, whose underlying mechanisms remain unclear. Here, we explored pathologic changes in the olfactory pathway of transgenic (Tg) mice of both sexes expressing the human A30P mutant α-synuclein (α-syn; α-syn-Tg mice) at 6-7 and 12-14 months of age, representing early and late-stages of motor progression, respectively. α-Syn-Tg mice at late stages exhibited olfactory behavioral deficits, which correlated with severe α-syn pathology in projection neurons (PNs) of the olfactory pathway.

Sequential Maturation of Olfactory Sensory Neurons in the Mature Olfactory Epithelium.

The formation of the olfactory nerve and olfactory bulb (OB) glomeruli begins embryonically in mice. However, the development of the olfactory system continues throughout life with the addition of new olfactory sensory neurons (OSNs) in the olfactory epithelium (OE). Much attention has been given to the perinatal innervation of the OB by OSN axons, but in the young adult the process of OSN maturation and axon targeting to the OB remains controversial.

Embryonic and postnatal development of mouse olfactory tubercle.

The olfactory tubercle (OT) is located in the ventral-medial region of the brain where it receives primary input from olfactory bulb (OB) projection neurons and processes olfactory behaviors related to motivation, hedonics of smell and sexual encounters. The OT is part of the dopamine reward system that shares characteristics with the striatum. Together with the nucleus accumbens, the OT has been referred to as the "ventral striatum".

Development of piriform cortex interhemispheric connections via the anterior commissure: progressive and regressive strategies.

The anterior commissure (AC) is a phylogenetically conserved inter-hemispheric connection found among vertebrates with bilateral symmetry. The AC connects predominantly olfactory areas but many aspects of its development and structure are unknown. To fill this gap, we investigated the embryonic and postnatal development of the AC by tracing axons with DiI and the piggyback transposon multicolor system.

The Laminar Organization of Piriform Cortex Follows a Selective Developmental and Migratory Program Established by Cell Lineage.

Piriform cortex (PC) is a 3-layer paleocortex receiving primary afferent input from the olfactory bulb. The past decade has seen significant progress in understanding the synaptic, cellular and functional organization of PC, but PC embryogenesis continues to be enigmatic. Here, using birthdating strategies and clonal analyses, we probed the early development and laminar specificity of neurogenesis/gliogenesis as it relates to the organization of the PC.

Changes in the regulation of the Notch signaling pathway are temporally correlated with regenerative failure in the mouse cochlea.

Sensorineural hearing loss is most commonly caused by the death of hair cells in the organ of Corti, and once lost, mammalian hair cells do not regenerate. In contrast, other vertebrates such as birds can regenerate hair cells by stimulating division and differentiation of neighboring supporting cells. We currently know little of the genetic networks which become active in supporting cells when hair cells die and that are activated in experimental models of hair cell regeneration.

Clonal astrocytic response to cortical injury.

Astrocytes are a heterogeneous population of glial cells with multifaceted roles in the central nervous system. Recently, the new method for the clonal analysis Star Track evidenced the link between astrocyte heterogeneity and lineage. Here, we tested the morphological response to mechanical injury of clonally related astrocytes using the Star Track approach, which labels each cell lineage with a specific code of colors.

Agar-based bridges as biocompatible candidates to provide guide cues in spinal cord injury repair.

Background: Spinal bridge implants are strategic to provide growth surfaces for axonal regeneration after spinal cord injuries. The design of an appropriate substrate, one that is suitable for implantation, must involve careful testing of the biomaterial properties both in vitro and in vivo.

Objective: The goal of this work was to test the structure, stability and biological response after spinal bridges implantation of several biopolymers, composed of mixtures of agar (AG), as structural matrix scaffold, with κ-carrageenan (Kc), gelatin (G), xanthan gum (Xn) and polysulfone (PS).

Influence of chitosan concentration on cell viability and proliferation in vitro by changing film topography.

Purpose: Chitosan is a natural polysaccharide which can form gels and scaffolds that support its use as a biomaterial in various tissue engineering applications. A useful feature of chitosan polymer is that you can manipulate its properties easily. Thus, in this work we studied the effect of varying chitosan concentration in the topography and the biological properties of the chitosan films, as well as the effects in the structure of 3D gels in order to be used as nerve bridges.

Postnatal characterization of cells in the accessory olfactory bulb of wild type and reeler mice.

Olfaction is the most relevant chemosensory sense of the rodents. General odors are primarily detected by the main olfactory system while most pheromonal signals are received by the accessory olfactory system. The first relay in the brain occurs in the olfactory bulb, which is subdivided in the main and accessory olfactory bulb (MOB/AOB).

Dab1 (Disable homolog-1) reelin adaptor protein is overexpressed in the olfactory bulb at early postnatal stages.

Dab1 mediates reelin signalling and plays critical roles in early brain development such as the stereotypical positioning of neurons in the brain. The olfactory bulb undergoes a prominent layering reorganization, but shows not apparent differences between wild type and reeler in the layer organization. Therefore, an accurate regional and cellular simultaneous analysis of these molecules becomes essential to clarify the role played by Dab1 upon Reelin effect.

Chitosan, gelatin and poly(L-lysine) polyelectrolyte-based scaffolds and films for neural tissue engineering.

Biomaterial implants are a promising strategy to replace neural tissue that is lost after traumatic nerve damage. Chitosan (Ch) is a suitable material for nerve implantation when it is used at a minimum amount of 2% (w/v). The goal of this study was to determine the best mixture of 2% Ch with gelatin (G) and poly(L-lysine) (PLL) for use in neural tissue engineering.

Differential adhesiveness and neurite-promoting activity for neural cells of chitosan, gelatin, and poly-L-lysine films.

Chitosan (Ch) and some of its derivatives have been proposed as good biomaterials for tissue engineering, to construct scaffolds promoting tissue regeneration. In this work we made composite films from Ch and mixtures of Ch with gelatin (G) and poly-l-lysine (PLL), and evaluated the growth on these films of PC12 and C6 lines as well as neurons and glial cells derived from cerebral tissue and dorsal root ganglia (DRG). C6 glioma cells proliferated on Ch, G, and Ch + G films, although metabolic activity was decreased by the presence of the G in the mixtures.

Gelation under dynamic conditions: a strategy for in vitro cell ordering.

Ordered gelation under spin-coating conditions, as reported here, is a suitable method to order cells in biogels. Cell ordering is of great importance for functional repair of central nervous system (CNS) injuries, because therapies must include strategies to bridge chystic gaps and facilitate axon growth towards its target. Organized biocompatible and biodegradable substrates may be used for this purpose, to supply trophic support and provide directional cues for neuronal process outgrowth.