Imaging and Recording Subventricular Zone Progenitor Cells in Live Tissue of Postnatal Mice

The subventricular zone (SVZ) is one of two regions where neurogenesis persists in the postnatal brain. The SVZ, located along the lateral ventricle, is the largest neurogenic zone in the brain that contains multiple cell populations including astrocyte-like cells and neuroblasts. Neuroblasts migrate in chains to the olfactory bulb where they differentiate into interneurons. Here, we discuss the experimental approaches to record the electrophysiology of these cells and image their migration and calcium activity in acute slices. Although these techniques were in place for studying glial cells and neurons in mature networks, the SVZ raises new challenges due to the unique properties of SVZ cells, the cellular diversity, and the architecture of the region. We emphasize different methods, such as the use of transgenic mice and in vivo electroporation that permit identification of the different SVZ cell populations for patch clamp recording or imaging. Electroporation also permits genetic labeling of cells using fluorescent reporter mice and modification of the system using either RNA interference technology or floxed mice. In this review, we aim to provide conceptual and technical details of the approaches to perform electrophysiological and imaging studies of SVZ cells

Dissociation between short-term increased graft survival and long-term functional improvements in Parkinsonian rats overexpressing glial cell line-derived neurotrophic factor.

The present study was designed to analyse whether continuous overexpression of glial cell line-derived neurotrophic factor (GDNF) in the striatum by a recombinant lentiviral vector can provide improved cell survival and additional long-term functional benefits after transplantation of fetal ventral mesencephalic cells in Parkinsonian rats. A four-site intrastriatal 6-hydroxydopamine lesion resulted in an 80–90% depletion of nigral dopamine cells and striatal fiber innervation, leading to stable motor impairments. Histological analysis performed at 4 weeks after grafting into the GDNF-overexpressing striatum revealed a twofold increase in the number of surviving tyrosine hydroxylase (TH)-positive cells, as compared with grafts placed in control (green fluorescent protein-overexpressing) animals. However, in animals that were allowed to survive for 6 months, the numbers of surviving TH-positive cells in the grafts were equal in both groups, suggesting that the cells initially protected at 4 weeks failed to survive despite the continued presence of GDNF. Although cell survival was similar in both grafted groups, the TH-positive fiber innervation density was lower in the GDNF-treated grafted animals (30% of normal) compared with animals with control grafts (55% of normal). The vesicular monoamine transporter-2-positive fiber density in the striatum, by contrast, was equal in both groups, suggesting that long-term GDNF overexpression induced a selective down-regulation of TH in the grafted dopamine neurons. Behavioral analysis in the long-term grafted animals showed that the control grafted animals improved their performance in spontaneous motor behaviors to approximately 50% of normal, whereas the GDNF treatment did not provide any additional recovery

S phase entry of neural progenitor cells correlates with increased blood flow in the young subventricular zone.

The postnatal subventricular zone (SVZ) contains proliferating neural progenitor cells in close proximity to blood vessels. Insults and drug treatments acutely stimulate cell proliferation in the SVZ, which was assessed by labeling cells entering S phase. Although G1-to-S progression is metabolically demanding on a minute-to-hour time scale, it remains unknown whether increased SVZ cell proliferation is accompanied by a local hemodynamic response. This neurovascular coupling provides energy substrates to active neuronal assemblies. Transcardial dye perfusion revealed the presence of capillaries throughout the SVZ that constrict upon applications of the thromboxane A(2) receptor agonist U-46119 in acute brain slice preparations. We then monitored in vivo blood flow using laser Doppler flowmetry via a microprobe located either in the SVZ or a mature network. U-46119 injections into the lateral ventricle decreased blood flow in the SVZ and the striatum, which are near the ventricle. A 1-hour ventricular injection of epidermal and basic fibroblast growth factor (EGF and bFGF) significantly increased the percentage of Sox2 transcription factor-positive cells in S phase 1.5 hours post-injection. This increase was accompanied by a sustained rise in blood flow in the SVZ but not in the striatum. Direct growth factor injections into the cortex did not alter local blood flow, ruling out direct effects on capillaries. These findings suggest that an acute increase in the number of G1-to-S cycling SVZ cells is accompanied by neurometabolic-vascular coupling, which may provide energy and nutrient for cell cycle progression

Automatic extraction of social determinants of health from medical notes of chronic lower back pain patients.

OBJECTIVE: We applied natural language processing and inference methods to extract social determinants of health (SDoH) information from clinical notes of patients with chronic low back pain (cLBP) to enhance future analyses of the associations between SDoH disparities and cLBP outcomes. MATERIALS AND METHODS: Clinical notes for patients with cLBP were annotated for 7 SDoH domains, as well as depression, anxiety, and pain scores, resulting in 626 notes with at least one annotated entity for 364 patients. We used a 2-tier taxonomy with these 10 first-level classes (domains) and 52 second-level classes. We developed and validated named entity recognition (NER) systems based on both rule-based and machine learning approaches and validated an entailment model. RESULTS: Annotators achieved a high interrater agreement (Cohens kappa of 95.3% at document level). A rule-based system (cTAKES), RoBERTa NER, and a hybrid model (combining rules and logistic regression) achieved performance of F1 = 47.1%, 84.4%, and 80.3%, respectively, for first-level classes. DISCUSSION: While the hybrid model had a lower F1 performance, it matched or outperformed RoBERTa NER model in terms of recall and had lower computational requirements. Applying an untuned RoBERTa entailment model, we detected many challenging wordings missed by NER systems. Still, the entailment model may be sensitive to hypothesis wording. CONCLUSION: This study developed a corpus of annotated clinical notes covering a broad spectrum of SDoH classes. This corpus provides a basis for training machine learning models and serves as a benchmark for predictive models for NER for SDoH and knowledge extraction from clinical texts

EGF and bFGF increases the number of G1-S cycling SVZ cells that express Sox2.

<p>(<b>A</b>) Grayscale image of EdU staining in the SVZ in coronal sections from animals that received growth factors (GF) or saline injections. (<b>B</b>) Bar graphs of the number of EdU⁺ cells per mm³ in the SVZ under different conditions (saline injection or GF injected in the ipsilateral (ipsi) ventricle). (<b>C</b>) % of control for the number of EdU⁺ cells in the ipsilateral versus contralateral (contra) SVZ. (<b>D</b>) Confocal photographs of EdU (green) and Sox2 (red) immunostaining. Arrows point to double-positive cells in the SVZ. (<b>E</b>) Bar graphs of the % of Sox2⁺ cells that were EdU⁺ under different conditions.</p

U-46119 decreases blood flow in the SVZ in vivo.

<p>(<b>A</b>) Image of a coronal section containing the SVZ (delineated by the dashed red line) and the track (black shadow) where the LDF microprobe was located. The blue circle highlights the recorded area. (<b>B and C</b>) Mean % change in blood flow (± SEM) against time that were obtained in the striatum (B) and SVZ (C) during and following U-46119 injections (1 µl, 100 nM, 20 s) into the lateral ventricle.</p

U-46119 constricts SVZ capillaries in acute slices.

<p>(<b>A</b>) Z-stack projection of GFAP staining (green, mature and SVZ astrocytes) and PECAM (red, blood vessels) in a horizontal section. The dashed lines encompass the SVZ. LV: lateral ventricle. (<b>B</b>) Texas Red (TR)-Dextran-filled vessels coursing through the SVZ in a live sagittal section. An arteriole (arrow) branches into capillaries. Note the presence of capillary branchpoints (arrowheads). <u>Inset</u>: zoom of the region delineated by the white rectangle in B. The white arrow points to the smooth muscle cells around the arteriole. (<b>C</b>) Z-stack projection of NG2 (green) and PECAM (red) immunofluorescence in a coronal section. NG2 cells on capillaries are pericytes (arrows). (<b>D</b>) Image of the capillary before (control) and during U-46119 (100 nM) application. The capillary was loaded with TR-Dextran through cardiac perfusion prior to slicing. The green arrows indicate the sites of constriction. (<b>E</b>) Mean % change in blood vessel diameters during and after U-46119 applications. Scale bars: 30 (A), 50 (B), 40 (C), and 15 µm (D).</p