Neuroinflammation and neurodegeneration following traumatic brain injuries.

Traumatic brain injuries (TBI) commonly occur following head trauma. TBI may result in short- and long-term complications which may lead to neurodegenerative consequences, including cognitive impairment post-TBI. When investigating the neurodegeneration following TBI, studies have highlighted the role reactive astrocytes have in the neuroinflammation and degeneration process. This review showcases a variety of markers that show reactive astrocyte presence under pathological conditions, including glial fibrillary acidic protein (GFAP), Crystallin Alpha-B (CRYA-B), Complement Component 3 (C3) and S100A10. Astrocyte activation may lead to white-matter inflammation, expressed as white-matter hyperintensities. Other white-matter changes in the brain following TBI include increased cortical thickness in the white matter. This review addresses the gaps in the literature regarding post-mortem human studies focussing on reactive astrocytes, alongside the potential uses of these proteins as markers in the future studies that investigate the proportions of astrocytes in the post-TBI brain has been discussed. This research may benefit future studies that focus on the role reactive astrocytes play in the post-TBI brain and may assist clinicians in managing patients who have suffered TBI.

A comparative analysis of the CP and CG using 2D and 3D visualisation approaches.

Investigations on the structural variations in the cribriform plate (CP), olfactory foramina and the Crista Galli showcase the benefits of using 3D imaging on smaller structures. These techniques reveal accurate details about bone morphology and density. Comparing different techniques, this project aims to examine the correlation between the CP, olfactory foramina, and Crista Galli. Computed tomography was used to translate and apply the findings acquired from the samples in radiographic studies on CPs for potential clinical significance. The findings show that the surface area measurements were significantly larger when using 3D imaging techniques in comparison with the 2D counterpart. Using 2D imaging, the maximum surface area of the CPs was 239.54 mm2, however, paired 3D samples showed the maximum surface area was 355.51 mm2. The findings show that Crista Galli's dimensions varied greatly, with length ranging from 15 to 26 mm, height ranging from 5 to 18 mm, and width ranging from 2 to 7 mm. The 3D imaging allowed for surface area measurements on the Crista Galli, and the surface area ranged from 130 to 390 mm2. When 3D imaging was used, significant correlations were found between the surface area of the CP and the length of the Crista Galli (p = 0.001). The findings show that measurements on the Crista Galli using 2D and 3D reconstructed radiographic imaging reflect similar ranges of dimensions to 3D imaging measurements. The findings also suggest that the Crista Galli may increase in length with the CP to support the latter and olfactory bulb during trauma which may be used by clinicians alongside 2D CT scans for optimal diagnosis.

Percutaneous intrarenal transplantation of differentiated induced pluripotent stem cells into newborn mice.

The in vivo engraftment of induced pluripotent stem cell (iPSC)-derived podocytes following allogeneic transplantation into host kidneys remains a challenge. Here we investigate the survival and engraftment of human dermal fibroblasts-derived differentiated iPSCs using a newborn mouse model, which represents a receptive immunoprivileged host environment. iPSCs were generated from skin biopsies of patients using Sendai virus reprogramming. Differentiation of nephrin (NPHS1)-green fluorescent protein (GFP) iPSCs into kidney podocytes (iPSC-PODs) was performed by the addition of Activin A, bone morphogenetic protein 7 (BMP7), and retinoic acid over 10 days of culture. To assess the in vivo incorporation of cells, undifferentiated iPSCs or day 10 iPSC-PODs, were labeled with either carboxyfluorescein succinimidyl ester (CFSE) or Qdot nanocrystals (Q705). Thereafter, 1 × 105 differentiated iPSC-PODs were injected directly into the kidneys of mouse pups at postnatal day one (P1). Using co-expression analysis of glomerular and podocyte-specific markers, Day 10 differentiated iPSC-PODs that were positive for podocin, were detected following direct kidney injection into newborn mice up to 1 week after transplantation. Undifferentiated iPSC-PODs were not detected at the same timepoint. The transplanted cells were viable and located in the outer nephrogenic zone where they were found to colocalize with, or sit adjacent to, cells positive for glomerular-specific markers including podocin, synaptopodin, and Wilms' tumor 1 (WT1). This study provides proof-of-principle that transplanted iPSC-POD can survive in recipient newborn mouse kidneys due to the immature and immunoprivileged nature of the developing postnatal kidneys.

The therapeutic effect of mesenchymal stem cells on pulmonary myeloid cells following neonatal hyperoxic lung injury in mice.

BACKGROUND: Exposure to high levels of oxygen (hyperoxia) after birth leads to lung injury. Our aims were to investigate the modulation of myeloid cell sub-populations and the reduction of fibrosis in the lungs following administration of human mesenchymal stem cells (hMSC) to neonatal mice exposed to hyperoxia. METHOD: Newborn mice were exposed to 90% O2 (hyperoxia) or 21% O2 (normoxia) from postnatal days 0-4. A sub-group of hyperoxia mice were injected intratracheally with 2.5X105 hMSCs. Using flow cytometry we assessed pulmonary immune cells at postnatal days 0, 4, 7 and 14. The following markers were chosen to identify these cells: CD45+ (leukocytes), Ly6C+Ly6G+ (granulocytes), CD11b+CD11c+ (macrophages); macrophage polarisation was assessed by F4/80 and CD206 expression. hMSCs expressing enhanced green fluorescent protein (eGFP) and firefly luciferase (fluc) were administered via the trachea at day 4. Lung macrophages in all groups were profiled using next generation sequencing (NGS) to assess alterations in macrophage phenotype. Pulmonary collagen deposition and morphometry were assessed at days 14 and 56 respectively. RESULTS: At day 4, hyperoxia increased the number of pulmonary Ly6C+Ly6G+ granulocytes and F4/80lowCD206low macrophages but decreased F4/80highCD206high macrophages. At days 7 and 14, hyperoxia increased numbers of CD45+ leukocytes, CD11b+CD11c+ alveolar macrophages and F4/80lowCD206low macrophages but decreased F4/80highCD206high macrophages. hMSCs administration ameliorated these effects of hyperoxia, notably reducing numbers of CD11b+CD11c+ and F4/80lowCD206low macrophages; in contrast, F4/80highCD206high macrophages were increased. Genes characteristic of anti-inflammatory 'M2' macrophages (Arg1, Stat6, Retnla, Mrc1, Il27ra, Chil3, and Il12b) were up-regulated, and pro-inflammatory 'M1' macrophages (Cd86, Stat1, Socs3, Slamf1, Tnf, Fcgr1, Il12b, Il6, Il1b, and Il27ra) were downregulated in isolated lung macrophages from hyperoxia-exposed mice administered hMSCs, compared to mice without hMSCs. Hydroxyproline assay at day 14 showed that the 2-fold increase in lung collagen following hyperoxia was reduced to control levels in mice administered hMSCs. By day 56 (early adulthood), hMSC administration had attenuated structural changes in hyperoxia-exposed lungs. CONCLUSIONS: Our findings suggest that hMSCs reduce neonatal lung injury caused by hyperoxia by modulation of macrophage phenotype. Not only did our cell-based therapy using hMSC induce structural repair, it limited the progression of pulmonary fibrosis.