Chondroitinase ABC combined with Schwann cell transplantation enhances restoration of neural connection and functional recovery following acute and chronic spinal cord injury

Schwann cell transplantation is considered one of the most promising cell-based therapy to repair injured spinal cord due to its unique growth-promoting and myelin-forming properties.A the Food and Drug Administration-approved Phase I clinical trial has been conducted to evaluate the safety of transplanted human autologous Schwann cells to treat patients with spinal cord injury.A major challenge for Schwann cell transplantation is that grafted Schwann cells are confined within the lesion cavity,and they do not migrate into the host environment due to the inhibitory barrier formed by injury-induced glial scar,thus limiting axonal reentry into the host spinal cord.Here we introduce a combinatorial strategy by suppressing the inhibitory extracellular environment with injection of lentivirus-mediated transfection of chondroitinase ABC gene at the rostral and caudal borders of the lesion site and simultaneously leveraging the repair capacity of transplanted Schwann cells in adult rats following a mid-thoracic contusive spinal cord injury.We report that when the glial scar was degraded by chondroitinase ABC at the rostral and caudal lesion borders,Schwann cells migrated for considerable distances in both rostral and caudal directions.Such Schwann cell migration led to enhanced axonal regrowth,including the serotonergic and dopaminergic axons originating from supraspinal regions,and promoted recovery of locomotor and urinary bladder functions.Importantly,the Schwann cell survival and axonal regrowth persisted up to 6 months after the injury,even when treatment was delayed for 3 months to mimic chronic spinal cord injury.These findings collectively show promising evidence for a combinatorial strategy with chondroitinase ABC and Schwann cells in promoting remodeling and recovery of function following spinal cord injury.

Using microglia-derived extracellular vesicles to capture diversity of microglial activation phenotypes following neurological injury

Microglia are one of the three glial cell populations in the central nervous system(CNS),along with astrocytes and oligodendrocytes.While microglia are unique among brain cells due to their hematologic origin and perform immune functions similar to peripheral macrophages,they are not simply macrophages of the CNS.

Mechanical suppression of breast cancer cell invasion and paracrine signaling to osteoclasts requires nucleo-cytoskeletal connectivity

Exercise benefits the musculoskeletal system and reduces the effects of cancer.The effects of exercise are multifactorial,where metabolic changes and tissue adaptation influence outcomes.Mechanical signals,a principal component of exercise,are anabolic to the musculoskeletal system and restrict cancer progression.We examined the mechanisms through which cancer cells sense and respond to low-magnitude mechanical signals introduced in the form of vibration.Low-magnitude,high-frequency vibration was applied to human breast cancer cells in the form of low-intensity vibration(LIV).LIV decreased matrix invasion and impaired secretion of osteolytic factors PTHLH,IL-11,and RANKL.Furthermore,paracrine signals from mechanically stimulated cancer cells,reduced osteoclast differentiation and resorptive capacity.Disconnecting the nucleus by knockdown of SUN1 and SUN2 impaired LIV-mediated suppression of invasion and osteolytic factor secretion.LIV increased cell stiffness;an effect dependent on the LINC complex.These data show that mechanical vibration reduces the metastatic potential of human breast cancer cells,where the nucleus serves as a mechanosensory apparatus to alter cell structure and intercellular signaling.

Sclerostin antibody improves alveolar bone quality in the Hyp mouse model of X-linked hypophosphatemia

X-linked hypophosphatemia (XLH) is a rare disease of elevated fibroblast growth factor 23 (FGF23) production that leads tohypophosphatemia and impaired mineralization of bone and teeth. The clinical manifestations of XLH include a high prevalence ofdental abscesses and periodontal disease, likely driven by poorly formed structures of the dentoalveolar complex, including thealveolar bone, cementum, dentin, and periodontal ligament. Our previous studies have demonstrated that sclerostin antibody (SclAb) treatment improves phosphate homeostasis, and increases long bone mass, strength, and mineralization in the Hyp mousemodel of XLH. In the current study, we investigated whether Scl-Ab impacts the dentoalveolar structures of Hyp mice. Male andfemale wild-type and Hyp littermates were injected with 25 mg·kg−1 of vehicle or Scl-Ab twice weekly beginning at 12 weeks of ageand euthanized at 20 weeks of age. Scl-Ab increased alveolar bone mass in both male and female mice and alveolar tissue mineraldensity in the male mice. The positive effects of Scl-Ab were consistent with an increase in the fraction of active(nonphosphorylated) β-catenin, dentin matrix protein 1 (DMP1) and osteopontin stained alveolar osteocytes. Scl-Ab had no effecton the mass and mineralization of dentin, enamel, acellular or cellular cementum. There was a nonsignificant trend towardincreased periodontal ligament (PDL) attachment fraction within the Hyp mice. Additional PDL fiber structural parameters were notaffected by Scl-Ab. The current study demonstrates that Scl-Ab can improve alveolar bone in adult Hyp mice.

Meeting report:a hard look at the state of enamel research

The Encouraging Novel Amelogenesis Models and Ex vivo cell Lines （ENAMEL） Development workshop was held on 23 June 2017 at the Bethesda headquarters of the National institute of Dental and Craniofacial Research （NIDCR）. Discussion topics included model organisms, stem cells/cell lines, and tissues/3D cell culture/organoids. Scientists from a number of disciplines, representing institutions from across the United States, gathered to discuss advances in our understanding of enamel, as well as future directions for the field.

Pyrimidine nucleotide starvation induces a decrease in the number of effector T cells but not memory T cells

Scherer et al.investigated the influence of de novo pyrimidine nucleotide synthesis on T-cell responses after antigen stimulation,particularly on effector and memory T-cell development[1].Their work focused on the effect of leflunomide(trade name Avara®),which is a direct inhibitor of dihydroorotate dehydrogenase(DHODH;a key enzyme in the de novo pyrimidine nucleotide pathway and located on the inner mitochondrial membrane).In this pathway,DHODH converts dihydroorotate to orotate and has been implicated in the reduction of ubiquinol to ubiquinone mediated by Complex III in the electron transport chain.The metabolic effects of DHODH inhibition are unclear[2,3].However,it is known to block S-phase progression by activating P53.Leflunomide was originally approved for the treatment of rheumatoid arthritis(RA)in 1998;the mechanism involves the induction of S-phase cell cycle arrest and apoptosis,inhibiting cell proliferation and self-renewal.Preclinical studies have demonstrated the therapeutic potential of leflunomide for cancer[4].Despite the efficacy of leflunomide,the mechanism by which it targets immune cells in the treatment of RA was unknown;however,the work of Scherer and colleagues has shed new light on this mechanism.

Interleukin-1β-induced inflammatory signaling in C20 human microglial cells

Aim: Increased inflammatory signaling in microglia is implicated in the pathogenesis of neurodegenerative diseases, trauma, psychiatric disorders, and anxiety/depression. Understanding inflammatory signaling in microglia is critical for advancing treatment options. Studying rodent-derived microglia has yielded substantial information, yet, much remains to better understand inflammatory signaling in human microglia. Hence, there is great interest in developing immortalized human microglial cell lines. The C20 human microglial cell line was recently developed and our primary objective was to advance our knowledge of inflammatory signaling in these cells. Methods: Expression of the microglia specific marker transmembrane protein 119 (TMEM119) was assessed by western blot analysis. Lipopolysaccharide (LPS)- and interleukin-1β (IL-1β)-induced cytokine/chemokine expression was determined by ELISA. Phosphorylation of inhibitory kappa B alpha (IκBα), nuclear factor (NF)-κB p65, and p38 mitogen-activated protein kinase (p38 MAPK) was measured by western blot analysis. Results: TMEM119 was expressed in unstimulated C20 cells, and to a greater extent in IL-1β-stimulated cells. IL-1βsignificantly induced IL-6, monocyte chemoattractant protein-1/CCL2, and interferon-γ inducible protein 10/CXCL10 expression. LPS induced CCL2 expression, but not IL-6 or CXCL10 expression. IL-1β induced inflammatory signaling as indicated by increased phosphorylation of IκBα, NF-κB p65 and p38 MAPK. Conclusion: We provide the first evidence that C20 microglia express TMEM119. This is the initial report of IL-1β-induced activation of IκBα, NF-κB p65, and p38 MAPK and subsequent CXCL10, CCL2 and IL-6 secretion in C20cells. These findings advance our understanding of inflammatory signaling in C20 cells and support the value of this cell line as a research tool.

Why are children less affected than adults by severe acute respiratory syndrome coronavirus 2 infection?

An adequate immune response to severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is crucial to not only clear the virus but also prevent tissue immunopathology.Because children generally experience a milder course of coronavirus disease 2019(COVID-19)than adults,it is important to characterize the immune responses to SARS-CoV-2 in children.