Search

Soft scaffold materials for cell cultures grafted onto the chorioallantoic membrane (CAM) provide innovative solutions for creating physiologically relevant environments by mimicking the host tissue. Biocompatible hydrogels represent an ideal medium for such applications, but the relationship between scaffold mechanical properties and reactions at the biological interface remains poorly understood. This study examines the attachment and integration of soft hydrogels on the CAM using an accessible ex ovo system. Composite hydrogels of polyvinyl alcohol and Phytagel were fabricated by sterile freeze-thawing. CAM assays, as an alternative to traditional in vivo models, enabled the evaluation of the compatibility, attachment, and biointegration of hydrogels with three distinct compositions. The mechanomimetic properties of the hydrogels were assessed through cyclic compression–tension tests, with nominal peak stresses ranging from 0.26 to 2.82 kPa in tension and −0.33 to −2.92 kPa in compression. Mechanical attachment to the CAM was measured by pull-off tests after five days of incubation. On the first day, the interface strength was similar for all hydrogel compositions. On day 5, softer hydrogels showed the greatest increase (p=0.008), followed by intermediate hydrogels (p=0.020), while the denser hydrogels showed negligible changes (p=0.073). Histological analyses revealed cell infiltration in 100% of soft, 75% of intermediate, and 13% of dense hydrogels, suggesting that softer hydrogels integrate better into the CAM by facilitating cell migration and enhancing interface strength. Chicken embryo survival rates and cytotoxicity assays confirmed the biocompatibility of the hydrogels and supported their potential for use in soft, hydrated three-dimensional scaffolds that mimic tissue environments in dynamic biological systems.Statement of significance Current research on soft scaffold materials for cell cultures often overlooks the critical relationship between mechanical properties and biological integration of these materials with host tissues. Although hydrogels, as soft porous materials, hold promise for creating physiologically relevant environments, the mechanisms driving their attachment and biointegration, especially on the chorioallantoic membrane (CAM), remain largely unexplored. This study addresses this gap by investigating the interaction between soft hydrogels and the CAM, providing valuable insights into how material properties and microstructure influence cellular responses. Our findings emphasize the importance of understanding these dynamics to develop biocompatible scaffolds that better mimic tissue environments, advancing applications in three-dimensional cell cultures on CAM assays and other biological systems.

Abstract Background Cortical demyelination represents a prominent feature of the multiple sclerosis (MS) brain, especially in (late) progressive stages. We recently developed a new rat model that reassembles critical features of cortical pathology characteristic to progressive types of MS. In persons affected by MS, B-cell depleting anti-CD20 therapy proved successful in the relapsing remitting as well as the early progressive course of MS, with respect to reducing the relapse rate and number of newly formed lesions. However, if the development of cortical pathology can be prevented or at least slowed down is still not clear. The main goal of this study was thus to increase our understanding for the mode of action of B-cells and B-cell directed therapy on cortical lesions in our rat model. Methods For this purpose, we set up two separate experiments, with two different induction modes of B-cell depletion. Brain tissues were analyzed thoroughly using histology. Results We observed a marked reduction of cortical demyelination, microglial activation, astrocytic reaction, and apoptotic cell loss in anti-CD20 antibody treated groups. At the same time, we noted increased neuronal preservation compared to control groups, indicating a favorable impact of anti-CD20 therapy. Conclusion These findings might pave the way for further research on the mode of action of B-cells and therefore help to improve therapeutic options for progressive MS.

Postnatal bone fractures of the growth plate (GP) are often associated with regenerative complications such as growth impairment. In order to understand the underlying processes of trauma-associated growth impairment within postnatal bone, an ex vivo rat femur slice model was developed. To achieve this, a 2 mm horizontal cut was made through the GP of rat femur prior to the organotypic culture being cultivated for 15 days in vitro. Histological analysis showed disrupted endochondral ossification, including disordered architecture, increased chondrocyte metabolic activity, and a loss of hypertrophic zone throughout the distal femur. Furthermore, altered expression patterns of Col2α1, Acan, and ColX, and increased chondrocyte metabolic activity in the TZ and MZ at day 7 and day 15 postinjury were observed. STEM revealed the presence of stem cells, fibroblasts, and chondrocytes within the injury site at day 7. In summary, the findings of this study suggest that the ex vivo organotypic GP injury model could be a valuable tool for investigating the underlying mechanisms of GP regeneration post-trauma, as well as other tissue engineering and disease studies.

Modulation of neuronal activity for seizure control using various methods of neurostimulation is a rapidly developing field in epileptology, especially in treatment of refractory epilepsy. Promising results in human clinical practice, such as diminished seizure burden, reduced incidence of sudden unexplained death in epilepsy, and improved quality of life has brought neurostimulation into the focus of veterinary medicine as a therapeutic option. This article provides a comprehensive review of available neurostimulation methods for seizure management in drug-resistant epilepsy in canine patients. Recent progress in non-invasive modalities, such as repetitive transcranial magnetic stimulation and transcutaneous vagus nerve stimulation is highlighted. We further discuss potential future advances and their plausible application as means for preventing epileptogenesis in dogs.

Summary: Decreased cognitive performance is a hallmark of brain aging, but the underlying mechanisms and potential therapeutic avenues remain poorly understood. Recent studies have revealed health-protective and lifespan-extending effects of dietary spermidine, a natural autophagy-promoting polyamine. Here, we show that dietary spermidine passes the blood-brain barrier in mice and increases hippocampal eIF5A hypusination and mitochondrial function. Spermidine feeding in aged mice affects behavior in homecage environment tasks, improves spatial learning, and increases hippocampal respiratory competence. In a Drosophila aging model, spermidine boosts mitochondrial respiratory capacity, an effect that requires the autophagy regulator Atg7 and the mitophagy mediators Parkin and Pink1. Neuron-specific Pink1 knockdown abolishes spermidine-induced improvement of olfactory associative learning. This suggests that the maintenance of mitochondrial and autophagic function is essential for enhanced cognition by spermidine feeding. Finally, we show large-scale prospective data linking higher dietary spermidine intake with a reduced risk for cognitive impairment in humans.

MiR-451a is best known for its role in erythropoiesis and for its tumour suppressor features. Here we show a role for miR-451a in neuronal differentiation through analysis of endogenous and ectopically expressed or silenced miR-451a in Ntera2/D1 cells during neuronal differentiation. Furthermore, we compared neuronal differentiation in the dentate gyrus of hippocampus of miR-451a-/- and wild type mice. MiR-451a overexpression in lentiviral transduced Ntera2/D1 cells was associated with a significant shifting of mRNA expression of the developmental markers Nestin, βIII Tubulin, NF200, DCX and MAP2 to earlier developmental time points, compared to control vector transduced cells. In line with this, accelerated neuronal network formation in AB.G.miR-451a transduced cells, as well as an increase in neurite outgrowth both in number and length was observed. MiR-451a targets genes MIF, AKT1, CAB39, YWHAZ, RAB14, TSC1, OSR1, POU3F2, TNS4, PSMB8, CXCL16, CDKN2D and IL6R were, moreover, either constantly downregulated or exhibited shifted expression profiles in AB.G.miR-451a transduced cells. Lentiviral knockdown of endogenous miR-451a expression in Ntera2/D1 cells resulted in decelerated differentiation. Endogenous miR-451a expression was upregulated during development in the hippocampus of wildtype mice. In situ hybridization revealed intensively stained single cells in the subgranular zone and the hilus of the dentate gyrus of wild type mice, while genetic ablation of miR-451a was observed to promote an imbalance between proliferation and neuronal differentiation in neurogenic brain regions, suggested by Ki67 and DCX staining. Taken together, these results provide strong support for a role of miR-451a in neuronal maturation processes in vitro and in vivo.