Aggregation of Human Trophoblast Cells into Three-Dimensional Culture System Enhances Anti-Inflammatory Characteristics through Cytoskeleton Regulation

KLF6 negatively regulates HIF-1α in extravillous trophoblasts under hypoxia

INTRODUCTION

HIF-1α, the master regulator of hypoxia cellular response, is stabilized under low oxygen levels and degraded in the presence of oxygen but its transcription, translation, and degradation are tightly regulated by numerous pathways. KLF6 is a transcription factor involved in proliferation, differentiation, and apoptosis in several cell systems. Under hypoxia it is upregulated in a HIF-1α-dependent manner in extravillous trophoblasts. Considering the importance of hypoxia modulation of EVT behavior through HIF1-α we aimed to study whether KLF6 modulates HIF-1α expression in HTR8/SVneo cells.

METHODS

HTR8/SVneo cells were cultured in a 1 % oxygen chamber or in 3D format where a spontaneous oxygen gradient is generated. qRT-PCR and Western blot were performed to analyze mRNA and protein expression, respectively. SiRNA, shRNA, or plasmids were used to down- or up-regulate gene expression. Wound healing assay was performed under hypoxia to evaluate migration. The NFκB pathway was modulated with dominant negative mutants and a chemical inhibitor. Cobalt chloride was used to block HIF-1α degradation.

RESULTS

KLF6 up- and down-regulation in HTR8/SVneo cells exposed to acute hypoxia revealed a negative regulation on HIF-1α. KLF6 silencing led to a partially HIF-1α-dependent increase in MMP9 and VEGF. The NF-κB pathway and HIF-1α degradation were involved in KLF6-dependent HIF-1α regulation. HTR8/SVneo-3D culture showed that KLF6 negatively regulates HIF-1α in a microenvironment with naturally generated hypoxia.

DISCUSSION

Present results reveal that KLF6 contributes to a fine tune modulation of HIF-1α level under hypoxia. Thus, sustaining a HIF-1α homeostatic level, KLF6 might contribute to control EVT adaptation to hypoxia.

Two Sides to Every Question: Attempts to Activate Chicken Innate Immunity in 2D and 3D Hepatic Cell Cultures

The liver with resident tissue macrophages is the site of vivid innate immunity, activated also by pathogen-associated molecular patterns (PAMPs) leaking through the intestinal barrier. As gut-derived inflammatory diseases are of outstanding importance in broiler chickens, the present study aimed to establish a proper hepatic inflammatory model by comparing the action of different PAMPs from poultry pathogens on chicken 2D and 3D primary hepatocyte—non-parenchymal cell co-cultures, the latter newly developed with a magnetic bioprinting method. The cultures were challenged by the bacterial endotoxins lipopolysaccharide (LPS) from Escherichia coli, lipoteichoic acid (LTA) from Staphylococcus aureus and by enterotoxin (ETxB) from Escherichia coli, Salmonella Typhimurium derived flagellin, phorbol myristate acetate (PMA) as a model proinflammatory agent and polyinosinic polycytidylic acid (poly I:C) for mimicking viral RNA exposure. Cellular metabolic activity was assessed with the CCK-8 test, membrane damage was monitored with the lactate dehydrogenase (LDH) leakage assay and interleukin-6 and -8 (Il-6 and -8) concentrations were measured in cell culture medium with a chicken specific ELISA. Both LPS and LTA increased the metabolic activity of the 3D cultures, concomitantly decreasing the LDH leakage, while in 2D cultures ETxB stimulated, PMA and poly I:C depressed the metabolic activity. Based on the moderately increased extracellular LDH activity, LTA seemed to diminish cell membrane integrity in 2D and poly I:C in both cell culture models. The applied endotoxins remarkably reduced the IL-8 release of 3D cultured cells, suggesting the effective metabolic adaptation and the presumably initiated anti-inflammatory mechanisms of the 3D spheroids. Notwithstanding that the IL-6 and IL-8 production of 2D cells was mostly not influenced by the endotoxins used, only the higher LTA dose was capable to evoke an IL-8 surge. Flagellin, PMA and poly I:C exerted proinflammatory action in certain concentrations in both 2D and 3D cultures, reflected by the increased cellular IL-6 release. Based on these data, LTA, flagellin, PMA and poly I:C can be considered as potent candidates to induce inflammation in chicken primary hepatic cell cultures, while LPS failed to trigger proinflammatory cytokine production, suggesting the relatively high tolerance of avian liver cells to certain bacterial endotoxins. These results substantiate that the established 3D co-cultures seemed to be proper tools for testing potential proinflammatory molecules; however, the remarkable differences between 2D and 3D models should be addressed and further studied.

Cryopreserved Spontaneous Spheroids from Compact Bone-Derived Mesenchymal Stromal Cells for Bone Tissue Engineering

Spontaneously formed spheroids from mouse compact bone-derived mesenchymal stromal cells (CB-MSCs) possess enhanced stemness and superior plasticity. In this study, the effect of cryopreservation on viability, stemness, and osteogenic differentiation capability of spontaneous CB-MSC spheroids were investigated. CB-MSCs were isolated from mouse femur and tibia. Spheroids were cryopreserved with various concentrations of dimethyl sulfoxide (DMSO). After thawing, the number of living and dead cells was measured. The expression levels of stem cell markers and osteogenic marker genes were analyzed. The cryopreserved and noncryopreserved spheroids were transplanted in mice with a beta-tricalcium phosphate as a scaffold to evaluate the in vivo bone-forming capability. The percentage of living cells was highest when 5% DMSO was used as a cryoprotectant, confirmed by the number of dead cells. The expression of stem cell marker genes and osteogenic differentiation capability were maintained after cryopreservation with 5% DMSO. The cryopreserved spontaneous CB-MSC spheroids showed remarkable new bone formation in vivo, identical to that of the noncryopreserved spheroids even without osteogenic induction. The cryopreserved spontaneous CB-MSC spheroids retained stemness and osteogenic differentiation capability and highlight the utility of spontaneous CB-MSC spheroids as ready-to-use tissue-engineered products for bone tissue engineering.

Human Female Reproductive System Organoids: Applications in Developmental Biology, Disease Modelling, and Drug Discovery

Organoid technique has achieved significant progress in recent years, owing to the rapid development of the three-dimensional (3D) culture techniques in adult stem cells (ASCs) and pluripotent stem cells (PSCs) that are capable of self-renewal and induced differentiation. However, our understanding of human female reproductive system organoids is in its infancy. Recently, scientists have established self-organizing 3D organoids for human endometrium, fallopian tubes, oocyte, and trophoblasts by culturing stem cells with a cocktail of cytokines in a 3D scaffold. These organoids express multicellular biomarkers and show functional characteristics similar to those of their origin organs, which provide potential avenues to explore reproductive system development, disease modelling, and patient-specific therapy. Nevertheless, advanced culture methods, such as co-culture system, 3D bioprinting and organoid-on-a-chip technology, remain to be explored, and more efforts should be made for further elucidation of cell-cell crosstalk. This review describes the development and applications of human female reproductive system organoids. Graphical abstract Figure: Applications in developmental biology, disease modelling, and drug discovery of human female reproductive system organoids. ASCs: adult stem cells; PSCs: pluripotent stem cells.

A Dynamic Hanging-Drop System for Mesenchymal Stem Cell Culture

There have been many microfluid technologies combined with hanging-drop for cell culture gotten developed in the past decade. A common problem within these devices is that the cell suspension introduced at the central inlet could cause a number of cells in each microwell to not regularize. Also, the instability of droplets during the spheroid formation remains an unsolved ordeal. In this study, we designed a microfluidic-based hanging-drop culture system with the design of taper-tube that can increase the stability of droplets while enhancing the rate of liquid exchange. A ring is surrounding the taper-tube. The ring can hold the cells to enable us to seed an adequate amount of cells before perfusion. Moreover, during the period of cell culture, the mechanical force around the cell is relatively low to prevent stem cells from differentiate and maintain the phenotype. As a result of our hanging system design, cells are designed to accumulate at the bottom of the droplet. This method enhances convenience for observation activities and analysis of experiments. Thus, this microfluid chip can be used as an in vitro platform representing in vivo physiological conditions, and can be useful in regenerative therapy.

Novel 3D in vitro models to evaluate trophoblast migration and invasion

PROBLEM

Embryo implantation depends on the interactions between the developing embryo and the maternal endometrium. Signals originating from the decidua play a critical role in the process of implantation and trophoblast invasion; however, the molecular mechanisms mediating this interaction are poorly understood. The objective of this study was to develop in vitro models that would mimic the processes of attachment, migration, and early invasion of the trophoblast.

METHODS OF STUDY

First trimester trophoblast cells (Sw.71 cells) were cultured in low attachment plates to form blastocyst-like spheroids (BLS). Epithelial-mesenchymal transition (EMT) characterization during BLS formation was determined by RT-PCR and Western Blot. The two 3D in vitro culture models consist of (a) trophoblast migration: BLS cultured in suspension (b) trophoblast invasion: human endometrium stromal cells (HESC) plated in the bottom of a 96-well plate, covered by Matrigel and BLS transferred on top. Matrigel was used to mimic the human endometrial extracellular matrix.

RESULTS

Using 3D cell culture systems and real-time imaging, we are able to determine the impact of endometrial factors on trophoblast cell function. Endometrial stromal cells promote blastocyst-like spheroid migration of trophoblast cells and invasion of the extracellular matrix.

CONCLUSION

We report the characterization of 3D in vitro models to evaluate the interaction between endometrial cells and trophoblast during the process of migration and invasion. The models are useful tools in order to further study the molecular mechanism of embryo-maternal uterine cells interactions.