Mouse Corneal Epithelial and Stromal Cell Isolation and Culture

Corneal epithelium and stroma are the major cellular structures for ocular protection and vision accuracy; they play important roles in corneal wound healing and inflammation under pathological conditions. Unlike human, murine corneal and stromal fibroblast cells are difficult to isolate for cell culture. In our laboratory, we successfully used an ex vivo culture procedure and an enzymatic procedure to isolate, purify, and culture mouse corneal epithelial and stromal fibroblast cells. Key features • Primary cell culture models of a disease are critical for cellular and molecular mechanism studies. • Corneal tissues with the limbus contain stem cells to generate both epithelial and stromal cells. • An ex vivo corneal culture provides a constant generation of primary corneal cells for multiple passages. • The isolated cells are validated by the corneal epithelial cell markers Krt12 and Cdh1 and the stromal fibroblast marker Vim.

The Influence of Protein Secretomes of Enterococcus durans on ex vivo Human Gut Microbiome

The gut microbiome plays a critical role to all animals and humans health. Methods based on ex vivo cultures are time and cost-effective solutions for rapid evaluation of probiotic effects on microbiomes. In this study, we assessed whether the protein secretome from the potential probiotic Enterococcus durans LAB18S grown on fructoligosaccharides (FOS) and galactoligosaccharides (GOS) had specific effects on ex vivo cultured intestinal microbiome obtained from a healthy individual. Metaproteomics was used to evaluate changes in microbial communities of the human intestinal microbiome. Hierarchical clustering analysis revealed 654 differentially abundant proteins from the metaproteome samples, showing that gut microbial protein expression varied on the presence of different E. durans secretomes. Increased amount of Bacteroidetes phylum was observed in treatments with secretomes from E. durans cultures on FOS, GOS and albumin, resulting in a decrease of the Firmicutes to Bacteroidetes (F/B) ratio. The most functionally abundant bacterial taxa were Roseburia, Bacteroides, Alistipes and Faecalibacterium. The results suggest that the secretome of E. durans may have favorable effects on the intestinal microbial composition, stimulating growth and different protein expression of beneficial bacteria. These findings suggest that proteins secreted by E. durans growing on FOS and GOS have different effects on the modulation of gut microbiota functional activities during cultivation.

Ex vivo Culture and Contractile Force Measurements of Non-human Primate Heart Slices

Cardiovascular diseases are the leading cause of death and morbidity worldwide. Patient mortality has been successfully reduced by nearly half in the last four decades, mainly due to advances in minimally invasive surgery techniques and interventional cardiology methods. However, a major hurdle is still the translational gap between preclinical findings and the conversion into effective therapies, which is partly due to the use of model systems that fail to recapitulate key aspects of human physiology and disease. Large animal models such as pigs and non-human primates are highly valuable because they closely resemble humans but are costly and time intensive. Here, we provide a method for long-term ex vivo culture of non-human primate (NHP) myocardial tissue that offers a powerful alternative for a wide range of applications including electrophysiology studies, drug screening, and gene function analyses.

Identification of a window of androgen sensitivity for somatic cell function in human fetal testis cultured ex vivo

BACKGROUND

Reduced androgen action during early fetal development has been suggested as the origin of reproductive disorders comprised within the testicular dysgenesis syndrome (TDS). This hypothesis has been supported by studies in rats demonstrating that normal male development and adult reproductive function depend on sufficient androgen exposure during a sensitive fetal period, called the masculinization programming window (MPW). The main aim of this study was therefore to examine the effects of manipulating androgen production during different timepoints during early human fetal testis development to identify the existence and timing of a possible window of androgen sensitivity resembling the MPW in rats.

METHODS

The effects of experimentally reduced androgen exposure during different periods of human fetal testis development and function were examined using an established and validated human ex vivo tissue culture model. The androgen production was reduced by treatment with ketoconazole and validated by treatment with flutamide which blocks the androgen receptor. Testicular hormone production ex vivo was measured by liquid chromatography-tandem mass spectrometry or ELISA assays, and selected protein markers were assessed by immunohistochemistry.

RESULTS

Ketoconazole reduced androgen production in testes from gestational weeks (GW) 7-21, which were subsequently divided into four age groups: GW 7-10, 10-12, 12-16 and 16-21. Additionally, reduced secretion of testicular hormones INSL3, AMH and Inhibin B was observed, but only in the age groups GW 7-10 and 10-12, while a decrease in the total density of germ cells and OCT4⁺ gonocytes was found in the GW 7-10 age group. Flutamide treatment in specimens aged GW 7-12 did not alter androgen production, but the secretion of INSL3, AMH and Inhibin B was reduced, and a reduced number of pre-spermatogonia was observed.

CONCLUSIONS

This study showed that reduced androgen action during early development affects the function and density of several cell types in the human fetal testis, with similar effects observed after ketoconazole and flutamide treatment. The effects were only observed within the GW 7-14 period-thereby indicating the presence of a window of androgen sensitivity in the human fetal testis.

Multidimensional Fluorescence Imaging of Embryonic and Postnatal Mammary Gland Development

Multidimensional fluorescence imaging represents a powerful approach for studying the dynamic cellular processes underpinning the development, function, and maintenance of the mammary gland. Here, we describe key multidimensional imaging strategies that enable visualization of mammary branching morphogenesis and epithelial cell fate dynamics during postnatal and embryonic mammary gland development. These include 4-dimensional intravital microscopy and ex vivo imaging of embryonic mammary cultures, in addition to methods that facilitate 3-dimensional imaging of the ductal epithelium at single-cell resolution within its native stroma. Collectively, these approaches provide a window into mammary developmental dynamics, and the perturbations underlying tissue dysfunction and disease.

Real-Time Monitoring of Circadian Rhythms in the Eye

The mammalian eye harbors a full circadian system that controls several physiologically relevant functions within this organ. During the last two decades a few laboratories have developed transgenic animal models in which circadian rhythms can be monitored in real time using luciferase activity. The most famous transgenic mouse to record bioluminescence rhythms from different tissues and organs is the PERIOD2::LUCIFERASE (PER2::LUC) mouse developed by the Takahashi laboratory in early 2000. Since then, several studies have used this mouse model to dissect the mammalian circadian system by monitoring the circadian rhythm in the brain, the eye, and in many other peripheral organs and tissues. This chapter describes the methodology to record and analyze bioluminescence rhythms from the retina, retinal pigment epithelium, and cornea of PER2::LUC mice.

Patient-Derived Explant Cultures of Normal and Tumor Human Breast Tissue

Tissue culture has evolved considerably over the last few years, including cell culture in three dimensions, organoids, cocultures of different cell types and the use of diverse types of matrices in an attempt to mimic conditions that more closely resemble those found in the original tissue or organ. In this chapter, we describe how patient-derived breast tissue can be cultured on sponges for several days, maintaining their original architecture and with the capacity to respond to treatments. This protocol facilitates the study of the tissue responses without the need for extensive tissue manipulation, cell digestion or use of a biomaterial as scaffold, while maintaining the stroma and extracellular matrix organization. This method has the potential to improve preclinical testing by contributing to provide more accurate data reflecting cell-cell and cell-matrix interactions, tumor microenvironment, drug effects or stem cell function in normal- and pathophysiology of the breast.

Chicken Second Branchial Arch Progenitor Cells Contribute to Heart Musculature in vitro and in vivo

In the past, the heart muscle was thought to originate from a single source of myocardial progenitor cells. More recently, however, an additional source of myocardial progenitors has been revealed to be the second heart field, and chicken embryos were important for establishing this concept. However, there have been few studies in chicken on how this field contributes to heart muscles in vitro. We have developed an ex vivo experimental system from chicken embryos between stages HH17-20 to investigate how mesodermal progenitors in the second branchial arch (BA2) differentiate into cardiac muscles. Using this method, we presented evidence that the progenitor cells within the BA2 arch differentiated into beating cardiomyocytes in vitro. The beating explant cells were positive for cardiac actin, Nkx2.5, and ventricular myosin heavy chain. In addition, we performed a time course for the expression of second heart field markers (Isl1 and Nkx2.5) in the BA2 from stage HH16 to stage HH21 using in situ hybridization. Accordingly, using EGFP-based cell labeling techniques and quail-chicken cell injection, we demonstrated that mesodermal cells from the BA2 contributed to the outflow tract and ventricular myocardium in vivo. Thus, our findings highlight the cardiogenic potential of chicken BA2 mesodermal cells in vitro and in vivo.

Dynamic differences between DNA damage repair responses in primary tumors and cell lines

The study of DNA damage repair response (DDR) in prostate cancer is restricted by the limited number of prostate cancer cell lines and lack of surrogates for heterogeneity in clinical samples. Here, we sought to leverage our experience with patient derived explants (PDEs) cultured ex vivo to study dynamics of DDR in primary tumors following application of clinically relevant doses of ionizing radiation (IR) to tumor cells in their native 3-dimensional microenvironment. We compared DDR dynamics between prostate cancer cell lines, PDEs and xenograft derived explants (XDEs) following treatment with IR (2Gy) either alone or in combination with pharmacological modulators of DDR. We have shown that following treatment with 2Gy, DDR can be consistently detected in PDEs from multiple solid tumors, including prostate, kidney, testes, lung and breast, as evidenced by γ-H2AX, 53BP1, phospho-ATM and phospho-DNA-PKcs foci. By examining kinetics of resolution of IR-induced foci, we have shown that DDR in prostate PDEs (complete resolution in 8 h) is much faster than in prostate cancer cell lines (<50% resolution in 8 h). The transcriptional profile of DDR genes following 2Gy IR appears to be distinct between PDEs and cell lines. Pre-treatment with drugs targeting DDR pathways differentially alter the kinetics of DDR in the PDEs and cell lines, as evidenced by altered kinetics of foci resolution. This study highlights the utility of PDEs as a robust model system for short-term evaluation of DDR in primary solid tumors in clinically relevant microenvironment.

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IR induces distinct DNA damage repair kinetics in prostate cancer PDEs and cell lines.

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IR induces a distinct transcriptional program in prostate cancer PDE and cell lines.

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DNA-PKcs inhibition blocks IR-induced DDR in prostate cancer PDE.

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Inhibition of AR impairs NHEJ in prostate cancer PDEs.

Ex vivo cultures and drug testing of primary acute myeloid leukemia samples: Current techniques and implications for experimental design and outcome

New treatment options of acute myeloid leukemia (AML) are rapidly emerging. Pre-clinical models such as ex vivo cultures are extensively used towards the development of novel drugs and to study synergistic drug combinations, as well as to discover biomarkers for both drug response and anti-cancer drug resistance. Although these approaches empower efficient investigation of multiple drugs in a multitude of primary AML samples, their translational value and reproducibility are hampered by the lack of standardized methodologies and by culture system-specific behavior of AML cells and chemotherapeutic drugs. Moreover, distinct research questions require specific methods which rely on specific technical knowledge and skills. To address these aspects, we herein review commonly used culture techniques in light of diverse research questions. In addition, culture-dependent effects on drug resistance towards commonly used drugs in the treatment of AML are summarized including several pitfalls that may arise because of culture technique artifacts. The primary aim of the current review is to provide practical guidelines for ex vivo primary AML culture experimental design.

Ex vivo culture of head and neck cancer explants in cell sheet for testing chemotherapeutic sensitivity

PURPOSE

Tumor explant culture systems can mimic the in vivo tumor microenvironment, proposing as a substitute for preclinical studies for prediction of individual treatment response. Therefore, our study evaluated the potential usefulness of ex vivo tumor explants culture assembled into the cell sheets by anticancer drug screening in patients with head and neck squamous cell carcinoma (HNSCC).

METHODS

Our model included tumor explants incorporated into cell sheet composing of epithelium and subepithelial stroma using tumor and mucosal samples obtained from the HNSCC patients who underwent surgery. Cell growth, viability, and hypoxia were measured by cell counting kit-8, live/dead assay, propidium iodide, and LOX-1 staining, and were compared among the different treatment groups with vehicle, cisplatin or docetaxel.

RESULTS

Tumor explants stably survived in the cell sheet over 10 days after explantation, whereas most of the explants in non-matrix culture became nonviable within 5-8 days with the significant daily decrease of viability. The live tissue areas of tumor explants in the cell sheet maintained over 30 days without significant changes although hypoxic cell areas gradually increased up to 5 days. Tissue viability and live cancer tissue areas significantly decreased after the treatment of cisplatin or docetaxel in the dose and time-dependent manners.

CONCLUSION

Our cell sheet-based tumor explants model might be applied to the reliable ex vivo screening for anticancer chemotherapeutics for HNSCC.

Mouse Embryonic Tooth Germ Dissection and Ex vivo Culture Protocol

A tooth germ ex vivo organ culture allows visualization of its development in different stages, thus enabling investigation of the molecular mechanisms of regulatory factors. Tooth germs can be rapidly dissected from E13 mouse embryos and placed on cell culture inserts for observation of subsequent tooth germ development in a three-dimensional situation in real time. This method is also suitable for other organs that develop by epithelial-mesenchymal interactions, including salivary gland, hair, lung, and kidney. In addition, siRNAs or growth factors can be easily added to ex vivo tooth germ cultures to investigate the detailed molecular function of specific genes. The present protocol provides an efficient and practical method for isolation and ex vivo culture of embryonic tooth germs.

Ex vivo culture of lesional psoriasis skin for pharmacological testing

BACKGROUND

Psoriasis is a chronic, inflammatory skin disorder resulting from a complex interplay between immune and skin cells via release of soluble mediators. While a lot is known about the molecular mechanisms behind psoriasis pathogenesis, there is still a need for preclinical research models that accuratelyreplicate the disease.

OBJECTIVE

This study aimed to develop and characterize ex vivo culture of psoriasis skin as a model for pharmacological testing, where the immunological events of psoriasis can be followed.

METHODS

Full thickness punch biopsies of lesional psoriasis skin were cultured in submerged conditions up to 144 h followingin situ T cell stimulation with rhIL-23 and anti-CD3 and anti-CD28 antibodies. The T cell mediated skin inflammation was assessed by gene and protein l analysis for a panel of inflammatory mediators. Tissue integrity and morphology were evaluated by histological analysis.

RESULTS

T cell stimulation resulted in functional and psoriasis specificin situ activation of T cells. The expression levels of most of the proinflammatory mediators related to both immune and skin cells were comparable to these in freshly isolated tissue at 48 and 96 h of culture. Tissue integrity and morphology were sustained up to 96 h. Treatment with a corticosteroid reduced the expression of several pro-inflammatory cytokines and chemokines, whereas anti-IL-17A antibody treatment reduced the expression of the IL-17A downstream markers IL-8 and DEFB4.

CONCLUSION

By preserving keyimmunopathological mechanisms of psoriasis, ex vivo culture of psoriasis skin can be used for the investigation of inflammatory processes of psoriasis and for preclinical drug discovery research.

Ex vivo tissue slice culture system to measure drug-response rates of hepatic metastatic colorectal cancer

Background

The lack of predictive biomarkers or test systems contributes to high failure rates of systemic therapy in metastasized colorectal carcinoma, accounting for a still unfavorable prognosis. Here, we present an ex vivo functional assay to measure drug-response based on a tissue slice culture approach.

Methods

Tumor tissue slices of hepatic metastases of nine patients suffering from colorectal carcinoma were cultivated for 72 h and treated with different concentrations of the clinically relevant drugs Oxaliplatin, Cetuximab and Pembrolizumab. Easy to use, objective and automated analysis routines based on the Halo platform were developed to measure changes in proliferative activity and the morphometric make-up of the tumor. Apoptotic indices were assessed semiquantitatively.

Results

Untreated tumor tissue slices showed high morphological comparability with the original “in vivo”-tumor, preserving proliferation and stromal-tumor interactions. All but one patients showed a dosage dependent susceptibility to treatment with Oxaliplatin, whereas only two patients showed responses to Cetuximab and Pembrolizumab, respectively. Furthermore, we identified possible non-responders to Cetuximab therapy in absence of RAS-mutations.

Conclusions

This is the first time to demonstrate feasibility of the tissue slice culture approach for metastatic tissue of colorectal carcinoma. An automated readout of proliferation and tumor-morphometry allows for quantification of drug susceptibility. This strongly indicates a potential value of this technique as a patient-specific test-system of targeted therapy in metastatic colorectal cancer. Co-clinical trials are needed to customize for clinical application and to define adequate read-out cut-off values.

Explant Culture for Studying Lung Development

Lung development is a complex process that requires the input of various signaling pathways to coordinate the specification and differentiation of multiple cell types. Ex vivo culture of the lung is a very useful technique that represents an attractive model for investigating many different processes critical to lung development, function, and disease pathology. Ex vivo cultured lungs remain comparable to the in vivo lung both in structure and function, which makes them more suitable than cell cultures for physiological studies. Lung explant cultures offer several significant advantages for studies of morphogenetic events that guide lung development including budding, branching, and fusion. It also maintains the native physiological interactions between cells in the developing lung, enabling investigations of the direct and indirect signaling taking place between tissues and cells throughout the developmental process. Studying temporal and spatial control of gene expression by transcriptional factors using different reporters to understand their regulatory function at different moments of development is another valuable advantage of lung explants culture.

A Method for Culturing Mouse Whisker Follicles to Study Circadian Rhythms ex vivo

Ex vivo tissue-culture experiments are often performed in the field of circadian biology. The major aim of these experiments is to evaluate circadian characteristics such as period length at the tissue-autonomous level by monitoring clock gene expression in real time. This culture method is also used to examine the tissue specificity of circadian entrainment factors. However, an ex vivo culture method for monitoring clock gene expression in hair follicles has yet to be established. In the present study, we developed an experimental method to analogize and evaluate circadian characteristics by performing ex vivo culture of mouse whisker follicles and monitoring clock gene expression in real time.

Ex Vivo Fetal Whole Ovarian Culture Model: An Essential Tool for Studies in Reproductive Toxicology and Pharmacology

Major limitations in understanding the direct effects of endocrine-disrupting chemicals (EDCs) and cell signaling events in ovarian cellular dynamics in mammals include a lack of proper and simple tools/techniques as well as gaps in knowledge regarding the critical window(s) of vulnerability. Identifying and validating such tools and evaluating the effects of EDCs on molecular dynamics and cellular events during the critical windows of ovarian development are very important to improve the fertility in women and preserve the future health of the developing fetuses. Therefore, we developed a fetal whole ovarian ex vivo culture model. Ex vivo ovary culture models allow varying culture parameters in a highly controlled manner and thus have the potential to allow a more thorough evaluation for reproductive toxicity studies and drug response. This chapter describes clear and thorough details for setting up and maintaining an ex vivo culture system from the rat ovaries and further analyses of mRNA and protein expressions and estimating follicle numbers.

Ex-vivo observation of calcification process in chick tibia slice: Augmented calcification along collagen fiber orientation in specimens subjected to static stretch

Bone formation through matrix synthesis and calcification in response to mechanical loading is an essential process of the maturation in immature animals, although how mechanical loading applied to the tissue increases the calcification and improves mechanical properties, and which directions the calcification progresses within the tissue are largely unknown. To address these issues, we investigated the calcification of immature chick bone under static tensile stretch using a newly developed real-time observation bioreactor system. Bone slices perpendicular to the longitudinal axis obtained from the tibia in 2- to 4-day-old chick legs were cultured in the system mounted on a microscope, and their calcification was observed up to 24 h while they were stretched in the direction parallel to the slice. Increase in the calcified area, traveling distance and the direction of the calcification and collagen fiber orientation in the newly calcified region were analyzed. There was a significant increase in calcified area in the bone explant subjected to tensile strain over ∼3%, which corresponds to the threshold strain for collagen fibers showing alignment in the direction of stretch, indicating that the fiber alignment may enhance tissue calcification. The calcification progressed to a greater distance to the stretching direction in the presence of the loading. Moreover, collagen fiber orientation in the calcified area in the loaded samples was coincided with the progression angle of the calcification. These results clearly show that the application of static tensile strain enhanced tissue calcification, which progresses along collagen fibers aligned to the loading direction.

Functional comparison of distinct Brachyury+ states in a renal differentiation assay

Mesodermal populations can be generated in vitro from mouse embryonic stem cells (mESCs) using three-dimensional (3-D) aggregates called embryoid bodies or two-dimensional (2-D) monolayer culture systems. Here, we investigated whether Brachyury-expressing mesodermal cells generated using 3-D or 2-D culture systems are equivalent or, instead, have different properties. Using a Brachyury-GFP/E2-Crimson reporter mESC line, we isolated Brachyury-GFP ⁺ mesoderm cells using flow-activated cell sorting and compared their gene expression profiles and ex vivo differentiation patterns. Quantitative real-time polymerase chain reaction analysis showed significant up-regulation of Cdx2, Foxf1 and Hoxb1 in the Brachyury-GFP⁺ cells isolated from the 3-D system compared with those isolated from the 2-D system. Furthermore, using an ex vivo mouse kidney rudiment assay, we found that, irrespective of their source, Brachyury-GFP⁺ cells failed to integrate into developing nephrons, which are derived from the intermediate mesoderm. However, Brachyury-GFP⁺ cells isolated under 3-D conditions appeared to differentiate into endothelial-like cells within the kidney rudiments, whereas the Brachyury-GFP⁺ isolated from the 2-D conditions only did so to a limited degree. The high expression of Foxf1 in the 3-D Brachyury-GFP⁺ cells combined with their tendency to differentiate into endothelial-like cells suggests that these mesodermal cells may represent lateral plate mesoderm.

Cell Migration in Tissues: Explant Culture and Live Imaging

Cell migration is a process that ensures correct cell localization and function in development and homeostasis. In disease such as cancer, cells acquire an upregulated migratory capacity that leads to their dissemination throughout the body. Live imaging of cell migration allows for better understanding of cell behaviors in development, adult tissue homeostasis and disease. We have optimized live imaging procedures to track cell migration in adult murine tissue explants derived from: (1) healthy gut; (2) primary intestinal carcinoma; and (3) the liver, a common metastatic site. To track epithelial cell migration in the gut, we generated an inducible fluorescent reporter mouse, enabling us to visualize and track individual cells in unperturbed gut epithelium. To image intratumoral cancer cells, we use a spontaneous intestinal cancer model based on the activation of Notch1 and deletion of p53 in the mouse intestinal epithelium, which gives rise to aggressive carcinoma. Interaction of cancer cells with a metastatic niche, the mouse liver, is addressed using a liver colonization model. In summary, we describe a method for long-term 3D imaging of tissue explants by two-photon excitation microscopy. Explant culturing and imaging can help understand dynamic behavior of cells in homeostasis and disease, and would be applicable to various tissues.

Dissecting Regulatory Mechanisms Using Mouse Fetal Liver-Derived Erythroid Cells

Multipotent hematopoietic stem cells differentiate into an ensemble of committed progenitor cells that produce the diverse blood cells essential for life. Physiological mechanisms governing hematopoiesis, and mechanistic aberrations underlying non-malignant and malignant hematologic disorders, are often very similar in mouse and man. Thus, mouse models provide powerful systems for unraveling mechanisms that control hematopoietic stem/progenitor cell (HSPC) function in their resident microenvironments in vivo. Ex vivo systems, involving the culture of HSPCs generated in vivo, allow one to dissociate microenvironment-based and cell intrinsic mechanisms, and therefore have considerable utility. Dissecting mechanisms controlling cellular proliferation and differentiation is facilitated by the use of primary cells, since mutations and chromosome aberrations in immortalized and cancer cell lines corrupt normal mechanisms. Primary erythroid precursor cells can be expanded or differentiated in culture to yield large numbers of progeny at discrete maturation stages. We described a robust method for isolation, culture, and analysis of primary mouse erythroid precursor cells and their progeny.

Cellular and molecular characterization of gametogenic progression in ex vivo cultured prepuberal mouse testes

BACKGROUND

Recently, an effective testis culture method using a gas-liquid interphase, capable of differentiate male germ cells from neonatal spermatogonia to spermatozoa has been developed. Nevertheless, this methodology needs deep analyses that allow future experimental approaches in basic, pathologic and/or reprotoxicologic studies. Because of this, we characterized at cellular and molecular levels the entire in vitro spermatogenic progression, in order to understand and evaluate the characteristics that define the spermatogenic process in ex vivo cultured testes compared to the in vivo development.

METHODS

Testicular explants of CD1 mice aged 6 and 10 days post-partum were respectively cultured during 55 and 89 days. Cytological and molecular approaches were performed, analyzing germ cell proportion at different time culture points, meiotic markers immunodetecting synaptonemal complex protein SYCP3 by immunocytochemistry and the relative expression of different marker genes along the differentiation process by Reverse Transcription - quantitative Polymerase Chain Reaction. In addition, microRNA and piwi-interactingRNA profiles were also evaluated by Next Generation Sequencing and bioinformatic approaches.

RESULTS

The method promoted and maintained the spermatogenic process during 89 days. At a cytological level we detected spermatogenic development delays of cultured explants compared to the natural in vivo process. The expression of different spermatogenic stages gene markers correlated with the proportion of different cell types detected in the cytological preparations.

CONCLUSIONS

In vitro progression analysis of the different spermatogenic cell types, from both 6.5 dpp and 10.5 dpp testes explants, has revealed a relative delay in relation to in vivo process. The expression of the genes studied as biomarkers correlates with the cytologically and functional detected progression and differential expression identified in vivo. After a first analysis of deep sequencing data it has been observed that as long as cultures progress, the proportion of microRNAs declined respect to piwi-interactingRNAs levels that increased, showing a similar propensity than which happens in in vivo spermatogenesis. Our study allows to improve and potentially to control the ex vivo spermatogenesis development, opening new perspectives in the reproductive biology fields including male fertility.

The use of primary murine fibroblasts to ascertain if Spirocerca lupi secretory/excretory protein products are mitogenic ex vivo

Background

Spirocerca lupi is a nematode that parasitizes vertebrates in particular canids, by forming nodules in the thoracic cavity specifically in the oesophagus. In 25% of Spirocerca infections of the domestic dog, nodules progress from inflammatory to pre-neoplastic to sarcomatous neoplasia. With the mechanism of neoplastic transformation being incompletely understood, this study investigates if S. lupi parasite proteinaceous secretory/excretory products (ESPs) play a role in the neoplastic transformation.

Methods

To facilitate collection of ESPs, we maintained naturally harvested adult parasites in the laboratory under artificial conditions. Media in which the parasites were grown was subsequently evaluated for the presence of proteinaceous compounds using a mass spectroscopy library as well as for their ability to be mitogenic in primary murine fibroblastic cells.

Results

Chromatrography of the ethyl acetate extracted incubation media showed the presence of 9 protein compounds, of which three were identified as non-specific proteins isolated from Nematostella vectensis, Caenorhabditis brenneri and Sus scrofa, with the rest being unknown. Acetone, methanol, hexane and ethylacetate extracted culture media were unable to induce a mitogenic change in primary murine fibroblasts in comparison to the controls.

Conclusion

While no mitogenic effect was evident, further studies are required to understand the role of worm excretory/secretory products on clastogenesis under chronic exposure. In addition, while not of primary importance for this study, the observed duration of parasite survival indicates that ex vivo studies on S. lupi are possible. For the latter we believe that the worm culture method can be further optimized if longer survival times are required.

Effects of cyclic compression on the mechanical properties and calcification process of immature chick bone tissue in culture

Contribution of mechanical loading to tissue growth during both the development and post-natal maturation is of a particular interest, as its understanding would be important to strategies in bone tissue engineering and regenerative medicine. The present study has been performed to investigate how immature bone responds to mechanical loading using an ex vivo culture system. A slice of the tibia, with the thickness of 3 mm, was obtained from 0-day-old chick. For the ex vivo culture experiment in conjunction with cyclic compressive loading, we developed a custom-made, bioreactor system where both the load and the deformation applied to the specimen was recorded. Cyclic compression, with an amplitude of 0.3 N corresponding to 1 to 2% compressive strain, was applied to immature bone specimen during a 3-day culture period at an overall loading rate 3–4 cycles/min, in the presence of β-glycerol phosphate and dexamethasone in culture medium. The stress-strain relationship was obtained at the beginning and the end of the culture experiment. In addition, analyses for alkaline phosphate release, cell viability and tissue calcification were also performed. It was exhibited that elastic moduli of bone slices were significantly elevated at the end of the 3-day culture in the presence of cyclic compression, which was a similar phenomenon to significant elevation of the elastic moduli of bone tissue by the maturation from 0-day old to 3-day old. By contrast, no significant changes in the moduli were observed in the absence of cyclic compression or in deactivated, cell-free samples. The increases in the moduli were coincided with the increase in calcified area in the bone samples. It was confirmed that immature bone can respond to compressive loading in vitro and demonstrate the growth of bone matrix, similar to natural, in vivo maturation. The elevation of the elastic moduli was attributable to the increased calcified area and the realignment of collagen fibers parallel to the loading direction. The ex vivo loading system established here can be further applied to study responses to mechanical loading in osteogenesis as well as callus maturation for better understanding of factors to consider in successful bone regeneration with mechanical factors.

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We examined how immature bone responds to cyclic compressive loading, using a newly established tissue loading system.

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Loading culture of 0-day-old chick tibia slice for 3 days significantly increased elastic moduli and calcified area.

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The moduli and calcified area after 3-day loading culture were comparable with those from 3-day-old chick tibia.

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No increases in the moduli or in calcified area were observed in non-loaded samples and deactivated samples.

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It was suggested that cyclic compressive loading is an essential factor of normal bone growth in ex vivo bone culture.

Validation of murine and human placental explant cultures for use in sex steroid and phase II conjugation toxicology studies

Human primary placental explant culture is well established for cytokine signaling and toxicity, but has not been validated for steroidogenic or metabolic toxicology. The technique has never been investigated in the mouse. We characterized human and mouse placental explants for up to 96 h in culture. Explant viability (Lactate dehydrogenase) and sex steroid levels were measured in media using spectrophotometry and ELISA, respectively. Expression and activities of the steroidogenic (3β-hydroxysteroid dehydrogenase, Cytochrome P45017A1, Cytochrome P45019), conjugation (UDP-glucuronosyltransferase, sulfotransferase (SULT)), and regeneration (β-glucuronidase, arylsulfatase C (ASC)) enzymes were determined biochemically in tissues with fluorimetric and spectrophotometric assays, and western blot. Explants were viable up to 96 h, but progesterone, estrone, and 17β-estradiol secretion decreased. Steroidogenic enzyme expression and activities were stable in mouse explants and similar to levels in freshly isolated tissues, but were lower in human explants than in fresh tissue (P<0.01). Human and mouse explants exhibited significantly less conjugation after 96 h, SULT was not detected in the mouse, and neither explants had active ASC, although proteins were expressed. Mouse explants may be useful for steroid biochemistry and endocrine disruption studies, but not metabolic conjugation. In contrast, human explants may be useful for studying conjugation for <48 h, but not for steroid/endocrine studies.