Differentiation Potential of Mesenchymal Stem Cells Derived from Adipose Tissue vs Bone Marrow Toward Annulus Fibrosus Cells In vitro

BACKGROUND

Bone marrow stem cells (BMSCs) and adipose-derived stem cells (ADSCs) are two types of stem cells that commonly used in exogenous tissue engineering as well as endogenous tissue repair, however which type of cell is superior remains unknown.

OBJECTIVE

This study was conducted to compare differentiation potential of BMSCs and ADSCs from Sprague-Dawley rats towards annulus fibrosus (AF)-like cells.

METHOD

Stem cells and AF cells were cocultured with direct cell-to-cell contact in coculture plates with 0.4m pore size up till 21 days. AF markers expression at the histological level and molecular level were evaluated by histological analysis and dimethplmethplene blue (DMMB) assay as well as quantitative reverse-transcription polymerase chain reaction (qRT-PCR).

RESULTS

qRT-PCR) results showed up regulation in AF marker gene expressions of both two MSCs after coculture. BMSCs demonstrated a statistically increased expression of collagen II and aggrecan from 7 days of coculture. However, these gene expressions in ADSCs showed a statistically increase at day 14 and day 21. And there was a statistically increase of Collagen I expression in BMSCs at 14 days and 21 days. But only after 21 days of coculture, ADSCs showed a statistically increase in collagen I expression. Moreover, histological analysis and dimethplmethplene blue (DMMB) assay mirrored the results of qRT-PCR. Morphologically, BMSCs became enlarged and triangular, while ADSCs were enlarged and rounded after coculture.

CONCLUSION

These findings suggested that BMSCs might be superior as a cell source for annulus fibrosus repair compared to ADSCs.

Relative Abundances of Candida albicans and Candida glabrata in In Vitro Coculture Biofilms Impact Biofilm Structure and Formation

Candida is a member of the normal human microbiota and often resides on mucosal surfaces such as the oral cavity or the gastrointestinal tract. In addition to their commensality, Candida species can opportunistically become pathogenic if the host microbiota is disrupted or if the host immune system becomes compromised. An important factor for Candida pathogenesis is its ability to form biofilm communities. The two most medically important species-Candida albicans and Candida glabrata-are often coisolated from infection sites, suggesting the importance of Candida coculture biofilms. In this work, we report that biofilm formation of the coculture population depends on the relative ratio of starting cell concentrations of C. albicans and C. glabrata When using a starting ratio of C. albicans to C. glabrata of 1:3, ∼6.5- and ∼2.5-fold increases in biofilm biomass were observed relative to those of a C. albicans monoculture and a C. albicans/C. glabrata ratio of 1:1, respectively. Confocal microscopy analysis revealed the heterogeneity and complex structures composed of long C. albicans hyphae and C. glabrata cell clusters in the coculture biofilms, and reverse transcription-quantitative PCR (qRT-PCR) studies showed increases in the relative expression of the HWP1 and ALS3 adhesion genes in the C. albicans/C. glabrata 1:3 biofilm compared to that in the C. albicans monoculture biofilm. Additionally, only the 1:3 C. albicans/C. glabrata biofilm demonstrated an increased resistance to the antifungal drug caspofungin. Overall, the results suggest that interspecific interactions between these two fungal pathogens increase biofilm formation and virulence-related gene expression in a coculture composition-dependent manner.IMPORTANCECandida albicans and Candida glabrata are often coisolated during infection, and the occurrence of coisolation increases with increasing inflammation, suggesting possible synergistic interactions between the two Candida species in pathogenesis. During the course of an infection, the prevalence of each Candida species may change over time due to differences in metabolism and in the resistance of each species to antifungal therapies. Therefore, it is necessary to understand the dynamics between C. albicans and C. glabrata in coculture to develop better therapeutic strategies against Candida infections. Existing in vitro work has focused on understanding how an equal-part culture of C. albicans and C. glabrata impacts biofilm formation and pathogenesis. What is not understood, and what is investigated in this work, is how the composition of Candida species in coculture impacts overall biofilm formation, virulence gene expression, and the therapeutic treatment of biofilms.

Enterococcus faecalis Demonstrates Pathogenicity through Increased Attachment in an Ex Vivo Polymicrobial Pulpal Infection

This study investigated the host response to a polymicrobial pulpal infection consisting of Streptococcus anginosus and Enterococcus faecalis, bacteria commonly implicated in dental abscesses and endodontic failure, using a validated ex vivo rat tooth model. Tooth slices were inoculated with planktonic cultures of S. anginosus or E. faecalis alone or in coculture at S. anginosus/E. faecalis ratios of 50:50 and 90:10. Attachment was semiquantified by measuring the area covered by fluorescently labeled bacteria. Host response was established by viable histological cell counts, and inflammatory response was measured using reverse transcription-quantitative PCR (RT-qPCR) and immunohistochemistry. A significant reduction in cell viability was observed for single and polymicrobial infections, with no significant differences between infection types (∼2,000 cells/mm² for infected pulps compared to ∼4,000 cells/mm² for uninfected pulps). E. faecalis demonstrated significantly higher levels of attachment (6.5%) than S. anginosus alone (2.3%) and mixed-species infections (3.4% for 50:50 and 2.3% for 90:10), with a remarkable affinity for the pulpal vasculature. Infections with E. faecalis demonstrated the greatest increase in tumor necrosis factor alpha (TNF-α) (47.1-fold for E. faecalis, 14.6-fold for S. anginosus, 60.1-fold for 50:50, and 25.0-fold for 90:10) and interleukin 1β (IL-1β) expression (54.8-fold for E. faecalis, 8.8-fold for S. anginosus, 54.5-fold for 50:50, and 39.9-fold for 90:10) compared to uninfected samples. Immunohistochemistry confirmed this, with the majority of inflammation localized to the pulpal vasculature and odontoblast regions. Interestingly, E. faecalis supernatant and heat-killed E. faecalis treatments were unable to induce the same inflammatory response, suggesting E. faecalis pathogenicity in pulpitis is linked to its greater ability to attach to the pulpal vasculature.

Human Wharton's Jelly Cells Activate Degenerative Nucleus Pulposus Cells In Vitro

To investigate the interaction between human Wharton's jelly cells (WJCs) and degenerative nucleus pulposus cells (NPCs), human WJCs were cocultured with degenerative NPCs with or without direct cell-cell contact. WJCs were isolated from the human umbilical cord and degenerative NPCs were isolated from the surgically obtained degenerative intervertebral disc tissue. The isolated WJCs positively expressed CD73, CD105, CD90, CD29, CD166, and human leukocyte antigen (HLA)-ABC, but negatively expressed CD34, CD45, and HLA-DR. After coculturing with three different WJCs:NPCs ratios for 7 days, the real-time polymerase chain reaction showed that the relative gene expression of nucleus pulposus (NP)-marker genes [aggrecan, type II collagen, and SRY-type HMG box-9 (SOX-9)] was significantly upgraded in all coculture groups (all p < 0.05 compared with control groups). Coculture either with or without cell-cell contact significantly activated the expression of NP-maker genes than controls, but coculture with cell-cell contact yielded a higher gene expression than coculture without cell-cell contact. In coculturing with cell-cell contact and WJCs:NPCs of 25:75, the relative gene expression of aggrecan, type II collagen, SOX-9 for WJCs yielded the highest increase by 721-, 1507-, and 1463-folds, respectively (all p < 0.05 compared with WJCs control). In contrast, the highest relative gene expression of aggrecan, type II collagen, SOX-9 for NPCs was 112-, 84-, and 109-folds, respectively, in coculture with cell-cell contact and in WJCs:NPCs of 75:25 (all p < 0.05 compared with NPCs control). In conclusion, the data indicated that coculturing human WJCs with degenerative NPCs induced the NP-like cell differentiation of WJCs and restored the biological status of degenerative NPCs and coculture WJCs and NPCs with direct cell-cell contact yielded more favorable gene expressions.

Multilineage Constructs for Scaffold-Based Tissue Engineering: A Review of Tissue-Specific Challenges

There is a growing interest in the regeneration of tissue in interfacial regions, where biological, physical, and chemical attributes vary across tissue type. The simultaneous use of distinct cell lineages can help in developing in vitro structures, analogous to native composite tissues. This literature review gathers the recent reports that have investigated multiple cell types of various sources and lineages in a coculture system for tissue-engineered constructs. Such studies aim at mimicking the native organization of tissues and their interfaces, and/or to improve the development of complex tissue substitutes. This paper thus distinguishes itself from those focusing on technical aspects of coculturing for a single specific tissue. The first part of this review is dedicated to variables of cocultured tissue engineering such as scaffold, cells, and in vitro culture environment. Next, tissue-specific coculture methods and approaches are covered for the most studied tissues. Finally, cross-analysis is performed to highlight emerging trends in coculture principles and to discuss how tissue-specific challenges can inspire new approaches for regeneration of different interfaces to improve the outcomes of various tissue engineering strategies.

Mesenchymal stem cells promote cell invasion and migration and autophagy-induced epithelial-mesenchymal transition in A549 lung adenocarcinoma cells

Mesenchymal stem cells (MSCs) are recruited into the tumour microenvironment and promote tumour growth and metastasis. Tumour microenvironment-induced autophagy is considered to suppress primary tumour formation by impairing migration and invasion. Whether these recruited MSCs regulate tumour autophagy and whether autophagy affects tumour growth are controversial. Our data showed that MSCs promote autophagy activation, reactive oxygen species production, and epithelial-mesenchymal transition (EMT) as well as increased migration and invasion in A549 cells. Decreased expression of E-cadherin and increased expression of vimentin and Snail were observed in A549 cells cocultured with MSCs. Conversely, MSC coculture-mediated autophagy positively promoted tumour EMT. Autophagy inhibition suppressed MSC coculture-mediated EMT and reduced A549 cell migration and invasion slightly. Furthermore, the migratory and invasive abilities of A549 cells were additional increased when autophagy was further enhanced by rapamycin treatment. Taken together, this work suggests that microenvironments containing MSCs can promote autophagy activation for enhancing EMT; MSCs also increase the migratory and invasive abilities of A549 lung adenocarcinoma cells. Mesenchymal stem cell-containing microenvironments and MSC-induced autophagy signalling may be potential targets for blocking lung cancer cell migration and invasion.

A mini-review of TAT-MyoD fused proteins: state of the art and problems to solve

The transcriptional activator TAT is a small peptide essential for viral replication and possesses the property of entering the cells from the extracellular milieu, acting as a membrane shuttle. In order to safely differentiate cells an innovative methodology, based on the fusion of transcription factors and the TAT sequence, is discussed in this short review. In several studies, it has been demonstrated that TAT protein can be observed in the cell nucleus after few hours from the inoculation although its way of action is not fully understood. However, further studies will be necessary to develop this methodology for clinical purposes.

Antitumor Activity of the Chinese Medicine JC-001 Is Mediated by Immunomodulation in a Murine Model of Hepatocellular Carcinoma

JC-001 is a Chinese medicine that has been used to treat liver disease; however, its significance in cancer treatment has not been characterized. In this study, we used an immunocompetent tumor model to characterize the antitumor activity of JC-001. A total of 48 Hepa 1-6 tumor-bearing C57BL/6 mice were randomly grouped into 4 groups and treated with H2O or JC-001 via oral administration. After hepatoma cell lines, including HepG2, Hep3B, SK-Hep-1, and Hepa 1-6, underwent 96 hours of JC-001 treatment, a low cytotoxic effect was observed. In contrast, no direct cytotoxic effect of JC-001 on a normal human liver cell line, THLE-3, was observed under the same incubation conditions. Using a murine tumor model, we found that tumor growth could be inhibited by JC-001 in C57BL/6 mice but not in immunodeficient mice. Histopathological analysis of tumors from C57BL/6 mice revealed immune cell infiltration in tumors from the JC-001-treated group, as observed by hematoxylin and eosin staining; in addition, Ki67, hypoxia-inducible factor-1-α, and high mobility group box 1 expression levels were suppressed in the tumors. Both the coculture assay and murine spleen mRNA quantitative PCR analyses demonstrated that JC-001 could suppress Th17 immunity. Our data suggest that JC-001 is a Chinese medicine with low cytotoxicity that can significantly suppress tumor growth by immune regulation. This herbal remedy has great potential for future clinical application in hepatoma therapy.

Epithelial Cells Induce a Cyclo-Oxygenase-1-Dependent Endogenous Reduction in Airway Smooth Muscle Contractile Phenotype

Airway smooth muscle cells (ASMCs) are phenotypically regulated to exist in either a proliferative or a contractile state. However, the influence of other airway structural cell types on ASMC phenotype is largely unknown. Although epithelial cells are known to drive ASM proliferation, their effects on the contractile phenotype are uncertain. In the current study, we tested the hypothesis that epithelial cells reduce the contractile phenotype of ASMCs. To do so, we measured force production by traction microscopy, gene and protein expression, as well as calcium release by Fura-2 ratiometric imaging. ASMCs incubated with epithelial-derived medium produced less force after histamine stimulation. We observed reduced expression of myocardin, α-smooth muscle actin, and calponin within ASMCs after coculture with epithelial cells. Peak calcium release in response to histamine was diminished, and depended on the synthesis of cyclo-oxygenase-1 products by ASM and on prostaglandin E receptors 2 and 4. Together, these in vitro results demonstrate that epithelial cells have the capacity to coordinately reduce ASM contraction by functional antagonism and by reduction of the expression of certain contractile proteins.

Systematic Three-Dimensional Coculture Rapidly Recapitulates Interactions between Human Neurons and Astrocytes

Human astrocytes network with neurons in dynamic ways that are still poorly defined. Our ability to model this relationship is hampered by the lack of relevant and convenient tools to recapitulate this complex interaction. To address this barrier, we have devised efficient coculture systems utilizing 3D organoid-like spheres, termed asteroids, containing pre-differentiated human pluripotent stem cell (hPSC)-derived astrocytes (hAstros) combined with neurons generated from hPSC-derived neural stem cells (hNeurons) or directly induced via Neurogenin 2 overexpression (iNeurons). Our systematic methods rapidly produce structurally complex hAstros and synapses in high-density coculture with iNeurons in precise numbers, allowing for improved studies of neural circuit function, disease modeling, and drug screening. We conclude that these bioengineered neural circuit model systems are reliable and scalable tools to accurately study aspects of human astrocyte-neuron functional properties while being easily accessible for cell-type-specific manipulations and observations.

Amniotic mesenchymal stem cells mitigate osteoarthritis progression in a synovial macrophage-mediated in vitro explant coculture model

Osteoarthritis (OA) is a disease of the synovial joint marked by chronic, low-grade inflammation leading to cartilage destruction. Regenerative medicine strategies for mitigating OA progression and/or promoting cartilage regeneration must be assessed using models that mimic the hallmarks of OA. More specifically, these models should maintain synovial macrophage phenotype in their native micro-environment. Herein, an in vitro coculture model of patient-matched human OA cartilage and synovium was assessed for viability, macrophage phenotype, and progressive cartilage destruction in the presence of an inflammatory milieu. Additionally, the influence of synovial macrophages and their polarization within the model was defined using depletion studies. Finally, the model was used to compare the ability of human amniotic stem cells (hAMSCs) and human adipose stem cells (hADSCs) to mitigate OA progression. OA cocultures demonstrated progressive and significant reductions in chondrocyte viability and cartilage glycosaminoglycan content within a proinflammatory environment. Selective depletion of synovial macrophages resulted in significant decreases in M1:M2 percentage ratio yielding significant reductions in concentrations of interleukin-1 beta, matrix metalloproteinase-13 and attenuation of cartilage damage. Finally, hAMSCs were found to be more chondroprotective versus hADSCs as indicated by significantly improved OA chondrocyte viability (89.8 ± 2.4% vs. 58.4 ± 2.4%) and cartilage glycosaminoglycan content (499.0 ± 101.9 μg/mg dry weight vs. 155.0 ± 26.3 μg/mg dry weight) and were more effective at shifting OA synovial macrophage M1:M2 ratio (1.3:1 vs. 5:1), respectively. Taken together, the coculture model mimics salient features of OA, including macrophage-mediated cartilage destruction that was effectively abrogated by hAMSCs but not hADSCs.

Recipient-Biased Competition for an Intracellularly Generated Cross-Fed Nutrient Is Required for Coexistence of Microbial Mutualists

Many mutualistic microbial relationships are based on nutrient cross-feeding. Traditionally, cross-feeding is viewed as being unidirectional, from the producer to the recipient. This is likely true when a producer’s waste, such as a fermentation product, has value only for a recipient. However, in some cases the cross-fed nutrient holds value for both the producer and the recipient. In such cases, there is potential for nutrient reacquisition by producer cells in a population, leading to competition against recipients. Here, we investigated the consequences of interpartner competition for cross-fed nutrients on mutualism dynamics by using an anaerobic coculture pairing fermentative Escherichia coli and phototrophic Rhodopseudomonas palustris. In this coculture, E. coli excretes waste organic acids that provide a carbon source for R. palustris. In return, R. palustris cross-feeds E. coli ammonium (NH₄⁺), a compound that both species value. To explore the potential for interpartner competition, we first used a kinetic model to simulate cocultures with varied affinities for NH₄⁺ in each species. The model predicted that interpartner competition for NH₄⁺ could profoundly impact population dynamics. We then experimentally tested the predictions by culturing mutants lacking NH₄⁺ transporters in both NH₄⁺ competition assays and mutualistic cocultures. Both theoretical and experimental results indicated that the recipient must have a competitive advantage in acquiring cross-fed NH₄⁺ to sustain the mutualism. This recipient-biased competitive advantage is predicted to be crucial, particularly when the communally valuable nutrient is generated intracellularly. Thus, the very metabolites that form the basis for mutualistic cross-feeding can also be subject to competition between mutualistic partners.

Mutualistic relationships, particularly those based on nutrient cross-feeding, promote stability of diverse ecosystems and drive global biogeochemical cycles. Cross-fed nutrients within these systems can be either waste products valued by only one partner or nutrients valued by both partners. Here, we explored how interpartner competition for a communally valuable cross-fed nutrient impacts mutualism dynamics. We discovered that mutualism stability necessitates that the recipient have a competitive advantage against the producer in obtaining the cross-fed nutrient, provided that the nutrient is generated intracellularly. We propose that the requirement for recipient-biased competition is a general rule for mutualistic coexistence based on the transfer of intracellularly generated, communally valuable resources.

Differentiation of Mouse Ovarian Stem Cells Toward Oocyte-Like Structure by Coculture with Granulosa Cells

An increasing body of evidence has confirmed existence and function of ovarian stem cells (OSCs). In this study, a novel approach on differentiation of OSCs into oocyte-like cells (OLCs) has been addressed. Recently, different methods have been recruited to isolate and describe aspects of OSCs, but newer and more convenient strategies in isolation are still growing. Herein, a morphology-based method was used to isolate OSCs. Cell suspension of mouse neonatal ovaries was cultured and formed colonies were harvested mechanically and cultivated on mouse embryonic fibroblasts. For differentiation induction, colonies transferred on inactive granulosa cells. Results showed that cells in colonies were positive for alkaline phosphatase activity and reverse transcription-polymerase chain reaction (RT-PCR) confirmed the pluripotency characteristics of cells. Immunofluorescence revealed a positive signal for OCT4, DAZL, MVH, and SSEA1 in colonies as well. Results of RT-PCR and immunofluorescence confirmed that some OLCs were generated within the germ stem cell (GSCs) colonies. The applicability of morphological selection for isolation of GSCs was verified. This method is easier and more economic than other techniques. Our results demonstrate that granulosa cells were effective in inducing the differentiation of OSCs into OLCs through direct cell-to-cell contacts.

Determining the cross-talk between smooth muscle cells and macrophages on a cobalt-chromium stent material surface using an in vitro postimplantation coculture model

Smooth muscle cells (SMCs) and macrophages are important cellular components involved in the development of complications following the implantation of cardiovascular devices. This leads to various disorders such as restenosis, chronic inflammation, and may ultimately result in device failure. In this study, we developed a postimplant stent coculture model using different ratios of SMCs and macrophages seeded on to cobalt-chromium alloy. The macrophages had an increased affinity to the coculture surfaces, which resulted in decreased SMC attachment to the alloy surfaces at the initial time point. Once adhered, the macrophages spread freely and displayed advanced stages of inflammation at 48 h when cocultured with SMCs. This resulted in an increased secretion of proinflammatory cytokines (tumor necrosis factor alpha, monocyte chemotactic protein 1, interleukin [IL]-6, and IL-8) by 48 h in the coculture samples with the greatest increase observed with the high number of macrophages. Therefore, the increased levels of proinflammatory cytokines promoted the growth of SMCs in coculture to a greater extent than when the SMCs were culture alone. Thus, this study demonstrated the constant cross-talk between SMCs and macrophages occurring on the postimplant stent surface. Similar coculture models can be used to test the biocompatibility of drugs and biomaterials at possible postimplantation scenarios. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 673-685, 2018.

Coculture of endothelial progenitor cells and mesenchymal stem cells enhanced their proliferation and angiogenesis through PDGF and Notch signaling

The beneficial effects of combined use of mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) on tissue repair and regeneration after injury have been demonstrated, but the underlying mechanism remains incompletely understood. This study aimed to investigate the effects of direct contact coculture of human bone marrow‐derived EPCs (hEPCs)/human bone marrow‐derived MSCs (hMSCs) on their proliferation and angiogenic capacities and the underlying mechanism. hEPCs and hMSCs were cocultured in a 2D mixed monolayer or a 3D transwell membrane cell‐to‐cell coculture system. Cell proliferation was determined by Cell Counting Kit‐8. Angiogenic capacity was evaluated by in vitro angiogenesis assay. Platelet‐derived growth factor‐BB (PDGF‐BB), PDGF receptor neutralizing antibody (AB‐PDGFR), and DAPT (a γ‐secretase inhibitor) were used to investigate PDGF and Notch signaling. Cell proliferation was significantly enhanced by hEPCs/hMSCs 3D‐coculture and PDGF‐BB treatment, but inhibited by AB‐PDGFR. Expression of cyclin D1, PDGFR, Notch1, and Hes1 was markedly enhanced by PDGF‐BB but inhibited by DAPT. In vitro angiogenesis assay showed that hEPCs/hMSCs coculture and PDGF‐BB significantly enhanced angiogenic capacity, whereas AB‐PDGFR significantly reduced the angiogenic capacity. PDGF‐BB increased the expression of kinase insert domain receptor (KDR, an endothelial marker) and activated Notch1 signaling in cocultured cells, while DAPT attenuated the promoting effect of PDGF‐BB on KDR expression of hEPCs/hMSCs coculture. hEPCs/hMSCs coculture enhanced their proliferation and angiogenic capacities. PDGF and Notch signaling pathways participated in the promoting effects of hEPCs/hMSCs coculture, and there was crosstalk between these two signaling pathways. Our findings should aid understanding of the mechanism of beneficial effects of hEPCs/hMSCs coculture.

Multi-layered silk film coculture system for human corneal epithelial and stromal stem cells

With insufficient options to meet the clinical demand for cornea transplants, one emerging area of emphasis is on cornea tissue engineering. In the present study, the goal was to combine the corneal stroma and epithelium into one coculture system, to monitor both human corneal stromal stem cell (hCSSC) and human corneal epithelial cell (hCE) growth and differentiation into keratocytes and differentiated epithelium in these three-dimensional tissue systems in vitro. Coculture conditions were first optimized, including the medium, air-liquid interface culture, and surface topography and chemistry of biomaterial scaffold films based on silk protein. The silk was used as scaffolding for both stromal and epithelial tissue layers because it is cell compatible, can be surface patterned, and is optically clear. Next, the effects of proliferating and differentiating hCEs and hCSSCs were studied in this in vitro system, including the effects on cell proliferation, matrix formation by immunochemistry, and gene expression by quantitative reverse transcription-polymerase chain reaction. The incorporation of both cell types into the coculture system demonstrated more complete differentiation and growth for both cell types compared to the corneal stromal cells and corneal epithelial cells alone. Silk films for corneal epithelial culture were optimized to combine a 4.0-μm-scale surface pattern with bulk-loaded collagen type IV. Differentiation of each cell type was in evidence based on increased expression of corneal stroma and epithelial proteins and transcript levels after 6 weeks in coculture on the optimized silk scaffolds.

Role of poly(ε-caprolactone) lipid-core nanocapsules on melanoma-neutrophil crosstalk

Metastatic melanoma is an aggressive cancer with increasing incidence and limited therapies in advanced stages. Systemic neutrophilia or abundant neutrophils in the tumor contribute toward its worst prognosis, and the interplay of cancer and the immune system has been shown in tumor development and metastasis. We recently showed the in vivo efficacy of poly(ε-caprolactone) lipid-core nanocapsule (LNC) or LNC loaded with acetyleugenol (AcE-LNC) to treat B16F10-induced melanoma in mice. In this study, we investigated whether LNC or AcE-LNC toxicity could involve modifications on crosstalk of melanoma cells and neutrophils. Therefore, melanoma cells (B16F10) were pretreated with vehicle, LNC, AcE or AcE-LNC for 24 h, washed and, further, cocultured for 18 h with peritoneal neutrophils obtained from C57Bl/6 mice. Melanoma cells were able to internalize the LNC or AcE-LNC after 2 h of incubation. LNC or AcE-LNC pretreatments did not cause melanoma cells death, but led melanoma cells to be more susceptible to death in serum deprivation or hypoxia or in the presence of neutrophils. Interestingly, the production of reactive oxygen species (ROS), which causes cell death, was increased by neutrophils in the presence of LNC- and AcE-LNC-pretreated melanoma cells. LNC or AcE-LNC treatments reduced the concentration of transforming growth factor-β (TGF-β) in the supernatant of melanoma cells, a known factor secreted by cancer cells to induce pro-tumoral actions of neutrophils in the tumor microenvironment. In addition, we found reduced levels of pro-tumoral chemical mediators VEGF, arginase-1, interleukin-10 (IL-10) and matrix metalloproteinase-9 (MMP-9) in the supernatant of LNC or AcE-LNC-pretreated melanoma cells and cocultured with neutrophils. Overall, our data show that the uptake of LNC or AcE-LNC by melanoma cells affects intracellular mechanisms leading to more susceptibility to death and also signals higher neutrophil antitumoral activity.

Hypoxia-induced activin A diminishes endothelial cell vasculogenic activity

Acute ischaemia causes a significant loss of blood vessels leading to deterioration of organ function. Multiple ischaemic conditions are associated with up‐regulation of activin A, but its effect on endothelial cells (EC) in the context of hypoxia is understudied. This study evaluated the role of activin A in vasculogenesis in hypoxia. An in vitro vasculogenesis model, in which EC were cocultured with adipose stromal cells (ASC), was used. Incubation of cocultures at 0.5% oxygen led to decrease in EC survival and vessel density. Hypoxia up‐regulated inhibin B_A (monomer of activin A) mRNA by 4.5‐fold and activin A accumulation in EC‐conditioned media by 10‐fold, but down‐regulated activin A inhibitor follistatin by twofold. Inhibin B_A expression was also increased in human EC injected into ischaemic mouse muscles. Activin A secretion was positively modulated by hypoxia mimetics dimethyloxalylglycine and desferrioxamine. Silencing HIF1α or HIF2α expression decreased activin A secretion in EC exposed to hypoxia. Introduction of activin A to cocultures decreased EC number and vascular density by 40%; conversely, blockade of activin A expression in EC or its activity improved vasculogenesis in hypoxia. Activin A affected EC survival directly and by modulating ASC paracrine activity leading to diminished ability of the ASC secretome to support EC survival and vasculogenesis. In conclusion, hypoxia up‐regulates EC secretion of activin A, which, by affecting both EC and adjacent mesenchymal cells, creates a micro‐environment unfavourable for vasculogenesis. This finding suggests that blockade of activin A signalling in ischaemic tissue may improve preservation of the affected tissue.

Hydrogen Peroxide and Lipopolysaccharide Differentially Affect the Expression of MicroRNAs 10a, 33a, 21, 221 in Endothelial Cells Before and After Coculture With Monocytes

Inflammation and oxidative stress are important risk factors affecting various cells in the formation of atherosclerosis. MicroRNAs (miRs) are regulators of inflammation and atherogenesis. The expressions of endothelial cell (EC)-specific miR-10a and miR-21 and monocyte-specific miR-33a and miR-221 were investigated using coculture of the ECs and monocytes upon exposure to H₂O₂ as an oxidative stressor, and endotoxin/lipopolysaccharide (LPS) as a microbial stressor. Human umbilical endothelial cells (HUVECs) and peripheral blood mononuclear cells (or monocytes) were cocultured in M199 complete medium and were incubated with LPS (20 ng/mL) or H₂O₂ (1%) for 8 hours at 37°C. The HUVECs and monocytes were then separated from the cellular mix using a magnetic bead negative selection technique. The relative expression of miRs was determined by real-time polymerase chain reaction. In both cell types, H₂O₂ induced miR10a ( P = 0.05) and LPS induced miR21 ( P = 0.0003) compared to the untreated controls. Coculture increased miR-10a and miR-21 expression in monocytes ( P = 0.0008 and <0.0001); however when cultured alone, HUVECs expressed higher levels of miR-10a and miR-21 ( P < 0.0001 and <0.0001). Coculture decreased the expression of miR-33a in monocytes ( P < 0.0001) while increasing miR221 in HUVECs and monocytes ( P < 0.0001 and <0.0001). The expression pattern of miRs in HUVECs and monocytes changes in the coculture compared to culturing alone in response to oxidative and microbial toxic compounds. Moreover, different cellular stressors induce different athero-miRs, which may affect the course of inflammation.

CD34+ cells seeded in collagen scaffolds promote bone formation in a mouse calvarial defect model

Bone tissue engineering (BTE) holds promise for managing the clinical problem of large bone defects. However, clinical adoption of BTE is limited due to limited vascularization of constructs, which could be circumvented by pre-cultivation of osteogenic and endothelial derived cells in natural-based polymer scaffolds. However, until now not many studies compared the effect of mono- and cocultures pre-seeded in collagen before implantation. We utilized a mouse calvarial defect model and compared five groups of collagen scaffolds: a negative control of a collagen scaffold alone, a positive control treated with BMP-7, monocultures of either human osteoblasts (hOBs) or CD34+ cells, and a coculture of hOB and CD34⁺ cells. Each pre-seeded collagen scaffold was implanted in mice. After 6 weeks mice were sacrificed and their skulls prepared for volumetric and histologic analysis. We found that a monoculture of CD34⁺ cells and a coculture of hOB and CD34⁺ cells pre-cultured in the collagen scaffold increased bone regeneration to a similar extend. In these groups, greater amounts of new bone were found compared with hOB monocultures. Interestingly, monoculture of CD34⁺ cells demonstrated better fracture healing than monoculture of hOBs, emphasizing the possible role of angiogenesis. Our results are promising regarding a cellular based collagen BTE construct, but more work is needed to understand the complex interaction between the osteogenic and endothelial cells. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1505-1516, 2018.

Complete Biosynthesis of Anthocyanins Using E. coli Polycultures

Fermentation-based chemical production strategies provide a feasible route for the rapid, safe, and sustainable production of a wide variety of important chemical products, ranging from fuels to pharmaceuticals. These strategies have yet to find wide industrial utilization due to their inability to economically compete with traditional extraction and chemical production methods. Here, we engineer for the first time the complex microbial biosynthesis of an anthocyanin plant natural product, starting from sugar. This was accomplished through the development of a synthetic, 4-strain Escherichia coli polyculture collectively expressing 15 exogenous or modified pathway enzymes from diverse plants and other microbes. This synthetic consortium-based approach enables the functional expression and connection of lengthy pathways while effectively managing the accompanying metabolic burden. The de novo production of specific anthocyanin molecules, such as calistephin, has been an elusive metabolic engineering target for over a decade. The utilization of our polyculture strategy affords milligram-per-liter production titers. This study also lays the groundwork for significant advances in strain and process design toward the development of cost-competitive biochemical production hosts through nontraditional methodologies.

To efficiently express active extensive recombinant pathways with high flux in microbial hosts requires careful balance and allocation of metabolic resources such as ATP, reducing equivalents, and malonyl coenzyme A (malonyl-CoA), as well as various other pathway-dependent cofactors and precursors. To address this issue, we report the design, characterization, and implementation of the first synthetic 4-strain polyculture. Division of the overexpression of 15 enzymes and transcription factors over 4 independent strain modules allowed for the division of metabolic burden and for independent strain optimization for module-specific metabolite needs. This study represents the most complex synthetic consortia constructed to date for metabolic engineering applications and provides a new paradigm in metabolic engineering for the reconstitution of extensive metabolic pathways in nonnative hosts.

Effects of silver nanoparticles on the interactions of neuron- and glia-like cells: Toxicity, uptake mechanisms, and lysosomal tracking

Silver nanoparticles (AgNPs) are commonly used nanomaterials in consumer products. Previous studies focused on its effects on neurons; however, little is known about their effects and uptake mechanisms on glial cells under normal or activated states. Here, ALT astrocyte-like, BV-2 microglia and differentiated N2a neuroblastoma cells were directly or indirectly exposed to 10 nm AgNPs using mono- and co-culture system. A lipopolysaccharide (LPS) was pretreated to activate glial cells before AgNP treatment for mimicking NP exposure under brain inflammation. From mono-culture, ALT took up the most AgNPs and had the lowest cell viability within three cells. Moreover, AgNPs induced H₂ O₂ and NO from ALT/activated ALT and BV-2, respectively. However, AgNPs did not induce cytokines release (IL-6, TNF-α, MCP-1). LPS-activated BV-2 took up more AgNPs than normal BV-2, while the induction of ROS and cytokines from activated cells were diminished. Ca²⁺ -regulated clathrin- and caveolae-independent endocytosis and phagocytosis were involved in the AgNP uptake in ALT, which caused more rapid NP translocation to lysosome than in macropinocytosis and clathrin-dependent endocytosis-involved BV-2. AgNPs directly caused apoptosis and necrosis in N2a cells, while by indirect NP exposure to bottom chamber ALT or BV-2 in Transwell, more apoptotic upper chamber N2a cells were observed. Cell viability of BV-2 also decreased in an ALT-BV-2 co-culturing study. The damaged cells correlated to NP-mediated H₂ O₂ release from ALT or NO from BV-2, which indicates that toxic response of AgNPs to neurons is not direct, but indirectly arises from AgNP-induced soluble factors from other glial cells.

Challenges on the road to a multicellular bioartificial liver

Over recent years, the progress in the development of a bioartificial liver (BAL) as an extracorporeal device or as a tissue engineered transplantable organ has been immense. However, many important BAL characteristics that are necessary to meet clinical demands have not been sufficiently addressed. This review describes the existing challenges in the development of a BAL for clinical applications, highlighting multicellularity and sinusoidal microarchitecture as crucial BAL characteristics to fulfil various liver functions. Currently available sources of nonparenchymal liver cells, such as endothelial cells, cholangiocytes and macrophages, used in BAL development are defined. Also, we discuss the recent studies on the reconstruction of the complex liver sinusoid microarchitecture using various liver cell types. Moreover, we highlight some other aspects of a BAL, such as liver zonation and formation of a vascular as well as biliary network for an adequate delivery, biotransformation and removal of substrates and waste products. Finally, the benefits of a multicellular BAL for the pharmaceutical industry are briefly described. Copyright © 2016 John Wiley & Sons, Ltd.

Antagonistic and Quantitative Assessment of Indigenous Lactic acid Bacteria in Different Varieties of Ogi against Gastrointestinal Pathogens

Introduction

Ogi is a popular fermented cereal gruel consumed mainly in the western part of Nigeria. Traditionally, uncooked Ogi is normally administered to diarrhoea patients to reduce the frequency of stooling. This study was therefore undertaken to identify, quantify and determine the antimicrobial properties of lactic acid bacteria (LAB) isolated from Ogi.

Methods

The Ogi samples (Yellow, white, sorghum) were obtained from different market in Ibadan, Nigeria and Ogi control (cooked, uncooked and Omidun) were prepared with the viable counts of bacteria monitored over 5 days period. LAB were isolated from the varieties and identified by partial sequencing of 16S rRNA gene. The antimicrobial activities of the cell free supernatant (CFS) and the viable cells of the isolated LAB against Escherichia coli EC004, Salmonella sp. SS11, Shigella sp. SS10 were investigated by agar diffusion assay, agar overlay method, and coculture growth studies.

Results

Omidun had the highest LAB count while cooked ogi has the lowest LAB count. Weissella paramesenteroides , L. brevis, L. rossiae, L. fermentum, L. plantarum, Acetobacter pasteurianus, Paenibacillus sp. and Bacillus sp. were isolated from Ogi in this study. Large zone of inhibition (11≤x≤20) was observed with CFS against Salmonella sp. SS11 and Shigella sp. SS10 and also the overlay method. Coculture studies of Weissella paramesenteroides, Lactobacillus fermentum, and L. plantarum with Salmonella sp. SS11 showed a 5-8 log reduction of the pathogens' growth after 24 hours as compared with the control.

Conclusion

Ogi and its contents have antimicrobial properties against pathogenic organisms.

Pirated Siderophores Promote Sporulation in Bacillus subtilis

In microbial communities, bacteria chemically and physically interact with one another. Some of these interactions are mediated by secreted specialized metabolites that act as either intraspecies or interspecies signals to alter gene expression and to change cell physiology. Bacillus subtilis is a well-characterized soil microbe that can differentiate into multiple cell types, including metabolically dormant endospores. We were interested in identifying microbial interactions that affected sporulation in B. subtilis. Using a fluorescent transcriptional reporter, we observed that coculturing B. subtilis with Escherichia coli promoted sporulation gene expression via a secreted metabolite. To identify the active compound, we screened the E. coli Keio Collection and identified the sporulation-accelerating cue as the siderophore enterobactin. B. subtilis has multiple iron acquisition systems that are used to take up the B. subtilis-produced siderophore bacillibactin, as well as to pirate exogenous siderophores such as enterobactin. While B. subtilis uses a single substrate binding protein (FeuA) to take up both bacillibactin and enterobactin, we discovered that it requires two distinct genes to sporulate in response to these siderophores (the esterase gene besA for bacillibactin and a putative esterase gene, ybbA, for enterobactin). In addition, we found that siderophores from a variety of other microbial species also promote sporulation in B. subtilis. Our results thus demonstrate that siderophores can act not only as bacterial iron acquisition systems but also as interspecies cues that alter cellular development and accelerate sporulation in B. subtilis.

IMPORTANCE While much is known about the genetic regulation of Bacillus subtilis sporulation, little is understood about how other bacteria influence this process. This work describes an interaction between Escherichia coli and B. subtilis that accelerates sporulation in B. subtilis. The interaction is mediated by the E. coli siderophore enterobactin; we show that other species' siderophores also promote sporulation gene expression in B. subtilis. These results suggest that siderophores not only may supply bacteria with the mineral nutrient iron but also may play a role in bacterial interspecies signaling, providing a cue for sporulation. Siderophores are produced by many bacterial species and thus potentially play important roles in altering bacterial cell physiology in diverse environments.