Inflammation Shapes Stem Cells and Stemness during Infection and Beyond

Incorporating Microbial Stimuli for Osteogenesis in a Rabbit Posterolateral Spinal Fusion Model

Autologous bone grafts are commonly used to repair defects in skeletal tissue, however, due to their limited supply there is a clinical need for alternatives. Synthetic ceramics present a promising option but currently lack biological activity to stimulate bone regeneration. One potential approach to address this limitation is the incorporation of immunomodulatory agents. In this study, we investigate the application of microbial stimuli to stimulate bone formation. Three different microbial stimuli were incorporated in a biphasic calcium phosphate (BCP) ceramic: Bacille Calmette-Guérin (BCG), gamma-irradiated Staphylococcus aureus (γi-S. aureus), or Candida albicans (γi-C. Albicans). The constructs were then implanted in both a rabbit posterolateral spinal fusion (PLF) and an intramuscular implant model for 10 weeks and compared to a non-stimulated control construct. For the PLF model, the formation of a bony bridge was evaluated by manual palpation, micro-CT, and histology. While complete fusion was not observed, the BCG condition was most promising with higher manual stiffness and almost twice as much bone volume in the central fusion mass compared to the control (9±4.4% bone area vs 4.6±2.3%, respectively). Conversely, the γi-S. aureus or γi-C. albicans appeared to inhibit bone formation (1.4±1.4% and 1.2±0.6% bone area). Bone induction was not observed in any of the intramuscular implants. This study indicates that incorporating immunomodulatory agents in ceramic bone substitutes can affect bone formation, which can be positive when selected carefully. The readily available and clinically approved BCG showed promising results, which warrants further research for clinical translation.

Trained innate immunity modulates osteoblast and osteoclast differentiation

Macrophages are key regulators in bone repair and regeneration. Recent studies have shown that long-term epigenetic changes and metabolic shifts occur during specific immune training of macrophages that affect their functional state, resulting in heightened (trained) or reduced (tolerant) responses upon exposure to a second stimulus. This is known as innate immune memory. Here, we study the impact of macrophages' memory trait on osteoblast differentiation of human mesenchymal stromal cells (hMSCs) and osteoclast differentiation. An in vitro trained immunity protocol of monocyte-derived macrophages was employed using inactivated Candida albicans and Bacillus Calmette-Guérin (BCG) to induce a 'trained' state and Pam3CSK4 (PAM) and Lipopolysaccharides (LPS) to induce a 'tolerance' state. Macrophages were subsequently cocultured with hMSCs undergoing osteogenic differentiation during either resting (unstimulated) or inflammatory conditions (restimulated with LPS). Alkaline phosphatase activity, mineralization, and cytokine levels (TNF, IL-6, oncostatin M and SDF-1α) were measured. In addition, macrophages underwent osteoclast differentiation. Our findings show that trained and tolerized macrophages induced opposing results. Under resting conditions, BCG-trained macrophages enhanced ALP levels (threefold), while under inflammatory conditions this was found in the LPS-tolerized macrophages (fourfold). Coculture of hMSCs with trained macrophages showed mineralization while tolerized macrophages inhibited the process under both resting and inflammatory conditions. While osteoclast differentiation was not affected in trained-macrophages, this ability was significantly loss in tolerized ones. This study further confirms the intricate cross talk between immune cells and bone cells, highlighting the need to consider this interaction in the development of personalized approaches for bone regenerative medicine.

Biology and pathophysiology of symptomatic neuromas

ABSTRACT

Neuromas are a substantial cause of morbidity and reduction in quality of life. This is not only caused by a disruption in motor and sensory function from the underlying nerve injury but also by the debilitating effects of neuropathic pain resulting from symptomatic neuromas. A wide range of surgical and therapeutic modalities have been introduced to mitigate this pain. Nevertheless, no single treatment option has been successful in completely resolving the associated constellation of symptoms. While certain novel surgical techniques have shown promising results in reducing neuroma-derived and phantom limb pain, their effectiveness and the exact mechanism behind their pain-relieving capacities have not yet been defined. Furthermore, surgery has inherent risks, may not be suitable for many patients, and may yet still fail to relieve pain. Therefore, there remains a great clinical need for additional therapeutic modalities to further improve treatment for patients with devastating injuries that lead to symptomatic neuromas. However, the molecular mechanisms and genetic contributions behind the regulatory programs that drive neuroma formation-as well as the resulting neuropathic pain-remain incompletely understood. Here, we review the histopathological features of symptomatic neuromas, our current understanding of the mechanisms that favor neuroma formation, and the putative contributory signals and regulatory programs that facilitate somatic pain, including neurotrophic factors, neuroinflammatory peptides, cytokines, along with transient receptor potential, and ionotropic channels that suggest possible approaches and innovations to identify novel clinical therapeutics.

Periodontal Stem Cells Synthesize Maresin Conjugate in Tissue Regeneration 3

Periodontal disease is a significant public health problem worldwide. Excess unresolved chronic inflammation destroys the periodontal tissues that surround and support the teeth, and efforts to control inflammation by removal of bacterial deposits on the teeth have limited long-term impact. Likewise, procedures aimed at regeneration of the periodontal tissues have shown limited success. Recent advances in stem cell research have shown promising novel prospects for the use of periodontal ligament stem cells (PDLSCs) in tissue regeneration; however, control of inflammation remains a barrier. Human PDLSCs have been shown to release specialized proresolving lipid mediators (SPMs) that modulate the immune response and promote resolution of inflammation, tissue repair, and regeneration. Studies on stem cell biology in periodontology have also been limited by the lack of a good large animal model. Herein, we describe PDLSC biology of the Yorkshire pig (pPDLSCs). pPDLSCs were isolated and characterized. Using lipid mediator profiling, we demonstrate for the first time that pPDLSCs biosynthesize cysteinyl-containing SPMs (cys-SPMs), specifically, maresin conjugates in tissue regeneration 3 (MCTR3) and its authentication using liquid chromatography/tandem mass spectrometry. The exogenous addition of the n-3 precursor docosahexaenoic acid enhances MCTR3 biosynthesis. Using immunocytochemistry, we show that pPDLSCs express 4 of the SPM biosynthetic pathway enzymes necessary for SPM biosynthesis, including 5-lipoxygenase, 12-lipoxygenase, and 15-lipoxygenase-1. In addition, we identified and quantified the cytokine/chemokine profile of pPDLSCs using a 13-plex immunology multiplex assay and found that the pretreatment of pPDLSCs with MCTR3 in an inflammatory environment reduced the production of acute and chronic proinflammatory cytokines/chemokines. Together, these results suggest that enhancing resolution of inflammation pathways and mediators may be a possible key early event in predictable periodontal regeneration.

Retina regeneration: lessons from vertebrates

Unlike mammals, vertebrates such as fishes and frogs exhibit remarkable tissue regeneration including the central nervous system. Retina being part of the central nervous system has attracted the interest of several research groups to explore its regenerative ability in different vertebrate models including mice. Fishes and frogs completely restore the size, shape and tissue structure of an injured retina. Several studies have unraveled molecular mechanisms underlying retina regeneration. In teleosts, soon after injury, the Müller glial cells of the retina reprogram to form a proliferating population of Müller glia-derived progenitor cells capable of differentiating into various neural cell types and Müller glia. In amphibians, the transdifferentiation of retinal pigment epithelium and differentiation of ciliary marginal zone cells contribute to retina regeneration. In chicks and mice, supplementation with external growth factors or genetic modifications cause a partial regenerative response in the damaged retina. The initiation of retina regeneration is achieved through sequential orchestration of gene expression through controlled modulations in the genetic and epigenetic landscape of the progenitor cells. Several developmental biology pathways are turned on during the Müller glia reprogramming, retinal pigment epithelium transdifferentiation and ciliary marginal zone differentiation. Further, several tumorigenic pathways and gene expression events also contribute to the complete regeneration cascade of events. In this review, we address the various retinal injury paradigms and subsequent gene expression events governed in different vertebrate species. Further, we compared how vertebrates such as teleost fishes and amphibians can achieve excellent regenerative responses in the retina compared with their mammalian counterparts.

The presentation and regulation of the IL-8 network in the epithelial cancer stem-like cell niche in patients with colorectal cancer

BACKGROUND

Accumulative evidence suggests that the biological behavior of cancer stem-like cells (CSCs) is regulated by their surrounding niche, in which cytokines function as one of the main mediators for the interaction between CSCs and their microenvironment in the colorectal cancer (CRC).

METHODS

We characterized the presentation of CSCs and the interleukin (IL)- 8 network in the adenoma/CRC epithelium using quantitative real-time PCR (q-PCR), immunohistochemistry (IHC) and double immunofluorescence. In addition, the capacity of IL-1β to stimulate epithelial IL-8 production in colon cancer Caco-2 cells was examined in vitro and the IL-8 product was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

IHC observation showed increased expression of both CSCs and IL-8 in the adenoma and CRC epithelium, and q-PCR results revealed that increased expression of IL-1β transcript was strongly correlated with increased IL-8 transcript levels in both adenoma and CRC tissues. Double immunofluorescence images demonstrated the coexpression of the IL-8 receptors IL-8RA and IL-8RB with LGR5 labeled CSCs in CRC tissue sections. Consistently, in vitro experiments showed that coculture of Caco-2 cells with IL-1β at concentrations of 1, 5, 10 and 20 ng/ml resulted in a dose-dependent release of IL-8, which could be specifically inhibited by cotreatment with the IL-1β receptor antagonist.

CONCLUSIONS

These results demonstrate activation of the IL-8 network in the niche of CSCs from the precancerous adenoma stage to the CRC stage, which is potentially stimulated by IL-1β in CRC cells.

Low Molecular Weight Sericin Enhances the In Vitro of Immunological Modulation and Cell Migration

Sericin, a waste product of the silk textile industry, has favorable physicochemical and biological properties. In this study, we extracted a low molecular weight (MW) sericin (LMW-sericin; below 10 kDa) by a performing high-temperature and high-pressure method and confirmed the MW using matrix-assisted laser desorption ionization-time of flight and liquid chromatography–mass spectrometry. Furthermore, we determined its biological effects on macrophages and human adipose stem cells (hASCs) as cell models to investigate the biocompatibility, immunomodulation behavior, and potential signaling pathway-related wound healing via analyses of gene expression of focal adhesion and human cytokines and chemokines using quantitative real-time polymerase chain reaction and cytokine assay. LMW-sericin showed good biocompatibility both in macrophages and hASCs. Macrophages cultured with 0.1 mg/ml LMW-sericin displayed an improved inflammatory response shown by the upregulation of CXCL9, IL12A, BMP7, and IL10, which developed Th1 and Th2 balance. LMW-sericin also improved the differentiation of macrophages toward the M2 phenotype by significantly enhancing the expression of Arg-1, which is conducive to the repair of the inflammatory environment. Moreover, the gene expression of hASCs showed that LMW-sericin promoted the secretion of beneficial adhesion molecules that potentially activate the gene transcription of differentiation and migration in hASCs, as well as significantly enhanced the levels of PKCβ1, RhoA, and RasGFR1 as fruitful molecules in wound healing. These findings provide insights into LMW-sericin application as a potential biomaterial for wound management.

Neonatal lung-derived SSEA-1+ cells exhibited distinct stem/progenitor characteristics and organoid developmental potential

Stem/progenitor cells, because of their self-renewal and multiple cell type differentiation abilities, have good potential in regenerative medicine. We previously reported a lung epithelial cell population that expressed the stem cell marker SSEA-1 was abundant in neonatal but scarce in adult mice. In the current study, neonatal and adult mouse-derived pulmonary SSEA-1⁺ cells were isolated for further characterization. The results showed that neonatal-derived pulmonary SSEA-1⁺ cells highly expressed lung development-associated genes and had enhanced organoid generation ability compared with the adult cells. Neonatal pulmonary SSEA-1⁺ cells generated airway-like and alveolar-like organoids, suggesting multilineage cell differentiation ability. Organoid generation of neonatal but not adult pulmonary SSEA-1⁺ cells was enhanced by fibroblast growth factor 7 (FGF 7). Furthermore, neonatal pulmonary SSEA-1⁺ cells colonized and developed in decellularized and injured lungs. These results suggest the potential of lung-derived neonatal-stage SSEA-1⁺ cells with enhanced stem/progenitor activity and shed light on future lung engineering applications.

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Pulmonary SSEA-1⁺ cells are abundant in neonatal and scarce in adult stages

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The stem/progenitor activity of pulmonary SSEA-1⁺ cells is enhanced in neonatal stage

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Neonatal pulmonary SSEA-1⁺ cells developed into airway- and alveolar-like organoids

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FGF7 regulates alveolar epithelium development of neonatal pulmonary SSEA-1⁺ cells

Quantitative assessment of the immune microenvironment in African American Triple Negative Breast Cancer: a case-control study

PURPOSE

Triple negative breast cancer (TNBC) is more common in African American (AA) than Non-AA (NAA) population. We hypothesize that tumor microenvironment (TME) contributes to this disparity. Here, we use multiplex quantitative immunofluorescence to characterize the expression of immunologic biomarkers in the TME in both populations.

PATIENTS AND METHODS

TNBC tumor resection specimen tissues from a 100-patient case: control cohort including 49 AA and 51 NAA were collected. TME markers including CD45, CD14, CD68, CD206, CD4, CD8, CD20, CD3, Ki67, GzB, Thy1, FAP, aSMA, CD34, Col4, VWF and PD-L1 we quantitatively assessed in every field of view. Mean expression levels were compared between cases and controls.

RESULTS

Although no significant differences were detected in individual lymphoid and myeloid markers, we found that infiltration with CD45+ immune cells (p = 0.0102) was higher in TNBC in AA population. AA TNBC tumors also had significantly higher level of lymphocytic infiltration defined as CD45+ CD14- cells (p = 0.0081). CD3+ T-cells in AA tumors expressed significantly higher levels of Ki67 (0.0066) compared to NAAs, indicating that a higher percentage of AA tumors contained activated T-cells. All other biomarkers showed no significant differences between the AA and NAA group.

CONCLUSIONS

While the TME in TNBC is rich in immune cells in both racial groups, there is a numerical increase in lymphoid infiltration in AA compared to NAA TNBC. Significantly, higher activated T cells seen in AA patients raises the possibility that there may be a subset of AA patients with improved response to immunotherapy.

Inflammation and Periodontal Regeneration

Technological innovations in cellular and molecular aspects of tissue engineering --scaffolds, stem cells and 3D printed tissues --have been dramatically increased in the last decade. However, regenerative treatment still has challenges in translation to clinic. This is partly due to failure of addressing an essential element of wound healing, inflammation. It is now well-recognized that inflammation is an active process. This paradigm shift opened up a new avenue of therapeutic approaches called "host-modulation." Host-modulation therapies capable of modulating inflammatory response at multiple levels and mimicking the natural sequence of wound healing offer a new direction and promising clinical translation.

In Vitro Cellular and Molecular Interplay between Human Foreskin-Derived Mesenchymal Stromal/Stem Cells and the Th17 Cell Pathway

Foreskin, considered a biological waste material, has been shown to be a reservoir of therapeutic cells. The immunomodulatory properties of mesenchymal stromal/stem cells (MSCs) from the foreskin (FSK-MSCs) are being evaluated in cell-based therapy for degenerative, inflammatory and autoimmune disorders. Within the injured/inflamed tissue, proinflammatory lymphocytes such as IL-17-producing T helper cells (Th17) may interact with the stromal microenvironment, including MSCs. In this context, MSCs may encounter different levels of T cells as well as specific inflammatory signals. Uncovering the cellular and molecular changes during this interplay is central for developing an efficient and safe immunotherapeutic tool. To this end, an in vitro human model of cocultures of FSK-MSCs and T cells was established. These cocultures were performed at different cell ratios in the presence of an inflammatory setting. After confirming that FSK-MSCs respond to ISCT criteria by showing a typical phenotype and multilineage potential, we evaluated by flow cytometry the expression of Th17 cell markers IL-17A, IL23 receptor and RORγt within the lymphocyte population. We also measured 15 human Th17 pathway-related cytokines. Regardless of the T cell/MSC ratio, we observed a significant increase in IL-17A expression associated with an increase in IL-23 receptor expression. Furthermore, we observed substantial modulation of IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, INF-γ, sCD40, and TNF-α secretion. These findings suggest that FSK-MSCs are receptive to their environment and modulate the T cell response accordingly. The changes within the secretome of the stromal and immune environment are likely relevant for the therapeutic effect of MSCs. FSK-MSCs represent a valuable cellular product for immunotherapeutic purposes that needs to be further clarified and developed.

The Transient Human Thyroid Progenitor Cell: Examining the Thyroid Continuum from Stem Cell to Follicular Cell

Background: The development of the thyroid follicular cell has been well characterized as it progresses from the original stem cell, either embryonic or adult, through a series of transitions to form a differentiated and functional thyroid cell. Summary: In this review, we briefly outline what is known about this transitional process with emphasis on characterizing the thyroid progenitor stem cell by using data obtained from both in vitro and in vivo studies and both mouse and human cells. It is of particular importance to note the influence of independent factors that guide the transcriptional control of the developing thyroid cell as it is subjected to extracellular signals, often working via epigenetic changes, and initiating intrinsic transcriptional changes leading to a functional cell. Conclusion: Thyroid stem cells fall into the category of dispositional stem cells and are greatly influenced by their environment.

Multifaceted Clinical Effects of Echinochrome

The marine drug histochrome is a special natural antioxidant. The active substance of the drug is echinochrome A (Ech A, 7-ethyl-2,3,5,6,8-pentahydroxy-1,4-naphthoquinone), the most abundant quinonoid pigment in sea urchins. The medicine is clinically used in cardiology and ophthalmology based on the unique properties of Ech A, which simultaneously block various links of free radical reactions. In the last decade, numerous studies have demonstrated the effectiveness of histochrome in various disease models without adverse effects. Here, we review the data on the various clinical effects and modes of action of Ech A in ophthalmic, cardiovascular, cerebrovascular, inflammatory, metabolic, and malignant diseases.

Inflammation Regulates the Multi-Step Process of Retinal Regeneration in Zebrafish

The ability to regenerate tissues varies between species and between tissues within a species. Mammals have a limited ability to regenerate tissues, whereas zebrafish possess the ability to regenerate almost all tissues and organs, including fin, heart, kidney, brain, and retina. In the zebrafish brain, injury and cell death activate complex signaling networks that stimulate radial glia to reprogram into neural stem-like cells that repair the injury. In the retina, a popular model for investigating neuronal regeneration, Müller glia, radial glia unique to the retina, reprogram into stem-like cells and undergo a single asymmetric division to generate multi-potent retinal progenitors. Müller glia-derived progenitors then divide rapidly, numerically matching the magnitude of the cell death, and differentiate into the ablated neurons. Emerging evidence reveals that inflammation plays an essential role in this multi-step process of retinal regeneration. This review summarizes the current knowledge of the inflammatory events during retinal regeneration and highlights the mechanisms whereby inflammatory molecules regulate the quiescence and division of Müller glia, the proliferation of Müller glia-derived progenitors and the survival of regenerated neurons.

Identification of Lactate as a Cardiac Protectant by Inhibiting Inflammation and Cardiac Hypertrophy Using a Zebrafish Acute Heart Failure Model

Acute heart failure (AHF) commonly arises from decompensated chronic heart failure or sudden structural and functional breakdown causing a decrease in cardiac contractility and consequently fluid accumulation and systemic congestion. Current treatment for AHF aims at reducing fluid overload and improving hemodynamic which results in quick symptom relief but still poor prognostic outcome. This study utilizes a zebrafish AHF model induced by aristolochic acid (AA) to look for natural products that could attenuate the progression of AHF. The project started off by testing nearly seventy herbal crude extracts. Two of the positive extracts were from Chinese water chestnuts and are further studied in this report. After several rounds of chromatographical chemical fractionation and biological tests, a near pure fraction, named A2-4-2-4, with several hydrophilic compounds was found to attenuate the AA-induced AHF. A2-4-2-4 appeared to inhibit inflammation and cardiac hypertrophy by reducing MAPK signaling activity. Chemical analyses revealed that the major compound in A2-4-2-4 is actually lactate. Pure sodium lactate showed attenuation of the AA-induced AHF and inflammation and cardiac hypertrophy suppression as well, suggesting that the AHF attenuation ability in A2-4-2-4 is attributable to lactate. Our studies identify lactate as a cardiac protectant and a new therapeutic agent for AHF.

Novel insights for improving the therapeutic safety and efficiency of mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) have attracted great interest in the field of regenerative medicine. They can home to damaged tissue, where they can exert pro-regenerative and anti-inflammatory properties. These therapeutic effects involve the secretion of growth factors, cytokines, and chemokines. Moreover, the functions of MSCs could be mediated by extracellular vesicles (EVs) that shuttle various signaling messengers. Although preclinical studies and clinical trials have demonstrated promising therapeutic results, the efficiency and the safety of MSCs need to be improved. After transplantation, MSCs face harsh environmental conditions, which likely dampen their therapeutic efficacy. A possible strategy aiming to improve the survival and therapeutic functions of MSCs needs to be developed. The preconditioning of MSCs ex vivo would strength their capacities by preparing them to survive and to better function in this hostile environment. In this review, we will discuss several preconditioning approaches that may improve the therapeutic capacity of MSCs. As stated above, EVs can recapitulate the beneficial effects of MSCs and may help avoid many risks associated with cell transplantation. As a result, this novel type of cell-free therapy may be safer and more efficient than the whole cell product. We will, therefore, also discuss current knowledge regarding the therapeutic properties of MSC-derived EVs.

A comparative analysis of immunomodulatory genes in two clonal subpopulations of CD90+ amniocytes isolated from human amniotic fluid

OBJECT

Immunosuppressive and immunomodulatory activity of mesenchymal stem cells derived from different sources, such as placental membranes, umbilical cord, and amniotic fluid has been proved. The heterogeneous nature of human amniocytes have been confirmed due to different clonal subpopulations found in amniotic fluid. The aim of this study was to investigate a 17-gene panel of immunomodulatory markers in two clonal subpopulations of CD90⁺ amniocytes, divided based on morphology into epithelioid and fibroblastoid cells.

METHOD

Semi-quantitative RT-PCR was used to study the expression of the chosen genes. Flow cytometry analysis confirmed the non-hematopoietic mesenchymal origin of isolated cells, based on lacking the hematopoietic marker of CD31, and the presence of mesenchymal marker of CD90 (both on more than 90% of cells).

RESULTS

Our results showed that besides growth characteristics, the two cell groups were different in expressional profile, so that, fibroblastoid clones displayed higher level of immunosuppression genes as well as mesenchymal surface marker of CD90 compared to epithelioid ones. Our previous investigation on these clones showed that epithelioid cells have a more potential to express the pluripotency genes. It seems there is an inverse relationship between genes associated with immunosuppression and pluripotency.

CONCLUSION

Although many reports have been published regarding the immunosuppressive properties of fetal stem cells, but few studies to date have explained whether the stemness state of human amniocytes may affect their immunosuppressive potential. Further study on amniocytes, which often has self-renewal ability and high immunomodulatory potential, can help to understand the details of this relationship.

Maresin-1 and Resolvin E1 Promote Regenerative Properties of Periodontal Ligament Stem Cells Under Inflammatory Conditions

Maresin-1 (MaR1) and Resolvin E1 (RvE1) are specialized pro-resolving lipid mediators (SPMs) that regulate inflammatory processes. We have previously demonstrated the hard and soft tissue regenerative capacity of RvE1 in an in vivo model of the periodontal disease characterized by inflammatory tissue destruction. Regeneration of periodontal tissues requires a well-orchestrated process mediated by periodontal ligament stem cells. However, limited data are available on how SPMs can regulate the regenerative properties of human periodontal ligament stem cells (hPDLSCs) under inflammatory conditions. Thus, we measured the impact of MaR1 and RvE1 in an in vitro model of hPDLSC under stimulation with IL-1β and TNF-α by evaluating pluripotency, migration, viability/cell death, periodontal ligament markers (α-smooth muscle actin, tenomodulin, and periostin), cementogenic-osteogenic differentiation, and phosphoproteomic perturbations. The data showed that the pro-inflammatory milieu suppresses pluripotency, viability, and migration of hPDLSCs; MaR1 and RvE1 both restored regenerative capacity by increasing hPDLSC viability, accelerating wound healing/migration, and up-regulating periodontal ligament markers and cementogenic-osteogenic differentiation. Protein phosphorylation perturbations were associated with the SPM-induced regenerative capacity of hPDLSCs. Together, these results demonstrate that MaR1 and RvE1 restore or improve the regenerative properties of highly specialized stem cells when inflammation is present and offer opportunities for direct pharmacologic treatment of lost tissue integrity.

Inflammation Differentially Modulates the Biological Features of Adult Derived Human Liver Stem/Progenitor Cells

The progression of mesenchymal stem cell-based therapy from concept to cure closely depends on the optimization of conditions that allow a better survival and favor the cells to achieve efficient liver regeneration. We have previously demonstrated that adult-derived human liver stem/progenitor cells (ADHLSC) display significant features that support their clinical development. The current work aims at studying the impact of a sustained pro-inflammatory environment on the principal biological features of ADHLSC in vitro. METHODS: ADHLSC from passages 4–7 were exposed to a cocktail of inflammatory cytokines for 24 h and 9 days and subsequently analyzed for their viability, expression, and secretion profiles by using flow cytometry, RT-qPCR, and antibody array assay. The impact of inflammation on the hepatocytic differentiation potential of ADHLSC was also evaluated. RESULTS: ADHLSC treated with a pro-inflammatory cocktail displayed significant decrease of cell yield at both times of treatment while cell mortality was observed at 9 days post-priming. After 24 h, no significant changes in the immuno-phenotype of ADHLSC expression profile could be noticed while after 9 days, the expression profile of relevant markers has changed both in the basal conditions and after inflammation treatment. Inflammation cocktail enhanced the release of IL-6, IL-8, CCL5, monocyte-chemo-attractant protein-2 and 3, CXCL1/GRO, and CXCL5/ENA78. Furthermore, while IP-10 secretion was increased after 24 h priming, granulocyte macrophage colony-stimulating factor enhanced secretion was noticed after 9 days treatment. Finally, priming of ADHLSC did not affect their potential to differentiate into hepatocyte-like cells. CONCLUSION: These results indicate that ADHLSCs are highly sensitive to inflammation and respond to such signals by adjusting their gene and protein expression. Accordingly, monitoring the inflammatory status of patients at the time of cell transplantation, will certainly help in enhancing ADHLSC safety and efficiency.

Treg regulation of the epithelial stem cell lineage

Tissue repair and maintenance in adult organisms is dependent on the interactions between stem cells (SCs) and constituent cells of their microenvironment, or niche. Accumulating evidence suggests that immune cells, specifically Foxp3⁺ CD4⁺ Regulatory T cells (Tregs), play an important role as a regulator of the SC niche. Undisputedly, Tregs are the major immunosuppressive lineage of the CD4⁺ T cell compartment, and reside within numerous secondary lymphoid organs, where they exert their functions. These cells are also specialised in facilitating protective functions specific to their tissue of residence. In this review, we discuss the emerging concepts supporting the SC-regulatory functions of tissue-resident Tregs, during both the steady-state and SC-mediated regeneration. We highlight the skin, intestines, and lung as model organs which are subject to recurrent microinjury,exposure to microbiota, and constantly replenished by resident stem cell populations. An in-depth understanding of the biology of the Treg-SC axis will inform ongoing immunotherapeutic endeavours to target specific subpopulations of tissue-resident Tregs.

The Impact of Cell-Expansion and Inflammation on The Immune-Biology of Human Adipose Tissue-Derived Mesenchymal Stromal Cells

Background: As a cell-based therapeutic, AT-MSCs need to create an immuno-reparative environment appropriate for tissue repair. In the presence of injury, MSCs may have to proliferate and face inflammation. Clinical application requires repeated administrations of a high number of cells with a well-established immune profile. Methods: We have established an immuno-comparative screening by determining the expression of 28 molecules implicated in immune regulation. This screening was performed during cell-expansion and inflammatory priming of AT-MSCs. Results: Our study confirms that AT-MSCs are highly expandable and sensitive to inflammation. Both conditions have substantially modulated the expression of a panel of immunological marker. Specifically, CD34 expression was substantially decreased upon cell-passaging. HLA-ABC, CD40 CD54, CD106, CD274 and CD112 were significantly increased by inflammation. In vitro cell-expansion also significantly altered the expression profile of HLA-DR, CD40, CD62L, CD106, CD166, HLA-G, CD200, HO-1, CD155 and ULBP-3. Conclusion: This study points out the response and characteristics of MSCs following expansion and inflammatory priming. It will strength our knowledge about the molecular mechanisms that may improve or hamper the therapeutic potential of MSCs. These immunological changes need to be further characterized to guarantee a safe cellular product with consistent quality and high therapeutic efficacy.

Epigenetic Silencing of Ubiquitin Specific Protease 4 by Snail1 Contributes to Macrophage-Dependent Inflammation and Therapeutic Resistance in Lung Cancer

There is a positive feedback loop driving tumorigenesis and tumor growth through coordinated regulation of epigenetics, inflammation, and stemness. Nevertheless, the molecular mechanism linking these processes is not well understood. In this study, we analyzed the correlation of de-ubiquitinases (DUBs) expression with survival data from the OncoLnc database. Among the DUBs analyzed, ubiquitin specific protease 4 (USP4) had the lowest negative Cox coefficient. Low expression of USP4 was associated with poor survival among lung cancer patients and was inversely correlated with expression of stemness and inflammation markers. Expression of USP4 were reduced at more advanced stages of lung cancer. Mechanistically, expression of USP4 was downregulated in snail1-overexpressing and stemness-enriched lung cancer cells. Snail1 was induced in lung cancer cells by interaction with macrophages, and epigenetically suppressed USP4 expression by promoter methylation. Stable knockdown of USP4 in lung cancer cells enhanced inflammatory responses, stemness properties, chemotherapy resistance, and the expression of molecules allowing escape from immunosurveillance. Further, mice injected with USP4 knockdown lung cancer cells demonstrated enhanced tumorigenesis and tumor growth. These results reveal that the Snail1-mediated suppression of USP4 is a potential mechanism to orchestrate epigenetic regulation, inflammation and stemness for macrophage-promoted tumor progression.

Infrapatellar Fat Pad Stem Cells Responsiveness to Microenvironment in Osteoarthritis: From Morphology to Function

Recently, infrapatellar fat pad (IFP) has been considered as a source of stem cells for cartilage regeneration in osteoarthritis (OA) due to their ability for differentiation into chondrocytes. However, stressful conditions, like that related to OA, may induce a pathogenic reprograming. The aim of this study was to characterize the structural and functional properties of a new population of stem cells isolated from osteoarthritic infrapatellar fat pad (OA-IFP). Nine OA patients undergoing total knee arthroplasty (TKA) were enrolled in this study [median age = 74 years, interquartile range (IQR) = 78.25-67.7; median body mass index = 29.4 Kg/m², IQR = 31.7-27.4]. OA-IFP stem cells were isolated and characterized for morphology, stemness, metabolic profile and multi-differentiative potential by transmission electron microscopy, flow cytometric analysis, gene expression study and cytochemistry. OA-IFP stem cells displayed a spindle-like morphology, self-renewal potential and responsiveness (CD44, CD105, VEGFR2, FGFR2, IL1R, and IL6R) to microenvironmental stimuli. Characterized by high grade of stemness (STAT3, NOTCH1, c-Myc, OCT-4, KLF4, and NANOG), the cells showed peculiar immunophenotypic properties (CD73⁺/CD39⁺/CD90⁺/CD105⁺/CD44^–/+/CD45^–). The expression of HLA-DR, CD34, Fas and FasL was indicative of a possible phenotypic reprograming induced by inflammation. Moreover, the response to mechanical stimuli together with high expression level of COL1A1 gene, suggested their possible protective response against in vivo mechanical overloading. Conversely, the low expression of CD38/NADase was indicative of their inability to counteract NAD⁺-mediated OA inflammation. Based on the ultrastructural, immunophenotypic and functional characterization, OA-IFP stem cells were hypothesized to be primed by the pathological environment and to exert incomplete protective activity from OA inflammation.

Differential Effector Response of Amnion- and Adipose-Derived Mesenchymal Stem Cells to Inflammation; Implications for Intradiscal Therapy

Intervertebral disc degeneration (IVDD) is a progressive condition marked by tissue destruction and inflammation. The therapeutic effector functions of mesenchymal stem cells (MSCs) makes them an attractive therapy for patients with IVDD. While several sources of MSCs exist, the optimal choice for use in the inflamed IVD remains a significant question. Adipose (AD)- and amnion (AM)-derived MSCs have several advantages compared with other sources, however, no study has directly compared the impact of IVDD inflammation on their effector functions. Human MSCs were cultured in media with or without supplementation of interleukin-1β (IL-1β) and tumor necrosis factor-α at concentrations reportedly produced by IVDD cells. MSC proliferation and production of pro- and anti-inflammatory cytokines were quantified following 24 and 48 h of culture. Additionally, the osteogenic and chondrogenic potential of AD- and AM-MSCs was characterized via histology and biochemical analysis following 28 days of culture. In inflammatory culture, AM-MSCs produced significantly more anti-inflammatory IL-10 (14.47 ± 2.39 pg/ml; p = 0.004) and larger chondrogenic pellets (5.67 ± 0.26 mm² ; p = 0.04) with greater percent area staining positively for glycosaminoglycan (82.03 ± 3.26%; p < 0.001) compared with AD-MSCs (0.00 ± 0.00 pg/ml; 2.76 ± 0.18 mm² ; 34.75 ± 2.49%; respectively). Conversely, AD-MSCs proliferated more resulting in higher cell numbers (221,000 ± 8,021 cells; p = 0.048) and produced higher concentrations of pro-inflammatory cytokines prostaglandin E₂ (1,118.30 ± 115.56 pg/ml; p = 0.030) and IL-1β (185.40 ± 7.63 pg/ml; p = 0.010) compared with AM-MSCs (109,667 ± 5,696 cells; 1,291.40 ± 78.47 pg/ml; 144.10 ± 4.57 pg/ml; respectively). AD-MSCs produced more mineralized extracellular matrix (3.34 ± 0.05 relative absorbance units [RAU]; p < 0.001) compared with AM-MSCs (1.08 ± 0.06 RAU). Under identical inflammatory conditions, a different effector response was observed with AM-MSCs producing more anti-inflammatories and demonstrating enhanced chondrogenesis compared with AD-MSCs, which produced more pro-inflammatory cytokines and demonstrated enhanced osteogenesis. These findings may begin to help inform researchers which MSC source may be optimal for IVD regeneration. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2445-2456, 2019.

Mesenchymal Stromal Cell-Based Therapy: New Perspectives and Challenges

Stem cells have been the focus of intense research opening up new possibilities for the treatment of various diseases. Mesenchymal stromal cells (MSCs) are multipotent cells with relevant immunomodulatory properties and are thus considered as a promising new strategy for immune disease management. To enhance their efficiency, several issues related to both MSC biology and functions are needed to be identified and, most importantly, well clarified. The sources from which MSCs are isolated are diverse and might affect their properties. Both clinicians and scientists need to handle a phenotypic-characterized population of MSCs, particularly regarding their immunological profile. Moreover, it is now recognized that the tissue-reparative effects of MSCs are based on their immunomodulatory functions that are activated following a priming/licensing step. Thus, finding the best ways to pre-conditionate MSCs before their injection will strengthen their activity potential. Finally, soluble elements derived from MSC-secretome, including extracellular vesicles (EVs), have been proposed as a cell-free alternative tool for therapeutic medicine. Collectively, these features have to be considered and developed to ensure the efficiency and safety of MSC-based therapy. By participating to this Special Issue “Mesenchymal Stem/Stromal Cells in Immunity and Disease”, your valuable contribution will certainly enrich the content and discussion related to the thematic of MSCs.

Immunohematology Mesenchymal Stromal Cell-based Therapy: From Research to Clinic

Mesenchymal stromal cells (MSC) are nonhematopoietic cells that can be isolated from several adult and fetal tissues. MSC present specific features as the capacity to support hematopoiesis and to regulate immune response. Thus, the use of MSC as a cell therapeutic product in the field of immune-hematology is of great importance. In this review, we focused on human MSC and discussed their immune-hematologic properties and their translation toward therapeutic clinical applications. Thus, these features hold great promise for cell-based therapy and are of important relevance for the field.

Immunological modulation following bone marrow-derived mesenchymal stromal cells and Th17 lymphocyte co-cultures

OBJECTIVE AND DESIGN

The objective of the study is to uncover the influence of human bone marrow-derived mesenchymal stem cells (BM-MSCs) on the generation of Th17 lymphocytes in co-cultures of both BM-MSCs and T cells.

MATERIALS AND METHODS

BM-MSCs, characterized according to the international society for cellular therapy (ISCT) criteria, were co-cultured with T cells isolated from peripheral blood. The expression levels of IL-17 receptor, RORγt and IL-23 receptor were evaluated using flow cytometry. The levels of cytokines involved in Th17 immunomodulation were measured using multiplex assay.

TREATMENT

Inflammatory primed and non-primed BM-MSCs were co-cultured with either activated or non-activated T cells either at (1/80) and (1/5) ratio respectively.

RESULTS

MSC/T-cell ratio and inflammation significantly influenced the effect of BM-MSCs on the generation of Th17 lymphocytes. Cocultures of either primed or non-primed BM-MSCs with activated T cells significantly induced IL-17A-expressing lymphocytes. Interestingly, the expression of the transcription factor RORγt was significantly increased when compared to levels in activated T cells. Finally, both cell ratio and priming of BM-MSCs with cytokines substantially influenced the cytokine profile of BM-MSCs and T cells.

CONCLUSION

Our findings suggest that BM-MSCs significantly modulate the Th17 lymphocyte pathway in a complex manner.

Diverse mechanisms for endogenous regeneration and repair in mammalian organs

Mammalian organs comprise an extraordinary diversity of cell and tissue types. Regenerative organs, such as the skin and gastrointestinal tract, use resident stem cells to maintain tissue function. Organs with a lower cellular turnover, such as the liver and lungs, mostly rely on proliferation of committed progenitor cells. In many organs, injury reveals the plasticity of both resident stem cells and differentiated cells. The ability of resident cells to maintain and repair organs diminishes with age, whereas, paradoxically, the risk of cancer increases. New therapeutic approaches aim to harness cell plasticity for tissue repair and regeneration while avoiding the risk of malignant transformation of cells.

Advanced Glycation End-Products-, C-Type Lectin- and Cysteinyl/ Leukotriene-Receptors in Distinct Mesenchymal Stromal Cell Populations: Differential Transcriptional Profiles in Response to Inflammation

OBJECTIVES

We aimed at characterizing the transcription profiles of immunological receptors associated with the biology of mesenchymal stromal cells (MSCs).

MATERIALS AND METHODS

In this experimental study, quantitative real time-polymerase chain reaction (qRTPCR) was performed to establish the transcription profiles of advanced glycation end-products (RAGE) receptor, C-type lectin receptors (CLRs, including DECTIN-1, DECTIN-2 and MINCLE), leukotriene B4 (LTB4) receptors (BLT1 and BLT2) and cysteinyl leukotrienes (CysLTs) receptors (CYSLTR1 and CYSLTR2) in distinct populations of MSCs grown under basic or inflammatory conditions.

RESULTS

MSCs derived from adipose tissue (AT), foreskin (FSK), Wharton's jelly (WJ) and bone marrow (BM) exhibited significantly different transcription levels for these genes. Interestingly, these transcription profiles substantially changed following exposure of MSCs to inflammatory signals.

CONCLUSIONS

Collectively, for the first time, our data highlights that MSCs depending on their tissue-source, present several relevant receptors potentially involved in the regulation of inflammatory and immunological responses. Understanding the roles of these receptors within MSCs immunobiology will incontestably improve the efficiency of utilization of MSCs during cell-based therapies.

Insights into inflammatory priming of mesenchymal stromal cells: functional biological impacts

Mesenchymal stromal cells (MSCs) are multipotent adult cells with relevant biological properties making them interesting tools for cell-based therapy. These cells have the ability to home to sites of injury and secrete bioactive factors as part of their therapeutic functions. However, depending on the local environment, diverse functions of MSCs can be modulated and thus can influence their therapeutic value. The specific cytokine milieu within the site of inflammation is vital in determining the fate and cell behaviors of MSCs. Indeed, inflammatory signals (called as inflammatory priming), may induce critical changes on the phenotype, multilineage potential, hematopoietic support and immunomodulatory capacity of MSCs. Thus, for appropriate clinical application of MSCs, it is important to well know and understand these effects. In summary, investigating MSC interactions with the inflammatory environment is necessary to empower the therapeutic value of MSCs.

Histone MacroH2A1: A Chromatin Point of Intersection between Fasting, Senescence and Cellular Regeneration

Histone variants confer chromatin unique properties. They have specific genomic distribution, regulated by specific deposition and removal machineries. Histone variants, mostly of canonical histones H2A, H2B and H3, have important roles in early embryonic development, in lineage commitment of stem cells, in the converse process of somatic cell reprogramming to pluripotency and, in some cases, in the modulation of animal aging and life span. MacroH2A1 is a variant of histone H2A, present in two alternatively exon-spliced isoforms macroH2A1.1 and macroH2A1.2, regulating cell plasticity and proliferation, during pluripotency and tumorigenesis. Furthermore, macroH2A1 participates in the formation of senescence-associated heterochromatic foci (SAHF) in senescent cells, and multiple lines of evidence in genetically modified mice suggest that macroH2A1 integrates nutritional cues from the extracellular environment to transcriptional programs. Here, we review current molecular evidence based on next generation sequencing data, cell assays and in vivo models supporting different mechanisms that could mediate the function of macroH2A1 in health span and life span. We will further discuss context-dependent and isoform-specific functions. The aim of this review is to provide guidance to assess histone variant macroH2A1 potential as a therapeutic intervention point.

The micronome of mesenchymal stromal cells is partially responsive to inflammation

Mesenchymal stromal cells (MSCs) display a special immunological profile that allows their potential use as immunotherapeutic cells. Nowadays, foreskin (FSK) represents a valuable reservoir of MSCs with International Society for Cellular Therapy (ISCT) compliant criteria and relevant functional properties. However, their mode of action is poorly understood and needs to be more elucidated to optimize their therapeutic use. Because microRNAs (miRNAs) act as key regulators in a wide variety of biological processes, we decided to establish the micronome of FSK-MSCs, the influence of inflammation and the predicted target pathways. Here, we provide the full list of unchanged and additional four differentially expressed miRNAs, miR-199b, -296-3p and -589-5p being downregulated whilst miR-146-3p being upregulated, in MSCs following their exposure to a cocktail of proinflammatory cytokines. MicroRNA target prediction in addition to Pathway enrichment analysis performed using miRNet, showed that miR-296-3p is linked to antigen processing and presentation pathway. Collectively, our data indicate that the micronome of FSK-MSCs is partially responsive to inflammation. Differentially expressed miRNAs are subsequently modulated by inflammation and seem to be involved in regulating the immunological fate of FSK-MSCs. These miRNAs deserve more attention in order to optimize MSC-based therapy and achieve the appropriate therapeutic effect.

Changing Stem Cell Dynamics during Papillomavirus Infection: Potential Roles for Cellular Plasticity in the Viral Lifecycle and Disease

Stem cells and cellular plasticity are likely important components of tissue response to infection. There is emerging evidence that stem cells harbor receptors for common pathogen motifs and that they are receptive to local inflammatory signals in ways suggesting that they are critical responders that determine the balance between health and disease. In the field of papillomaviruses stem cells have been speculated to play roles during the viral life cycle, particularly during maintenance, and virus-promoted carcinogenesis but little has been conclusively determined. I summarize here evidence that gives clues to the potential role of stem cells and cellular plasticity in the lifecycle papillomavirus and linked carcinogenesis. I also discuss outstanding questions which need to be resolved.

The immunosuppressive cytokine interleukin-4 increases the clonogenic potential of prostate stem-like cells by activation of STAT6 signalling

Interleukin-4 plays a critical role in the regulation of immune responses and has been detected at high levels in the tumour microenvironment of cancer patients, where concentrations correlate with the grade of malignancy. In prostate cancer, interleukin-4 has been associated with activation of the androgen receptor, increased proliferation and activation of survival pathways such as Akt and NF-κB. However, its role in therapy resistance has not yet been determined. Here we investigate the influence of interleukin-4 on primary epithelial cells from prostate cancer patients. Our data demonstrate an increase in the clonogenic potential of these cells when cultured in the presence of interleukin-4. In addition, a Phospho-Kinase Array revealed that in contrast to previously published work, signal transducer and activator of transcription6 (STAT6) is the only signalling molecule activated after interleukin-4 treatment. Using the STAT6-specific inhibitor AS1517499 we could confirm the role of STAT6 in increasing colony-forming frequency. However, clonogenic recovery assays revealed that interleukin-4 does not rescue the effects of either irradiation or docetaxel treatment. We therefore propose that although the interleukin-4/STAT6 axis does not appear to be involved in therapy resistance, it does play a crucial role in the colony-forming abilities of the basal cell population in prostate cancer. IL-4 may therefore contribute to disease relapse by providing a niche that is favourable for the clonogenic growth of prostate cancer stem cells.