Osteogenic differentiation of mesenchymal stem cells from dental bud: Role of integrins and cadherins

Several studies have reported the beneficial effects of mesenchymal stem cells (MSCs) in tissue repair and regeneration. New sources of stem cells in adult organisms are continuously emerging; dental tissues have been identified as a source of postnatal MSCs. Dental bud is the immature precursor of the tooth, is easy to access and we show in this study that it can yield a high number of cells with ≥95% expression of mesenchymal stemness makers and osteogenic capacity. Thus, these cells can be defined as Dental Bud Stem Cells (DBSCs) representing a promising source for bone regeneration of stomatognathic as well as other systems. Cell interactions with the extracellular matrix (ECM) and neighboring cells are critical for tissue morphogenesis and architecture; such interactions are mediated by integrins and cadherins respectively. We characterized DBSCs for the expression of these adhesion receptors and examined their pattern during osteogenic differentiation. Our data indicate that N-cadherin and cadherin-11 were expressed in undifferentiated DBSCs and their expression underwent changes during the osteogenic process (decreasing and increasing respectively), while expression of E-cadherin and P-cadherin was very low in DBSCs and did not change during the differentiation steps. Such expression pattern reflected the mesenchymal origin of DBSCs and confirmed their osteoblast-like features. On the other hand, osteogenic stimulation induced the upregulation of single subunits, αV, β3, α5, and the formation of integrin receptors α5β1 and αVβ3. DBSCs differentiation toward osteoblastic lineage was enhanced when cells were grown on fibronectin (FN), vitronectin (VTN), and osteopontin (OPN), ECM glycoproteins which contain an integrin-binding sequence, the RGD motif. In addition we established that integrin αVβ3 plays a crucial role during the commitment of MSCs to osteoblast lineage, whereas integrin α5β1 seems to be dispensable. These data suggest that functionalization of biomaterials with such ECM proteins would improve bone reconstruction therapies starting from dental stem cells.

DAMP production by human islets under low oxygen and nutrients in the presence or absence of an immunoisolating-capsule and necrostatin-1

In between the period of transplantation and revascularization, pancreatic islets are exposed to low-oxygen and low-nutrient conditions. In the present study we mimicked those conditions in vitro to study the involvement of different cell death processes, release of danger-associated molecular patterns (DAMP), and associated in vitro immune activation. Under low-oxygen and low-nutrient conditions, apoptosis, autophagy and necroptosis occur in human islets. Necroptosis is responsible for DAMP-release such as dsDNA, uric acid, and HMGB1. The sensors of the innate immune system able to recognize these DAMPs are mainly TLR, NOD receptors, and C-type lectins. By using cell-lines with a non-functional adaptor molecule MyD88, we were able to show that the islet-derived DAMPs signal mainly via TLR. Immunoisolation in immunoprotective membranes reduced DAMP release and immune activation via retention of the relative large DAMPs in the capsules. Another effective strategy was suppressing necroptosis using the inhibitor nec-1. Although the effect on cell-survival was minor, nec-1 was able to reduce the release of HMGB1 and its associated immune activation. Our data demonstrate that in the immediate post-transplant period islets release DAMPs that in vitro enhance responses of innate immune cells. DAMP release can be reduced in vitro by immunoisolation or intervention with nec-1.

In Vitro Conditioned Bone Marrow-Derived Mesenchymal Stem Cells Promote De Novo Functional Enteric Nerve Regeneration, but Not Through Direct-Transdifferentiation

Injury or neurodegenerative disorders of the enteric nervous system (ENS) cause gastrointestinal dysfunctions for which there is no effective therapy. This study, using the benzalkonium chloride-induced rat gastric denervation model, aimed to determine whether transplantation of bone marrow-derived mesenchymal stem cells (BMSC) could promote ENS neuron regeneration and if so, to elucidate the mechanism. Fluorescently labeled BMSC, isolated from either WT (BMSC labeled with bis-benzimide [BBM]) or green fluorescent protein (GFP)-transgenic rats, were preconditioned in vitro using fetal gut culture media containing glial cell-derived neurotrophic factor (GDNF), and transplanted subserosally into the denervated area of rat pylorus. In the nerve-ablated pylorus, grafted BMSC survived and migrated from the subserosa to the submucosa 28 days after transplantation, without apparent dedifferentiation. A massive number of PGP9.5/NSE/HuC/D/Tuj1-positive (but GFP- and BBM-negative) neurons were effectively regenerated in denervated pylorus grafted with preconditioned BMSC, suggesting that they were regenerated de novo, not originating from trans-differentiation of the transplanted BMSC. BMSC transplantation restored both basal pyloric contractility and electric field stimulation-induced relaxation. High levels of GDNF were induced in both in vitro-preconditioned BMSC as well as the previously denervated pylorus after transplantation of preconditioned BMSC. Thus, a BMSC-initiated GDNF-positive feedback mechanism is suggested to promote neuron regeneration and growth. In summary, we have demonstrated that allogeneically transplanted preconditioned BMSC initiate de novo regeneration of gastric neuronal cells/structures that in turn restore gastric contractility in pylorus-denervated rats. These neuronal structures did not originate from the grafted BMSC. Our data suggest that preconditioned allogeneic BMSC may have therapeutic value in treating enteric nerve disorders.

Clinical Trials With Mesenchymal Stem Cells: An Update

In the last year, the promising features of mesenchymal stem cells (MSCs), including their regenerative properties and ability to differentiate into diverse cell lineages, have generated great interest among researchers whose work has offered intriguing perspectives on cell-based therapies for various diseases. Currently the most commonly used adult stem cells in regenerative medicine, MSCs, can be isolated from several tissues, exhibit a strong capacity for replication in vitro, and can differentiate into osteoblasts, chondrocytes, and adipocytes. However, heterogeneous procedures for isolating and cultivating MSCs among laboratories have prompted the International Society for Cellular Therapy (ISCT) to issue criteria for identifying unique populations of these cells. Consequently, the isolation of MSCs according to ISCT criteria has produced heterogeneous, nonclonal cultures of stromal cells containing stem cells with different multipotent properties, committed progenitors, and differentiated cells. Though the nature and functions of MSCs remain unclear, nonclonal stromal cultures obtained from bone marrow and other tissues currently serve as sources of putative MSCs for therapeutic purposes, and several findings underscore their effectiveness in treating different diseases. To date, 493 MSC-based clinical trials, either complete or ongoing, appear in the database of the US National Institutes of Health. In the present article, we provide a comprehensive review of MSC-based clinical trials conducted worldwide that scrutinizes biological properties of MSCs, elucidates recent clinical findings and clinical trial phases of investigation, highlights therapeutic effects of MSCs, and identifies principal criticisms of the use of these cells. In particular, we analyze clinical trials using MSCs for representative diseases, including hematological disease, graft-versus-host disease, organ transplantation, diabetes, inflammatory diseases, and diseases in the liver, kidney, and lung, as well as cardiovascular, bone and cartilage, neurological, and autoimmune diseases.

Stimulating endogenous cardiac repair

The healthy adult heart has a low turnover of cardiac myocytes. The renewal capacity, however, is augmented after cardiac injury. Participants in cardiac regeneration include cardiac myocytes themselves, cardiac progenitor cells, and peripheral stem cells, particularly from the bone marrow compartment. Cardiac progenitor cells and bone marrow stem cells are augmented after cardiac injury, migrate to the myocardium, and support regeneration. Depletion studies of these populations have demonstrated their necessary role in cardiac repair. However, the potential of these cells to completely regenerate the heart is limited. Efforts are now being focused on ways to augment these natural pathways to improve cardiac healing, primarily after ischemic injury but in other cardiac pathologies as well. Cell and gene therapy or pharmacological interventions are proposed mechanisms. Cell therapy has demonstrated modest results and has passed into clinical trials. However, the beneficial effects of cell therapy have primarily been their ability to produce paracrine effects on the cardiac tissue and recruit endogenous stem cell populations as opposed to direct cardiac regeneration. Gene therapy efforts have focused on prolonging or reactivating natural signaling pathways. Positive results have been demonstrated to activate the endogenous stem cell populations and are currently being tested in clinical trials. A potential new avenue may be to refine pharmacological treatments that are currently in place in the clinic. Evidence is mounting that drugs such as statins or beta blockers may alter endogenous stem cell activity. Understanding the effects of these drugs on stem cell repair while keeping in mind their primary function may strike a balance in myocardial healing. To maximize endogenous cardiac regeneration, a combination of these approaches could ameliorate the overall repair process to incorporate the participation of multiple cellular players.

Extracellular Matrix and Integrins in Embryonic Stem Cell Differentiation

Embryonic stem cells (ESCs) are pluripotent cells with great therapeutic potentials. The in vitro differentiation of ESC was designed by recapitulating embryogenesis. Significant progress has been made to improve the in vitro differentiation protocols by toning soluble maintenance factors. However, more robust methods for lineage-specific differentiation and maturation are still under development. Considering the complexity of in vivo embryogenesis environment, extracellular matrix (ECM) cues should be considered besides growth factor cues. ECM proteins bind to cells and act as ligands of integrin receptors on cell surfaces. Here, we summarize the role of the ECM and integrins in the formation of three germ layer progenies. Various ECM–integrin interactions were found, facilitating differentiation toward definitive endoderm, hepatocyte-like cells, pancreatic beta cells, early mesodermal progenitors, cardiomyocytes, neuroectoderm lineages, and epidermal cells, such as keratinocytes and melanocytes. In the future, ECM combinations for the optimal ESC differentiation environment will require substantial study.

Easily-handled method to isolate mesenchymal stem cells from coagulated human bone marrow samples

AIM: To establish an easily-handled method to isolate mesenchymal stem cells (MSCs) from coagulated human bone marrow samples.

METHODS: Thrombin was added to aliquots of seven heparinized human bone marrow samples to mimic marrow coagulation. The clots were untreated, treated with urokinase or mechanically cut into pieces before culture for MSCs. The un-coagulated samples and the clots were also stored at 4 °C for 8 or 16 h before the treatment. The numbers of colony-forming unit-fibroblast (CFU-F) in the different samples were determined. The adherent cells from different groups were passaged and their surface profile was analyzed with flow cytometry. Their capacities of in vitro osteogenesis and adipogenesis were observed after the cells were exposed to specific inductive agents.

RESULTS: The average CFU-F number of urokinase-treated samples (16.85 ± 11.77/10⁶) was comparable to that of un-coagulated control samples (20.22 ± 10.65/10⁶, P = 0.293), which was significantly higher than those of mechanically-cut clots (6.5 ± 5.32/10⁶, P < 0.01) and untreated clots (1.95 ± 1.86/10⁶, P < 0.01). The CFU-F numbers decreased after samples were stored, but those of control and urokinase-treated clots remained higher than the other two groups. Consistently, the numbers of the attached cells at passage 0 were higher in control and urokinase-treated clots than those of mechanically-cut clots and untreated clots. The attached cells were fibroblast-like in morphology and homogenously positive for CD44, CD73 and CD90, and negative for CD31 and CD45. Also, they could be induced to differentiate into osteoblasts and adipocytes in vitro.

CONCLUSION: Urokinase pretreatment is an optimal strategy to isolate MSCs from human bone marrow samples that are poorly aspirated and clotted.

Emerging role of microRNAs in cancer stem cells: Implications in cancer therapy

A small subset of cancer cells that act as tumor initiating cells or cancer stem cells (CSCs) maintain self-renewal and growth promoting capabilities of cancer and are responsible for drug/treatment resistance, tumor recurrence and metastasis. Due to their potential clinical importance, many researchers have put their efforts over decades to unravel the molecular mechanisms that regulate CSCs functions. MicroRNAs (miRNAs) which are 21-23 nucleotide long, endogenous non-coding RNAs, regulate gene expression through gene silencing at post-transcriptional level by binding to the 3’-untranslated regions or the open reading frames of target genes, thereby result in target mRNA degradation or its translational repression and serve important role in several cellular, physiological and developmental processes. Aberrant miRNAs expression and their implication in CSCs regulation by controlling asymmetric cell division, drug/treatment resistance and metastasis make miRNAs a tool of great therapeutic potential against cancer. Recent advancements on the biological complexities of CSCs, modulation in CSCs properties by miRNA network and development of miRNA based treatment strategies specifically targeting the CSCs as an attractive therapeutic targets for clinical application are being critically analysed.

Intrinsic and extrinsic mechanical properties related to the differentiation of mesenchymal stem cells

Diverse intrinsic and extrinsic mechanical factors have a strong influence on the regulation of stem cell fate. In this work, we examined recent literature on the effects of mechanical environments on stem cells, especially on differentiation of mesenchymal stem cells (MSCs). We provide a brief review of intrinsic mechanical properties of single MSC and examined the correlation between the intrinsic mechanical property of MSC and the differentiation ability. The effects of extrinsic mechanical factors relevant to the differentiation of MSCs were considered separately. The effect of nanostructure and elasticity of the matrix on the differentiation of MSCs were summarized. Finally, we consider how the extrinsic mechanical properties transfer to MSCs and then how the effects on the intrinsic mechanical properties affect stem cell differentiation.

Recent knowledge on the pathophysiology of septic acute kidney injury: A narrative review

Sepsis is the commonest cause of acute kidney injury in critically ill patients. Its pathophysiology is complex and not well understood. Until recently, it was believed that kidney hypoperfusion is the major contributor of septic acute kidney injury. However, recent publications have improved our understanding on this topic. We now know that its mechanisms included the following: (1) renal macrocirculatory and microcirculatory disturbance, (2) surge of inflammatory markers and oxidative stress, (3) coagulation cascade activation, and (4) bioenergetics adaptive response with controlled cell-cycle arrest aiming to prevent cell death. Uncovering these complicated mechanisms may facilitate the development of more appropriate therapeutic measures in the future.

Epigenetic Therapy for Solid Tumors: Highlighting the Impact of Tumor Hypoxia

In the last few decades, epigenetics has emerged as an exciting new field in development and disease, with a more recent focus towards cancer. Epigenetics has classically referred to heritable patterns of gene expression, primarily mediated through DNA methylation patterns. More recently, it has come to include the reversible chemical modification of histones and DNA that dictate gene expression patterns. Both the epigenetic up-regulation of oncogenes and downregulation of tumor suppressors have been shown to drive tumor development. Current clinical trials for cancer therapy include pharmacological inhibition of DNA methylation and histone deacetylation, with the aim of reversing these cancer-promoting epigenetic changes. However, the DNA methyltransferase and histone deacetylase inhibitors have met with less than promising results in the treatment of solid tumors. Regions of hypoxia are a common occurrence in solid tumors. Tumor hypoxia is associated with increased aggressiveness and therapy resistance, and importantly, hypoxic tumor cells have a distinct epigenetic profile. In this review, we provide a summary of the recent clinical trials using epigenetic drugs in solid tumors, discuss the hypoxia-induced epigenetic changes and highlight the importance of testing the epigenetic drugs for efficacy against the most aggressive hypoxic fraction of the tumor in future preclinical testing.

Disparate Effects of Mesenchymal Stem Cells in Experimental Autoimmune Encephalomyelitis and Cuprizone-Induced Demyelination

Mesenchymal stem cells (MSCs) are pleiotropic cells with potential therapeutic benefits for a wide range of diseases. Because of their immunomodulatory properties they have been utilized to treat autoimmune diseases such as multiple sclerosis (MS), which is characterized by demyelination. The microenvironment surrounding MSCs is thought to affect their differentiation and phenotype, which could in turn affect the efficacy. We thus sought to dissect the potential for differential impact of MSCs on central nervous system (CNS) disease in T cell mediated and non-T cell mediated settings using the MOG_35–55 experimental autoimmune encephalomyelitis (EAE) and cuprizone-mediated demyelination models, respectively. As the pathogeneses of MS and EAE are thought to be mediated by IFNγ-producing (T_H1) and IL-17A-producing (T_H17) effector CD4+ T cells, we investigated the effect of MSCs on the development of these two key pathogenic cell groups. Although MSCs suppressed the activation and effector function of T_H17 cells, they did not affect T_H1 activation, but enhanced T_H1 effector function and ultimately produced no effect on EAE. In the non- T cell mediated cuprizone model of demyelination, MSC administration had a positive effect, with an overall increase in myelin abundance in the brain of MSC-treated mice compared to controls. These results highlight the potential variability of MSCs as a biologic therapeutic tool in the treatment of autoimmune disease and the need for further investigation into the multifaceted functions of MSCs in diverse microenvironments and the mechanisms behind the diversity.

Stem cell origin differently affects bone tissue engineering strategies

Bone tissue engineering approaches are encouraging for the improvement of conventional bone grafting technique drawbacks. Thanks to their self-renewal and multi-lineage differentiation ability, stem cells are one of the major actors in tissue engineering approaches, and among these adult mesenchymal stem cells (MSCs) hold a great promise for regenerative medicine strategies. Bone marrow MSCs (BM-MSCs) are the first- identified and well-recognized stem cell population used in bone tissue engineering. Nevertheless, several factors hamper BM-MSC clinical application and subsequently, new stem cell sources have been investigated for these purposes. The fruitful selection and combination of tissue engineered scaffold, progenitor cells, and physiologic signaling molecules allowed the surgeon to reconstruct the missing natural tissue. On the basis of these considerations, we analyzed the capability of two different scaffolds, planned for osteochondral tissue regeneration, to modulate differentiation of adult stem cells of dissimilar local sources (i.e., periodontal ligament, maxillary periosteum) as well as adipose-derived stem cells (ASCs), in view of possible craniofacial tissue engineering strategies. We demonstrated that cells are differently committed toward the osteoblastic phenotype and therefore, taking into account their specific features, they could be intriguing cell sources in different stem cell-based bone/periodontal tissue regeneration approaches.

Adipose Tissue Is a Neglected Viral Reservoir and an Inflammatory Site during Chronic HIV and SIV Infection

Two of the crucial aspects of human immunodeficiency virus (HIV) infection are (i) viral persistence in reservoirs (precluding viral eradication) and (ii) chronic inflammation (directly associated with all-cause morbidities in antiretroviral therapy (ART)-controlled HIV-infected patients). The objective of the present study was to assess the potential involvement of adipose tissue in these two aspects. Adipose tissue is composed of adipocytes and the stromal vascular fraction (SVF); the latter comprises immune cells such as CD4+ T cells and macrophages (both of which are important target cells for HIV). The inflammatory potential of adipose tissue has been extensively described in the context of obesity. During HIV infection, the inflammatory profile of adipose tissue has been revealed by the occurrence of lipodystrophies (primarily related to ART). Data on the impact of HIV on the SVF (especially in individuals not receiving ART) are scarce. We first analyzed the impact of simian immunodeficiency virus (SIV) infection on abdominal subcutaneous and visceral adipose tissues in SIVmac251 infected macaques and found that both adipocytes and adipose tissue immune cells were affected. The adipocyte density was elevated, and adipose tissue immune cells presented enhanced immune activation and/or inflammatory profiles. We detected cell-associated SIV DNA and RNA in the SVF and in sorted CD4+ T cells and macrophages from adipose tissue. We demonstrated that SVF cells (including CD4+ T cells) are infected in ART-controlled HIV-infected patients. Importantly, the production of HIV RNA was detected by in situ hybridization, and after the in vitro reactivation of sorted CD4+ T cells from adipose tissue. We thus identified adipose tissue as a crucial cofactor in both viral persistence and chronic immune activation/inflammation during HIV infection. These observations open up new therapeutic strategies for limiting the size of the viral reservoir and decreasing low-grade chronic inflammation via the modulation of adipose tissue-related pathways.

Open access chemical probes for epigenetic targets

Background

High attrition rates in drug discovery call for new approaches to improve target validation. Academia is filling gaps, but often lacks the experience and resources of the pharmaceutical industry resulting in poorly characterized tool compounds.

Discussion

The SGC has established an open access chemical probe consortium, currently encompassing ten pharmaceutical companies. One of its mandates is to create well-characterized inhibitors (chemical probes) for epigenetic targets to enable new biology and target validation for drug development.

Conclusion

Epigenetic probe compounds have proven to be very valuable and have not only spurred a plethora of novel biological findings, but also provided starting points for clinical trials. These probes have proven to be critical complementation to traditional genetic targeting strategies and provided sometimes surprising results.

Tumor Microenvironment Versus Cancer Stem Cells in Cholangiocarcinoma: Synergistic Effects?

Cholangiocarcinoma (CCAs) may be defined as tumors that derived from the biliary tree with the differentiation in the biliary epithelial cells. This tumor is malignant, extremely aggressive with a poor prognosis. It can be treated surgically and its pathogenesis is poorly understood. The tumor microenvironment (TME) is a very important factor in the regulation of tumor angiogenesis, invasion, and metastasis. Besides cancer stem cells (CSCs) can modulate tumor growth, stroma formation, and migratory capability. The initial stage of tumorigenesis is characterized by genetic mutations and epigenetic alterations due to intrinsic factors which lead to the generation of oncogenes thus inducing tumorigenesis. CSCs may result from precancerous stem cells, cell de-differentiation, normal stem cells, or an epithelial-mesenchymal transition (EMT). CSCs have been found in the cancer niche, and EMT may occur early within the tumor microenvironment. Previous studies have demonstrated evidence of cholangiocarcinoma stem cells (CD133, CD24, EpCAM, CD44, and others) and the presence of these markers has been associated with malignant potential. The interaction between TME and cholangiocarcinoma stem cells via signaling mediators may create an environment that accommodates tumor growth, yielding resistance to cytotoxic insults (chemotherarapeutic). While progress has been made in the understanding of the mechanisms, the interactions in the tumorigenic process still remain a major challenge. Our review, addresses recent concepts of TME-CSCs interaction and will emphasize the importance of early detection with the use of novel diagnostic mechanisms such as CCA-CSC biomarkers and the importance of tumor stroma to define new treatments. J. Cell. Physiol. 231: 768-776, 2016. © 2015 Wiley Periodicals, Inc.

Emerging targets for glioblastoma stem cell therapy

Glioblastoma multiforme (GBM), designated as World Health Organization (WHO) grade IV astrocytoma, is a lethal and therapy-resistant brain cancer comprised of several tumor cell subpopulations, including GBM stem cells (GSCs) which are believed to contribute to tumor recurrence following initial response to therapies. Emerging evidence demonstrates that GBM tumors are initiated from GSCs. The development and use of novel therapies including small molecule inhibitors of specific proteins in signaling pathways that regulate stemness, proliferation and migration of GSCs, immunotherapy, and non-coding microRNAs may provide better means of treating GBM. Identification and characterization of GSC-specific signaling pathways would be necessary to identify specific therapeutic targets which may lead to the development of more efficient therapies selectively targeting GSCs. Several signaling pathways including mTOR, AKT, maternal embryonic leucine zipper kinase (MELK), NOTCH1 and Wnt/β-catenin as well as expression of cancer stem cell markers CD133, CD44, Oct4, Sox2, Nanog, and ALDH1A1 maintain GSC properties. Moreover, the data published in the Cancer Genome Atlas (TCGA) specifically demonstrated the activated PI3K/AKT/mTOR pathway in GBM tumorigenesis. Studying such pathways may help to understand GSC biology and lead to the development of potential therapeutic interventions to render them more sensitive to chemotherapy and radiation therapy. Furthemore, recent demonstration of dedifferentiation of GBM cell lines into CSC-like cells prove that any successful therapeutic agent or combination of drugs for GBM therapy must eliminate not only GSCs, but the differentiated GBM cells and the entire bulk of tumor cells.

LPS-preconditioned mesenchymal stromal cells modify macrophage polarization for resolution of chronic inflammation via exosome-shuttled let-7b

BACKGROUND

Within the last few years, it has become evident that LPS-preconditioned mesenchymal stromal cells (LPS pre-MSCs) show enhanced paracrine effects, including increased trophic support and improved regenerative and repair properties. MSCs may release large amounts of exosomes for cell-to-cell communication and maintain a dynamic and homeostatic microenvironment for tissue repair. The present study assesses the therapeutic efficacy and mechanisms of LPS-preconditioned MSC-derived exosomes (LPS pre-Exo) for chronic inflammation and wound healing.

METHODS

We extracted exosomes from the supernatant of LPS pre-MSCs using a gradient centrifugation method. In vitro, THP-1 cells were cultured with high glucose (HG, 30 mM) as an inflammatory model and treated with LPS pre-Exo for 48 h. The expression of inflammation-related cytokines was detected by real-time RT-PCR, and the distribution of macrophage subtype was measured by immunofluorescence. Next, the miRNA expression profiles of LPS pre-Exo were evaluated using miRNA microarray analysis. The molecular signaling pathway responsible for the regenerative potential was identified by western blotting. In vivo, we established a cutaneous wound model in streptozotocin-induced diabetic rats, and LPS pre-Exo were injected dispersively into the wound edge. The curative effects of LPS pre-Exo on inflammation and wound healing were observed and evaluated.

RESULTS

LPS pre-Exo have a better ability than untreated MSC-derived exosomes (un-Exo) to modulate the balance of macrophages due to their upregulation of the expression of anti-inflammatory cytokines and promotion of M2 macrophage activation. Microarray analysis of LPS pre-Exo identified the unique expression of let-7b compared with un-Exo, and the let-7b/TLR4 pathway served as potential contributor to macrophage polarization and inflammatory ablation. Further investigation of the mechanisms that control let-7b expression demonstrated that a TLR4/NF-κB/STAT3/AKT regulatory signaling pathway plays a critical role in the regulation of macrophage plasticity. Knockdown of AKT in THP-1 cells similarly abolished the immunomodulatory effect of LPS pre-Exo. In vivo, LPS pre-Exo greatly alleviated inflammation and enhanced diabetic cutaneous wound healing.

CONCLUSION

LPS pre-Exo may have improved regulatory abilities for macrophage polarization and resolution of chronic inflammation by shuttling let-7b, and these exosomes carry much immunotherapeutic potential for wound healing.

Intraocular pressure reduction and neuroprotection conferred by bone marrow-derived mesenchymal stem cells in an animal model of glaucoma

INTRODUCTION

Glaucoma is a sight-threatening retinal neuropathy associated with elevated intraocular pressure (IOP) due to degeneration and fibrosis of the trabecular meshwork (TM). Glaucoma medications aim to reduce IOP without targeting the specific TM pathology, Bone-marrow mesenchymal stem cells (MSCs) are used today in various clinical studies. Here, we investigated the potential of MSCs therapy in an glaucoma-like ocular hypertension (OHT) model and decipher in vitro the effects of MSCs on primary human trabecular meshwork cells.

METHODS

Ocular hypertension model was performed by cauterization of 3 episcleral veins (EVC) of Long-Evans male rat eyes. MSCs were isolated from rat bone marrow, amplified in vitro and tagged with quantum dot nanocrystals. Animals were distributed as 1) MSCs group receiving 5.10(5)cells/6μl Minimum Essential Medium and 2) MEM group receiving 6μl MEM (n = 10 each). Injections were performed into the anterior chamber of 20 days-hypertensive eyes and IOP was monitored twice a week for 4 weeks. At the end of experiment, cell distribution in the anterior segment was examined in confocal microscopy on flat mounted corneas. Moreover, we tested in vitro effects of MSCs conditioned medium (MSC-CM) on primary human trabecular meshwork cells (hTM cells) using Akt activation, myosin phosphorylation and TGF-β2-dependent profibrotic phenotype in hTM cells.

RESULTS

We demonstrated a rapid and long-lasting in vivo effect of MSCs transplantation that significantly reduced IOP in hypertensive eyes induced by EVC. MSCs were located to the ciliary processes and the TM. Enumeration of RGCs on whole flat-mounted retina highlighted a protective effect of MSCs on RGCs death. In vitro, MSC-CM promotes: (i) hTM cells survival by activating the antiapoptotic pathway, Akt, (ii) hTM cells relaxation as analyzed by the decrease in myosin phosphorylation and (iii) inhibition of TGF-β2-dependent profibrotic phenotype acquisition in hTM cells.

CONCLUSIONS

MSCs injection in the ocular anterior chamber in a rat model of OHT provides neuroprotective effect in the glaucoma pathophysiology via TM protection. These results demonstrate that MSCs constitute promising tool for treating ocular hypertension and retinal cell degeneration.

Human myocardial pericytes: multipotent mesodermal precursors exhibiting cardiac specificity

Perivascular mesenchymal precursor cells (i.e., pericytes) reside in skeletal muscle where they contribute to myofiber regeneration; however, the existence of similar microvessel-associated regenerative precursor cells in cardiac muscle has not yet been documented. We tested whether microvascular pericytes within human myocardium exhibit phenotypes and multipotency similar to their anatomically and developmentally distinct counterparts. Fetal and adult human heart pericytes (hHPs) express canonical pericyte markers in situ, including CD146, NG2, platelet-derived growth factor receptor (PDGFR) β, PDGFRα, alpha-smooth muscle actin, and smooth muscle myosin heavy chain, but not CD117, CD133, and desmin, nor endothelial cell (EC) markers. hHPs were prospectively purified to homogeneity from ventricular myocardium by flow cytometry, based on a combination of positive- (CD146) and negative-selection (CD34, CD45, CD56, and CD117) cell lineage markers. Purified hHPs expanded in vitro were phenotypically similar to human skeletal muscle-derived pericytes (hSkMPs). hHPs express mesenchymal stem/stromal cell markers in situ and exhibited osteo-, chondro-, and adipogenic potentials but, importantly, no ability for skeletal myogenesis, diverging from pericytes of all other origins. hHPs supported network formation with/without ECs in Matrigel cultures; hHPs further stimulated angiogenic responses under hypoxia, markedly different from hSkMPs. The cardiomyogenic potential of hHPs was examined following 5-azacytidine treatment and neonatal cardiomyocyte coculture in vitro, and intramyocardial transplantation in vivo. Results indicated cardiomyocytic differentiation in a small fraction of hHPs. In conclusion, human myocardial pericytes share certain phenotypic and developmental similarities with their skeletal muscle homologs, yet exhibit different antigenic, myogenic, and angiogenic properties. This is the first example of an anatomical restriction in the developmental potential of pericytes as native mesenchymal stem cells.

Isolation of contractile cardiomyocytes from human pluripotent stem-cell-derived cardiomyogenic cultures using a human NCX1-EGFP reporter

The prospective isolation of defined contractile human pluripotent stem cell (hPSC)-derived cardiomyocytes is advantageous for regenerative medicine and drug screening applications. Currently, enrichment of cardiomyocyte populations from such cultures can be achieved by combinations of cell surface markers or the labor-intensive genetic modification of cardiac developmental genes, such as NKX2.5 or MYH6, with fluorescent reporters. To create a facile, portable method for the isolation of contractile cardiomyocytes from cardiomyogenic hPSC cultures, we employed a highly conserved cardiac enhancer sequence in the SLC8A1 (NCX1) gene to generate a lentivirally deliverable, antibiotic-selectable NCX1cp-EGFP reporter. We show that human embryonic stem cells (and induced pluripotent stem cells) transduced with the NCX1cp-EGFP reporter cassette exhibit enhanced green fluorescent protein (EGFP) expression in cardiac progenitors from 5 days into the directed cardiac hPSC differentiation protocol, with all reporter-positive cells transitioning to spontaneously contracting foci 3 days later. In subsequent stages of cardiomyocyte maturation, NCX1cp-EGFP expression was exclusively limited to contractile cells expressing high levels of cardiac troponin T (CTNT), MLC2a/v, and α-actinin proteins, and was not present in CD90/THY1(+) cardiac stromal cells or CD31/PECAM(+) endothelial cells. Flow-assisted cytometrically sorted EGFP(+) fractions of differentiated cultures were highly enriched in both early (NKX2.5 and TBX5) and late (CTNT/TNNI2, MYH6, MYH7, NPPA, and MYL2) cardiomyocyte markers, with a significant proportion of cells displaying a ventricular-like action potential pattern in patch-clamp recordings. We conclude that the use of the cardiac-specific promoter of the human SLC8A1(NCX1) gene is an effective strategy to isolate contractile cardiac cells and their progenitors from hPSC-derived cardiomyogenic cultures.

Mesenchymal stem cells in regenerative medicine: Focus on articular cartilage and intervertebral disc regeneration

Musculoskeletal disorders represent a major cause of disability and morbidity globally and result in enormous costs for health and social care systems. Development of cell-based therapies is rapidly proliferating in a number of disease areas, including musculoskeletal disorders. Novel biological therapies that can effectively treat joint and spine degeneration are high priorities in regenerative medicine. Mesenchymal stem cells (MSCs) isolated from bone marrow (BM-MSCs), adipose tissue (AD-MSCs) and umbilical cord (UC-MSCs) show considerable promise for use in cartilage and intervertebral disc (IVD) repair. This review article focuses on stem cell-based therapeutics for cartilage and IVD repair in the context of the rising global burden of musculoskeletal disorders. We discuss the biology MSCs and chondroprogenitor cells and specifically focus on umbilical cord/Wharton's jelly derived MSCs and examine their potential for regenerative applications. We also summarize key components of the molecular machinery and signaling pathways responsible for the control of chondrogenesis and explore biomimetic scaffolds and biomaterials for articular cartilage and IVD regeneration. This review explores the exciting opportunities afforded by MSCs and discusses the challenges associated with cartilage and IVD repair and regeneration. There are still many technical challenges associated with isolating, expanding, differentiating, and pre-conditioning MSCs for subsequent implantation into degenerate joints and the spine. However, the prospect of combining biomaterials and cell-based therapies that incorporate chondrocytes, chondroprogenitors and MSCs leads to the optimistic view that interdisciplinary approaches will lead to significant breakthroughs in regenerating musculoskeletal tissues, such as the joint and the spine in the near future.

The immune response of stem cells in subretinal transplantation

Stem cell transplantation is a potential curative treatment for degenerative diseases of the retina. Among cell injection sites, the subretinal space (SRS) is particularly advantageous as it is maintained as an immune privileged site by the retinal pigment epithelium (RPE) layer. Thus, the success of subretinal transplantation depends on maintenance of RPE integrity. Moreover, both embryonic stem cells (ESCs) and mesenchymal stem cells (MSCs) have negligible immunogenicity and in fact are immunosuppressive. Indeed, many studies have demonstrated that immunosuppressive drugs are not necessary for subretinal transplantation of stem cells if the blood-retinal barrier is not breached during surgery. The immunogenicity of induced pluripotent stem cells (iPSCs) appears more complex, and requires careful study before clinical application. Despite low rates of graft rejection in animal models, survival rates for ESCs, MSCs, and iPSCs in retina are generally poor, possibly due to resident microglia activated by cell transplantation. To improve graft survival in SRS transplantation, damage to the blood-retinal barrier must be minimized using appropriate surgical techniques. In addition, agents that inhibit microglial activation may be required. Finally, immunosuppressants may be required, at least temporarily, until the blood-retinal barrier heals. We review surgical methods and drug regimens to enhance the likelihood of graft survival after SRS transplantation.

Effect of SDF-1/CXCR4 axis on the migration of transplanted bone mesenchymal stem cells mobilized by erythropoietin toward lesion sites following spinal cord injury

Accumulating evidence has indicated that the stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) axis plays a crucial role in the recruitment of bone marrow-derived mesenchymal stem cells (BMSCs) into lesion sites in animal models. The aim of this study was to investigate the effects of the SDF-1/CXCR4 axis on the migration of transplanted BMSCs mobilized by erythropoietin (EPO) toward the lesion site following spinal cord injury (SCI). A model of SCI was established in rats using the modified Allen's test. In the EPO group, EPO was administered at a distance of 2 mm cranially and then 2 mm caudally from the site of injury. In the BMSC group, 10 μl of BMSC suspension was administered in the same manner. In the BMSC + EPO group, both BMSCs and EPO were administered as described above. In the BMSC + EPO + AMD3100 group, in addition to the injection of BMSCs and EPO, AMD3100 (a chemokine receptor antagonist) was administered. The Basso-Beattie-Bresnahan (BBB) Locomotor Rating Scale and a grid walk test were used to estimate the neurological recovery following SCI. Enzyme-linked immunosorbent assay (ELISA) was performed to assess the tumor necrosis factor-α (TNF-α) and SDF-1 expression levels. An immunofluorescence assay was performed to identify the distribution of the BMSCs in the injured spinal cord. A Transwell migration assay was performed to examine BMSC migration. A terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay was performed to detect the apoptotic index (AI). Western blot analysis was performed to measure the expression levels of erythropoietin receptor (EPOR) and CXCR4. Significant improvements in locomotor function were detected in the BMSC + EPO group compared with the BMSC group (P<0.05). GFP-labeled BMSCs were observed and were located at the lesion sites. Additionally, EPO significantly decreased the TNF-α levels and increased the SDF-1 levels in the injured spinal cord (P<0.05). The AI in the BMSC + EPO group was significantly lower compared with that in the other groups (P<0.05). Furthermore, EPO significantly upregulated the protein expression of CXCR4 in the BMSCs and promoted the migration of the BMSCs, whereas these effects were markedly inhibited when the BMSCs were co-transplanted with AMD3100. The findings of the present study confirm that EPO mobilizes BMSCs to the lesion site following SCI and enhances the anti-apoptotic effects of the BMSCs by upregulating the expression of SDF-1/CXCR4 axis.

Stem cell-derived exosomes: roles in stromal remodeling, tumor progression, and cancer immunotherapy

Stem cells are known to maintain stemness at least in part through secreted factors that promote stem-like phenotypes in resident cells. Accumulating evidence has clarified that stem cells release nano-vesicles, known as exosomes, which may serve as mediators of cell-to-cell communication and may potentially transmit stem cell phenotypes to recipient cells, facilitating stem cell maintenance, differentiation, self-renewal, and repair. It has become apparent that stem cell-derived exosomes mediate interactions among stromal elements, promote genetic instability in recipient cells, and induce malignant transformation. This review will therefore discuss the potential of stem cell-derived exosomes in the context of stromal remodeling and their ability to generate cancer-initiating cells in a tumor niche by inducing morphologic and functional differentiation of fibroblasts into tumor-initiating fibroblasts. In addition, the immunosuppressive potential of stem cell-derived exosomes in cancer immunotherapy and their prospective applications in cell-free therapies in future translational medicine is discussed.

Characterization of In Vitro Engineered Human Adipose Tissues: Relevant Adipokine Secretion and Impact of TNF-α

Representative modelling of human adipose tissue functions is central to metabolic research. Tridimensional models able to recreate human adipogenesis in a physiological tissue-like context in vitro are still scarce. We describe the engineering of white adipose tissues reconstructed from their cultured adipose-derived stromal precursor cells. We hypothesize that these reconstructed tissues can recapitulate key functions of AT under basal and pro-inflammatory conditions. These tissues, featuring human adipocytes surrounded by stroma, were stable and metabolically active in long-term cultures (at least 11 weeks). Secretion of major adipokines and growth factors by the reconstructed tissues was determined and compared to media conditioned by human native fat explants. Interestingly, the secretory profiles of the reconstructed adipose tissues indicated an abundant production of leptin, PAI-1 and angiopoietin-1 proteins, while higher HGF levels were detected for the human fat explants. We next demonstrated the responsiveness of the tissues to the pro-inflammatory stimulus TNF-α, as reflected by modulation of MCP-1, NGF and HGF secretion, while VEGF and leptin protein expression did not vary. TNF-α exposure induced changes in gene expression for adipocyte metabolism-associated mRNAs such as SLC2A4, FASN and LIPE, as well as for genes implicated in NF-κB activation. Finally, this model was customized to feature adipocytes representative of progressive stages of differentiation, thereby allowing investigations using newly differentiated or more mature adipocytes. In conclusion, we produced tridimensional tissues engineered in vitro that are able to recapitulate key characteristics of subcutaneous white adipose tissue. These tissues are produced from human cells and their neo-synthesized matrix elements without exogenous or synthetic biomaterials. Therefore, they represent unique tools to investigate the effects of pharmacologically active products on human stromal cells, extracellular matrix and differentiated adipocytes, in addition to compounds modulating adipogenesis from precursor cells.

Pluripotent Conversion of Muscle Stem Cells Without Reprogramming Factors or Small Molecules

Muscle derived stem cells (MDSCs) are multipotent stem cells that can differentiate into several lineages including skeletal muscle precursor cells. Here, we show that MDSCs from myostatin null mice (Mstn (-/-) ) can be readily induced into pluripotent stem cells without using reprogramming factors. Microarray studies revealed a strong upregulation of markers like Leukemia Inhibitory factor (LIF) and Leukemia Inhibitory factor receptor (LIFR) in Mstn (-/-) MDSCs as compared to wild type MDSCs (WT-MDSCs). Furthermore when cultured in mouse embryonic stem cell media with LIF for 95 days, Mstn (-/-) MDSCs formed embryonic stem cell (ES) like colonies. We termed such ES like cells as the culture-induced pluripotent stem cells (CiPSC). CiPSCs from Mstn (-/-) MDSCs were phenotypically similar to ESCs, expressed high levels of Oct4, Nanog, Sox2 and SSEA-1, maintained a normal karyotype. Furthermore, CiPSCs formed embryoid bodies and teratomas when injected into immunocompromised mice. In addition, CiPSCs differentiated into somatic cells of all three lineages. We further show that culturing in ES cell media, resulted in hypermethylation and downregulation of BMP2 in Mstn(-/-) MDSCs. Western blot further confirmed a down regulation of BMP2 signaling in Mstn (-/-) MDSCs in supportive of pluripotent reprogramming. Given that down regulation of BMP2 has been shown to induce pluripotency in cells, we propose that lack of myostatin epigenetically reprograms the MDSCs to become pluripotent stem cells. Thus, here we report the successful establishment of ES-like cells from adult stem cells of the non-germline origin under culture-induced conditions without introducing reprogramming genes.

New synthesis and biodistribution of the D-amino acid oxidase-magnetic nanoparticle system

Background:

Application of nanoenzymes, based on D-amino acid oxidase (DAAO) conjugated to magnetic nanoparticles (NPs), as anticancer system requires improvement of the synthesis protocol and in vivo distribution evaluation.

Results:

A new and more efficient synthesis via EDC-NHS produced an Fe₃O₄NP-APTES-DAAO system with a specific activity of 7 U/mg NPs. IR spectroscopy showed that all Fe₃O₄ NP sites are saturated with APTES and all available NH₂ sites with DAAO. The acute cytotoxicity of the new system does not differ from that of the previous one. In vivo experiments showed that the system did not cause adverse effects, cross the brain–blood barrier and accumulate in the heart.

Conclusions:

Our results support the possibility to use enzymes conjugated to magnetic NPs for cancer treatment. Besides, we think that enzymes and other biological molecules efficiently conjugated to magnetic NPs might constitute a category of ‘bionanoparticles’ to be exploited, not only in medical, but also in industrial biotechnology.

Lay abstract: We have linked magnetic nanoparticles to D-amino acid oxidase, an enzyme capable of producing, in the presence of its substrate, reactive oxygen species. The scope is to use the magnetic properties of the enzyme-nanoparticle system to direct it to a desired area where its cytotoxicity can be controlled by the addition of exogenous substrate. Besides the possible applications in cancer therapy, we think that enzymes and other biological molecules linked to magnetic nanoparticles might also be exploited in industrial biotechnology.

Brown adipose tissue: a potential target in the fight against obesity and the metabolic syndrome

BAT (brown adipose tissue) is the main site of thermogenesis in mammals. It is essential to ensure thermoregulation in newborns. It is also found in (some) adult humans. Its capacity to oxidize fatty acids and glucose without ATP production contributes to energy expenditure and glucose homoeostasis. Brown fat activation has thus emerged as an attractive therapeutic target for the treatment of obesity and the metabolic syndrome. In the present review, we integrate the recent advances on the metabolic role of BAT and its relation with other tissues as well as its potential contribution to fighting obesity and the metabolic syndrome.

Micro- and nanodevices integrated with biomolecular probes

Understanding how biomolecules, proteins and cells interact with their surroundings and other biological entities has become the fundamental design criterion for most biomedical micro- and nanodevices. Advances in biology, medicine, and nanofabrication technologies complement each other and allow us to engineer new tools based on biomolecules utilized as probes. Engineered micro/nanosystems and biomolecules in nature have remarkably robust compatibility in terms of function, size, and physical properties. This article presents the state of the art in micro- and nanoscale devices designed and fabricated with biomolecular probes as their vital constituents. General design and fabrication concepts are presented and three major platform technologies are highlighted: microcantilevers, micro/nanopillars, and microfluidics. Overview of each technology, typical fabrication details, and application areas are presented by emphasizing significant achievements, current challenges, and future opportunities.

Dynamic Expression Profiles of Marker Genes in Osteogenic Differentiation of Human Bone Marrow-derived Mesenchymal Stem Cells

OBJECTIVE

To observe the expression profiles of osteoblast-related genes in human mesenchymal stem cells (MSCs) derived from bone marrow during osteogenic differentiation.

METHODS

MSCs were induced to differentiate with MSC osteogenic differentiation medium for 7, 14, 21 and 28 days respectively. Alizarin Red staining was used to detect matrix mineralization. Expression of osteoblast-related genes, including osteocalcin, osteopontin, Runt-related transcription factor 2 (Runx2), alkaline phosphatase and collagen type 1, was assessed with quantitative reverse transcription-polymerase chain reaction.

RESULTS

On day 14 after induction of differentiation, cells were stained positively with Alizarin Red. The expression levels of these genes exhibited an upward trend as induction time was prolonged. Exposure to osteogenic differentiation medium less than 21 days did not significantly induce osteocalcin expression; osteocalcin expression levels in the differentiated cells induced for 21 and 28 days were 1.63 and 2.46 times as high as the undifferentiated cells respectively (all P<0.05). Stimulation with MSC osteogenic differentiation medium over 14 days significantly enhanced bone marrow-derived MSCs to express osteopontin and Runx2 genes (all P<0.05). Osteogenic differentiation medium could significantly induce the expressions of alkaline phosphatase and collagen type1 genes (all P<0.05). Their expressions reached the peak levels on day 21, which were increased more than 4- and 3-fold respectively.

CONCLUSION

Human bone marrow-derived MSCs could exhibit the sequential expression pattern of osteoblast marker genes during osteogenic differentiation in vitro.

HPV Infection of the Head and Neck Region and Its Stem Cells

The human papillomavirus (HPV) is an etiologic agent associated with the development of head and neck squamous carcinoma (HNSCC)-in particular, oropharyngeal squamous cell carcinoma. The HPV-positive HNSCC is characterized by genetic alterations, clinical progression, and therapeutic response, which are distinct from HPV-negative head and neck cancers, suggesting that virus-associated tumors constitute a unique entity among head and neck cancers. Malignant stem cells, or cancer stem cells, are a subpopulation of tumor cells that self-renew, initiate new tumors upon transplantation, and are resistant to therapy, and their discovery has revealed novel effects of oncovirus infection in cancer. In this review, we provide a virus-centric view and novel insights into HPV-positive head and neck pathogenesis. We discuss the influence of cancer stem cells, HPV oncoproteins, altered molecular pathways, and mutations in cancer initiation and cancer progression. We compiled a catalogue of the mutations associated with HPV-positive HNSCC, which may be a useful resource for genomic-based studies aiming to develop personalized therapies. We also explain recent changes in mass vaccination campaigns against HPV and the potential long-term impact of vaccinations on the prevention and treatment of HPV-positive head and neck cancers.

A new standardized clinical-grade protocol for banking human umbilical cord tissue cells

BACKGROUND

Mesenchymal stromal cells (MSCs) isolated from human umbilical cord tissue (UCT) can be considered the perfect candidates for cell-based therapies and regenerative medicine. UCT-derived MSCs can be cryogenically stored in cell banks and expanded as needed for therapeutic uses.

STUDY DESIGN AND METHODS

We developed a new method for UCT-MSC isolation, cryopreservation, and expansion, following all criteria required by a stem cell bank. UCT-MSCs were isolated either by manual dissociation (MM) or by a semiautomatic dissociation system (SAM). In both protocols UCTs were treated enzymatically using Type IV collagenase good manufacturing practices (GMP) graded and hyaluronidase (medicinal product). Isolated UCT-MSCs were cryopreserved and analyzed after thawing for phenotype; for proliferation rate; and for their osteogenic, adipogenic, and chondrogenic differentiation capabilities.

RESULTS

We found that SAM reduced the time of tissue enzyme exposure and enabled us to obtain a homogeneous single-cell suspension deprived of tissue fragments. The isolated cells in both groups showed high expression of MSC markers CD105, CD73, and CD90 and similar differentiation capabilities, phenotype, and proliferation potential. Moreover, the final yield of MSCs was comparable between the two techniques.

CONCLUSION

In this study, we have established a reliable and standardized protocol to isolate UCT-MSCs from UCT for cell banking purposes. Processing the whole umbilical tissue with GMP-graded enzymes using a semiautomatic dissociator allowed us to obtain a single-cell suspension product with a known number of isolated cells that can be cryopreserved right after isolation and thawed as needed for expansion and clinical use.

Mesenchymal stem cell therapy in a rat model of birth-trauma injury: functional improvements and biodistribution

INTRODUCTION AND HYPOTHESIS

We evaluated the potential role of human mesenchymal stem cells (hMSCs) in improvement of urinary continence following birth-trauma injury.

METHODS

Human MSCs were injected periurethrally or systemically into rats immediately after vaginal distention (VD) (n = 90). Control groups were non-VD (uninjured/untreated, n = 15), local or systemic saline (injection/control, n = 90), and dermofibroblast (cell therapy/control, n = 90). Leak-point pressure (LPP) was measured 4, 10, and 14 days later. Urethras were morphometrically evaluated. In another sets of VD and non-VD rats, the fate of periurethrally injected hMSC, biodistribution, and in vivo viability was studied using human Alu genomic repeat staining, PKH26 labeling, and luciferase-expression labeling, respectively.

RESULTS

Saline- and dermofibroblast-treated control rats demonstrated lower LPP than non-VD controls at days 4 and 14 (P < 0.01). LPP after systemic hMSC and periurethral hMSC treatment were comparable with non-VD controls at 4, 10, and 14 days (P > 0.05). Local saline controls demonstrated extensive urethral tissue bleeding. The connective tissue area/urethral section area proportion and vascular density were higher in the local hMSC- versus the saline-treated group at 4 and 14 days, respectively. No positive Alu-stained nuclei were observed in urethras at 4, 10, and 14 days. PKH26-labelled cells were found in all urethras at 2 and 24 h. Bioluminescence study showed increased luciferase expression from day 0 to 1 following hMSC injection.

CONCLUSIONS

Human MSCs restored the continence mechanism with an immediate and sustained effect in the VD model, while saline and dermofibroblast therapy did not. Human MSCs remained at the site of periurethral injection for <7 days. We hypothesize that periurethral hMSC treatment improves vascular, connective tissue, and hemorrhage status of urethral tissues after acute VD injury.

Beta Adrenergic Receptor Stimulation Suppresses Cell Migration in Association with Cell Cycle Transition in Osteoblasts-Live Imaging Analyses Based on FUCCI System

Osteoporosis affects over 20 million patients in the United States. Among those, disuse osteoporosis is serious as it is induced by bed-ridden conditions in patients suffering from aging-associated diseases including cardiovascular, neurological, and malignant neoplastic diseases. Although the phenomenon that loss of mechanical stress such as bed-ridden condition reduces bone mass is clear, molecular bases for the disuse osteoporosis are still incompletely understood. In disuse osteoporosis model, bone loss is interfered by inhibitors of sympathetic tone and adrenergic receptors that suppress bone formation. However, how beta adrenergic stimulation affects osteoblastic migration and associated proliferation is not known. Here we introduced a live imaging system, fluorescent ubiquitination-based cell cycle indicator (FUCCI), in osteoblast biology and examined isoproterenol regulation of cell cycle transition and cell migration in osteoblasts. Isoproterenol treatment suppresses the levels of first entry peak of quiescent osteoblastic cells into cell cycle phase by shifting from G1 /G0 to S/G2 /M and also suppresses the levels of second major peak population that enters into S/G2 /M. The isoproterenol regulation of osteoblastic cell cycle transition is associated with isoproterenol suppression on the velocity of migration. This isoproterenol regulation of migration velocity is cell cycle phase specific as it suppresses migration velocity of osteoblasts in G1 phase but not in G1 /S nor in G2 /M phase. Finally, these observations on isoproterenol regulation of osteoblastic migration and cell cycle transition are opposite to the PTH actions in osteoblasts. In summary, we discovered that sympathetic tone regulates osteoblastic migration in association with cell cycle transition by using FUCCI system.

Roles of sex-determining region Y-box 2 in cell pluripotency and tumor-related signaling pathways

The sex-determining region Y-box 2 (SOX2) gene, a member of the Sry-like high-mobility group box (SOX) gene family, encodes the transcription factor Sox2, which significantly contributes to the regulation of cell pluripotency. Sox2 is closely associated with early embryonic development, neural differentiation and other biological processes. An inreasing number of recent studies suggest that Sox2 exerts a positive effect on malignant tumors. According to these results, Sox2 is expected to become a novel target for cancer therapy by unveiling the mechanism through which it affects the biological behavior of tumors. Therefore, it is crucial to elucidate the detailed association of Sox2 with malignant tumors. The aim of this study was to review the role of Sox2 in pluripotency maintenance, early embryonic development and neural differentiation, as well as investigate the detailed mechanism through which Sox2 regulates cancer stem cells and tumorigenesis.

Progress in understanding role of epithelial to mesenchymal transition in acquisition of stem cell properties by colorectal tumor cells

Epithelial-mesenchymal transition (EMT) is a dynamic process in which cells lose epithelial features and gain mesenchymal properties. This process not only contributes to the normal development of tissues and organs, inflammation and wound-related fibrosis or mucosal repair but also participates in carcinoma progression, promotes tumor cell invasion and metastasis and induces stem cell properties. EMT also contributes to occurrence of tumor recurrence, metastasis and multi-drug resistance. This review illuminates the mechanism that EMT promotes colorectal carcinoma cells to obtain stemness in terms of microRNAs, signaling pathways and microenvironment, with an aim to provide novel and safe strategies for clinical target therapy.

Epithelial mesenchymal transition related molecular markers and invasion and metastasis of cholangiocarcinoma

Tumor metastasis is a major cause of death in patients with solid tumors. Epithelial mesenchymal transition (EMT) is a process in which the epithelial cells are transformed into the stroma cells. This process is accompanied by changes in gene expression and cell phenotype, which are often activated during tumor invasion and metastasis. Cholangiocarcinoma is a kind of malignancy originating from the bile duct epithelium, and its main biological characteristics are early invasion, metastasis and recurrence. The research of cholangiocarcinoma metastasis could provide a theoretical basis for the development of new treatment strategies to manage this malignancy. This paper reviews the roles of EMT related molecular markers metastasis in the invasion and metastasis of cholangiocarcinoma.

Double compartmented and hybrid implant outfitted with well-organized 3D stem cells for osteochondral regenerative nanomedicine

AIM

Articular cartilage repair remains challenging, because most clinical failures are due to the lack of subchondral bone regeneration. We report an innovative approach improving cartilage repair by regenerating a robust subchondral bone, supporting articular cartilage.

MATERIALS & METHODS

We developed a compartmented living implant containing triple-3D structure: stem cells as microtissues for embryonic endochondral development mimic, nanofibrous collagen to enhance mineralization for subchondral bone and alginate hydrogel for cartilage regeneration.

RESULTS & CONCLUSION

This system mimics the natural gradient of the osteochondral unit, using only one kind of stem cell, targeting their ability to express specific bone or cartilage proteins. Mineralization gradient of articular cartilage and the natural 'glue' between subchondral bone and cartilage were reproduced in vitro.

Ex vivo identification and characterization of a population of CD13(high) CD105(+) CD45(-) mesenchymal stem cells in human bone marrow

Introduction

Mesenchymal stem cells (MSCs) are multipotent cells capable of self-renewal and multilineage differentiation. Their multipotential capacity and immunomodulatory properties have led to an increasing interest in their biological properties and therapeutic applications. Currently, the definition of MSCs relies on a combination of phenotypic, morphological and functional characteristics which are typically evaluated upon in vitro expansion, a process that may ultimately lead to modulation of the immunophenotypic, functional and/or genetic features of these cells. Therefore, at present there is great interest in providing markers and phenotypes for direct in vivo and ex vivo identification and isolation of MSCs.

Methods

Multiparameter flow cytometry immunophenotypic studies were performed on 65 bone marrow (BM) samples for characterization of CD13^high CD105⁺ CD45^– cells. Isolation and expansion of these cells was performed in a subset of samples in parallel to the expansion of MSCs from mononuclear cells following currently established procedures. The protein expression profile of these cells was further assessed on (paired) primary and in vitro expanded BM MSCs, and their adipogenic, chondrogenic and osteogenic differentiation potential was also determined.

Results

Our results show that the CD13^high CD105⁺ CD45⁻ immunophenotype defines a minor subset of cells that are systematically present ex vivo in normal/reactive BM (n = 65) and that display immunophenotypic features, plastic adherence ability, and osteogenic, adipogenic and chondrogenic differentiation capacities fully compatible with those of MSCs. In addition, we also show that in vitro expansion of these cells modulates their immunophenotypic characteristics, including changes in the expression of markers currently used for the definition of MSCs, such as CD105, CD146 and HLA-DR.

Conclusions

BM MSCs can be identified ex vivo in normal/reactive BM, based on a robust CD13^high CD105⁺ and CD45⁻ immunophenotypic profile. Furthermore, in vitro expansion of these cells is associated with significant changes in the immunophenotypic profile of MSCs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0152-8) contains supplementary material, which is available to authorized users.

Drug delivery, cell-based therapies, and tissue engineering approaches for spinal cord injury

Spinal cord injury (SCI) results in devastating neurological and pathological consequences, causing major dysfunction to the motor, sensory, and autonomic systems. The primary traumatic injury to the spinal cord triggers a cascade of acute and chronic degenerative events, leading to further secondary injury. Many therapeutic strategies have been developed to potentially intervene in these progressive neurodegenerative events and minimize secondary damage to the spinal cord. Additionally, significant efforts have been directed toward regenerative therapies that may facilitate neuronal repair and establish connectivity across the injury site. Despite the promise that these approaches have shown in preclinical animal models of SCI, challenges with respect to successful clinical translation still remain. The factors that could have contributed to failure include important biologic and physiologic differences between the preclinical models and the human condition, study designs that do not mirror clinical reality, discrepancies in dosing and the timing of therapeutic interventions, and dose-limiting toxicity. With a better understanding of the pathobiology of events following acute SCI, developing integrated approaches aimed at preventing secondary damage and also facilitating neuroregenerative recovery is possible and hopefully will lead to effective treatments for this devastating injury. The focus of this review is to highlight the progress that has been made in drug therapies and delivery systems, and also cell-based and tissue engineering approaches for SCI.

Regulatory T cell-mediated anti-inflammatory effects promote successful tissue repair in both indirect and direct manners

Regulatory T cells (Tregs) offer new immunotherapeutic options to control undesired immune reactions, such as those in transplant rejection and autoimmunity. In addition, tissue repair and regeneration depend on a multitude of tightly regulated immune and non-immune cells and signaling molecules. There is mounting evidence that adequate innate responses, and even more importantly balanced adaptive immune responses, are key players in the tissue repair and regeneration processes, even in absence of any immune-related disease or infection. Thus, the anti-inflammatory and anti-apoptotic capacities of Treg can affect not only the effector immune response, creating the appropriate immune environment for successful tissue repair and regeneration, but growing evidence shows that they also have direct effects on tissue cell functions. Here we summarize the present views on how Treg might support tissue regeneration by direct control of undesired immune reactivity and also by direct interaction with non-immune tissue cells. We describe tissue-resident Treg and their specific phenotypes in skin, visceral adipose tissue, and skeletal muscle. In addition, we touch on the topic of osteoimmunology, discussing the direct interactions of Treg with bone-forming cells, such as osteoblasts and their mesenchymal stromal cell (MSC) progenitors-a field which is under-investigated. We hypothesize a cross-talk between Treg and bone-forming cells through the CD39-CD73-(adenosine)-adenosine receptor pathway, which might also potentiate the differentiation of MSCs, thus facilitating bone regeneration. This hypothesis may provide a road map for further investigations on the cross-talk between the immune and the skeletal system, and also enable the development of better strategies to promote bone repair and regeneration.

Autologous transplantation of mesenchymal stromal cells tends to prevent progress of interstitial fibrosis in a rhesus Macaca mulatta monkey model of chronic kidney disease

BACKGROUND AIMS

Chronic kidney disease (CKD) attributed to cisplatin is well documented. Mesenchymal stromal cells (MSCs) are proven to be renotropic. Although they have been shown to improve function in CKD and reduce fibrosis in different experimental rodent models, their efficiency in primates is unknown. The present study aimed to evaluate the prevention of CKD and reduction of fibrosis in monkeys treated with MSCs after cisplatin nephrotoxicity.

METHODS

We induced CKD in adult rhesus Macaca mulatta monkeys by means of intravenous administration of cisplatin. Autologous MSCs were transplanted by means of intrarenal arterial injections to assess the adverse effects of cisplatin in two CKD models: preventative and stable. Preventative CKD monkeys (n = 3) underwent cell transplantation 4 days after the cisplatin injection. The stable CKD monkeys (n = 2) underwent cell transplantation 6 months after the cisplatin injection. Non-treated (n = 4) and normal saline-injected animals (n = 3) comprised the control and vehicle groups, respectively. We followed the animals for survival rate, serum biochemistry, urine analysis and histopathological indices.

RESULTS

In the preventive CKD model, MSC transplantation tended to improve some renal functions but significantly reduced the histopathologic score compared with the vehicle and control groups. In the stable CKD model, MSCs did not ameliorate renal function or pathological score.

CONCLUSIONS

These results suggest that MSCs tend to delay progression of CKD and fibrosis but do not reduce established interstitial fibrosis in this unique primate model of cisplatin-induced nephrotoxicity.

Advances in Neurotrophic Factor and Cell-Based Therapies for Parkinson's Disease: A Mini-Review

Parkinson's disease (PD) affects an estimated 7-10 million people worldwide and remains without definitive or disease-modifying treatment. There have been many recent developments in cell-based therapy (CBT) to replace lost circuitry and provide chronic biological sources of therapeutic agents to the PD-affected brain. Early neural transplantation studies underscored the challenges of immune compatibility, graft integration and the need for renewable, autologous graft sources. Neurotrophic factors (NTFs) offer a potential class of cytoprotective pharmacotherapeutics that may complement dopamine (DA) replacement and CBT strategies in PD. Chronic NTF delivery may be an integral goal of CBT, with grafts consisting of autologous drug-producing (e.g., DA, NTF) cells that are capable of integration and function in the host brain. In this mini-review, we outline the past experience and recent advances in NTF technology and CBT as promising and integrated approaches for the treatment of PD.