Human bronchial fibroblasts exhibit a mesenchymal stem cell phenotype and multilineage differentiating potentialities

Potency Biomarker Signature Genes from Multiparametric Osteogenesis Assays: Will cGMP Human Bone Marrow Mesenchymal Stromal Cells Make Bone?

In skeletal regeneration approaches using human bone marrow derived mesenchymal stromal cells (hBM-MSC), functional evaluation before implantation has traditionally used biomarkers identified using fetal bovine serum-based osteogenic induction media and time courses of at least two weeks. However, emerging pre-clinical evidence indicates donor-dependent discrepancies between these ex vivo measurements and the ability to form bone, calling for improved tests. Therefore, we adopted a multiparametric approach aiming to generate an osteogenic potency assay with improved correlation. hBM-MSC populations from six donors, each expanded under clinical-grade (cGMP) conditions, showed heterogeneity for ex vivo growth response, mineralization and bone-forming ability in a murine xenograft assay. A subset of literature-based biomarker genes was reproducibly upregulated to a significant extent across all populations as cells responded to two different osteogenic induction media. These 12 biomarkers were also measurable in a one-week assay, befitting clinical cell expansion time frames and cGMP growth conditions. They were selected for further challenge using a combinatorial approach aimed at determining ex vivo and in vivo consistency. We identified five globally relevant osteogenic signature genes, notably TGF-ß1 pathway interactors; ALPL, COL1A2, DCN, ELN and RUNX2. Used in agglomerative cluster analysis, they correctly grouped the bone-forming cell populations as distinct. Although donor #6 cells were correlation slope outliers, they contrastingly formed bone without showing ex vivo mineralization. Mathematical expression level normalization of the most discrepantly upregulated signature gene COL1A2, sufficed to cluster donor #6 with the bone-forming classification. Moreover, attenuating factors causing genuine COL1A2 gene down-regulation, restored ex vivo mineralization. This suggested that the signature gene had an osteogenically influential role; nonetheless no single biomarker was fully deterministic whereas all five signature genes together led to accurate cluster analysis. We show proof of principle for an osteogenic potency assay providing early characterization of primary cGMP-hBM-MSC cultures according to their donor-specific bone-forming potential.

Adenosine production: a common path for mesenchymal stem-cell and regulatory T-cell-mediated immunosuppression

Adenosine is an important molecule that exerts control on the immune system, by signaling through receptors lying on the surface of immune cells. This nucleotide is produced, in part, by the action of the ectoenzymes CD39 and CD73. Interestingly, these proteins are expressed on the cell surface of regulatory T-cells (Tregs) and mesenchymal stromal cells (MSCs)-two cell populations that have emerged as potential therapeutic tools in the field of cell therapy. In fact, the production of adenosine constitutes a mechanism used by both cell types to control the immune response. Recently, great scientific progress was obtained regarding the role of adenosine in the inflammatory environment. In this context, the present review focuses on the advances related to the impact of adenosine production over the immune modulatory activity of Tregs and MSCs, and how this nucleotide controls the biological functions of these cells. Finally, we mention the main challenges and hurdles to bring such molecule to clinical settings.

Isolation and biological characterization of a novel type of pulmonary mesenchymal stem cells derived from Wuzhishan miniature pig embryo

Pulmonary mesenchymal stem cells (PMSCs) have great potential in lung tissue engineering and represent attractive candidates for disease treatment in human and veterinary research. However, a reliable method for isolation and localization of porcine PMSCs in situ is still uncertain. In this study, we successfully isolated PMSCs from Wuzhishan miniature pig embryos in vitro and also attempted to unravel its fundamental differentiation potential and biological characteristics. The isolated PMSCs, which could be cultured and passaged for at least 15 passages, exhibited a typical fibroblast-like morphology and high proliferative potential. Moreover, the PMSCs could express pluripotent marker genes (Oct4 and Nanog) and MSCs-related surface antigens (β-integrin, CD44, CD71, CD73, CD90, and CD105), while the expressions of CD34 and CD45 were negative. Cell cycle examination showed that the rate of G0/G1 was about 72.1-90.2%. Additionally, the PMSCs not only could be induced to transdifferentiate into mesoblastic cells such as osteoblasts, chondrocytes, and adipocytes in vitro, but also the neural ectoderm and endoderm. Together, these data demonstrate the multiple differentiations potential of PMSCs in vitro, which confers potential use in serving as desirable cell types for lung injury regeneration.

Intratracheal Administration of Mesenchymal Stem Cells Modulates Tachykinin System, Suppresses Airway Remodeling and Reduces Airway Hyperresponsiveness in an Animal Model

BACKGROUND

The need for new options for chronic lung diseases promotes the research on stem cells for lung repair. Bone marrow-derived mesenchymal stem cells (MSCs) can modulate lung inflammation, but the data on cellular processes involved in early airway remodeling and the potential involvement of neuropeptides are scarce.

OBJECTIVES

To elucidate the mechanisms by which local administration of MSCs interferes with pathophysiological features of airway hyperresponsiveness in an animal model.

METHODS

GFP-tagged mouse MSCs were intratracheally delivered in the ovalbumin mouse model with subsequent functional tests, the analysis of cytokine levels, neuropeptide expression and histological evaluation of MSCs fate and airway pathology. Additionally, MSCs were exposed to pro-inflammatory factors in vitro.

RESULTS

Functional improvement was observed after MSC administration. Although MSCs did not adopt lung cell phenotypes, cell therapy positively affected airway remodeling reducing the hyperplastic phase of the gain in bronchial smooth muscle mass, decreasing the proliferation of epithelium in which mucus metaplasia was also lowered. Decrease of interleukin-4, interleukin-5, interleukin-13 and increase of interleukin-10 in bronchoalveolar lavage was also observed. Exposed to pro-inflammatory cytokines, MSCs upregulated indoleamine 2,3-dioxygenase. Moreover, asthma-related in vivo upregulation of pro-inflammatory neurokinin 1 and neurokinin 2 receptors was counteracted by MSCs that also determined a partial restoration of VIP, a neuropeptide with anti-inflammatory properties.

CONCLUSION

Intratracheally administered MSCs positively modulate airway remodeling, reduce inflammation and improve function, demonstrating their ability to promote tissue homeostasis in the course of experimental allergic asthma. Because of a limited tissue retention, the functional impact of MSCs may be attributed to their immunomodulatory response combined with the interference of neuropeptide system activation and tissue remodeling.

Characterization of intercellular communication and mitochondrial donation by mesenchymal stromal cells derived from the human lung

Background

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are capable of repairing wounded lung epithelial cells by donating cytoplasmic material and mitochondria. Recently, we characterized two populations of human lung-derived mesenchymal stromal cells isolated from digested parenchymal lung tissue (LT-MSCs) from healthy individuals or from lung transplant recipients’ bronchoalveolar lavage fluid (BAL-MSCs). The aim of this study was to determine whether LT-MSCs and BAL-MSCs are also capable of donating cytoplasmic content and mitochondria to lung epithelial cells.

Methods

Cytoplasmic and mitochondrial transfer was assessed by co-culturing BEAS2B epithelial cells with Calcein AM or Mitotracker Green FM-labelled MSCs. Transfer was then measured by flow cytometry and validated by fluorescent microscopy. Molecular inhibitors were used to determine the contribution of microtubules/tunnelling nanotubes (TNTs, cytochalasin D), gap junctions (carbenoxolone), connexin-43 (gap26) and microvesicles (dynasore).

Results

F-actin microtubules/TNTs extending from BM-MSCs, LT-MSCs and BAL-MSCs to bronchial epithelial cells formed within 45 minutes of co-culturing cells. Each MSC population transferred a similar volume of cytoplasmic content to epithelial cells. Inhibiting microtubule/TNTs, gap junction formation and microvesicle endocytosis abrogated the transfer of cytoplasmic material from BM-MSCs, LT-MSCs and BAL-MSCs to epithelial cells. In contrast, blocking connexin-43 gap junction formation had no effect on cytoplasmic transfer. All MSC populations donated mitochondria to bronchial epithelial cells with similar efficiency. Mitochondrial transfer was reduced in all co-cultures after microtubule/TNT or endocytosis inhibition. Gap junction formation inhibition reduced mitochondrial transfer in BM-MSC and BAL-MSC co-cultures but had no effect on transfer in LT-MSC co-cultures. Connexin-43 inhibition did not impact mitochondrial transfer. Finally, bronchial epithelial cells were incapable of donating cytoplasmic content or mitochondria to any MSC population.

Conclusion

Similar to their bone marrow counterparts, LT-MSCs and BAL-MSCs can donate cytoplasmic content and mitochondria to bronchial epithelial cells via multiple mechanisms. Given that BM-MSCs utilize these mechanisms to mediate the repair of damaged bronchial epithelial cells, both LT-MSCs and BAL-MSCs will probably function similarly.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0354-8) contains supplementary material, which is available to authorized users.

Mesenchymal Stromal Cells are Readily Recoverable from Lung Tissue, but not the Alveolar Space, in Healthy Humans

Stromal support is critical for lung homeostasis and the maintenance of an effective epithelial barrier. Despite this, previous studies have found a positive association between the number of mesenchymal stromal cells (MSCs) isolated from the alveolar compartment and human lung diseases associated with epithelial dysfunction. We hypothesised that bronchoalveolar lavage derived MSCs (BAL-MSCs) are dysfunctional and distinct from resident lung tissue MSCs (LT-MSCs). In this study, we comprehensively interrogated the phenotype and transcriptome of human BAL-MSCs and LT-MSCs. We found that MSCs were rarely recoverable from the alveolar space in healthy humans, but could be readily isolated from lung transplant recipients by bronchoalveolar lavage. BAL-MSCs exhibited a CD90^Hi , CD73^Hi , CD45^Neg , CD105^Lo immunophenotype and were bipotent, lacking adipogenic potential. In contrast, MSCs were readily recoverable from healthy human lung tissue and were CD90^{Hi or Lo} , CD73^Hi , CD45^Neg , CD105^Int and had full tri-lineage potential. Transcriptional profiling of the two populations confirmed their status as bona fide MSCs and revealed a high degree of similarity between each other and the archetypal bone-marrow MSC. 105 genes were differentially expressed; 76 of which were increased in BAL-MSCs including genes involved in fibroblast activation, extracellular matrix deposition and tissue remodelling. Finally, we found the fibroblast markers collagen 1A1 and α-smooth muscle actin were increased in BAL-MSCs. Our data suggests that in healthy humans, lung MSCs reside within the tissue, but in disease can differentiate to acquire a profibrotic phenotype and migrate from their in-tissue niche into the alveolar space. Stem Cells 2016;34:2548-2558.

Fibroblasts and Mesenchymal Stromal/Stem Cells Are Phenotypically Indistinguishable

BACKGROUND/AIMS

Human mesenchymal stromal/stem cells (MSCs), derived from many different tissues, are characterized by a fibroblast-like morphology, the expression of certain cell surface markers and their ability to differentiate into adipocytes, chondrocytes and osteoblasts. A number of studies have shown that MSCs share many characteristics with fibroblasts; however, there is no well-defined set of phenotypic characteristics that could distinguish between these 2 types of cells.

METHODS

We used 4 well-established human fibroblast strains from 3 different tissue sources and several human MSC strains from 2 different tissue sources to compare the phenotypic and immunological characteristics of these cells.

RESULTS

Fibroblast strains had a similar morphology to MSCs, expressed the same cell surface markers as MSCs and could also differentiate into adipocytes, chondrocytes and osteoblasts. Also, similar to MSCs, these fibroblasts were capable of suppressing T cell proliferation and modulating the immunophenotype of macrophages. We also show that MSCs deposit extracellular matrices of collagen type I and fibronectin, and express FSP1 in patterns similar to fibroblasts.

CONCLUSIONS

Based on currently accepted definitions for cultured human MSCs and fibroblasts, we could not find any immunophenotypic property that could make a characteristic distinction between MSCs and fibroblasts.

Immunotherapy for tuberculosis: future prospects

Tuberculosis (TB) is still a major global health problem. A third of the world’s population is infected with Mycobacterium tuberculosis. Only ~10% of infected individuals develop TB but there are 9 million TB cases with 1.5 million deaths annually. The standard prophylactic treatment regimens for latent TB infection take 3–9 months, and new cases of TB require at least 6 months of treatment with multiple drugs. The management of latent TB infection and TB has become more challenging because of the spread of multidrug-resistant and extremely drug-resistant TB. Intensified efforts to find new TB drugs and immunotherapies are needed. Immunotherapies could modulate the immune system in patients with latent TB infection or active disease, enabling better control of M. tuberculosis replication. This review describes several types of potential immunotherapies with a focus on those which have been tested in humans.

Key transcription factors in the differentiation of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent cells that represent a promising source for regenerative medicine. MSCs are capable of osteogenic, chondrogenic, adipogenic and myogenic differentiation. Efficacy of differentiated MSCs to regenerate cells in the injured tissues requires the ability to maintain the differentiation toward the desired cell fate. Since MSCs represent an attractive source for autologous transplantation, cellular and molecular signaling pathways and micro-environmental changes have been studied in order to understand the role of cytokines, chemokines, and transcription factors on the differentiation of MSCs. The differentiation of MSC into a mesenchymal lineage is genetically manipulated and promoted by specific transcription factors associated with a particular cell lineage. Recent studies have explored the integration of transcription factors, including Runx2, Sox9, PPARγ, MyoD, GATA4, and GATA6 in the differentiation of MSCs. Therefore, the overexpression of a single transcription factor in MSCs may promote trans-differentiation into specific cell lineage, which can be used for treatment of some diseases. In this review, we critically discussed and evaluated the role of transcription factors and related signaling pathways that affect the differentiation of MSCs toward adipocytes, chondrocytes, osteocytes, skeletal muscle cells, cardiomyocytes, and smooth muscle cells.

Cellular therapy in tuberculosis

Cellular therapy now offer promise of potential adjunct therapeutic options for treatment of drug-resistant tuberculosis (TB). We review here the role of Mesenchymal stromal cells, (MSCs), as well as other immune effector cells in the therapy of infectious diseases with a focus on TB. MSCs represent a population of tissue-resident non-hematopoietic adult progenitor cells which home into injured tissues increase the proliferative potential of broncho-alveolar stem cells and restore lung epithelium. MSCs have been shown to be immune-modulatory and anti-inflammatory mediated via cell-cell contacts as well as soluble factors. We discuss the functional profile of MSCs and their potential use for adjunct cellular therapy of multi-drug resistant TB, with the aim of limiting tissue damage, and to convert unproductive inflammatory responses into effective anti-pathogen directed immune responses. Adjunct cellular therapy could potentially offer salvage therapy options for patients with drug-resistant TB, increase clinically relevant anti-M.tuberculosis directed immune responses and possibly shorten the duration of anti-TB therapy.

Fibroblast Growth Factor-10 (FGF-10) Mobilizes Lung-resident Mesenchymal Stem Cells and Protects Against Acute Lung Injury

FGF-10 can prevent or reduce lung specific inflammation due to traumatic or infectious lung injury. However, the exact mechanisms are poorly characterized. Additionally, the effect of FGF-10 on lung-resident mesenchymal stem cells (LR-MSCs) has not been studied. To better characterize the effect of FGF-10 on LR-MSCs, FGF-10 was intratracheally delivered into the lungs of rats. Three days after instillation, bronchoalveolar lavage was performed and plastic-adherent cells were cultured, characterized and then delivered therapeutically to rats after LPS intratracheal instillation. Immunophenotyping analysis of FGF-10 mobilized and cultured cells revealed expression of the MSC markers CD29, CD73, CD90, and CD105, and the absence of the hematopoietic lineage markers CD34 and CD45. Multipotency of these cells was demonstrated by their capacity to differentiate into osteocytes, adipocytes, and chondrocytes. Delivery of LR-MSCs into the lungs after LPS injury reduced the inflammatory response as evidenced by decreased wet-to-dry ratio, reduced neutrophil and leukocyte recruitment and decreased inflammatory cytokines compared to control rats. Lastly, direct delivery of FGF-10 in the lungs of rats led to an increase of LR-MSCs in the treated lungs, suggesting that the protective effect of FGF-10 might be mediated, in part, by the mobilization of LR-MSCs in lungs.

Protocols for in vitro Differentiation of Human Mesenchymal Stem Cells into Osteogenic, Chondrogenic and Adipogenic Lineages

Mesenchymal stem cells (MSC) possess high plasticity and the potential to differentiate into several different cell types; this characteristic has implications for cell therapy and reparative biotechnologies. MSC have been originally isolated from the bone marrow (BM-MSC), but they have been found also in other tissues such as adipose tissue, cord blood, synovium, skeletal muscle, and lung. MSC are able to differentiate in vitro and in vivo into several cell types such as bone, osteocytes, chondrocytes, adipocytes, and skeletal myocytes, just to name a few.During the last two decades, an increasing number of studies have proven the therapeutic potential of MSC for the treatment of neurodegenerative diseases, spinal cord and brain injuries, cardiovascular diseases, diabetes mellitus, and diseases of the skeleton. Their immuno-privileged profile allows both autologous and allogeneic use. For all these reasons, the scientific appeal of MSC is constantly on the rise.The identity of MSC is currently based on three main criteria: plastic-adherence capacity, defined epitope profile, and capacity to differentiate in vitro into osteocytes, chondrocytes, and adipocytes. Here, we describe standard protocols for the differentiation of BM-MSC into the osteogenic, chondrogenic, and adipogenic lineages.

Mesenchymal Stem Cell-Like Properties of Orbital Fibroblasts in Graves' Orbitopathy

PURPOSE

Graves' orbitopathy (GO) is a sight-threatening autoimmune disorder causing extraocular muscle fibrosis, upper lid retraction and eye bulging due to orbital fat expansion. These clinical features are mediated by aspects of orbital fibroblasts differentiation, including adipogenesis and fibrosis. Our previous work suggested that this dual phenotype might be a manifestation of mixed cell populations, partially linked to the expression of mesenchymal stem cell (MSC) marker CD90. Thus, we set out to determine whether GO orbital fibroblasts displayed MSC properties.

METHODS

Control and GO orbital fibroblasts previously characterized for CD90 and CD45 expression were analyzed by flow cytometry for classical MSC positive (CD73, CD105) and negative (CD14, CD19, HLA-DR, and CD34) markers. Graves' orbitopathy fibroblasts were tested further for their ability to undergo lineage specific differentiation following standard protocols.

RESULTS

Control and GO fibroblasts strongly expressed CD73 and CD105, with a higher percentage of positive cells and stronger expression levels in GO. Neither cell type expresses CD14, CD19, and HLA-DR. Protein CD34 was expressed at low levels by 45% to 70% of the cells, with its expression significantly lower in GO cells. Graves' orbitopathy fibroblasts displayed features of osteogenesis (calcium deposits, and osteocalcin [BGLAP] and osteonectin [SPARC] expression), chondrogenesis (glycosaminoglycan production; SOX9 and aggrecan [ACAN] expression), myogenesis (α-smooth muscle actin expression), and neurogenesis (β-III tubulin expression) upon differentiation.

CONCLUSIONS

Our findings suggest that orbital fibroblasts contain a population of cells that fulfil the criteria defining MSC. This subpopulation may be increased in GO, possibly underlying the complex differentiation phenotype of the disease.

How to Improve the Survival of Transplanted Mesenchymal Stem Cell in Ischemic Heart?

Mesenchymal stem cell (MSC) is an intensely studied stem cell type applied for cardiac repair. For decades, the preclinical researches on animal model and clinical trials have suggested that MSC transplantation exerts therapeutic effect on ischemic heart disease. However, there remain major limitations to be overcome, one of which is the very low survival rate after transplantation in heart tissue. Various strategies have been tried to improve the MSC survival, and many of them showed promising results. In this review, we analyzed the studies in recent years to summarize the methods, effects, and mechanisms of the new strategies to address this question.

Isolation, in vitro culture and identification of a new type of mesenchymal stem cell derived from fetal bovine lung tissues

Lung‑derived mesenchymal stem cells (LMSCs) are considered to be important in lung tissue repair and regenerative processes. However, the biological characteristics and differentiation potential of LMSCs remain to be elucidated. In the present study, fetal lung‑derived mesenchymal stem cells (FLMSCs) were isolated from fetal bovine lung tissues by collagenase digestion. The in vitro culture conditions were optimized and stabilized and the self‑renewal ability and differentiation potential were evaluated. The results demonstrated that the FLMSCs were morphologically consistent with fibroblasts, were able to be cultured and passaged for at least 33 passages and the cell morphology and proliferative ability were stable during the first 10 passages. In addition, FLMSCs were found to express CD29, CD44, CD73 and CD166, however, they did not express hematopoietic cell specific markers, including CD34, CD45 and BOLA‑DRα. The growth kinetics of FLMSCs consisted of a lag phase, a logarithmic phase and a plateau phase, and as the passages increased, the proliferative ability of cells gradually decreased. The majority of FLMSCs were in G0/G1 phase. Following osteogenic induction, FLMSCs were positive for the expression of osteopontin and collagen type I α2. Following neurogenic differentiation, the cells were morphologically consistent with neuronal cells and positive for microtubule‑associated protein 2 and nestin expression. It was concluded that the isolated FLMSCs exhibited typical characteristics of mesenchymal stem cells and that the culture conditions were suitable for their proliferation and the maintenance of stemness. The present study illustrated the potential application of lung tissue as an adult stem cell source for regenerative therapies.

Functional fingerprinting of human mesenchymal stem cells using high-throughput RNAi screening

Mesenchymal stem cells (MSCs) are promising candidates for cellular therapies ranging from tissue repair in regenerative medicine to immunomodulation in graft versus host disease after allogeneic transplantation or in autoimmune diseases. Nonetheless, progress has been hampered by their enormous phenotypic as well as functional heterogeneity and the lack of uniform standards and guidelines for quality control. In this study, we describe a method to perform cellular phenotyping by high-throughput RNA interference in primary human bone marrow MSCs. We have shown that despite heterogeneity of MSC populations, robust functional assays can be established that are suitable for high-throughput and high-content screening. We profiled primary human MSCs against human fibroblasts. Network analysis showed a kinome fingerprint that differs from human primary fibroblasts as well as fibroblast cell lines. In conclusion, this study shows that high-throughput screening in primary human MSCs can be reliably used for kinome fingerprinting.

Human adipose-derived stem cells partially rescue the stroke syndromes by promoting spatial learning and memory in mouse middle cerebral artery occlusion model

INTRODUCTION

Growing evidence has brought stem cell therapy to the forefront as new promising approaches towards stroke treatment. Of all candidate seeding cells, adipose-derived stem cells (ADSCs) are considered as one of the most appropriate for stroke treatment. However, previous experimental data could not reach to an agreement on the efficacy of ADSC transplantation for treating stroke in vivo as well as its mechanism which hinders their further clinical translational application.

METHODS

To explore their in vivo mechanism of hADSC administration on neurological injury, hADSC were labeled with Enhanced Green Fluorescence Protein expressing FG12 lentivirus and injected into MCAO mouse infarct area by in situ way. Neurological function was evaluated by Rogers Scaling System and their spatial learning and memory was determined by Morris Test. 2,3,5-triphenyltetrazolium chloride was carried out to compare the infarct area among groups. Histoimmunostaining was used to track the injected hADSCs for their in vivo migration, transdifferentiation and integration with the endogenous neuronal circuitry. To better address the underlying rescuing mechanism, qRT-PCR was performed on neural markers of MBP, MAP2, GFAP, microglia marker of Iba1.

RESULTS

It was found that hADSCs could promote both spatial learning and memory of MCAO mice. Co-localization of GFP and MAP2 were found in the whole cortex with significantly (P<0.01) higher percentage at the contralateral cortex compared with the ipsilateral cortex. Low percentage of GFP and GFAP co-localized cells were found at whole cortex. Meanwhile, Iba1(+) microglia and GFAP(+) astrocyte cells were significantly (P<0.05) suppressed by hADSC injection.

CONCLUSIONS

hADSCs could transdifferentiate into neuron like cells (MAP2(+)) in vivo and probably used as seeding cells for replacement based stem cell therapy of stroke. Also, significant immunomodulation was found. Meanwhile hADSCs could significantly protect the endogenous neuron survival. This study demonstrated that hADSC intervention with MCAO mice could apparently ameliorate stroke symptoms by direct cell replacement, enhanced immnunosuppression and increasing the viability of endogenous neurons.

Murine embryonic fibroblast cell lines differentiate into three mesenchymal lineages to different extents: new models to investigate differentiation processes

Various diseases, injuries, and congenital abnormalities may result in degeneration and loss of organs and tissues. Recently, tissue engineering has offered new treatment options for these common, severe, and costly problems in human health care. Its application is often based on the usage of differentiated stem cells. However, despite intensive research and growing knowledge, many questions remain unresolved in the process of cell differentiation. The aim of this study was to find standardized cell models for analyzing molecular mechanisms of cell differentiation. We investigated the multipotency of three standardized murine embryonic fibroblast cell cultures using histological staining, western blotting, and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Our results demonstrated that NIH-3T3 and mouse embryonic fibroblast (MEF) cells were able to differentiate into adipogenic, chondrogenic, and osteogenic lineages expressing typical differentiation markers. Interestingly, Flp-In-3T3 cells did not differentiate into any of the three mesenchymal lineages, although this cell line is genetically closely related to NIH-3T3. The results were confirmed by histological staining. Flp-In-3T3, NIH-3T3, and MEF cells have usually been used for DNA transfections, recombinant protein expression, and as "feeder cells." Unlike mesenchymal stem cells (MSCs) and mesenchymal progenitor cells (MPCs), they are easy to obtain and to expand and are less prone to change their structure and morphology, even at higher passages. Our results suggest that Flp-In-3T3, MEF, and NIH-3T3 cells are highly suitable to be used as models to analyze molecular mechanisms of cell differentiation.

Lung fibroblasts share mesenchymal stem cell features which are altered in chronic obstructive pulmonary disease via the overactivation of the Hedgehog signaling pathway

Background

Alteration of functional regenerative properties of parenchymal lung fibroblasts is widely proposed as a pathogenic mechanism for chronic obstructive pulmonary disease (COPD). However, what these functions are and how they are impaired in COPD remain poorly understood. Apart from the role of fibroblasts in producing extracellular matrix, recent studies in organs different from the lung suggest that such cells might contribute to repair processes by acting like mesenchymal stem cells. In addition, several reports sustain that the Hedgehog pathway is altered in COPD patients thus aggravating the disease. Nevertheless, whether this pathway is dysregulated in COPD fibroblasts remains unknown.

Objectives and Methods

We investigated the stem cell features and the expression of Hedgehog components in human lung fibroblasts isolated from histologically-normal parenchymal tissue from 25 patients—8 non-smokers/non-COPD, 8 smokers-non COPD and 9 smokers with COPD—who were undergoing surgery for lung tumor resection.

Results

We found that lung fibroblasts resemble mesenchymal stem cells in terms of cell surface marker expression, differentiation ability and immunosuppressive potential and that these properties were altered in lung fibroblasts from smokers and even more in COPD patients. Furthermore, we showed that some of these phenotypic changes can be explained by an over activation of the Hedgehog signaling in smoker and COPD fibroblasts.

Conclusions

Our study reveals that lung fibroblasts possess mesenchymal stem cell-features which are impaired in COPD via the contribution of an abnormal Hedgehog signaling. These processes should constitute a novel pathomechanism accounting for disease occurrence and progression.

Lung mesenchymal cells function as an inductive microenvironment for human lung cancer propagating cells†

OBJECTIVES

The aim of the present study was to characterize the biological properties and in vivo tumourigenic potential of mesenchymal cells (MCs) obtained from non-small-cell lung cancer (NSCLC) samples.

METHODS

NSCLC samples (53 adenocarcinomas and 24 squamous-cell carcinomas) surgically removed from 46 males and 31 females were processed to identify mesenchymal cells from human lung cancer (hLc-MCs). hLc-MCs were separated from neoplastic epithelial cells, expanded and extensively characterized in vitro. Subsequently, female BALB/c nude mice were subcutaneously injected with either 10(6) or 2.5 × 10(6) Calu-3 (human adenocarcinoma cell line able to reproducibly induce xenografted tumours) alone or in combination with equal doses of hLc-MCs. Control animals were injected with the two doses of hLc-MCs only.

RESULTS

Primary cultures of hLc-MCs were obtained from >80% of NSCLC specimens. The typical MCs immunophenotype was documented by the expression of CD90, CD105, CD73, CD13 and CD44 at fluorescence-activated cell sorting analysis. CD45, CD14, CD34 and epithelial antigens were negative while CD117 (c-kit) and CD133 (prominin) were partially expressed. Interestingly, nuclear transcription factors octamer-binding transcription factor 3/4 and sex determining region Y-box 2 involved in stemness, thyroid transcription factor 1 in bronchoalveolar commitment, and ETS1 in carcinogenesis, were expressed in hLc-MCs isolated from NSCLC. Specific conditioned media and cocultures confirmed the supportive role of hLc-MCs for cancer cells. In vivo experiments showed that at both doses Calu-3 xenografts doubled in size when hLc-MCs were coinjected. Cell tracking in xenografted tumours, by immunofluorescence combined with fluorescence in situ hybridization analysis, documented hX-chromosome-labelled, Calu-3-derived cytokeratin-positive adenocarcinoma structures surrounded by hLc-MCs.

CONCLUSIONS

Tumour-propagating cells require the inductive interaction of resident mesenchymal cells to foster lung cancer development.

Specific subsets of mesenchymal stroma cells to treat lung disorders--finding the Holy Grail

Accumulating studies, both in animals and human clinical trials with mesenchymal stroma cells (MSC) support the hypothesis of therapeutic effects of these cells in various disorders. However, despite success in immune-mediated disorders such as Crohns' disease, lung disorders such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary disease (IPF) treated with MSC have so far not yielded a revolutionary effect on clinical symptoms. Promising data on immunomodulatory effects in COPD have kept nourishing the research into finding specific traits of MSC beneficial in disease. A heterogeneous population of injected cells might drown a potential therapeutic role of a specific group of MSC. Thus careful analysis of MSC regarding their molecular capabilities such as delivering specific therapeutic vesicles to the environment, or plain cytokine/chemokine fingerprinting might prove useful in augmenting therapies against lung diseases.

Walking along the Fibroblast Growth Factor 10 Route: A Key Pathway to Understand the Control and Regulation of Epithelial and Mesenchymal Cell-Lineage Formation during Lung Development and Repair after Injury

Basic research on embryonic lung development offers unique opportunities to make important discoveries that will impact human health. Developmental biologists interested in the molecular control of branching morphogenesis have intensively studied the developing lung, with its complex and seemingly stereotyped ramified structure. However, it is also an organ that is linked to a vast array of clinical problems in humans such as bronchopulmonary dysplasia in premature babies and emphysema, chronic obstructive pulmonary disease, fibrosis, and cancer in adults. Epithelial stem/progenitor cells reside in niches where they interact with specific extracellular matrices as well as with mesenchymal cells; the latter are still poorly characterized. Interactions of epithelial stem/progenitor cells with their microenvironments are usually instructive, controlling quiescence versus activation, proliferation, differentiation, and migration. During the past 18 years, Fgf10 has emerged not only as a marker for the distal lung mesenchyme during early lung development, but also as a key player in branching morphogenesis and a critical component of the niche for epithelial stem cells. In this paper, we will present the current knowledge regarding the lineage tree in the lung, with special emphasis on cell-lineage decisions in the lung mesenchyme and the role of Fgf10 in this context.

Regulation of fibroblast lipid storage and myofibroblast phenotypes during alveolar septation in mice

Signaling through platelet-derived growth factor receptor-α (PDGFRα) is required for alveolar septation and participates in alveolar regeneration after pneumonectomy. In both adipose tissue and skeletal muscle, bipotent pdgfrα-expressing progenitors expressing delta-like ligand-1 or sex-determining region Y box 9 (Sox9) may differentiate into either lipid storage cells or myofibroblasts. We analyzed markers of mesenchymal progenitors and differentiation in lung fibroblasts (LF) with different levels (absent, low, or high) of pdgfrα gene expression. A larger proportion of pdgfrα-expressing than nonexpressing LF contained Sox9. Neutral lipids, CD166, and Tcf21 were more abundant in LF with a lower compared with a higher level of pdgfrα gene expression. PDGF-A increased Sox9 in primary LF cultures, suggesting that active signaling through PDGFRα is required to maintain Sox9. As alveolar septation progresses from postnatal day (P) 8 to P12, fewer pdgfrα-expressing LF contain Sox9, whereas more of these LF contain myocardin-like transcription factor-A, showing that Sox9 diminishes as LF become myofibroblasts. At P8, neutral lipid droplets predominate in LF with the lower level of pdgfrα gene expression, whereas transgelin (tagln) was predominantly expressed in LF with higher pdgfrα gene expression. Targeted deletion of pdgfrα in LF, which expressed tagln, reduced Sox9 in α-actin (α-SMA, ACTA2)-containing LF, whereas it increased the abundance of cell surface delta-like protein-1 (as well as peroxisome proliferator-activated receptor-γ and tcf21 mRNA in LF, which also expressed stem cell antigen-1). Thus pdgfrα deletion differentially alters delta-like protein-1 and Sox9, suggesting that targeting different downstream pathways in PDGF-A-responsive LF could identify strategies that promote lung regeneration without initiating fibrosis.

Primary pulmonary myxoid sarcomas with EWSR1-CREB1 translocation might originate from primitive peribronchial mesenchymal cells undergoing (myo)fibroblastic differentiation

Primary pulmonary myxoid sarcoma (PPMS) is a very rare lung tumor that has recently been shown to harbor an EWSR1-CREB1 translocation. However, the histogenesis and biological behavior of PPMS remains unclear. To provide insight into the histogenesis of PPMS, we studied surgical resection specimens of four patients, two females and two males with an age range of 26 to 65 years, all non-smokers with mild anemia. The tumors, three of which are endobronchial, measured between 4 and 13 cm. One patient developed metastasis to the contra-lateral lung 7 months after resection. Other patients remained alive without tumor for 1.5, 10, and 13 years. Fluorescence in situ hybridization (FISH) analysis with a gene break apart probe showed an EWSR1 translocation in all cases. The EWSR1-CREB1 fusion transcript was detected in all cases by reverse-transcription PCR. Immunohistochemical staining showed diffuse positive staining of the tumor cells only for vimentin. Tumor cells expressed no other myoid, epithelial, endothelial, melanocytic, myoepithelial, or neuroendocrine markers, except for smooth muscle actin and epithelial membrane antigen, which were only focally positive in individual cases. Ultrastructural analyses revealed the presence in the tumor cells of intermediate filaments with focal densities along the sub-cytoplasmic membrane as well as dense plaques. These results suggest that PPMS exhibits myofibroblastic differentiation. We conclude that PPMS is an intermediate grade malignant lung tumor harboring EWSR1 translocations, which may originate from mesenchymal cells that undergo fibroblastic or myofibroblastic differentiation.

Patient-tailored application for Duchene muscular dystrophy on mdx mice based induced mesenchymal stem cells

Mesenchymal stem cells (MSCs) may be used as powerful tools for the repair and regeneration of damaged tissues. However, isolating tissue specific-derived MSCs may cause pain and increased infection rates in patients, and repetitive isolations may be required. To overcome these difficulties, we have examined alternative methods for MSC production. Here, we show that induced pluripotent stem cells (iPSCs) may be differentiated into mesenchymal stem cells (iMSCs) following exposure to SB431542. Purified iMSCs were administered to mdx mice to study skeletal muscle regeneration in a murine model of muscular dystrophy. Purified iMSCs displayed fibroblast-like morphology, formed three-dimensional spheroid structures, and expressed characteristic mesenchymal stem cell surface markers such as CD29, CD33, CD73, CD90, and CD105. Moreover, iMSCs were capable of differentiating into adipogenic, osteogenic, and chondrogenic lineages. Transplanting iMSC cells to tibialis anterior skeletal muscle tissue in mdx mice lowered oxidative damage as evidenced by a reduction in nitrotyrosine levels, and normal dystrophin expression levels were restored. This study demonstrates the therapeutic potential of purified iMSCs in skeletal muscle regeneration in mdx mice, and suggests that iPSCs are a viable alternate source for deriving MSCs as needed.

Stem cells, cell therapies, and bioengineering in lung biology and diseases. Comprehensive review of the recent literature 2010-2012

A conference, "Stem Cells and Cell Therapies in Lung Biology and Lung Diseases," was held July 25 to 28, 2011 at the University of Vermont to review the current understanding of the role of stem and progenitor cells in lung repair after injury and to review the current status of cell therapy and ex vivo bioengineering approaches for lung diseases. These are rapidly expanding areas of study that provide further insight into and challenge traditional views of mechanisms of lung repair after injury and pathogenesis of several lung diseases. The goals of the conference were to summarize the current state of the field, to discuss and debate current controversies, and to identify future research directions and opportunities for basic and translational research in cell-based therapies for lung diseases. The goal of this article, which accompanies the formal conference report, is to provide a comprehensive review of the published literature in lung regenerative medicine from the last conference report through December 2012.

Primary mesenchymal stem cells in human transplanted lungs are CD90/CD105 perivascularly located tissue-resident cells

Background

Mesenchymal stem cells (MSC) have not only been implicated in the development of lung diseases, but they have also been proposed as a future cell-based therapy for lung diseases. However, the cellular identity of the primary MSC in human lung tissues has not yet been reported. This study therefore aimed to identify and characterise the ‘bona fide’ MSC in human lungs and to investigate if the MSC numbers correlate with the development of bronchiolitis obliterans syndrome in lung-transplanted patients.

Methods

Primary lung MSC were directly isolated or culture-derived from central and peripheral transbronchial biopsies of lung-transplanted patients and evaluated using a comprehensive panel of in vitro and in vivo assays.

Results

Primary MSC were enriched in the CD90/CD105 mononuclear cell fraction with mesenchymal progenitor frequencies of up to four colony-forming units, fibroblast/100 cells. In situ staining of lung tissues revealed that CD90/CD105 MSCs were located perivascularly. MSC were tissue-resident and exclusively donor lung-derived even in biopsies obtained from patients as long as 16 years after transplantation. Culture-derived mesenchymal stromal cells showed typical in vitro MSC properties; however, xenotransplantation into non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice showed that lung MSC readily differentiated into adipocytes and stromal tissues, but lacked significant in vivo bone formation.

Conclusions

These data clearly demonstrate that primary MSC in human lung tissues are not only tissue resident but also tissue-specific. The identification and phenotypic characterisation of primary lung MSC is an important first step in identifying the role of MSC in normal lung physiology and pulmonary diseases.

Cartilage tissue engineering: molecular control of chondrocyte differentiation for proper cartilage matrix reconstruction

BACKGROUND

Articular cartilage defects are a veritable therapeutic problem because therapeutic options are very scarce. Due to the poor self-regeneration capacity of cartilage, minor cartilage defects often lead to osteoarthritis. Several surgical strategies have been developed to repair damaged cartilage. Autologous chondrocyte implantation (ACI) gives encouraging results, but this cell-based therapy involves a step of chondrocyte expansion in a monolayer, which results in the loss in the differentiated phenotype. Thus, despite improvement in the quality of life for patients, reconstructed cartilage is in fact fibrocartilage. Successful ACI, according to the particular physiology of chondrocytes in vitro, requires active and phenotypically stabilized chondrocytes.

SCOPE OF REVIEW

This review describes the unique physiology of cartilage, with the factors involved in its formation, stabilization and degradation. Then, we focus on some of the most recent advances in cell therapy and tissue engineering that open up interesting perspectives for maintaining or obtaining the chondrogenic character of cells in order to treat cartilage lesions.

MAJOR CONCLUSIONS

Current research involves the use of chondrocytes or progenitor stem cells, associated with "smart" biomaterials and growth factors. Other influential factors, such as cell sources, oxygen pressure and mechanical strain are considered, as are recent developments in gene therapy to control the chondrocyte differentiation/dedifferentiation process.

GENERAL SIGNIFICANCE

This review provides new information on the mechanisms regulating the state of differentiation of chondrocytes and the chondrogenesis of mesenchymal stem cells that will lead to the development of new restorative cell therapy approaches in humans. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Autologous mesenchymal stromal cell infusion as adjunct treatment in patients with multidrug and extensively drug-resistant tuberculosis: an open-label phase 1 safety trial

BACKGROUND

Novel treatment options are urgently needed for multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis, which are associated with immune dysfunction and poor treatment outcomes. Mesenchymal stromal cells (MSCs) are immunomodulatory and adjunct autologous treatment with bone marrow-derived MSCs might improve clinical outcome by transforming chronic inflammation into productive immune responses. Our aim was to assess the safety of infusion of autologous MSCs as an adjunct treatment in patients with tuberculosis.

METHODS

30 patients with microbiologically confirmed MDR or XDR tuberculosis were treated with single-dose autologous bone marrow-derived MSCs (aimed for 1×10(6) cells per kg), within 4 weeks of the start of antituberculosis-drug treatment in a specialist centre in Minsk, Belarus. Inclusion patients were those with pulmonary tuberculosis confirmed by sputum smear microscopy, culture, or both; MDR or XDR tuberculosis confirmed by drug-susceptibility testing to first-line and second-line drugs; age older than 21 years to 65 years or younger; and absence of lesion compatible with a malignant process or ongoing tuberculosis in organs other than the lungs and pleura. In addition to the inclusion criteria, patients were excluded if they were pregnant, coinfected with HIV, or infected with hepatitis B, C, or both. The primary endpoint was safety measured by MSC-infusion related events; any tuberculosis-related event within the 6 month observation period that related to a worsening of the underlying infectious disease, measured by conversion of Mycobacterium tuberculosis culture or microscopic examination; or any adverse event defined clinically or by changes in blood haematology and biochemistry variables, measured monthly for 6 months after MSC infusion per protocol. This study is registered with the German Clinical Trials Registry, number DRKS00000763.

FINDINGS

The most common (grade 1 or 2) adverse events were high cholesterol levels (14 of 30 patients), nausea (11 of 30 patients), and lymphopenia or diarrhoea (ten of 30 patients). There were no serious adverse events reported. We recorded two grade 3 events that were transitory-ie, increased plasma potassium ion concentrations in one patient and a transitory grade 3 γ-glutamyltransferase elevation in another patient.

INTERPRETATION

MSCs as an adjunct therapy are safe and can now be explored further for the treatment of patients with MDR or XDR tuberculosis in combination with standard drug regimens. Adjunct treatment with MSCs needs to be evaluated in controlled phase 2 trials to assess effects on immune responses and clinical and microbiological outcomes.

Mesenchymal stem cells for cardiac therapy: practical challenges and potential mechanisms

Cell based treatments for myocardial infarction have demonstrated efficacy in the laboratory and in phase I clinical trials, but the understanding of such therapies remains incomplete. Mesenchymal stem cells (MSCs) are classically defined as maintaining the ability to generate mesenchyme-derived cell types, namely adipocytes, chondrocytes and osteocytes. Recent evidence suggests these cells may in fact harbor much greater potency than originally realized, as several groups have found that MSCs can form cardiac lineage cells in vitro. Additionally, experimental coculture of MSCs with cardiomyocytes appears to improve contractile function of the latter. Bolstered by such findings, several clinical trials have begun to test MSC transplantation for improving post-infarct cardiac function in human patients. The results of these trials have been mixed, underscoring the need to develop a deeper understanding of the underlying stem cell biology. To help synthesize the breadth of studies on the topic, this paper discusses current challenges in the field of MSC cellular therapies for cardiac repair, including methods of cell delivery and the identification of molecular markers that accurately specify the therapeutically relevant mesenchymal cell types. The various possible mechanisms of MSC mediated cardiac improvement, including somatic reprogramming, transdifferentiation, paracrine signaling, and direct electrophysiological coupling are also reviewed. Finally, we consider the traditional cell culture microenvironment, and the promise of cardiac tissue engineering to provide biomimetic in vitro model systems to more faithfully investigate MSC biology, helping to safely and effectively translate exciting discoveries in the laboratory to meaningful therapies in the clinic.

Optimization of the cardiovascular therapeutic properties of mesenchymal stromal/stem cells-taking the next step

Despite current treatment options, cardiac failure is associated with significant morbidity and mortality highlighting a compelling clinical need for novel therapeutic approaches. Based on promising pre-clinical data, stem cell therapy has been suggested as a possible therapeutic strategy. Of the candidate cell types evaluated, mesenchymal stromal/stem cells (MSCs) have been widely evaluated due to their ease of isolation and ex vivo expansion, potential allogeneic utility and capacity to promote neo-angiogenesis and endogenous cardiac repair. However, the clinical application of MSCs for mainstream cardiovascular use is currently hindered by several important limitations, including suboptimal retention and engraftment and restricted capacity for bona fide cardiomyocyte regeneration. Consequently, this has prompted intense efforts to advance the therapeutic properties of MSCs for cardiovascular disease. In this review, we consider the scope of benefit from traditional plastic adherence-isolated MSCs and the lessons learned from their conventional use in preclinical and clinical studies. Focus is then given to the evolving strategies aimed at optimizing MSC therapy, including discussion of cell-targeted techniques that encompass the preparation, pre-conditioning and manipulation of these cells ex vivo, methods to improve their delivery to the heart and innovative substrate-directed strategies to support their interaction with the host myocardium.

Immunomodulatory nature and site specific affinity of mesenchymal stem cells: a hope in cell therapy

Immunosuppressive ability of mesenchymal stem cells (MSCs), their differentiation properties to various specialized tissue types, ease of in vitro and in vivo expansion and specific migration capacity, make them to be tested in different clinical trials for the treatment of various diseases. The immunomodulatory effects of MSCs are less identified which probably has high clinically significance. The clinical trials based on primary research will cause better understanding the ability of MSCs in immunomodulatory applications and site specific migration in the optimization of therapy. So, this review focus on MSCs functional role in modulating immune responses, their ability in homing to tumor, their potency as delivery vehicle and their medical importance.

Postischemic revascularization: from cellular and molecular mechanisms to clinical applications

After the onset of ischemia, cardiac or skeletal muscle undergoes a continuum of molecular, cellular, and extracellular responses that determine the function and the remodeling of the ischemic tissue. Hypoxia-related pathways, immunoinflammatory balance, circulating or local vascular progenitor cells, as well as changes in hemodynamical forces within vascular wall trigger all the processes regulating vascular homeostasis, including vasculogenesis, angiogenesis, arteriogenesis, and collateral growth, which act in concert to establish a functional vascular network in ischemic zones. In patients with ischemic diseases, most of the cellular (mainly those involving bone marrow-derived cells and local stem/progenitor cells) and molecular mechanisms involved in the activation of vessel growth and vascular remodeling are markedly impaired by the deleterious microenvironment characterized by fibrosis, inflammation, hypoperfusion, and inhibition of endogenous angiogenic and regenerative programs. Furthermore, cardiovascular risk factors, including diabetes, hypercholesterolemia, hypertension, diabetes, and aging, constitute a deleterious macroenvironment that participates to the abrogation of postischemic revascularization and tissue regeneration observed in these patient populations. Thus stimulation of vessel growth and/or remodeling has emerged as a new therapeutic option in patients with ischemic diseases. Many strategies of therapeutic revascularization, based on the administration of growth factors or stem/progenitor cells from diverse sources, have been proposed and are currently tested in patients with peripheral arterial disease or cardiac diseases. This review provides an overview from our current knowledge regarding molecular and cellular mechanisms involved in postischemic revascularization, as well as advances in the clinical application of such strategies of therapeutic revascularization.

Mesenchymal stem cells in immune-mediated bone marrow failure syndromes

Immune-mediated bone marrow failure syndromes (BMFS) are characterized by ineffective marrow haemopoiesis and subsequent peripheral cytopenias. Ineffective haemopoiesis is the result of a complex marrow deregulation including genetic, epigenetic, and immune-mediated alterations in haemopoietic stem/progenitor cells, as well as abnormal haemopoietic-to-stromal cell interactions, with abnormal release of haemopoietic growth factors, chemokines, and inhibitors. Mesenchymal stem/stromal cells (MSCs) and their progeny (i.e., osteoblasts, adipocytes, and reticular cells) are considered as key cellular components of the bone marrow haemopoietic niche. MSCs may interfere with haemopoietic as well as immune regulation. Evidence suggests that bone marrow MSCs may be involved in immune-mediated BMFS underlying pathophysiology, harboring either native abnormalities and/or secondary defects, caused by exposure to activated marrow components. This review summarizes previous as well as more recent information related to the biologic/functional characteristics of bone marrow MSCs in myelodysplastic syndromes, acquired aplastic anemia, and chronic idiopathic neutropenia.

Tropism of avian influenza A (H5N1) virus to mesenchymal stem cells and CD34+ hematopoietic stem cells

The presence of abnormal hematologic findings such as lymphopenia, thrombocytopenia, and pancytopenia were diagnosed in severe cases of avian influenza A H5N1. Whether direct viral dissemination to bone marrow (BM) cells causes this phenomenon remains elusive. We explore the susceptibility of the two stem cell types; hematopoietic stem cells (HSCs) and mesenchymal stromal cells (MSCs) isolated from human BM cells or cord blood, to infection with avian H5N1 viruses. For the first time, we demonstrated that the H5N1 virus could productively infect and induce cell death in both human stem cell types. In contrast, these activities were not observed upon human influenza virus infection. We also determined whether infection affects the immunomodulatory function of MSCs. We noted a consequent dysregulation of MSC-mediated immune modulation as observed by high cytokine and chemokine production in H5N1 infected MSCs and monocytes cocultures. These findings provide a better understanding of H5N1 pathogenesis in terms of broad tissue tropism and systemic spread.

Do the Fibroblasts Contained in Early Passage MSC Population Adversely Affect the Characteristics of Stem Cell Population Obtained from Human Placenta?

BACKGROUND AND OBJECTIVES

Mesenchymal stem cells (MSCs) have been obtained from various human tissues by harvesting plastic adherent fibroblast-like cell population. For potential use in regeneration medicine, early passage MSC population is preferred to avoid cell senescence. The early passage adherent cell population contains MSCs as well as fibroblasts, however, the significance of the contained fibroblasts has not been well investigated. Thus, we investigated the stem cell characteristics of the early passage MSC population with and without fibroblasts depletion.

METHODS AND RESULTS

We obtained adherent cell populations from full term placenta at passage 2∼3 and divided them into two subpopulations: fibroblasts depleted (popFD) and non-depleted population (popFND) using magnetic cell sorting method. The two subpopulations were compared in terms of cell morphology, potential for long term culture, colony forming ability, and tri-lineage differentiation for adipogenic, chondrogenic, and osteogenic differentiation. The percentage of fibroblasts contained in the early passage MSC population was 5.3% (2.9∼8.4). Both the popFD and popFND was spindle shaped from early passages and maintained long term culture up to 20∼22 passages. CFU-F assay showed no difference between the subpopulations. Overall, tri-lineage differentiation showed a tendency of better differentiation potential of popFND than popFD.

CONCLUSIONS

We confirmed that fibroblasts are contained in early population of placenta-derived MSCs obtained by current method. This study revealed that the contained fibroblasts in early passage MSC population do not adversely affect the properties of MSCs in terms of cell morphology, potential for long term culture, colony forming ability, and tri-lineage differentiation.

Human salivary gland stem cells ameliorate hyposalivation of radiation-damaged rat salivary glands

Salivary function in mammals may be defective for various reasons, such as aging, Sjogren's syndrome or radiation therapy in head and neck cancer patients. Recently, tissue-specific stem cell therapy has attracted public attention as a next-generation therapeutic reagent. In the present study, we isolated tissue-specific stem cells from the human submandibular salivary gland (hSGSCs). To efficiently isolate and amplify hSGSCs in large amounts, we developed a culture system (lasting 4–5 weeks) without any selection. After five passages, we obtained adherent cells that expressed mesenchymal stem cell surface antigen markers, such as CD44, CD49f, CD90 and CD105, but not the hematopoietic stem cell markers, CD34 and CD45, and that were able to undergo adipogenic, osteogenic and chondrogenic differentiation. In addition, hSGSCs were differentiated into amylase-expressing cells by using a two-step differentiation method. Transplantation of hSGSCs to radiation-damaged rat salivary glands rescued hyposalivation and body weight loss, restored acinar and duct cell structure, and decreased the amount of apoptotic cells. These data suggest that the isolated hSGSCs, which may have characteristics of mesenchymal-like stem cells, could be used as a cell therapy agent for the damaged salivary gland.

Perspective and challenges of mesenchymal stem cells for cardiovascular regeneration

Mesenchymal stem cells (MSCs) exhibit multipotent differentiation potential and can be derived from embryonic, neonatal and adult differentiation stage III tissue sources. While increasing preclinical studies and clinical trials have indicated that MSC-based therapy is a promising strategy for cardiovascular regeneration, there are major challenges to overcome before this stem-cell technology can be widely applied in clinical settings. In this review, the following important issues will be addressed. First, optimal sources of MSC derivation suitable for myocardial repair are not determined. Second, assessments for preclinical and clinical studies of MSCs require more scientific data analysis. Third, mechanisms of MSC-based therapy for cardiovascular regeneration have not been fully understood yet. Finally, the potential benefit-risk ratio of MSC therapy needs to be evaluated systematically. Additionally, future development of MSC therapy will be discussed.

In vitro testing of immunosupressive effects of mesenchymal stromal cells on lymphocytes stimulated with alloantigens

AIMS

Mesenchymal stromal cells (MSC) derived from adult bone marrow or adipose tissue offer the potential to open a new frontier in medicine. MSC are involved in modulating immune response and tissue repair in vitro and in vivo. Experimental evidence and preliminary clinical studies have demonstrated that MSC exhibit an important immunomodulatory function in patients with graft versus host disease (GVHD) following allogeneic hematopoietic stem cell transplantation. The immunosuppressive properties of MSC have already been exploited in the clinical setting. However the precise mechanisms are being still investigated.

METHODS

We examined the immunosuppressive function of MSC by coculturing them with stimulated HLA incompatible allogeneic lymphocytes in a mixed lymphocyte culture test. The metabolic and proliferative activity of lymphocytes was determined by MTT test.

RESULTS

After stimulation with alloantigens the presence of MSC caused significant decrease of absorbance levels by 62% (P<0.01), 26% (P<0.01) and 6% (P=0.0437) in comparison to positive control depending on the MSC/lymphocyte ratio (1:5, 1:50, 1:500). The mitogenic stimulation of lymphocytes with fMLP or PHA was also significantly reduced during MSC cocultivation. The absorbance was reduced by 42% (P<0.001) and 67% (P<0.001).

CONCLUSIONS

Allogeneic bone marrow is an ideal source of MSC for clinical application. The experiments confirmed the dose-dependent inhibitory effect of MSC on lymphocyte proliferation triggered by cellular or mitogenic stimulation. The mixed lymphocyte culture test offers a simple method for characterization and verification of the immunosuppressive potential of MSC, being prepared for clinical use.

Bradykinin-induced asthmatic fibroblast/myofibroblast activities via bradykinin B2 receptor and different MAPK pathways

Bradykinin drives normal lung fibroblasts into myofibroblasts, induces fibroblast proliferation and activates mitogen activated protein kinase pathways (MAPK) but its effects on bronchial fibroblasts from asthmatics (HBAFb) have not been yet studied. We studied bradykinin-induced fibroblast proliferation and differentiation and the related intracellular mechanisms in HBAFb compared to normal bronchial fibroblasts (HNBFb). Bradykinin-stimulated HBAFb and HNBFb were used to assess: bradykinin B2 receptor expression by Western blot analysis; cell proliferation by [(3)H] thymidine incorporation; α-smooth muscle actin (SMA) expression/polymerization by Western blot and immunofluorescence; epidermal growth factor (EGF) receptor, extracellular-regulated kinase (ERK) 1/2 and p38 MAPK activation by immunoprecipitation and Western blot, respectively. Constitutive bradykinin B2 receptor and α-SMA expression was higher in HBAFb as compared to HNBFb. Bradykinin increased bradykinin B2 receptor expression in HBAFb. Bradykinin, via bradykinin B2 receptor, significantly increased fibroblast proliferation at lower concentration (10(-11)M) and α-SMA expression/polymerization at higher concentration (10(-6)M) in both cells. Bradykinin increased ERK1/2 and p38 phosphorylation via bradykinin B2 receptor; EGF receptor inhibitor AG1478 and panmetalloproteinase inhibitor GM6001 blocked bradykinin-induced ERK1/2 activation but not p38 phosphorylation. Bradykinin, via bradykinin B2 receptor, induced EGF receptor phosphorylation that was suppressed by AG1478. In HBAFb AG1478, GM6001, the ERK1/2-inhibitor U0126 and the p38 inhibitor SB203580 suppressed bradykinin-induced cell proliferation, but only SB203580 reduced myofibroblast differentiation. These data indicate that bradykinin is actively involved in asthmatic bronchial fibroblast proliferation and differentiation, through MAPK pathways and EGF receptor transactivation, by which bradykinin may contribute to airway remodeling in asthma, opening new horizons for potential therapeutic implications in asthmatic patients.

[Genic and cellular therapy for peripheral arterial diseases]

Late evolution of peripheral arterial disease consists in the apparition of critical limb ischemia. Surgical treatments allow to treat these patients during long time; however, in most patients, especially the diabetic ones, there a very few options and the clinical evolution is rapidly dramatic. For these reasons, the critical limb ischemia is one of the first diseases treated by genic or cellular therapies aiming to improve blood flow perfusion in the lower-limbs. In this short review, we describe the main clinical trials of genic therapy; most of them have been abandoned because serious side effects, modest effects and major risks. Different types of stem cells are now used for cell therapy: endothelial progenitor cells, early or late, activated or not, mesenchymal stem cells, embryonic stem cells and human induced pluripotent stem cells. Problems of characterization are described and the results of the most important clinical trials are reported.

In vivo formation of bone and haematopoietic territories by transplanted human bone marrow stromal cells generated in medium with and without osteogenic supplements

Autologous transplantation of human bone marrow stromal cells (BMSCs) has been successfully used for bone reconstruction. However, in order to advance this approach into the mainstream of bone tissue engineering, the conditions for BMSC cultivation and transplantation must be optimized. In a recent report, cultivation with dexamethasone (Dex) significantly increased bone formation by human BMSCs in vivo. Based on this important conclusion, we analysed the data accumulated by our laboratory, where human BMSCs have been routinely generated using media both with and without a combination of two osteogenic supplements: Dex at 10(-8)  m and ascorbic acid phosphate (AscP) at 10(-4)  m. Our data demonstrate that for 22/24 donors, BMSC strains propagated with and without Dex/AscP formed similar amounts of bone in vivo. Thus, human BMSCs do not appear to need to be induced to osteogenic differentiation ex vivo prior to transplantation. Similarly, for 12/14 donors, BMSC strains cultured with and without Dex/AscP formed haematopoietic territories to a comparable extent. While Dex/AscP did not increase bone formation, they significantly stimulated BMSC in vitro proliferation without affecting the number of BMSC colonies formed by the colony-forming units-fibroblasts. We conclude that for the substantial majority of donors, Dex/AscP have no effect on the ability of BMSCs to form bone and myelosupportive stroma in vivo. However, due to increased BMSC proliferation, the total osteogenic population obtained from a single marrow sample is larger after cultivation with Dex/AscP than without them. Secondary to increased BMSC proliferation, Dex/AscP may stimulate bone formation if BMSCs and/or the transplantation system are less than optimal. Published 2011. This article is a U.S. Government work and is in the public domain in the USA.