Mesenchymal stem cells as vectors for lung disease

The effects of IL-1β stimulated human umbilical cord mesenchymal stem cells on polarization and apoptosis of macrophages in rheumatoid arthritis

Macrophages play an important role in the pathogenesis of rheumatoid arthritis (RA), in which the functions of pro-inflammatory macrophages (M1) and anti-inflammatory macrophages (M2) are different. Our previous studies have demonstrated that interleukin-1β (IL-1β) stimulated human umbilical cord mesenchymal stem cells (hUCMSCs) increase the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and initiate breast cancer cell apoptosis via ligand to death receptor 4 (DR4) and DR5. In this study, we examined the effect of IL-1β stimulated hUCMSCs (IL-1β-hUCMSCs) on immunoregulation of M1 and M2 macrophages in vitro and in the RA mouse model. The results showed that IL-1β-hUCMSCs increased macrophage polarization into M2 macrophages and enhanced apoptosis of M1 macrophages in vitro. Moreover, the intravenous injected IL-1β-hUCMSCs in RA mice rehabilitated the imbalance of M1/M2 ratio and thus demonstrated the potential to reduce inflammation in RA. This study advances our knowledge of the underlying immunoregulatory mechanisms involved in IL-1β-hUCMSCs to induce M1 macrophage apoptosis and promote the anti-inflammatory polarization of M2 macrophages and demonstrates the potential of IL-1β-hUCMSCs to reduce inflammation in RA.

Interleukin-1β Enhances Umbilical Cord Mesenchymal Stem Cell Adhesion Ability on Human Umbilical Vein Endothelial Cells via LFA-1/ICAM-1 Interaction

The migration of administered mesenchymal stem cells (MSCs) to sites of injury via the bloodstream has been demonstrated. However, the underlying mechanisms of umbilical cord MSC adhesion to endothelial cells during transendothelial migration are still unclear. In this study, our data showed that IL-1β induced LFA-1 expression on MSCs and ICAM-1 expression on HUVECs. We then pretreated MSCs with protein synthesis inhibitor cycloheximide. The results showed that IL-1β induced LFA-1 expression on the surface of MSCs via the protein synthesis pathway. Through the p38 MAPK signaling pathway inhibitor SB 203580, we found that IL-1β induces the expression of LFA-1 through p38 MAPK signaling and enhances ICAM-1 expression in HUVECs. In addition, IL-1β-induced MSC adhesion to HUVECs was found to be inhibited by IL-1RA and the LFA-1 inhibitor lovastatin. These results indicate that IL-1β promotes the cell adhesion of MSCs to HUVECs through LFA-1/ICAM-1 interaction. We address the evidence that the cell adhesion mechanism of IL-1β promotes MSC adhesion to HUVECs. The implications of these findings could enhance the therapeutic potential of MSCs.

Human pluripotent stem cell-derived mesenchymal stem cells prevent chronic allergic airway inflammation via TGF-β1-Smad2/Smad3 signaling pathway in mice

BACKGROUND

Asthma is a chronic disease involving inflamed airways, which were previously demonstrated, can be modulated by the mesenchymal stem cells derived from induced pluripotent stem cells (iPSC-MSCs). However, the long-term effects of iPSC-MSCs in inflamed airways are still unidentified. This study investigated the long-term effects and potential mechanisms involved in the immunomodulatory effects of iPSC-MSCs in the chronic mouse asthma model.

METHODS

Both human iPSC-MSCs and bone marrow (BM)-MSCs were transplanted into the long-term ovalbumin-induced mice before sensitization phase or during the challenge phase. Airway hyper-respnsiveness measurement, immunohistochemistry and ELISA were employed to assess the effects of MSCs. In addition, Smad2/3 levels were assessed by western blot analysis to investigate the possible mechanism involved.

RESULTS

The systemic administration of human iPSC-MSCs before the challenge protected the mice from the characters of the chronic allergic airway inflammation, in particular improving the airway remodeling and preventing fibrosis. In addition, the TGF-β1/Smad pathway was identified involved in the immunomodulatory effects of iPSC-MSCs on chronic allergic airway inflammation.

CONCLUSIONS

The study demonstrated that iPSC-MSCs are capable of preventing chronic allergic airway inflammation over a prolonged period, which further proved the iPSC-MSC therapeutic potential for allergic airway inflammation in a clinical scenario.

Drug-releasing mesenchymal cells strongly suppress B16 lung metastasis in a syngeneic murine model

BACKGROUND

Mesenchymal stromal cells (MSCs) are considered an important therapeutic tool in cancer therapy. They possess intrinsic therapeutic potential and can also be in vitro manipulated and engineered to produce therapeutic molecules that can be delivered to the site of diseases, through their capacity to home pathological tissues. We have recently demonstrated that MSCs, upon in vitro priming with anti-cancer drug, become drug-releasing mesenchymal cells (Dr-MCs) able to strongly inhibit cancer cells growth.

METHODS

Murine mesenchymal stromal cells were loaded with Paclitaxel (Dr-MCsPTX) according to a standardized procedure and their ability to inhibit the growth of a murine B16 melanoma was verified by in vitro assays. The anti-metastatic activity of Dr-MCsPTX was then studied in mice injected i.v. with B16 melanoma cells that produced lung metastatic nodules. Lung nodules were counted under a dissecting stereomicroscope and metastasis investigated by histological analysis.

RESULTS

We found that three i.v. injections of Dr-MCsPTX on day 5, 10 and 15 after tumor injection almost completely abolished B16 lung metastasis. Dr-MCsPTX arrested into lung by interacting with endothelium and migrate toward cancer nodule through a complex mechanism involving primarily mouse lung stromal cells (mL-StCs) and SDF-1/CXCR4/CXCR7 axis.

CONCLUSIONS

Our results show for the first time that Dr-MCsPTX are very effective to inhibit lung metastasis formation. Actually, a cure for lung metastasis in humans is mostly unlikely and we do not know whether a therapy combining engineered MSCs and Dr-MCs may work synergistically. However, we think that our approach using Dr-MCs loaded with PTX may represent a new valid and additive therapeutic tool to fight lung metastases and, perhaps, primary lung cancers in human.

Polymeric vector-mediated gene transfection of MSCs for dual bioluminescent and MRI tracking in vivo

MSC's transplantation is a promising cell-based therapy for injuries in regenerative medicine, and in vivo visualization of transplanted MSCs with noninvasive technique is essential for the tracking of cell infusion and homing. A new cationic polymer, poly(ethylene glycol)-block-poly(l-aspartic acid)-grafted polyethylenimine functionalized with superparamagnetic iron oxide nanoparticles (PAI/SPION), was constructed as a magnetic resonance imaging (MRI)-visible non-viral vector for the delivery of plasmids DNA (pDNA) encoding for luciferase and red fluorescence protein (RFP) as reporter genes into MSCs. As a result, the MSCs were labeled with SPION and reporter genes. The PAI/SPION complexes exhibited high transfection efficiency in transferring pDNA into MSCs, which resulted in efficient luciferase and RFP co-expression. Furthermore, the complexes did not significantly affect the viability and multilineage differentiation capacity of MSCs. After the labeled MSCs were transplanted into the rats with acute liver injury via the superior mesenteric vein (SMV) injection, the migration behavior and organ-specific accumulation of the cells could be effectively monitored using the in vivo imaging system (IVIS) and MRI, respectively. The immunohistochemical analysis further confirmed that the transplanted MSCs were predominantly distributed in the liver parenchyma. Our results indicate that the PAI/SPION is a MRI-visible gene delivery agent which can effectively label MSCs to provide the basis for bimodal bioluminescence and MRI tracking in vivo.

Human mesenchymal stromal cells can uptake and release ciprofloxacin, acquiring in vitro anti-bacterial activity

BACKGROUND AIMS

Traditional antibiotic therapy is based on the oral or systemic injection of antibiotics that are often unable to stop a deep infection (eg, osteomyelitis). We studied whether or not bone marrow stromal cells (BM-MSCs) are able to uptake and release ciprofloxacin (CPX), a fluoroquinolone considered the drug of choice for the treatment of chronic osteomyelitis because of its favorable penetration into poorly vascularized sites of infection.

METHODS

Human bone marrow stromal cells (BM-MSCs) were primed with CPX (BM-MSCsCPX) according to a methodology previously standardized in our laboratory for paclitaxel (PTX). The anti-microbial activity of CPX released from BM-MSCs cells (BM-MSCsCPX-CM) or supernatant from cell lysate (BM-MSCsCPX-LYS) was evaluated by agar dilution and microdilution methods on three bacterial strains (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa). To investigate whether or not primed cells (BM-MSCsCPX) were able to directly act on the bacterial growth, co-colture was performed by mixing E. coli suspension to an increasing number of BM-MSCsCPX. The anti-bacterial activity was determined as number of BM-MSCsCPX that completely inhibited bacterial growth.

RESULTS

The results demonstrated that BM-MSCsCPX are able to uptake and then release CPX in the conditioned medium. The loaded antibiotic maintains its active form throughout the process as tested on bacteria.

CONCLUSIONS

Our findings suggest that CPX-loaded MSCs may represent an important device for carrying and delivering CPX (and perhaps other antibiotics) into infected deep microenvironments; they could be used for local application and by systemic infusion when their homing capacity into the bone is cleared.

Paracrine effects and heterogeneity of marrow-derived stem/progenitor cells: relevance for the treatment of respiratory diseases

Stem cell-based treatment may represent a hope for the treatment of acute lung injury and pulmonary fibrosis, and other chronic lung diseases, such as cystic fibrosis, asthma and chronic obstructive pulmonary disease (COPD). It is well established in preclinical models that bone marrow-derived stem and progenitor cells exert beneficial effects on inflammation, immune responses and repairing of damage in virtually all lung-borne diseases. While it was initially thought that the positive outcome was due to a direct engraftment of these cells into the lung as endothelial and epithelial cells, paracrine factors are now considered the main mechanism through which stem and progenitor cells exert their therapeutic effect. This knowledge has led to the clinical use of marrow cells in pulmonary hypertension with endothelial progenitor cells (EPCs) and in COPD with mesenchymal stromal (stem) cells (MSCs). Bone marrow-derived stem cells, including hematopoietic stem/progenitor cells, MSCs, EPCs and fibrocytes, encompass a wide array of cell subsets with different capacities of engraftment and injured tissue-regenerating potential. The characterization/isolation of the stem cell subpopulations represents a major challenge to improve the efficacy of transplantation protocols used in regenerative medicine and applied to lung disorders.

Aerosol-based delivery of fibroblast cells for treatment of lung diseases

BACKGROUND

Cell-based therapy has great potential to treat patients with lung diseases. The administration of cells into an injured lung is one method of repairing and replacing lost lung tissue. However, different types of delivery have been studied and compared, and none of the techniques resulted in engraftment of a high number of cells into the targeted organ. In this in vitro study, a novel method of cell delivery was introduced to investigate the possibility of delivering aerosolized skin-derived fibroblasts.

METHODS

Skin-derived fibroblasts were trypsinized and resuspended in growth medium. A syringe filled with cells (10(5) cells/mL) was attached to MicroSprayer(®) Aerosolizer, a device that can modify a liquid into an aerosol. The tip of the MicroSprayer Aerosolizer was channeled into a T25 flask containing growth medium. Survivability following aerosolization was observed on a daily basis. HeLa cells were used for comparison. The same aerosolization and culture methods were used to treat HeLa cells.

RESULTS

One day following aerosolization, skin-derived fibroblasts showed no sign of vacuolation due to cell stress. They attached to the surface of the flask, indicating that most of them survived aerosolization. The surviving cells were also able to proliferate rapidly, forming a confluent monolayer of cells at day 4. In contrast, HeLa cells were unable to proliferate even after 21 days of culture.

CONCLUSIONS

This study provides the first evidence that cells can be aerosolized without the risk of low cell survivability and stress. The high survival rate of fibroblast cells following aerosolization illustrates the potential for delivering of such cells in future aerosol cell-based therapy to treat lung diseases.

Identification of functional progenitor cells in the pulmonary vasculature

The pulmonary vasculature comprises a complex network of branching arteries and veins all functioning to reoxygenate the blood for circulation around the body. The cell types of the pulmonary artery are able to respond to changes in oxygen tension in order to match ventilation to perfusion. Stem and progenitor cells in the pulmonary vasculature are also involved, be it in angiogenesis, endothelial dysfunction or formation of vascular lesions. Stem and progenitor cells may be circulating around the body, residing in the pulmonary artery wall or stimulated for release from a central niche like the bone marrow and home to the pulmonary vasculature along a chemotactic gradient. There may currently be some controversy over the pathogenic versus therapeutic roles of stem and progenitor cells and, indeed, it is likely both chains of evidence are correct due to the specific influence of the immediate environmental niche a progenitor cell may be in. Due to their great plasticity and a lack of specific markers for stem and progenitor cells, they can be difficult to precisely identify. This review discusses the methodological approaches used to validate the presence of and subtype of progenitors cells in the pulmonary vasculature while putting it in context of the current knowledge of the therapeutic and pathogenic roles for such progenitor cells.

Characterization of sarcoma-like cells derived from endarterectomized tissues from patients with CTEPH and establishment of a mouse model of pulmonary artery intimal sarcoma

In general, intravascular thrombus formation in the pulmonary arteries is considered to be the most common cause of chronic thromboembolic pulmonary hypertension (CTEPH). The current mainstay of therapy for patients with CTEPH is pulmonary endarterectomy (PEA). Recently, the existence of myofibroblast-like cells in endarterectomized tissues has been demonstrated. At the 2nd passage of these myofibroblast-like cells, a pleomorphic cell type was isolated. Pulmonary intimal sarcoma is a very uncommon neoplastic tumor thought to originate from subendothelial-mesenchymal cells of the pulmonary vascular wall. Because these pleomorphic cells were isolated from the pulmonary vascular beds, it is believed that the analysis of these cells may contribute to the understanding of pulmonary intimal sarcoma. We isolated cells from the endarterectomized tissue from patients with CTEPH and identified one type as sarcoma-like cells (SCLs). The SCLs were characterized as hyperproliferative, anchorage-independent, invasive and serum-independent. Moreover, C.B-17/lcr-scid/scidJcl mice injected subcutaneously with SCLs developed solid, undifferentiated tumors at the site of injection, and those injected intravenously with SCLs via the tail vein developed tumors which grew along the intimal surface of the pulmonary vessels, thus, demonstrating the high tumorigenic potential of these cells. The behavior of SCLs indicated that these cells may have a vascular cell-like potential which can affiliate them with the intimal surface of the pulmonary artery, and which may be shared with pulmonary intimal sarcoma. A further investigation of this mouse model with SCLs may elucidate the mechanism(s) underlying the development of pulmonary intimal sarcoma.

Cell-based drug-delivery platforms

Cell systems have recently emerged as biological drug carriers, as an interesting alternative to other systems such as micro- and nano-particles. Different cells, such as carrier erythrocytes, bacterial ghosts and genetically engineered stem and dendritic cells have been used. They provide sustained release and specific delivery of drugs, enzymatic systems and genetic material to certain organs and tissues. Cell systems have potential applications for the treatment of cancer, HIV, intracellular infections, cardiovascular diseases, Parkinson’s disease or in gene therapy. Carrier erythrocytes containing enzymes such us L-asparaginase, or drugs such as corticosteroids have been successfully used in humans. Bacterial ghosts have been widely used in the field of vaccines and also with drugs such as doxorubicin. Genetically engineered stem cells have been tested for cancer treatment and dendritic cells for immunotherapeutic vaccines. Although further research and more clinical trials are necessary, cell-based platforms are a promising strategy for drug delivery.

Monitoring transplanted adipose tissue-derived stem cells combined with heparin in the liver by fluorescence imaging using quantum dots

Adipose tissue-derived stem cell (ASC) transplantation, when used in combination with heparin, has proven to be an effective treatment for acute liver failure in mice. However, the behavior and organ-specific accumulation of transplanted ASCs alone or in combination with heparin is poorly understood. In this paper, we investigated whether quantum dots (QDs) labeling using octa-arginine peptide (R8) for ASCs could be applied for in vivo fluorescence imaging in mice with acute liver failure, and analyzed the behavior and organ-specific accumulation of ASCs that were transplanted alone or in combination with heparin using an IVIS(®) Spectrum analysis. Almost all of the transplanted ASCs were observed to accumulate in the lungs within 10 min without heparin. However, when heparin was used in combination with the ASCs, the accumulation of the transplanted ASCs was found not only in the lungs but also in the liver. The region of interest (ROI) analysis of ex vivo fluorescence imaging showed that the accumulation rate of transplanted ASCs in the liver increased to about 30%. In the time course analysis, the accumulation rate of ASCs in the liver was about 10% in 1 day and was maintained at that level for at least 2 day. We observed that heparin was effective for increasing the accumulation of transplanted ASCs in the liver using fluorescence imaging technology. We suggest that fluorescence imaging by means of QDs labeling using R8 can be useful for tracing the transplanted cells.

Mobilization of bone marrow cells by CSF3 protects mice from bleomycin-induced lung injury

BACKGROUND

Bone marrow-derived cells may play a role in tissue injury and repair. Growth factors facilitate the mobilization of bone marrow-derived cells to the site of injury.

OBJECTIVES

The aim of this study was to determine the effect of the mobilization of autologous bone marrow-derived cells by granulocyte colony-stimulating factor (CSF3) on bleomycin-induced lung injury in mice.

METHODS

The bone marrow from male green fluorescent protein transgenic (C57Bl/6J) mice was transplanted into irradiated female C57Bl/6J mice. Bleomycin lung injury was induced in these bone marrow-reconstituted mice and unreconstituted C57Bl/6J mice, and some mice were treated with recombinant CSF3. Lung histology, survival, cytokine expression and matrix metalloproteinase (MMP) expression were evaluated to determine the effect of CSF3 after bleomycin-induced lung injury.

RESULTS

Histology and flow cytometry analysis showed successful mobilization of bone marrow-derived cells by CSF3 treatment in the recipient lungs. Importantly, CSF3 attenuated bleomycin-induced lung injury and improved survival. Furthermore, CSF3 administration regulated transforming growth factor-β, interferon-γ, MMP9 and tissue inhibitors of MMP1 expression during bleomycin injury.

CONCLUSIONS

These data demonstrated that the mobilization of bone marrow-derived cells by CSF3 has a protective effect against bleomycin-induced lung injury and fibrosis.

Mechanisms of cellular therapy in respiratory diseases

PURPOSE

Stem cells present a variety of clinical implications in the lungs. According to their origin, these cells can be divided into embryonic and adult stem cells; however, due to the important ethical and safety limitations that are involved in the embryonic stem cell use, most studies have chosen to focus on adult stem cell therapy. This article aims to present and clarify the recent advances in the field of stem cell biology, as well as to highlight the effects of mesenchymal stem cell (MSC) therapy in the context of acute lung injury/acute respiratory distress syndrome and chronic disorders such as lung fibrosis and chronic obstructive pulmonary disease.

METHODS

For this purpose, we performed a critical review of adult stem cell therapies, covering the main clinical and experimental studies published in Pubmed databases in the past 11 years. Different characteristics were extracted from these articles, such as: the experimental model, strain, cellular type and administration route used as well as the positive or negative effects obtained.

RESULTS

There is evidence for beneficial effects of MSC on lung development, repair, and remodeling. The engraftment in the injured lung does not occur easily, but several studies report that paracrine factors can be effective in reducing inflammation and promoting tissue repair. MSC releases several growth factors and anti-inflammatory cytokines that regulate endothelial and epithelial permeability and reduce the severity of inflammation.

CONCLUSION

A better understanding of the mechanisms that control cell division and differentiation, as well as of their paracrine effects, is required to enable the optimal use of bone marrow-derived stem cell therapy to treat human respiratory diseases.

Stem cells and cell therapies in lung biology and lung diseases

The University of Vermont College of Medicine and the Vermont Lung Center, with support of the National Heart, Lung, and Blood Institute (NHLBI), the Alpha-1 Foundation, the American Thoracic Society, the Emory Center for Respiratory Health,the Lymphangioleiomyomatosis (LAM) Treatment Alliance,and the Pulmonary Fibrosis Foundation, convened a workshop,‘‘Stem Cells and Cell Therapies in Lung Biology and Lung Diseases,’’ held July 26-29, 2009 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 approaches for lung diseases. These are rapidly expanding areas of study that provide further insight into and challenge traditional views of the 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, discuss and debate current controversies, and identify future research directions and opportunities for both basic and translational research in cell-based therapies for lung diseases.

Paracrine factors of multipotent stromal cells ameliorate lung injury in an elastase-induced emphysema model

Multipotent stromal cells (MSCs) ameliorate several types of lung injury. The differentiation of MSCs into specific cells at the injury site has been considered as the important process in the MSC effect. However, although MSCs reduce destruction in an elastase-induced lung emphysema model, MSC differentiation is relatively rare, suggesting that MSC differentiation into specific cells does not adequately explain the recuperation observed. Humoral factors secreted by MSCs may also play an important role in ameliorating emphysema. To confirm this hypothesis, emphysema was induced in the lungs of C57BL/6 mice by intratracheal elastase injection 14 days before intratracheal MSC or phosphate-buffered saline (PBS) administration. Thereafter, lungs were collected at several time points and evaluated. Our results showed that MSCs reduced the destruction in elastase-induced emphysema. Furthermore, double immunofluorescence staining revealed infrequent MSC engraftment and differentiation into epithelial cells. Real-time PCR showed increased levels of hepatocyte growth factor (HGF) and epidermal growth factor (EGF). Real-time PCR and western blotting showed enhanced production of secretory leukocyte protease inhibitor (SLPI) in the lung. In-vitro coculture studies confirmed the in vivo observations. Our findings suggest that paracrine factors derived from MSCs is the main mechanism for the protection of lung tissues from elastase injury.

Transplantation of adipose derived stromal cells into the developing mouse eye

Adipose derived stromal cells (ADSCs) were transplanted into a developing mouse eye to investigate the influence of a developing host micro environment on integration and differentiation. Green fluorescent protein-expressing ADSCs were transplanted by intraocular injections. The age of the mouse was in the range of 1 to 10 days postnatal (PN). Survival dates ranged from 7 to 28 post transplantation (DPT), at which time immunohistochemistry was performed. The transplanted ADSCs displayed some morphological differentiations in the host eye. Some cells expressed microtubule associated protein 2 (marker for mature neuron), or glial fibrillary acid protein (marker for glial cell). In addition, some cells integrated into the ganglion cell layer. The integration and differentiation of the transplanted ADSCs in the 5 and 10 PN 7 DPT were better than in the host eye the other age ranges. This study was aimed at demonstrating how the age of host micro environment would influence the differentiation and integration of the transplanted ADSCs. However, it was found that the integration and differentiation into the developing retina were very limited when compared with other stem cells, such as murine brain progenitor cell.

TRAIL-expressing mesenchymal stem cells kill the putative cancer stem cell population

BACKGROUND

Tumours contain stem-like, side population (SP) cells, which have increased tumorigenic potential, resistance to traditional therapies and may be responsible for treatment failures and relapse in patients.

METHODS

Mesenchymal stem cells (MSCs) were engineered to express the apoptotic ligand, TNF-related apoptosis-inducing ligand (TRAIL). Squamous (H357) and lung (A549) cancer cell lines were sorted into side and non-side populations (non-SP) by Hoechst flow cytometry. The survival and growth of both SP and non-SP cancer populations, in conjunction with TRAIL-expressing MSCs and mitoxantrone chemotherapy, were assessed by flow cytometry and colony forming ability.

RESULTS

Mesenchymal stem cells expressing TRAIL migrate to tumours and reduce the growth of primary cancers and metastases. This report demonstrates that these cells cause apoptosis, death and reduced colony formation of the SP of squamous and adenocarcinoma lung cancer cells and are synergistic when combined with traditional chemotherapy in apoptosis induction.

CONCLUSIONS

The sensitivity of putative cancer stem cells to TRAIL-expressing MSCs, suggests their possible role in the prevention of cancer relapse.

Developing cell therapy techniques for respiratory disease: intratracheal delivery of genetically engineered stem cells in a murine model of airway injury

Interest has increased in the use of exogenous stem cells to optimize lung repair and serve as carriers of a therapeutic gene for genetic airway diseases such as cystic fibrosis. We investigated the survival and engraftment of exogenous stem cells after intratracheal injection, in a murine model of acute epithelial airway injury already used in gene therapy experiments on cystic fibrosis. Embryonic stem cells and mesenchymal stem cells were intratracheally injected 24 hr after 2% polidocanol administration, when epithelial airway injury was maximal. Stem cells were transfected with reporter genes immediately before administration. Reporter gene expression was analyzed in trachea-lungs and bronchoalveolar lavage, using nonfluorescence, quantitative, and sensitive methods. Enzyme-linked immunosorbent assay quantitative results showed that 0.4 to 5.5% of stem cells survived in the injured airway. Importantly, no stem cells survived in healthy airway or in the epithelial lining fluid. Using 5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside staining, transduced mesenchymal stem cells were detected in injured trachea and bronchi lumen. When the epithelium was spontaneously regenerated, the in vivo amount of engrafted mesenchymal stem cells from cell lines decreased dramatically. No stem cells from primary culture were located within the lungs at 7 days. This study demonstrated the feasibility of intratracheal cell delivery for airway diseases with acute epithelial injury.

Human mesenchymal stem cells suppress chronic airway inflammation in the murine ovalbumin asthma model

Allogeneic human mesenchymal stem cells (hMSCs) introduced intravenously can have profound anti-inflammatory activity resulting in suppression of graft vs. host disease as well as regenerative events in the case of stroke, infarct, spinal cord injury, meniscus regeneration, tendinitis, acute renal failure, and heart disease in human and animal models of these diseases. hMSCs produce bioactive factors that provide molecular cuing for: 1) immunosuppression of T cells; 2) antiscarring; 3) angiogenesis; 4) antiapoptosis; and 5) regeneration (i.e., mitotic for host-derived progenitor cells). Studies have shown that hMSCs have profound effects on the immune system and are well-tolerated and therapeutically active in immunocompetent rodent models of multiple sclerosis and stroke. Furthermore, intravenous administration of MSCs results in pulmonary localization. Asthma is a major debilitating pulmonary disease that impacts in excess of 150 million people in the world with uncontrolled asthma potentially leading to death. In addition, the socioeconomic impact of asthma-associated illnesses at the pediatric and adult level are in the millions of dollars in healthcare costs and lost days of work. hMSCs may provide a viable multiaction therapeutic for this inflammatory lung disease by secreting bioactive factors or directing cellular activity. Our studies show the effectiveness and specificity of the hMSCs on decreasing chronic airway inflammation associated with the murine ovalbumin model of asthma. In addition, the results from these studies verify the in vivo immunoeffectiveness of hMSCs in rodents and support the potential therapeutic use of hMSCs for the treatment of airway inflammation associated with chronic asthma.

Mesenchymal stem cells modulate lung injury

Mesenchymal stem cells (MSCs) have been shown to differentiate into a variety of mesenchymal cell types, including fibroblasts, myofibroblasts, osteoblasts, chondroblasts, adipocytes, and myoblasts, as well as epithelial cells. It has been shown that these cells can be recovered from bone marrow as well as umbilical cord blood, and they can be propagated, stored, and administered to animals and patients in clinical trials. It is clear that the cells engraft in the lung, and several laboratories have demonstrated an ameliorating effect in models of acute injury caused by LPS and in chronic lung injury induced by bleomycin and asbestos. However, it is not at all clear under what conditions these cells must be applied to provide an advantage and when using these cells might cause exacerbation of the lung injury. This brief review focuses on the biology of MSCs in vitro, how the cells have been used in some animal models, and the potential for their use in therapeutic strategies for diseases as diverse as lung cancer and interstitial fibrosis.

Importin 13 serves as a potential marker for corneal epithelial progenitor cells

Importin13 (IPO13), the newest member of importin-beta family discovered recently, is a unique nucleus-cytoplasm bidirectional transport receptor protein. In this study, IPO13 expression in human corneal tissue, limbal epithelial primary explant and clonal culture was evaluated by immunostaining and reverse-transcription polymerase chain reasgon. IPO13 function was evaluated in the corneal epithelial culture treated with IPO13 inhibitor, or fetal bovine serum (FBS)-containing Dulbecco's modified Eagle's medium (DMEM) medium by colony-forming efficiency, clone growth capacity, MTT, immunostaining, and Western blotting assay. IPO13 protein was expressed mainly in nuclei of limbal epithelial basal cells, but not in the other cell layers of limbus and full thickness of corneal epithelia. IPO13 was expressed in the majority of epithelial cells in early-stage clones and in the margin of late-stage clones. IPO13 was positively expressed in mouse TKE2 progenitor cells cultured in keratinocyte serum-free defined medium, while it became negative in FBS-containing DMEM, which promoted TKE2 cell differentiation. In the presence of IPO13 inhibitor, IPO13 expression and the proliferative capacity decreased in human limbal epithelial clones and mouse TKE2 cells, which were accompanied with the cell differentiation. In conclusion, our findings demonstrate for the first time that IPO13 is uniquely expressed by human limbal basal epithelial cells, and plays an important role in maintaining the phenotype, high proliferative potential, and less differentiation of corneal epithelial progenitor cells, suggesting that IPO13 could serve as a novel potential marker for corneal epithelial progenitor cells.

Magnetic resonance imaging of mesenchymal stem cells homing to pulmonary metastases using biocompatible magnetic nanoparticles

The ability of mesenchymal stem cells (MSC) to specifically home to tumors has suggested their potential use as a delivery vehicle for cancer therapeutics. MSC integration into tumors has been shown in animal models using histopathologic techniques after animal sacrifice. Tracking the delivery and engraftment of MSCs into human tumors will need in vivo imaging techniques. We hypothesized that labeling MSCs with iron oxide nanoparticles would enable in vivo tracking with magnetic resonance imaging (MRI). Human MSCs were labeled in vitro with superparamagnetic iron oxide nanoparticles, with no effect on differentiation potential, proliferation, survival, or migration of the cells. In initial experiments, we showed that as few as 1,000 MSCs carrying iron oxide nanoparticles can be detected by MRI one month after their coinjection with breast cancer cells that formed subcutaneous tumors. Subsequently, we show that i.v.- injected iron-labeled MSCs could be tracked in vivo to multiple lung metastases using MRI, observations that were confirmed histologically. This is the first study to use MRI to track MSCs to lung metastases in vivo. This technique has the potential to show MSC integration into human tumors, allowing early-phase clinical studies examining MSC homing in patients with metastatic tumors.

WNT signaling in lung disease: a failure or a regeneration signal?

The WNT family of signaling proteins is essential to organ development in general and lung morphogenesis in particular. Originally identified as a developmentally active signaling pathway, the WNT pathway has recently been linked to the pathogenesis of important lung diseases, in particular lung cancer and pulmonary fibrosis. This review summarizes our current understanding about WNT signaling in lung development and disease, and is structured into three chapters. The first chapter presents an introduction to WNT signaling, outlining WNT proteins, their receptors and signaling intermediates, as well as the regulation of this complex pathway. The second chapter focuses on the role of WNT signaling in the normal embryonic and adult lung, and highlights recent findings of altered WNT signaling in lung diseases, such as lung cancer, pulmonary fibrosis, or pulmonary arterial hypertension. In the last chapter, we will discuss novel data and ideas about the biological effects of WNT signaling on the cellular level, highlighting pleiotropic effects induced by WNT ligands on distinct cell types, and how these cellular effects may be relevant to the pathogenesis of the aforementioned diseases.

Intravenous vitamin D therapy reduces PTH-(1-84)/large C fragments ratio in chronic hemodialysis patients

BACKGROUND

Renal osteodystrophy is one of the major complications in patients with chronic renal failure. Large C-PTH fragments are secreted from the parathyroid glands and exert antagonistic actions against PTH-(1-84). The PTH-(1-84)/large C-PTH fragments ratio reflects both biosynthesis and processing of PTH; however the alteration of the ratio under vitamin D therapy has not been investigated.

METHODS

Seventeen hemodialysis patients with intact PTH levels of >300 pg/ml were enrolled. Calcitriol or maxacalcitol were administered intravenously for 78 weeks. Intact PTH, PTH-(1-84), and the PTH-(1-84)/large C-PTH fragments ratio were measured at 0, 13, 26, 52 and 78 weeks.

RESULTS

Intact PTH and PTH-(1-84) levels, which were 492.0 +/- 115.7 and 303.4 +/- 105.4 pg/ml, respectively, at baseline, significantly decreased at the end of the study to 268.9 +/- 121.9 (p < 0.0001) and 190.7 +/- 106.9 pg/ml (p = 0.0008), respectively. In contrast, large C-PTH fragments, which were 152.7 +/- 53.5 pg/ml at baseline, did not significantly change at 78 weeks (144.5 +/- 72.2 pg/ml, p = 0.7612). Consequently, the PTH-(1-84)/large C-PTH fragments ratio was significantly reduced from 2.25 +/- 1.31 to 1.47 +/- 0.89 (p = 0.0004).

CONCLUSION

The PTH-(1-84)/large C-PTH fragments ratio reflects the change of PTH biosynthesis, processing and secretion from the parathyroid glands, and it may be a beneficial marker to evaluate the overall biological PTH action and predict bone turnover status in hemodialysis patients under intravenous vitamin D therapy.