Cunye Qu

Mesenchymal-stem-cell-induced immunoregulation involves FAS-ligand-/FAS-mediated T cell apoptosis

Systemic infusion of bone marrow mesenchymal stem cells (BMMSCs) yields therapeutic benefit for a variety of autoimmune diseases, but the underlying mechanisms are poorly understood. Here we show that in mice systemic infusion of BMMSCs induced transient T cell apoptosis via the FAS ligand (FASL)-dependent FAS pathway and could ameliorate disease phenotypes in fibrillin-1 mutated systemic sclerosis (SS) and dextran-sulfate-sodium-induced experimental colitis. FASL(-/-) BMMSCs did not induce T cell apoptosis in recipients, and could not ameliorate SS and colitis. Mechanistic analysis revealed that FAS-regulated monocyte chemotactic protein 1 (MCP-1) secretion by BMMSCs recruited T cells for FASL-mediated apoptosis. The apoptotic T cells subsequently triggered macrophages to produce high levels of TGFβ, which in turn led to the upregulation of CD4(+)CD25(+)Foxp3(+) regulatory T cells and, ultimately, immune tolerance. These data therefore demonstrate a previously unrecognized mechanism underlying BMMSC-based immunotherapy involving coupling via FAS/FASL to induce T cell apoptosis.

iPS cells reprogrammed from human mesenchymal-like Stem/Progenitor cells of dental Tissue Origin

Generation of induced pluripotent stem (iPS) cells holds a great promise for regenerative medicine and other aspects of clinical applications. Many types of cells have been successfully reprogrammed into iPS cells in the mouse system; however, reprogramming human cells have been more difficult. To date, human dermal fibroblasts are the most accessible and feasible cell source for iPS generation. Dental tissues derived from ectomesenchyme harbor mesenchymal-like stem/progenitor cells and some of the tissues have been treated as biomedical wastes, for example, exfoliated primary teeth and extracted third molars. We asked whether stem/progenitor cells from discarded dental tissues can be reprogrammed into iPS cells. The 4 factors Lin28/Nanog/Oct4/Sox2 or c-Myc/Klf4/Oct4/Sox2 carried by viral vectors were used to reprogram 3 different dental stem/progenitor cells: stem cells from exfoliated deciduous teeth (SHED), stem cells from apical papilla (SCAP), and dental pulp stem cells (DPSCs). We showed that all 3 can be reprogrammed into iPS cells and appeared to be at a higher rate than fibroblasts. They exhibited a morphology indistinguishable from human embryonic stem (hES) cells in cultures and expressed hES cell markers SSEA-4, TRA-1-60, TRA-1-80, TRA-2-49, Nanog, Oct4, and Sox2. They formed embryoid bodies in vitro and teratomas in vivo containing tissues of all 3 germ layers. We conclude that cells of ectomesenchymal origin serve as an excellent alternative source for generating iPS cells.

Vitamin C Treatment Promotes Mesenchymal Stem Cell Sheet Formation and Tissue Regeneration by Elevating Telomerase Activity

Cell sheet engineering has been developed as an alternative approach to improve mesenchymal stem cell‐mediated tissue regeneration. In this study, we found that vitamin C (Vc) was capable of inducing telomerase activity in periodontal ligament stem cells (PDLSCs), leading to the up‐regulated expression of extracellular matrix type I collagen, fibronectin, and integrin β1, stem cell markers Oct4, Sox2, and Nanog as well as osteogenic markers RUNX2, ALP, OCN. Under Vc treatment, PDLSCs can form cell sheet structures because of increased cell matrix production. Interestingly, PDLSC sheets demonstrated a significant improvement in tissue regeneration compared with untreated control dissociated PDLSCs and offered an effective treatment for periodontal defects in a swine model. In addition, bone marrow mesenchymal stem cell sheets and umbilical cord mesenchymal stem cell sheets were also well constructed using this method. The development of Vc‐mediated mesenchymal stem cell sheets may provide an easy and practical approach for cell‐based tissue regeneration. J. Cell. Physiol. 227: 3216–3224, 2012.

Hydrogen Sulfide Promotes Tet1- and Tet2-Mediated Foxp3 Demethylation to Drive Regulatory T Cell Differentiation and Maintain Immune Homeostasis

Regulatory T (Treg) cells are essential for maintenance of immune homeostasis. Here we found that hydrogen sulfide (H2S) was required for Foxp3(+) Treg cell differentiation and function and that H2S deficiency led to systemic autoimmune disease. H2S maintained expression of methylcytosine dioxygenases Tet1 and Tet2 by sulfhydrating nuclear transcription factor Y subunit beta (NFYB) to facilitate its binding to Tet1 and Tet2 promoters. Transforming growth factor-β (TGF-β)-activated Smad3 and interleukin-2 (IL-2)-activated Stat5 facilitated Tet1 and Tet2 binding to Foxp3. Tet1 and Tet2 catalyzed conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) in Foxp3 to establish a Treg-cell-specific hypomethylation pattern and stable Foxp3 expression. Consequently, Tet1 and Tet2 deletion led to Foxp3 hypermethylation, impaired Treg cell differentiation and function, and autoimmune disease. Thus, H2S promotes Tet1 and Tet2 expression, which are recruited to Foxp3 by TGF-β and IL-2 signaling to maintain Foxp3 demethylation and Treg-cell-associated immune homeostasis.

IFN‐γ and TNF‐α Synergistically Induce Mesenchymal Stem Cell Impairment and Tumorigenesis via NFκB Signaling

An inflammatory microenvironment may cause organ degenerative diseases and malignant tumors. However, the precise mechanisms of inflammation‐induced diseases are not fully understood. Here, we show that the proinflammatory cytokines interferon‐γ (IFN‐γ) and tumor necrosis factor α (TNF‐α) synergistically impair self‐renewal and differentiation of mesenchymal stem cells (MSCs) via nuclear factor κB (NFκB)‐mediated activation of mothers against decapentaplegic homolog 7 (SMAD7) in ovariectomized (OVX) mice. More interestingly, a long‐term elevated levels of IFN‐γ and TNF‐α result in significantly increased susceptibility to malignant transformation in MSCs through NFκB‐mediated upregulation of the oncogenes c‐Fos and c‐Myc. Depletion of either IFN‐γ or TNF‐α in OVX mice abolishes MSC impairment and the tendency toward malignant transformation with no NFκB‐mediated oncogene activation. Systemic administration of aspirin, which significantly reduces the levels of IFN‐γ and TNF‐α, results in blockage of MSC deficiency and tumorigenesis by inhibition of NFκB/SMAD7 and NFκB/c‐FOS and c‐MYC pathways in OVX mice. In summary, this study reveals that inflammation factors, such as IFN‐γ and TNF‐α, synergistically induce MSC deficiency via NFκB/SMAD7 signaling and tumorigenesis via NFκB‐mediated oncogene activation. STEM Cells2013;31:1383–1395

A subset of IL-17+ mesenchymal stem cells possesses anti-Candida albicans effect

Bone marrow mesenchymal stem cells (MSCs) comprise a heterogeneous population of postnatal progenitor cells with profound immunomodulatory properties, such as upregulation of Foxp3+ regulatory T cells (Tregs) and downregulation of Th17 cells. However, it is unknown whether different MSC subpopulations possess the same range of immunomodulatory function. Here, we show that a subset of single colony-derived MSCs producing IL-17 is different from bulk MSC population in that it cannot upregulate Tregs, downregulate Th17 cells, or ameliorate disease phenotypes in a colitis mouse model. Mechanistically, we reveal that IL-17, produced by these MSCs, activates the NFκB pathway to downregulate TGF-β production in MSCs, resulting in abolishment of MSC-based immunomodulation. Furthermore, we show that NFκB is able to directly bind to TGF-β promoter region to regulate TGF-β expression in MSCs. Moreover, these IL-17+ MSCs possess anti-Candida albicans growth effects in vitro and therapeutic effect in C. albicans-infected mice. In summary, this study shows that MSCs contain an IL-17+ subset capable of inhibiting C. albicans growth, but attenuating MSC-based immunosuppression via NFκB-mediated downregulation of TGF-β.

Basic fibroblast growth factor inhibits osteogenic differentiation of stem cells from human exfoliated deciduous teeth through ERK signaling

Objective Stem cells from human exfoliated deciduous teeth (SHED) are a unique postnatal stem cell population capable of regenerating mineralized tissue and treating immune disorders. However, the mechanism that controls SHED differentiation is not fully understood. Here, we showed that basic fibroblast growth factor (bFGF) treatment attenuated SHED-mediated mineralized tissue regeneration through activation of the extracellular signal-regulated kinase (ERK) 1/2 pathway.OBJECTIVE Stem cells from human exfoliated deciduous teeth (SHED) are a unique postnatal stem cell population capable of regenerating mineralized tissue and treating immune disorders. However, the mechanism that controls SHED differentiation is not fully understood. Here, we showed that basic fibroblast growth factor (bFGF) treatment attenuated SHED-mediated mineralized tissue regeneration through activation of the extracellular signal-regulated kinase (ERK) 1/2 pathway. MATERIAL AND METHOD The level of mineralized nodule formation was assessed by alizarin red staining. Expression levels of osteogenic genes, osteocalcin and runt-related transcription factor 2, were examined by RT-PCR. Subcutaneous implantation approach was used to assess in vivo bone formation. Downstream signaling pathways of bFGF were examined by Western blotting. RESULT Activation of ERK1/2 signaling by bFGF treatment inhibited WNT/β-catenin pathway, leading to osteogenic deficiency of SHED. ERK1/2 inhibitor treatment rescued bFGF-induced osteogenic differentiation deficiency. CONCLUSION These data suggest that bFGF inhibits osteogenic differentiation of SHED via ERK1/2 pathway. Blockade ERK1/2 signaling by small molecular inhibitor treatment improves bone formation of SHED after bFGF treatment.

Ossifying fibroma tumor stem cells are maintained by epigenetic regulation of a TSP1/TGF-β/SMAD3 autocrine loop.

Abnormal stem cell function makes a known contribution to many malignant tumors, but the role of stem cells in benign tumors is not well understood. Here, we show that ossifying fibroma (OF) contains a stem cell population that resembles mesenchymal stem cells (OFMSCs) and is capable of generating OF-like tumor xenografts. Mechanistically, OFMSCs show enhanced TGF-β signaling that induces aberrant proliferation and deficient osteogenesis via Notch and BMP signaling pathways, respectively. The elevated TGF-β activity is tightly regulated by JHDM1D-mediated epigenetic regulation of thrombospondin-1 (TSP1), forming a JHDM1D/TSP1/TGF-β/SMAD3 autocrine loop. Inhibition of TGF-β signaling in OFMSCs can rescue their abnormal osteogenic differentiation and elevated proliferation rate. Furthermore, chronic activation of TGF-β can convert normal MSCs into OF-like MSCs via establishment of this JHDM1D/TSP1/TGF-β/SMAD3 autocrine loop. These results reveal that epigenetic regulation of TGF-β signaling in MSCs governs the benign tumor phenotype in OF and highlight TGF-β signaling as a candidate therapeutic target.

Trends in therapeutic monoclonal antibodies of cancer.

Therapeutic monoclonal antibodies are increasingly applied in clinical application with great success. A variety of antibody products have been approved by the FDA since 1997. Furthermore, the industries have been paying more attention to and efforts in the field of antibody development than ever, suggesting the grand potential of the market and benefits. At present, many monoclonal antibodies have proven their therapeutic value in combination with established treatment for many diseases, as shown in FDA approved expanded indications. This old-fashioned immunotherapy exerts profound effects in many refractory and formidable diseases, especially cancers. With further understanding of the interaction between immune system and cancer, more target molecules were discovered and more promising therapeutic antibodies with improved effects will be feasible in the future. Regardless of initial development or ultimate approved drug, therapeutic monoclonal antibodies have always been associated with numerous patent applications. This review mainly focuses on potential therapeutic monoclonal antibodies in oncology and related antibody patents, and discusses the trend for antibody development and therapeutic applications in humans.

Genetic mutations associated with metastatic clear cell renal cell carcinoma

Metastasis is the major cause of death among cancer patients, yet early detection and intervention of metastasis could significantly improve their clinical outcomes. We have sequenced and analyzed RNA (Expression) and DNA (Mutations) from the primary tumor (PT), tumor extension (TE) and lymphatic metastatic (LM) sites of patients with clear cell renal cell carcinoma (CCRCC) before treatment. Here, we report a three-nucleotide deletion near the C-region of Plk5 that is specifically associated with the lymphatic metastasis. This mutation is un-detectable in the PT, becomes detectable in the TE and dominates the LM tissue. So while only a few primary cancer cells carry this mutation, the majority of metastatic cells have this mutation. The increasing frequency of this mutation in metastatic tissue suggests that this Plk5 deletion could be used as an early indicator of CCRCC metastasis, and be identified by low cost PCR assay. A large scale clinical trial could reveal whether a simple PCR assay for this mutation at the time of nephrectomy could identify and stratify high-risk CCRCC patients for treatments.