Substance P signaling mediates BMP-dependent heterotopic ossification

Heterotopic ossification (HO) is a disabling condition associated with neurologic injury, inflammation, and overactive bone morphogenetic protein (BMP) signaling. The inductive factors involved in lesion formation are unknown. We found that the expression of the neuro-inflammatory factor Substance P (SP) is dramatically increased in early lesional tissue in patients who have either fibrodysplasia ossificans progressiva (FOP) or acquired HO, and in three independent mouse models of HO. In Nse-BMP4, a mouse model of HO, robust HO forms in response to tissue injury; however, null mutations of the preprotachykinin (PPT) gene encoding SP prevent HO. Importantly, ablation of SP(+) sensory neurons, treatment with an antagonist of SP receptor NK1r, deletion of NK1r gene, or genetic down-regulation of NK1r-expressing mast cells also profoundly inhibit injury-induced HO. These observations establish a potent neuro-inflammatory induction and amplification circuit for BMP-dependent HO lesion formation, and identify novel molecular targets for prevention of HO.     

Recombinant BMP 4/7 fusion protein induces differentiation of bone marrow stem cells

Bone morphogenetic proteins (BMPs) induce differentiation of mesenchymal cells to cartilage and bone. We cloned BMP4 and BMP7 cDNAs from human placenta and fetal cartilage cells, respectively, and used an Escherichia coli expression system to produce recombinant BMP4 and BMP4/7 proteins. Differentiation of primary cultures of bone marrow stem cells (BMSC) treated with BMP4 or BMP4/7 was evaluated by Von Kossa staining and by determining alkaline phosphatase activity and osteocalcin level. BMP4/7-induced BMSC differentiation more potently than BMP4. We showed that BMP4/7 fusion protein expressed in E. coli is biologically active and is a novel strategy to treat bone injury in a clinical setting.     

BMP2 induces osteoblast apoptosis in a maturation state and noggin-dependent manner

Large doses of bone morphogenetic protein 2 (BMP2) are used clinically to induce bone formation in challenging bone defects. However, complications after treatment include swelling, ectopic bone formation, and adjacent bone resorption. While BMP2 can be effective, it is important to characterize the mechanism of the deleterious effects to optimize its use. The aim of this study was to determine the effect of BMP2 on apoptosis in osteoblast lineage cells and to determine the role of the BMP inhibitor Noggin in this process. Human mesenchymal stem cells (MSCs), immature osteoblast‐like MG63 cells, and mature normal human osteoblasts (NHOst) were treated with BMP2. A model system of increased endogenous BMP signaling was created by silencing Noggin (shNOG‐MG63). Finally, the BMP pathway regulating apoptosis in NHOst was examined using BMP signaling inhibitors (5Z‐7‐oxozeaenol, dorsomorphin, H‐8). Apoptosis was characterized by caspase‐3, BAX/BCL2, p53, and DNA fragmentation. BMP2 induced apoptosis in a cell‐type dependent manner. While the effect was minor in MSCs, MG63 cells had modest increases and NHOst cells had robust increases apoptosis after BMP2 treatment. Apoptosis was significantly higher in shNOG‐MG63 than MG63 cells. 5Z‐7‐oxozeaenol and dorsomorphin eliminated the BMP2‐induced increase in DNA fragmentation in NHOst, suggesting roles for TAB/TAK1 and Smad signaling. These results indicate that the apoptotic effect of BMP2 is dependent on cell maturation state, inducing apoptosis in committed osteoblasts through Smad and TAB/TAK1 signaling, and is regulated by Noggin. Dose and delivery must be optimized in therapeutic applications of BMP2 to minimize complications. J. Cell. Biochem. 113: 3236–3245, 2012. © 2012 Wiley Periodicals, Inc.     

Effect of mesenchymal stem cells on inhibiting airway remodeling and airway inflammation in chronic asthma

Previous studies proved that bone marrow‐derived mesenchymal stem cells (BMSCs) could improve a variety of immune‐mediated disease by its immunomodulatory properties. In this study, we investigated the effect on airway remodeling and airway inflammation by administrating BMSCs in chronic asthmatic mice. Forty‐eight female BALB/c mice were randomly distributed into PBS group, BMSCs treatment group, BMSCs control group, and asthmatic group. The levels of cytokine and immunoglobulin in serum and bronchoalveolar lavage fluid were detected by enzyme‐linked immunosorbent assay. The number of CD4⁺CD25⁺regulatory T cells and morphometric analysis was determined by flow cytometry, hematoxylin‐eosin, immunofluorescence staining, periodic‐acid Schiff, and masson staining, respectively. We found that airway remodeling and airway inflammation were evident in asthmatic mice. Moreover, low level of IL‐12 and high levels of IL‐13, IL‐4, OVA‐specific IgG1, IgE, and IgG2a and the fewer number of CD4⁺CD25⁺regulatory T cells were present in asthmatic group. However, transplantation of BMSCs significantly decreased airway inflammation and airway remodeling and level of IL‐4, OVA‐specific IgE, and OVA‐specific IgG1, but elevated level of IL‐12 and the number of CD4 + CD25 + regulatory T cells in asthma (P < 0.05). However, BMSCs did not contribute to lung regeneration and had no significant effect on levels of IL‐10, IFN‐Y, and IL‐13. In our study, BMSCs engraftment prohibited airway inflammation and airway remodeling in chronic asthmatic group. The beneficial effect of BMSCs might involved the modulation imbalance cytokine toward a new balance Th1–Th2 profiles and up‐regulation of protective CD4 + CD25 + regulatory T cells in asthma, but not contribution to lung regeneration. J. Cell. Biochem. 114: 1595–1605, 2013. © 2013 Wiley Periodicals, Inc.