Changyu Zheng

Using poly(lactic-co-glycolic acid) microspheres to encapsulate plasmid of bone morphogenetic protein 2/polyethylenimine nanoparticles to promote bone formation in vitro and in vivo

Repair of large bone defects is a major challenge, requiring sustained stimulation to continually promote bone formation locally. Bone morphogenetic protein 2 (BMP-2) plays an important role in bone development. In an attempt to overcome this difficulty of bone repair, we created a delivery system to slowly release human BMP-2 cDNA plasmid locally, efficiently transfecting local target cells and secreting functional human BMP-2 protein. For transfection, we used polyethylenimine (PEI) to create pBMP-2/PEI nanoparticles, and to ensure slow release we used poly(lactic-co-glycolic acid) (PLGA) to create microsphere encapsulated pBMP-2/PEI nanoparticles, PLGA@pBMP-2/PEI. We demonstrated that pBMP-2/PEI nanoparticles could slowly release from the PLGA@pBMP-2/PEI microspheres for a long period of time. The 3–15 μm diameter of the PLGA@pBMP-2/PEI further supported this slow release ability of the PLGA@pBMP-2/PEI. In vitro transfection assays demonstrated that pBMP-2/PEI released from PLGA@pBMP-2/PEI could efficiently transfect MC3T3-E1 cells, causing MC3T3-E1 cells to secrete human BMP-2 protein, increase calcium deposition and gene expressions of alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX2), SP7 and I type collagen (COLL I), and finally induce MC3T3-E1 cell differentiation. Importantly, in vivo data from micro-computed tomography (micro-CT) and histological staining demonstrated that the human BMP-2 released from PLGA@pBMP-2/PEI had a long-term effect locally and efficiently promoted bone formation in the bone defect area compared to control animals. All our data suggest that our PLGA-nanoparticle delivery system efficiently and functionally delivers the human BMP-2 cDNA and has potential clinical application in the future after further modification.

Erythropoietin Promotes Bone Formation through EphrinB2/EphB4 Signaling

Recent studies have demonstrated that erythropoietin (EPO) has extensive nonhematopoietic biological functions. However, little is known about how EPO regulates bone formation, although several studies suggested that EPO can affect bone homeostasis. In this study, we investigated the effects of EPO on the communication between osteoclasts and osteoblasts through the ephrinB2/EphB4 signaling pathway. We found that EPO slightly promotes osteoblastic differentiation with the increased expression of EphB4 in ST2 cells. However, EPO increased the expression of Nfatc1 and ephrinB2 but decreased the expression of Mmp9 in RAW264.7 cells, resulting in an increase of ephrinB2-expressing osteoclasts and a decrease in resorption activity. The stimulation of ephrinB2/EphB4 signaling via ephrinB2-Fc significantly promoted EPO-mediated osteoblastic differentiation in ST2 cells. EphB4 knockdown through EphB4 shRNA inhibited EPO-mediated osteoblastic phenotypes. Furthermore, in vivo assays clearly demonstrated that EPO efficiently induces new bone formation in the alveolar bone regeneration model. Taken together, these results suggest that ephrinB2/EphB4 signaling may play an important role in EPO-mediated bone formation.

Antitumor effect of human TRAIL on adenoid cystic carcinoma using magnetic nanoparticle–mediated gene expression

UNLABELLEDnTo overcome treatment limitations of adenoid cystic carcinoma, we developed a novel treatment combining gene therapy and nanotechnology. In this study, we created a plasmid, pACTERT-TRAIL, which used the human telomerase reverse transcriptase promoter, a tumor-specific promoter, to drive tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). A Fe(3)O(4)-PEI-plasmid complex (FPP) was generated, in which the iron oxide nanoparticles were modified by positively charged polyethylenimine (PEI) to enable them to carry the negatively charged plasmid. In vitro transfection assays showed that efficiency of magnetofection (i.e., FPP transfection) was sixfold higher compared to PEI alone or Lipofectamine 2000 (hereafter referred to as lipofectin) (P < 0.05). Importantly, apoptotic assays demonstrated that FPP-mediated TRAIL gene transfer could efficiently induce apoptosis of SACC-83 cells in vitro and in vivo. These results demonstrate that magnetofection of the plasmids driven by the tumor-specific promoter hTERT provides an effective way to deliver therapeutic genes for the treatment of adenoid cystic carcinoma in the future.nnnFROM THE CLINICAL EDITORnIn this novel study addressing adenoid cystic carcinoma, the authors created a plasmid to drive tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Following that, a Fe(3)O(4)-PEI-plasmid complex (FPP) was generated, in which the iron oxide nanoparticles were modified by positively charged polyethylenimine (PEI) enabling them to carry the negatively charged plasmid, giving rise to sixfold higher transfection rates compared to standard technology.

Adenoviral mediated transduction of adenoid cystic carcinoma by human TRAIL gene driven with hTERT tumor specific promoter induces apoptosis.

Adenoid cystic carcinoma (ACC) is a common malignant tumor in salivary glands. Unfortunately, current treatment modalities which include surgery, radiation and chemotherapy have limited success rates. To develop new treatment strategies we hypothesized that a cancer-specific apoptotic ligand driven by a tumor specific promoter would specifically induce apoptosis in ACC. To test this concept, we selected tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and the human telomerase reverse transcriptase (hTERT) promoter. The latter is highly active in 85% of human cancer cells while it is mostly inactive in somatic cells. Using immunohistochemistry we confirmed that ACC samples but not normal salivary cells were positive for hTERT. Similar results were also seen in an ACC cell line, SACC-83. We then constructed first generation Ad5 vectors which used the hTERT promoter to drive TRAIL (AdTERT- TRAIL). Transduction of SACC-83, but not of control human embryo-fibrocyte lung (HEL) cells, led to apoptosis as measured by MTT assay and flow cytomerty. We used the SACC-83 cells for a subcutaneous tumor model in vivo. Intratumoral injections of AdTERT-TRAIL (5x109 particles/ tumor) but not of AdTERT-EGFP or PBS resulted in significant (p

Efficiently engineered cell sheet using a complex of polyethylenimine–alginate nanocomposites plus bone morphogenetic protein 2 gene to promote new bone formation

Regeneration of large bone defects is a common clinical problem. Recently, stem cell sheet has been an emerging strategy in bone tissue engineering. To enhance the osteogenic potential of stem cell sheet, we fabricated bone morphogenetic protein 2 (BMP-2) gene-engineered cell sheet using a complex of polyethylenimine–alginate (PEI–al) nanocomposites plus human BMP-2 complementary(c)DNA plasmid, and studied its osteogenesis in vitro and in vivo. PEI–al nanocomposites carrying BMP-2 gene could efficiently transfect bone marrow mesenchymal stem cells. The cell sheet was made by culturing the cells in medium containing vitamin C for 10 days. Assays on the cell culture showed that the genetically engineered cells released the BMP-2 for at least 14 days. The expression of osteogenesis-related gene was increased, which demonstrated that released BMP-2 could effectively induce the cell sheet osteogenic differentiation in vitro. To further test the osteogenic potential of the cell sheet in vivo, enhanced green fluorescent protein or BMP-2-producing cell sheets were treated on the cranial bone defects. The results indicated that the BMP-2-producing cell sheet group was more efficient than other groups in promoting bone formation in the defect area. Our results suggested that PEI–al nanocomposites efficiently deliver the BMP-2 gene to bone marrow mesenchymal stem cells and that BMP-2 gene-engineered cell sheet is an effective way for promoting bone regeneration.

Effective delivery of bone morphogenetic protein 2 gene using chitosan–polyethylenimine nanoparticle to promote bone formation

Treating bone defects is still a challenge in clinical practice. Recently, researchers used human bone morphogenetic protein 2 gene (hBMP-2) to induce osteoblast differentiation and promote new bone formation. However, an efficient way to deliver hBMP-2 still needs to be created. In this study, we evaluated whether chitosan–polyethylenimine (CS–PEI) nanoparticle could effectively deliver hBMP-2 locally with lower or no toxicity and promote osteoblast differentiation and new bone formation in vitro and in vivo. Data demonstrated that the synthesized CS–PEI/hBMP-2 nanoparticle at a W/W ratio of 20 to 1, which was the smallest size (162 nm) and highest zeta potential (24 mV), effectively transfected MC3T3-E1 cells without cytotoxicity in vitro, and had the ability to promote cell proliferation. Interestingly, the CS–PEI/hBMP-2 nanoparticle eliminated disadvantages of lower transfection efficiency from chitosan and cytotoxicity from PEI. RT-QPCR data showed that MC3T3-E1 cells treated with CS–PEI/hBMP-2 nanoparticle dramatically expressed higher levels of BMP-2 and significantly increased gene expressions of Col1 on days 3 and 14, Sp7 on days 3, 7, and 14, and ALP on day 14. Alizarin red staining demonstrated that CS–PEI/hBMP-2 nanoparticle-treated MC3T3-E1 cells significantly increased cell mineralization. These in vitro data suggest that the CS–PEI/hBMP-2 nanoparticle can effectively induce osteogenic differentiation of MC3T3-E1 cells in vitro. Western blot analysis further demonstrated that transgene BMP-2 indeed phosphorylated Smad1/5/8, which indicates that CS–PEI/hBMP-2 nanoparticle affects cell differentiation through a BMP-2 signal pathway. Importantly, in vivo data showed that CS–PEI/hBMP-2 nanoparticle clearly promoted new bone formation at the bone defect area 12 weeks post-implantation. This indicates that synthesized CS–PEI/hBMP-2 nanoparticle has the potential to become a useful therapeutic vector for bone defect treatment with further modification.

Antitumor Effect of TRAIL on Oral Squamous Cell Carcinoma using Magnetic Nanoparticle-Mediated Gene Expression

AbstractnWe developed a new magnetic nanovector to improve the efficiency and targeting of transgene therapy for oral squamous cell carcinoma (OSCC). Positively charged polymer PEI-modified Fe3O4 magnetic nanoparticles were tested as gene transfer vectors in the presence of a magnetic field. The Fe3O4 nanoparticles were prepared by a co-precipitation method and had good dispersibility in water. These nanoparticles modified by PEI were combined with negatively charged pACTERT-EGFP via electrostatic interaction. The transfection efficiency of the magnetic nano-gene vector with the magnetic field was determined by a fluorescence-inverted microscope and flow cytometry. The results showed significant improvement compared with the control group (pxa0<xa00.05). The magnetic complexes also exhibited up to 6-times higher transfection efficiency compared with commonly used PEI or lipofectin. On the basis of these results, the antitumor effect with suicide gene therapy using pACTERT-TRAIL in vitro and vivo was evaluated. In vitro apoptosis was determined with the Annexin V-FITC Apoptosis Detection Kit. The results suggested that PEI-modified Fe3O4 nanoparticles could mediate the killing of Tca83 cells. Furthermore, treatment with pACTERT-TRAIL delivered by magnetic nanoparticles showed a significant cytostatic effect through the induction of apoptosis in a xenograft model. This indicates that magnetic nano-gene vectors could improve the transgene efficiency for Tca83 cells and could exhibit antitumor functions with the plasmid pACTERT-TRAIL. This may be a new way to treat OSCC.

Effects of human vascular endothelial growth factor on reparative dentin formation

It is a challenge for dentists to save dental pulp in patients with pulp disease without resorting to root canal therapy. Formation of tertiary dentin to maintain pulp vitality is a key odontoblast response to dental pulp injury. Vascular endothelial growth factor (VEGF) is the most potent angiogenic and vasculogenic factor involved in tertiary dentin formation. It was hypothesized that VEGF may be used to treat pulp diseases such as pulpitis. To explore this hypothesis, the first step was to assess whether VEGF affects dental pulp cells to promote reparative dentin formation. In the current study, an AdCMV-hVEGF vector was constructed to deliver hVEGF into dental pulp cells of exfoliated deciduous teeth (hDPCs) in vitro and dental pulp cells in a rat model in vivo. The collected data clearly demonstrated that hVEGF increased alkaline phosphatase and mineralization by enzymatic activity. RT-qPCR data demonstrated that hVEGF significantly increased the expression levels of genes commonly involved in osteogenesis/odontogenesis. Data from the in vivo assays indicated that hVEGF enhanced pulp cell proliferation and neovascularization, and markedly increased formation of reparative dentin in dental pulp. The in vitro and in vivo data suggest that hVEGF may have potential clinical applications, thus may aid in the development of novel treatment strategies for dental pulpitis.

Characteristics of three sizes of silica nanoparticles in the osteoblastic cell line, MC3T3-E1

Reconstruction of bone defects is still challenging for the clinician, owing to the little achievement in the effect of bone materials on osteoblastic cells. In this work, the size effect of silica nanoparticles (SNs) on cellular uptake, cytotoxicity, and cell function in the osteoblast cell line, MC3T3-E1, is studied to reveal the potentials of SNs for bone regeneration. The SNs with three different sizes are prepared using the Stober approach and labeled with FITC. Confocal laser scanning microscopy, fluorescence-activated cell sorting and fluorescence spectrophotometry are used to evaluate the effects. All three different sized FITC-labeled silica nanoparticles have similar cellular uptake (>90%), determined by fluorescence-activated cell sorting (FACS) analysis, which suggest that all three silica nanoparticles generally have good cellular affinity. Fluorescence spectrophotometry results, however, indicate that cellular uptake is increased with a decrease in the size of the SN. Interestingly, the smaller silica nanoparticles could induce more MC3T3-E1 cell apoptosis than that of larger silica nanoparticles, and it is dose-dependent. MTT assays demonstrated that all three SNs are capable to decrease cell proliferation at a higher concentration (100 μg ml−1). These results indicate that the SNs are cytotoxic, which is size and concentration-dependent. Importantly, all three SNs can directly stimulate mineralized nodule formation, which is also size-dependent. These results suggest that SNs are potentially applicable in bone regeneration, and it is possible to decrease unwanted side effects by controlling dose and size of SNs.

Rapamycin promotes osteogenesis under inflammatory conditions

Chronic periodontitis, a common oral disease, usually results in irreversible bone resorption. Bone regeneration is a complex process between bone-forming activity of osteoblasts and bone-resorbing activity of osteoclasts, and still remains a challenge for physicians clinically. A previous study demonstrated that the mechanistic target of rapamycin signaling pathway is involved in osteogenic differentiation of mesenchymal stromal cells. Herein, whether rapamycin could be used to induce osteogenic differentiation of primary bone marrow-derived mesenchymal stem cells (BMSCs) in vitro and promote new bone formation in vivo were evaluated. The results demonstrated that rapamycin alone was not enough to fully induce osteoblast differentiation in vitro and enhanced bone regeneration in vivo. Interestingly, rapamycin in rapamycin plus lipopolysaccharide (LPS)-treated BMSCs significantly increased the gene expression levels of Sp7 transcription factor, runt related transcription factor 2, alkaline phosphatase (ALP) and collagen I (Col I), ALP activity, and calcium nodule at different time points in vitro, indicating that osteoblast differentiation occurs by rapamycin when BMSCs are exposed to LPS simultaneously. It was also demonstrated that rapamycin in rapamycin plus LPS-treated rats promoted bone regeneration in vivo. These results suggest that rapamycin may influence osteoblast differentiation and new bone formation after LPS induces an inflammatory environment. Rapamycin may be used to treat periodontitis associated with bone loss in future clinical practice.