Fanxuan Kong

Radiation therapy can cause haematopoietic damage, and mesenchymal stem cells (MSCs) derived extracellular vesicles (EVs) have been shown to reverse this damage. Our previous research showed that dental pulp stem cells (DPSCs) have a strong proliferation capacity and can produce abundant amounts of EVs to meet the requirements for use in vitro and in vivo. DPSCs derived EVs (DPSCs-EVs) are evaluated for their effect on reducing haematopoietic damage. Haematopoietic stem cell (HSC) numbers and function were assessed by flow cytometry, peripheral blood cell counts, histology and bone marrow transplantation. Epidermal growth factor (EGF) was used as a reference for evaluating the efficiency of EVs. miRNA microarray was employed to find out the changes of miRNA expression after cells being irradiated in vivo and the role they may play in mitigation the radiation caused injury. We observed the effect of DPSCs-EVs on promoting proliferation and inhibiting apoptosis of human umbilical vein endothelial cells (HUVECs) and FDC-P1 cells in vitro. We found that DPSCs-EVs and EGF could comparably inhibit the decrease in WBC, CFU count and KSL cells in vivo. We also verified that EVs could accelerate the recovery of long-term HSCs. In summary, DPSCs-EVs showed an apoptosis resistant effect on HUVECs and FDC-P1 cells after radiation injury in vitro. EVs from DPSCs were comparable to EGF in their ability to regulate haematopoietic regeneration after radiation injury in vivo. Radiation could alter the expression of some miRNAs in bone marrow cells, and EVs could correct these changes to some extent.

The majority of advanced breast cancer patients develop distal metastasis, including lung and bone metastasis. However, effective therapeutic strategies to prevent metastasis are still lacking. Decorin is a natural inhibitor of transforming growth factor β, which plays a pivotal role in tumor metastasis. An oncolytic adenovirus expressing decorin, rAd.DCN, has been developed previously. In an immune-competent breast tumor (4T1) model, intratumoral (i.t.) as well as intravenous (i.v.) delivery of rAd.DCN inhibited growth of orthotopic tumors and spontaneous lung metastasis. It was shown that i.t. delivery of rAd.DCN produced higher levels of transgene expression and evoked stronger oncolysis of the tumors compared to i.v. delivery. However, i.v. delivery resulted in higher amount of virus accumulation in the lungs and produced stronger responses to prevent tumor lung metastasis. Oncolytic adenovirus-mediated decorin expression in the tumors downregulated the decorin target genes and decreased epithelial mesenchymal transition markers. Decorin expression in lung tissues also increased Th1 cytokine expression, such as interleukin (IL)-2, IL-12, and tumor necrosis factor α, and decreased Th2 cytokines, such as transforming growth factor β and IL-6. Moreover, rAd.DCN treatment induced strong systemic inflammatory responses and upregulated CD8 ⁺ T lymphocytes. In conclusion, rAd.DCN inhibits tumor growth and lung metastasis of breast cancer via regulating wnt/β-catenin, vascular endothelial growth factor (VEGF), and Met pathways, and modulating the antitumor inflammatory and immune responses. Considering that i.v. delivery was much more effective in preventing lung metastasis, systemic delivery of rAd.DCN might be a promising strategy to treat breast cancer lung metastasis.

Stem cells and gene therapy have become promising strategies for treating ischemia diseases and regenerating tissue. Hepatocyte growth factor (HGF) is an angiogenic growth factor with multiple functions including promoting angiogenesis, regulating inflammation, inhibiting fibrosis and activating tissue regeneration. Numerous preclinical experiments and clinical trials have demonstrated the feasibility and efficacy of HGF gene therapy in treatment of ischemia diseases and tissue regeneration. This review summarized the current advances of therapeutic angiogenesis using HGF gene transfer and modified stem cells. The physiological roles of HGF in angiogenesis and tissue regeneration were revisited. The current advances of clinical trials of plasmid and adenovirus HGF in treatment of critical limb ischemia (CLI) and coronary heart disease (CHD) in China were introduced. Furthermore, valuable insight was provided into prospective future of novel regenerative strategies using HGF modified mesenchymal stem cells. HGF gene therapy is presented as a promising therapeutic approach in regenerative medicine.

Investigations based on mesenchymal stem cells (MSCs) for osteoporosis have attracted attention recently. MSCs can be derived from various tissues, such as bone marrow, adipose, umbilical cord, placenta, and dental pulp. Among these, dental pulp–derived MSCs (DPSCs) and hepatocyte growth factor (HGF)-modified DPSCs (DPSCs-HGF) highly express osteogenic-related genes and have stronger osteogenic differentiation capacities. DPSCs have more benefits in treating osteoporosis. The purpose of this study was to investigate the roles of HGF gene-modified DPSCs in bone regeneration using a mouse model of ovariectomy (OVX)-induced bone loss. The HGF and luciferase genes were transferred into human DPSCs using recombinant adenovirus. These transduced cells were assayed for distribution or bone regeneration assay by transplantation into an OVX-induced osteoporosis model. By using bioluminogenic imaging, it was determined that some DPSCs could survive for >1 month in vivo. The DPSCs were mainly distributed to the lung in the early stage and to the liver in the late stage of OVX osteoporosis after administration, but they were scarcely distributed to the bone. The homing efficiency of DPSCs is higher when administrated in the early stage of a mouse OVX model. Micro-computed tomography indicated that DPSCs-Null or DPSCs-HGF transplantation significantly reduces OVX-induced bone loss in the trabecular bone of the distal femur metaphysis, and DPSCs-HGF show a stronger capacity to reduce bone loss. The data suggest that systemic infusion of DPSCs-HGF is a potential therapeutic approach for OVX-induced bone loss, which might be mediated by paracrine mechanisms.

Purpose: To investigate alterations of mitochondria in irradiated endothelial cells to further elucidate the mechanism underlying radiation-induced heart disease. Materials and methods: Experiments were performed using human umbilical vein endothelial cells (HUVECs). HUVECs were irradiated with single gamma ray dose of 0, 5, 10 and 20 Gy, respectively. Apoptosis was assessed by flow cytometry at 24, 48 and 72 h post-irradiation, respectively. The intracellular reactive oxygen species (ROS) was measured with 2′,7′-dichlorofluorescein-diacetate (DCFH-DA) at 24 h post-irradiation. Mitochondrial membrane potential (ΔΨm) by JC-1 and the opening of mitochondrial permeability transition pore (mPTP) by a calcein-cobalt quenching method were detected at 24 h post-irradiation in order to measure changes of mitochondria induced by gamma ray irradiation. Results: Gamma ray irradiation increased HUVECs apoptosis in a dose-dependent and time-dependent manner. Irradiation also promoted ROS production in HUVECs in a dose-dependent manner. At 24 h post-irradiation, the results showed that irradiation decreases ΔΨm, however, paradoxically, flow cytometry showed green fluorescence instensity higher in irradiated HUVECs than in control HUVECs in an irradiation dose-dependent manner which indicated gamma ray irradiation inhibited mPTP opening in HUVECs. Conclusions: Gamma ray irradiation induces apoptosis and ROS production of endothelial cells, and decreases ΔΨm meanwhile contradictorily inhibiting the opening of mPTP.