Masaya Nishikawa

Dental pulp-derived stem cell conditioned medium reduces cardiac injury following ischemia-reperfusion.

Stem cells from human exfoliated deciduous teeth (SHEDs) can regenerate various tissues. We investigated the impact of SHED-conditioned medium (SHED-CM) on myocardial injury in a mouse model of ischemia-reperfusion (I/R). Wild-type (WT) mice were subjected to myocardial ischemia followed by reperfusion. SHED-CM was intravenously injected at 5 min after reperfusion. Administration of SHED-CM reduced myocardial infarct size as well as decreased apoptosis and inflammatory cytokine levels, such as TNF-α, IL-6, and IL-β, in the myocardium following I/R. In cultured cardiac myocytes, SHED-CM significantly suppressed apoptosis under hypoxia/serum-deprivation and reduced LPS-induced expression of pro-inflammatory genes. Furthermore, anti-apoptotic action of SHED-CM was stronger than bone marrow-derived stem cell (BMSC)-CM or adipose-derived stem cell (ADSC)-CM in cardiac myocytes. SHED-CM contains a higher concentration of hepatocyte growth factor (HGF) than BMSC-CM and ADSC-CM, and neutralization of HGF attenuated the inhibitory actions of SHED-CM on apoptosis in cardiac myocytes. Finally, WT mice were intravenously treated with an HGF-depleted SHED-CM, followed by myocardial I/R. HGF depletion significantly attenuated the inhibitory actions of SHED-CM on myocardial infarct size and apoptosis after I/R. SHED-CM protects the heart from acute ischemic injury because it suppresses inflammation and apoptosis. SHED-CM could be a useful treatment option for acute myocardial infarction.

Factors secreted from dental pulp stem cells show multifaceted benefits for treating experimental rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial hyperplasia and chronic inflammation, which lead to the progressive destruction of cartilage and bone in the joints. Numerous studies have reported that administrations of various types of MSCs improve arthritis symptoms in animal models, by paracrine mechanisms. However, the therapeutic effects of the secreted factors alone, without the cell graft, have been uncertain. Here, we show that a single intravenous administration of serum-free conditioned medium (CM) from human deciduous dental pulp stem cells (SHED-CM) into anti-collagen type II antibody-induced arthritis (CAIA), a mouse model of rheumatoid arthritis (RA), markedly improved the arthritis symptoms and joint destruction. The therapeutic efficacy of SHED-CM was associated with an induction of anti-inflammatory M2 macrophages in the CAIA joints and the abrogation of RANKL expression. SHED-CM specifically depleted of an M2 macrophage inducer, the secreted ectodomain of sialic acid-binding Ig-like lectin-9 (ED-Siglec-9), exhibited a reduced ability to induce M2-related gene expression and attenuate CAIA. SHED-CM also inhibited the RANKL-induced osteoclastogenesis in vitro. Collectively, our findings suggest that SHED-CM provides multifaceted therapeutic effects for treating CAIA, including the ED-Siglec-9-dependent induction of M2 macrophage polarization and inhibition of osteoclastogenesis. Thus, SHED-CM may represent a novel anti-inflammatory and reparative therapy for RA.

Improvement of transduction efficiency of recombinant adenovirus vector conjugated with cationic liposome for human oral squamous cell carcinoma cell lines

Adenovirus (Ad) vectors are commonly used in gene therapy trials because of their efficiency in gene transfer. However, their use is limited by immune responses that reduce transgene expression and decrease the efficiency of repeated vector administration. In this study, the efficacy of gene transduction and the tumor-cell killing effect on four human oral (SAS, HSC-2, HSC-3, HSC-4) and one murine squamous cell carcinoma cell (SCC-7, a kind gift of Dr. M. Hiraoka, Kyoto University) lines in vitro with Ad vector conjugated with catioic liposome (Ad/SUV) was evaluated. Ad/SUV resulted in two to five-fold over higher transduction efficiency in four human and one murine cell lines in vitro than Ad vector alone. The optimal Ad-SUV ratio was determined as 10(6) pfu of Ad vector with 1 micromol SUV. Ad/SUV showed more tumor-cell killing effect than Ad vector alone. Furthermore, the shielding effects of Ad vector with Ad/SUV from neutralizing antibody were evaluated. We also found that Ad/SUV is less susceptible to inactivation by neutralizing antibodies in vitro. The efficacy of gene transduction with Ad vector was blocked more than 70% with neutralizing serum, while Ad/SUV retained approximately 50% of the control activity in vitro. On the basis of these results, the anti-tumor effect with suicide gene therapy using Ad/SUV in vivo was evaluated. Three injections of Ad/SUV showed the inhibition of tumor growth compared with control in vivo. Our results suggested that an enhanced anti-tumor effect on human oral squamous cell carcinoma would be obtained with repeated administrations of Ad/SUV.