Periodontitis is one of the most widespread infectious diseases in humans. It is the main cause of tooth loss and associated with a number of systemic diseases. Until now, there is no appropriate method for functional periodontal tissue regeneration. Here, we establish a novel approach of using allogeneic periodontal ligament stem cells (PDLSCs) sheet to curing periodontitis in a miniature pig periodontitis model. Significant periodontal tissue regeneration was achieved in both the autologous and the allogeneic PDLSCs transplantation group at 12 weeks post-PDLSCs transplantation. Based on clinical assessments, computed tomography (CT) scanning, and histological examination, there was no marked difference between the autologous and allogeneic PDLSCs transplantation groups. In addition, lack of immunological rejections in the animals that received the allogeneic PDLSCs transplantation was observed. Interestingly, we found that human PDLSCs fail to express human leukocyte antigen (HLA)-II DR and costimulatory molecules. PDLSCs were not able to elicit T-cell proliferation and inhibit T-cell proliferation when stimulated with mismatched major histocompatibility complex molecules. Furthermore, we found that prostaglandin E2 (PGE2) plays a crucial role in PDLSCs-mediated immunomodulation and periodontal tissue regeneration in vitro and in vivo. Our study demonstrated that PDLSCs possess low immunogenicity and marked immunosuppression via PGE2-induced T-cell anergy. We developed a standard technological procedure of using allogeneic PDLSCs to cure periodontitis in swine. Stem Cells 2010;28:1829–1838

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IL-25 (IL-17E) is a T-helper cell type 2 (Th2) cytokine best described as a potentiator of Th2 memory responses. Reports of expression of its receptor, IL-25R, on airways structural cells suggest a wider role for IL-25 in remodeling. We hypothesized that IL-25 stimulates local angiogenesis in the asthmatic bronchial mucosa. Immunoreactive IL-25 + , IL-25R + , and CD31 + (endothelial) cells in sections of bronchial biopsies from asthmatics and controls were detected by immunohistochemistry. The effect of IL-25 on angiogenesis was examined using an in vitro assay. Real-time PCR was used to detect expression of IL-25R and VEGF mRNA in cultured human vascular endothelial cells (HUVEC), and a cell proliferation kit (WST-8) was used to measure the effect of IL-25 on HUVEC proliferation. Immunostaining showed that IL-25 + , IL-25R + , and CD31 + /IL-25R + cells were significantly elevated in the bronchial mucosa of asthmatics compared with controls (P < 0.003). In asthmatics, the numbers of IL-25 + cells correlated inversely with the forced expiratory volume in 1 s (r = −0.639; P = 0.01). In vitro, HUVEC constitutively expressed IL-25R, which was up-regulated further by TNF-α. IL-25 and TNF-α also increased expression of VEGF and VEGF receptors. IL-25 increased HUVEC proliferation and the number, length, and area of microvessel structures in a concentration-dependent manner in vitro. VEGF blockade, the PI3K-specific inhibitor LY294002, and the MAPK/ERK1/2 (MEK1/2)-specific inhibitor U0126 all markedly attenuated IL-25-induced angiogenesis, and the inhibitors also reduced IL-25-induced proliferation and VEGF expression. Our findings suggest that IL-25 is elevated in asthma and contributes to angiogenesis, at least partly by increasing endothelial cell VEGF/VEGF receptor expression through PI3K/Akt and Erk/MAPK pathways.

Lactoferrin (LF), a cationic 80-kDa protein present in polymorphonuclear leukocytes and in mucosal secretions, is known to have antibacterial effects on gram-negative bacteria, with a concomitant release of lipopolysaccharides (LPS, endotoxin). In addition, LF is known to decrease LPS-induced cytokine release by monocytes and LPS priming of polymorphonuclear leukocytes. Its mechanism of action is incompletely understood. We have now demonstrated by in vitro-binding studies that LF binds directly to isolated lipid A and intact LPS of clinically relevant serotypes of the species which most frequently cause bacteremia (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa), as well as to lipid A and LPS of mucosal pathogens (among others, Neisseria meningitides and Haemophilus influenzae). Binding to LPS was inhibitable by lipid A and polymyxin B but not by KDO (3-deoxy-D-manno-octulosonate), a glycoside residue present in the inner core of LPS. Binding of LF to lipid A was saturable, and an affinity constant of 2 x 109 M-1 was calculated for the LF-lipid A interaction. Our data may explain, in part, the mechanism whereby LF exerts its antibacterial and anti-endotoxic effects. Further studies on the ability of LF to block the detrimental effects of LPS, both in vitro and in vivo, are warranted.

Stem cells from apical papilla (SCAP) are a novel population of multipotent stem cells that, although similar to dental pulp stem cells, are a discrete source of dental stem cells. SCAP have potential roles in root development, apexogenesis, pulp/dentin regeneration, and bioroot engineering. However, procedures to store and preserve SCAP for future clinical applications have not been explored. In this study, we compared human freshly isolated SCAP (fSCAP) with cryopreserved SCAP (cSCAP) in terms of cell viability, colony-forming efficiency, cell proliferation rate, multilineage differentiation potential, profiles of mesenchymal stem cell (MSC) markers, karyotype analysis, and immunological assays. cSCAP showed a similar viable cell ratio, colony-forming efficiency, cell proliferation rate, multilineage differentiation potential, MSC surface markers, apoptotic rate, and G-banded karyotype when compared to fSCAP. There was no significant difference between fSCAP and cSCAP with regard to immune properties. In addition, cSCAP of miniature pig possessed the similar proliferation rate, differentiation potential, and immunomodulatory function as seen in fSCAP. This study demonstrates that cryopreservation does not affect the biological and immunological properties of SCAP, supporting the feasibility of SCAP cryopreservation in nitrogen.