Mesenchymal stem/progenitor cell isolation from tooth extraction sockets.

Bone marrow-derived mesenchymal stem/progenitor cells (BMSCs) are commonly used in regeneration therapy. The current primary source of BMSCs is the iliac crest; however, the procedure is associated with various burdens on the patient, including the risk of pain and infection. Hence, the possibility to collect BMSCs from other, more accessible, sources would be an attractive approach. It is well known that stem cells migrate from surrounding tissues and play important roles in wound healing. We thus hypothesized that stem/progenitor cells could be isolated from granulation tissue in the dental socket, and we subsequently collected granulation tissue from dog dental socket 3 d after tooth extraction. After enzyme digestion of the collected tissue, the cells forming colonies constituted the dental socket-derived stem/progenitor cells (dDSCs). Next, dDSCs were compared with dog BMSCs (dBMSCs) for phenotype characterization. A flow cytometric analysis showed that dDSCs were positive for CD44, CD90, and CD271 but negative for CD34 and CD45, similar to dBMSCs. dDSCs also exhibited osteogenic, adipogenic, and chondrogenic differentiation ability, similar to dBMSCs, with a higher capacity for colony formation, proliferation, and motility than dBMSCs. In addition, an in vivo ectopic bone formation assay showed that dDSCs and dBMSCs both induced hard tissue formation, although only dDSCs formed a fibrous tissue-like structure connected to the newly formed bone. Finally, we tested the ability of dDSCs to regenerate periodontal tissue in a one-wall defect model. The defects in the dDSC-transplanted group (ß-TCP/PGA/dDSCs) were regenerated with cementum-like and periodontal ligament-like tissues and alveolar bone, whereas only bony tissue was observed in the control group (ß-TCP/PGA). In conclusion, we identified and characterized a population of stem/progenitor cells in granulation tissue obtained from the dental socket that exhibited several characteristics similar to those of BMSCs. Dental sockets could therefore be a novel source for isolating stem/progenitor cells from bone.

Predicted trends in the supply and demand of veterinarians in Japan.

Currently in Japan, there are 32,000 active veterinarians, mainly engaged in small and large animal practice and public animal health and public health services. In the face of the notable increase in recent years in the proportion of female students enrolled in veterinary schools and in the number of households with companion animals, a model was developed to predict the supply and demand of veterinarians toward 2040 in Japan. Surveys were conducted on sampled households and veterinarians to estimate input variables used in the supply and demand model. From this data it is predicted that there might be somewhere between a shortage of 1,000 to an over-supply of 3,700 veterinarians engaged in small animal practice in 2040. This, however, will depend on possible changes in the number of visits made to veterinarians by small animal owners and the efficiency of practices in the future. The model also predicts that there will be a shortage of around 1,100 veterinarians in large animal practice in 2040. Considering the many assumptions made to estimate the input variables used in the model, the results of this study do not provide definitive conclusions, but provide a base for discussions on what will be needed in the veterinary profession in the future.

Nematode infection in Alymphoplasia (aly) mice: worm species-dependent differential effect of defects of the gut-associated lymphatic tissue system.

Mice homologous for the alymphoplasia mutation (aly) show the systemic absence of secondary lymphoid tissues, with disorganized splenic architecture, including the absence of the germinal centre and follicular dendritic cells. In this study, we examined the influence of defects of gut-associated lymphoid tissue (GALT), such as Peyer's patches and the mesenteric lymph nodes, on the host response to helminth infection in aly/aly mice. The present study showed that most of the worms were expelled by day 7 after Nippostrongylus brasiliensis infection in both control aly/+ and aly/aly mice. In aly/aly mice, the number of peripheral blood eosinophils, intestinal goblet cells and mucosal mast cells were increased by N. brasiliensis infection in aly/aly mice to the same level as in the controls. Conversely, aly/aly mice developed more severe Heligmosomoides polygyrus infections than control aly/+ mice, as demonstrated by increased faecal egg counts, with reduced immune responses such as the numbers of intestinal goblet cells and mucosal mast cells. These results suggested that the dependency of GALT in activation of Th2 responses against gastrointestinal nematodes was different depending on the species of nematode.