The sinR ortholog PGN_0088 encodes a transcriptional regulator that inhibits polysaccharide synthesis in Porphyromonas gingivalis ATCC 33277 biofilms.

Biofilm-forming cells are distinct from well characterized planktonic cells and aggregate in the extracellular matrix, the so-called extracellular polymeric substances (EPS). The sinR gene of Bacillus subtilis encodes a transcriptional regulator that is known to be involved in the biosynthesis of EPS in biofilms. Porphyromonas gingivalis inhabits the subgingival and extraradicular biofilm of humans and is one of the primary pathogens that cause progressive marginal and refractory apical periodontitis. Furthermore, P. gingivalis possesses PGN_0088, which encodes a putative ortholog of B. subtilis sinR. Here, we investigated the role of PGN_0088 (sinR) on biofilm formation. P. gingivalis strains formed biofilms on saliva-coated glass surfaces in phosphate buffered saline. Quantitative analysis indicated that the biofilm of the sinR null mutant consisted of dense exopolysaccharide. Microscopic observations showed that the increased levels of exopolysaccharide produced by the sinR mutant changed the morphology of the EPS to a mesh-liked structure. Furthermore, physical analyses suggested that the enrichment of exopolysaccharide in the EPS enhanced the resistance of the biofilm to hydrodynamic shear force. The results presented here demonstrate sinR plays important roles in the ability of P. gingivalis strain ATCC 33277 to act as a negative mediator of exopolysaccharide accumulation and is indirectly associated with the structure of the EPS and the force of its adhesion to surfaces

Bone Marrow-Derived HipOP Cell Population Is Markedly Enriched in Osteoprogenitors

We recently succeeded in purifying a novel multipotential progenitor or stem cell population from bone marrow stromal cells (BMSCs). This population exhibited a very high frequency of colony forming units-osteoblast (CFU-O; 100 times higher than in BMSCs) and high expression levels of osteoblast differentiation markers. Furthermore, large masses of mineralized tissue were observed in in vivo transplants with this new population, designated highly purified osteoprogenitors (HipOPs). We now report the detailed presence and localization of HipOPs and recipient cells in transplants, and demonstrate that there is a strong relationship between the mineralized tissue volume formed and the transplanted number of HipOPs

Bone Marrow-Derived HipOP Cell Population Is Markedly Enriched in Osteoprogenitors

We recently succeeded in purifying a novel multipotential progenitor or stem cell population from bone marrow stromal cells (BMSCs). This population exhibited a very high frequency of colony forming units-osteoblast (CFU-O; 100 times higher than in BMSCs) and high expression levels of osteoblast differentiation markers. Furthermore, large masses of mineralized tissue were observed in <em>in vivo</em> transplants with this new population, designated highly purified osteoprogenitors (HipOPs). We now report the detailed presence and localization of HipOPs and recipient cells in transplants, and demonstrate that there is a strong relationship between the mineralized tissue volume formed and the transplanted number of HipOPs