ABSTRACT
When a tooth is diseased or damaged through caries, bioactive molecules are liberated from the pulp and dentin as part of the natural response to injury and these are key molecules for stimulating stem cell responses for tissue repair. Incorporation of these extracellular-matrix (ECM)-derived molecules into a hydrogel model can mimic in vivo conditions to enable dentin-pulp complex regeneration. Here, a chitosan/alginate (C/A) hydrogel is developed to sequester bovine ECM extracts. Human dental pulp cells (hDPCs) are cultured with these constructs and proliferation and cytotoxicity assays confirm that these C/A hydrogels are bioactive. Sequential z-axis fluorescent imaging visualizes hDPCs protruding into the hydrogel as it degraded. Alizarin red S staining shows that hDPCs cultured with the hydrogels display increased calcium-ion deposition, with dentin ECM stimulating the highest levels. Alkaline phosphatase activity is increased, as is expression of transforming growth factor-beta as demonstrated using immunocytochemistry. Directional analysis following phase contrast kinetic image capture demonstrates that both dentin and pulp ECM molecules act as chemoattractants for hDPCs. Data from this study demonstrate that purified ECM from dental pulp and dentin when delivered in a C/A hydrogel stimulates dental tissue repair processes in vitro.
ABSTRACT
OBJECTIVE: Wholegrain foods vary in the extent of processing. We investigated whether wholegrain particle size in bread influences postprandial glycemia in type 2 diabetes. RESEARCH DESIGN AND METHODS: Postprandial glycemia (incremental area under the blood glucose curve [iAUC]) was measured after consumption of three breads made with roller-milled wholegrain flour and added grains and a fourth made with stone-ground flour. All flours and grains were 100% wholegrain wheat. Breads were nutrient matched. RESULTS: Fifteen adults (64 ± 10 years, HbA1c 58 ± 13 mmol/mol) completed the study. iAUC for the three breads made with roller-milled flour ranged from 376 to 641 mmol-1min-1, inverse linear trend for grain particle size P = 0.039. The iAUC for stone-ground wholegrain bread (503) was smaller than predicted from mean particle size. CONCLUSIONS: Wholegrain structural integrity in bread is a determinant of glycemic response. These findings have implications for dietary advice and the definition of the term "'wholegrain."
