Isolation of Matrix Vesicles associating with Dentinogenesis and Application for Pulpotomy

Matrix vesicles are involved in the早期stages of the mineralization process现在似乎已经成为普遍接受的，他们是原始加密组。研究这些vesicles during initial dentinogenesis and to investigate theapplication for pulpotomy.Apical pulps of Wistar rats excised with a razor blade. Small slicesof them were incubated with collagenase. Pulp digest was centrifuged. Fractions were obtained asfollows:(1) 40,000 x g for 20min；300,000 x g for 10min . Electron microscopy of the centrifugal sediments showed intact cells andcell fragments,和partially fragmented endoplasmic reticulum in fraction 1. Vesicles closely resembling the matrixvesicles, because of their small size, electron-dense contents，concentrated in the 2nd fraction. the specific activity for alkaline phosphatase was 4.57 <+！0.76 U. Total protein contents were 0.73 <+！-> 0.10 <mu> g /mg wet weight. Needle-like crystals did not grow within matrix vesicles in Casolution containing ATP (2 - 5h，37 C).这些结果indicate that matrix vesicles first isolated from dental pulp has biologicalactivity and similar fine structure to of in体内ones. Further研究would be necessory toform the hydroxyapatite in matrix vesicles in vitro；the contents of incubation medium and culture condition可能被决定因素This futureinvestigation could catch the basic data to applicate these vesicles for pulpotomy。

Matrix vesicles are involved in the early stages of the mineralization process, and it now seems to be generally agreed that they are sites of initial crystal formation. Present study was carried out to isolate these vesicles during initial dentinogenesis and to investigate the application for pulpotomy.Apical pulps of Wistar rats were excised with a razor blade. Small slices of them were incubated with collagenase. Pulp digest was centrifuged. Fractions were obtained as follows : (1) 40,000 x g for 20 min ; (2) 300,000 x g for 10 min. Electron microscopy of the centrifugal sediments showed intact cells and cell fragments, and partially fragmented endoplasmic reticulum in fraction 1. Vesicles closely resembling the matrix vesicles, because of their small size, electron-dense contents, were concentrated in the 2nd fraction. The specific activity for alkaline phosphatase was 4.57 <+!-> 0.76 U. Total protein contents were 0.73 <+!-> 0.10 <mu> g /mg wet weight. Needle-like crystals did not grow within matrix vesicles in Ca・P solution containing ATP ( 2 - 5 h, 37゜C ).These results indicate that matrix vesicles first isolated from dental pulp has biological activity and similar fine structure to that of in vivo ones. Further study would be necessory to form the hydroxyapatite in matrix vesicles in vitro; the contents of incubation medium and culture condition might be decisive factors. This future investigation could catch the basic data to applicate these vesicles for pulpotomy.