Location Of Undifferentiated Palatal Mesenchymal Cell In Postnatal Retinoic Acid- Induced Mouse

Background: Congenital cleft lip and palate are the most common congenital developmental malformations, often because of short leaving palate surgery is difficult to fully repair the defect. Tissue regeneration of lip and palate is only found in regeneration of bone with stem cells. And it has not been reported in other tissue of palate including bone, muscle and muscle tendon, cartilage and nerves.Objective: In this study, using BrdU marked slow-cycling long term label- retaining cells(LRCs), while taking advantage of candidate mesenchymal stem cell markers Stro-1, P75, and CD57 staining, location undifferentiated mesenchymal cells in palate of after birth normal mouse, detection of differences in expression sites and patterns of palate undifferentiated mesenchymal cells between retinoic acid(RA)- induced cleft palate and normal in mouse.Methods: ICR pregnant mice at the E10 of SPF level were selected, and RA was given by tube- feeding as the experimental group, establish a mouse model of cleft palate. Using differentiation potential of cells has characteristics of slow cell cycle, at E12 intraperitoneal inject into pregnant mouse with 80mg/kg of the BrdU. At P0 obtain newborn mice tissue of control and experimental groups to fixation, conventional dehydration,Transparent, dip wax and embedded,continuous 4μm wax reserve.Using immunofluorescence to detect BrdU and stro-1, P75, and CD57 expression levels and distribution of palatal mesenchymal cells.Results: 1. P75 and CD57 expression on the cell membrane. In the normal control group, strongly expressed in the undifferentiated mesenchymal cells of no ossification in median palatine suture,P75 expression was also in the neighboring epithelial mesenchymal. CD57 expression was in the whole layer of the spinous cells in the palatal epithelial cells, the P75 specifically expressed in cells adjacent to the basal layer of the spinous cells. In the retinoic acid induced cleft palate group, mainly expressed in the undifferentiated mesenchymal cells around the perivascular and ossification centers. CD57 has a strong positive expression in the distal end of palate. Both of the tow markers showed no expression in the epithelium.2. BrdU expressed in the nucleus, divided into two types including strongly expression the type of dense and weak expression of granules scattered. In the normal control group, strongly expression of dense type gathered in the undifferentiated mesenchymal cells of no ossification in median palatine suture,there is no significant difference between palatal anterior part and posterior part(P>0.05). In the retinoic acid induced cleft palate group, strongly expression of dense type and distribution on the palatal median crest and perivascular mesenchymal cells, the expression of palatal anterior part more than the posterior part. The expression of BrdU in the retinoic acid induced cleft palate group is more than the control group(P<0.01). Stro-1 and BrdU dense type overlap expressed around the blood vessels. However, it has the small number of positive cells expressed around the blood vessels.Conclusions: There is small number of undifferentiated mesenchymal cells in palate of after birth normal mouse, and mainly confined to median palatine suture; and after the birth of retinoic acid-induced cleft palate in mouse,a larger number and more widely of the undifferentiated mesenchymal cells around the palatal vessels provide possibility for tissue engineering repair.