Promotion On The Maturity Of Human Fetal AECsⅡ Treated With ABX And DEX

BackgroundNeonatal respiratory distress syndrome (NRDS) which usually occurs in premature infant will threaten neonatal lives seriously. The main cause seems to be the developmental immaturity of neonatal lung, which seems due to that type II epithelial cells (AECs II) can not synthesize enough pulmonary surfactant (PS). Dexamethasone (DEX) is generally used clinically to promote the synthesis and secretion of PS by AECs II, so as to induce the maturity of fetal lung. However, the side effects of DEX, such as dependence of gestational weeks, suppression of fetus growth and aggravating infection of mother and fetus, are drawing more attention.Ambroxol(ABX), as a fast expectoration drug, can not only advance venting of secretion substance from respiratory passage, but also promote the synthesis and secretion of PS and raise the L/S ratio, so as to induce the maturity of fetal lung, and has no significant side effects compared with DEX, which is shown by recent studies.In this study, we investigated the effect of simultaneous treatment with ABX and DEX on the maturity of AECs II of human fetal lung in vitro, compared with the effect of either ABX or DEX group, in order to determine whether ABX and DEX have combined effect.Materials and Methods1. The source of materials12 dead fetuses inducted of labor with induction by intra-amniotic injection according to medical indications were obtained from China Medical University affiliating Shengjing Hospital maternity department between 2006.4 and 2006.12. Each fetal cadaver was agreed by parents and family members to be disposed by the hospital. Gestational weeks are between 28 and 34 weeks, with no limits on fetal gender. Both sides of fetal lung was obtained as experimental object.2. Major agentsPercoll; 15%FCS-RPMI 1640;DEX;ABX.3. Empirical methodAfter dissection and digestion with 0.25% trypsinase on the fetal lung tissue,we use density gradient centrifugation to isolate and purify the AECs II ,and cultivate them under the condition of 15%FCS-RPMI1640,37℃,until cells grow to monolaye .To observe the cells under the inverted microscope ,to indentify them under the TEM.To treat AECs II with ABX,DEX and ABX+DEX,and continue to cultivate them for 48h. Determination of disaturated phospholipids production by Bartlett Method,and determination of the total protein level by Modified Lowry Method.Data were expressed as the means±SD. Statistical analysis is using SPSS software 13.0. T-test is used to contrast the means between groups. Significant level standard equals 0.05(α=0.05).Result1 .Observation AECs II below the inverted microscopeAECs II are epithelial-like cells below the inverted microscope , polygonal or spindle-shaped, adherence to the wall and connection to monolayer,the cellular nucleus are clear and the endochylem are abundant.2. Characterization AECs II below transmission electron microscopeAECs II are spherical below TEM, with stunted microvilli on the surface and high-density secretory granule in the cytoplasm. They are different in shape and size, most of which have lamellar structure, i.e. typical lamellar body. 3.The influence of ABX, DEX and ABX+DEX on DSPC/TP ratio of AECs II(1)The DSPC/TP ratio of the control group is 1.99±0.375μmol/mg, and the DSPC/TP ratio of the ABX,DEX and ABX+DEX group is 2.78±0.34μmol/mg,2.95±0.49μmol/mgå’Œ3.46±0.46μmol/mg, respectively.(2)Compared with the control group, the difference of DSPC/TP ratio of group ABX, DEX and ABX+DEX is significant, with P value being 0.0079,0.0096 and 0.0140, respectively;the difference of DSPC/TP ratio between group ABX+DEX and group ABX is significant (P=0.0069);the difference of DSPC/TP ratio between group ABX+DEX and group ABX is significant (P=0.0150);the difference of DSPC/TP ratio between group ABX and group DEX is not significant (P=0.3200).4.The influence of ABX,DEX and ABX+DEX on DSPC/TP ratio of AECs II of different gestational ages(1)In the control group,the DSPC/TP ratio of the gestational ages 28⁺⁰～30⁽+77 and gestational ages 31⁺⁰～33⁺⁷ are 1.78±0.31μmol/mg and 2.20±0.32μmol/mg; 3.85±0.39μmol/mg and 3.74±0.31μmol/mg in the group ABX; 3.68±0.34μmol/mg and 4.23±0.48umol/mg in the group DEX; 4.78±0.55μmol/mg and 5.14±0.63μmol/mg in the group ABX+DEX.(2)In the control group,the difference of the DSPC/TP ratio between the gestational ages 28⁺⁰～30⁺⁷ and the gestational ages 31⁺⁰～33⁺⁷ is significant (P=0.0450);in the group ABX,the difference is not significant(P=0.483);in the group DEX,the difference is significant(P=0.044);in the group ABX+DEX,the-difference is not significant(P=0.312).Conclusion1. Both ABX and DEX have beneficial effects on the level of disatured phospholipids by AEC II on the fetal lung of Immature fetus; simultaneous treatment with ABX and DEX has more significant effect on the level of disaturated phospholipids than single treatment with ABX or DEX; the influence of treatment with single ABX or DEX on the level of disatured phospholipids by AECs II is same.2.The level of the disaturated phospholipids in elder gestational ages is higher than in younger gestational ages.