ABSTRACT
[Objective]To investigate the effect of human umbilical cord mesenchymal stem cells on infected state of human alve?olar type Ⅱ epithelial cells.[Methods]Human alveolar type Ⅱ epithelial cells A549(1×105/mL)2 mL and PA(3×104 CFU/mL)2 mL has grown after 6 hours,add hUCMSC(1 × 106/mL)2 mL as the experimental group,add equal amounts of phosphate buffer (PBS)for infection,A549 and PBS and the medium has grown as the control group. A549 cells morphological changes between the compared groups(Transmission electron microscope,TEM),A549 cell viability(new CCK-8 cell proliferation assay Kit),A549 cells apoptosis(Annexin V-FITC/PI double staining flow cytometry)and the expression of A549 pulmonary surfactant A(SP-A) (Western blot).[Results]Transmission electron microscope cell morphology observation displayed ,infection group A549 cell dam?aged obviously,cell quality appeared empty bubble degeneration,chromatin height agglutination,visible apoptosis bodies;experi?ment group cell package film structure full,nuclear film full,nucleolus obviously,nuclear chromatin electronic density low,chroma? tin uniform,no apoptotic bodies;control group A549 cell structure full,membrane surface micro-fluff rich,nuclear film full,nucle?ar week clearance structure normal,chromatin uniform;infection group and control group compared,Infection group A549 cell sur?vival significantly reduced[(70.35±2.89)% and(97.37±2.07)%,n=3,P<0.01],apoptosis rate significantly increased[(8.63%± 0.16)%and(2.55±0.11)%,n=3,P<0.01],In the infected group,PA could damage A549 cells and decrease the amount of SP-A ex?pression(n=5,P<0.05). In the experiment group,the protective effect of hUCMSC on the A549 cells after infection may increase the expression of SP-A(n=5,P<0.05);[Conclusions]HUCMSC inhibits the infection of A549 cells apoptosis and protection of A549 cells secrete SP-A.
ABSTRACT
Objective To investigate the apoptosis response to mechanical stretch in human alveolar type Ⅱ epithelial cells A549.Methods First,A549 cells were given different stretch(0%,5%,15%,30%) at frequency of 0.5 Hz for 4 h.Then,A549 cells were stretched for different periods(0 h,2 h,4 h,8 h) at stretch 15%,0.5 Hz.Last,A549 cells were stretched for different frequency(0 Hz,0.2 Hz,0.5 Hz and 1 Hz) at stretch 15% for 4 h.The early apoptosis was detected by flow cytometry. Results A549 cells submitted to cyclic stretch caused the early apoptosis in a time-,stretch-and frequency-dependent manner.In details,at 0.5 Hz and 4 h stretch-dependence occurred,at 15% stretch and 0.5 Hz time-dependence occurred,and at 15% stretch and 4 h frequency-dependence occurred. Conclusion Mechanical stretch can induce the early apoptosis in human alveolar type Ⅱ epithelial cells A549,which may be one of the mechanisms of ventilator-induced lung injury.