Objective:Toresearch the correlation between the effect of all-trans retinoic acid (ATRA) on recruitingMSCs and MMP-9 mRNA expression in damage tissue. Methods:MSCs and ATRA were separately used in experimental SD rats.At 2 weeks

3 weeks and 4 weeks after the treatment

RT-PCR assay was used to determine expressions of MMP-9 mRNA in lung tissues.Laser scanning microscope was used to observe the recruitment of implanted MSCs.Results:We found that

at each time point

experimental group had more implanted MSCs in the surface of alveoli and increased IOD than other groups.There was significant difference in these groups (P<0.05). At the same time

in control group and ATRA intervention group

there were overexpression of MMP-9 mRNA

but in MSCs implanted group the expression of MMP-9 mRNA decreased slowly

as compared with the above two groups (P<0.05).In experimental group

the drop of MMP-9 mRNA expression was clear

as compared with the above three groups (P<0.05).Conclusion:The effect of ATRA on recruitiment of MSCs had relationship with the drop of MMP-9 mRNA expression in damage tissue.