The Effect Of Umbilical Cord-derived Mesenchymal Stem Cell Transplantation And Doxycycline On Early Stage Of Pulmonary Fibrosis In Mice

BackgroundPulmonary fibrosis is a devastating and relentlessly progressive lung disorder.Progressive breathlessness and eventual respiratory failure are the most common natural history.To date,effective therapies to treat pulmonary fibrosis patients are lacking and conventional therapy may be harmful.The median survival time following diagnosis of pulmonary fibrosis is only 2 to 3years.Its mortality rate is therefore higher than that of most cancers.What’s worse,patient numbers are rising overall.This research may shed some light on the treatment.ObjectivesTo investigate the effect of umbilical cord-derived mesenchymal stem cell(UC-MSCs)transplantation and doxycycline in a mice model of pulmonary fibrosis and its mechanism.MethodsUC-MSCs was cultured by using tissue culture method,cell phenotype was analysed using the flow cytometry when cells experienced three times passage.C57BL/6 mice(female,8 W of age)were used.40 C57BL/6 mice were randomly divided into 5 groups: control group(A group),model group(B group),doxycycline group(C group),stem cell group(D group),combination treatment group(E group).Mice in the control group were intratracheal injected with NS under operating microscope.Mice in other groups were intratracheal injected with bleomycin under operating microscope.At the 48 h,mice in the control and model group were injected NS via the tail vein.Mice in the doxycycline group were injected doxycycline via abdomen.Mice in the stem cell group were injected UC-MSCs via the tail vein.Mice in the combination treatment group were injected UC-MSCs via the tail vein and injected doxycycline via the abdomen.At the 28 th day,mice lung tissues were collected,sliced into the paraffin sections.The paraffin sections were stained with hematoxylin and eosin(H&E)and Masson-trichrome.Histopathological scoring of pulmonary fibrosis was performed according to Szapiel’s method.The concentrations of hydroxyproline were determined using alkaline hydrolysis method.The concentrations of matrix metalloproteinases-9(MMP-9)and tissue inhibitor of metalloproteiuase-1(TIMP-1)were determined using immunohisto chemistry.Results(1)Mice pulmonary inflammation and fibrosis score: A group<E group <D group<C group<B group(P<0.05).(2)Expression of MMP-9: A group<E group <D group=C group<B group.Expression of TIMP-1: C group=B group<Agroup <Dgroup =E group(P<0.05).(3)Hydroxyproline content: A group<E group <D group< C group<B group(P<0.05).ConclusionsOn early stage of pulmonary fibrosis,UC-MSCs transplantation and doxycycline can relieve bleomycin-induced fibrosing alveolitis in mice.The mechanism might be related to the expression of MMP-9 and TIMP-1.