The Role Of PDGF-D/PDGFR-? Signaling In Myocardial Fibroplasia In Rats Resuscitated From Cardiac Arrest

Background:Cardiac arrest(CA)is a common and serious clinical event,but the survival rate of patients with CA has been low,at about 10.6 % in the United States in 2015.Post-resuscitation cardiac dysfunction(PRMD)is one of the main causes of early death after early restoration of spontaneous circulation(ROSC).Some studies have found that 3 days after resuscitation,color Doppler ultrasound(CDFI)in the rat heart suggests that there is still cardiac dysfunction,which is dominated by diastolic dysfunction.The severity of diastolic cardiac dysfunction was negatively correlated with the survival time.HE staining further found ventricular intramural interstitial hyperplasia on the 3 day after resuscitation,suggesting that the existing myocardial fiber hyperplasia.Myocardial fibrosis is one of the important pathological mechanisms leading to decreased cardiac compliance and diastolic heart failure.Platelet-derived growth factor(PDGF)play an important role in the process of multiple organ fibrosis by activating platelet-derived growth factor receptor(PDGFR),which in turn activates a series of intracellular signal transduction pathways.However,its role in myocardial interstitial hyperplasia after resuscitation is still unclear.Objective:To investigate the effects of PDGF-D/PDGFR-? signaling on interstitial collagen hyperplasia and fibroplasia of myocardium following cardiopulmonary resuscitation(CPR)in rats.Methods:1.The role of PDGF-D/PDGFR-? signaling Pathway in Myocardial Interstitial Fibrosis after Cardiopulmonary resuscitation in Rats(1)The experimental group.A total of 90 male Sprague-Dawley(SD)rats were randomly assigned into 5 groups: Sham,Control,Imatinib,Ad-GFP and Ad-PDGFR.Each group is further subdivided into post-resuscitation(PR)4h and PR72 h.(2)pathological changes were observed by HE stainingThe rats were killed at 4 h and 72 h after resuscitation respectively.The heart tissue of the rats was taken to make sections and stained with HE.(3)Cardiac collagen volume fraction(CVF)was measured with Sirius red staining.The rat heart tissue was sectioned and stained with Sirius red.The Leica microscope system was used to take pictures.Image J 1.8.0 image analysis software was used to measure the ratio of interstitial area to total field area of rat myocardium(CVF).(4)Serum PDGF-D levels were detected.Serum level of PDGF-D was examined by Enzyme-linked immunosorbent assay(ELISA)after ROSC via drawing blood from Cardiac.(5)Collagen ?,?-SMA,Vimentin and PDGFR-? detected by Western blotExpression of Collagen?,? smooth muscle actin(?-SMA),vimentin and PDGF receptor ?(PDGFR?)were detected by Western blot.Results:1.HE staining showed that the cardiac myocytes in the Sham group were arranged closely and orderly,and the nuclei were intact.Except for Sham group,PR4 h,showed swelling of cardiomyocytes,dissolution of myocytes and disarrangement of cardiomyocytes.With the exception of Sham group,cardiac myocytes were disordered in every group,and there was different degree of interstitial hyperplasia in all groups.2.At PR72 h,the CVF value in Control and Ad-PDGFR was significantly higher [(11.24 ± 0.31)vs(1.65 ± 0.19),(t = 10.81,P <0.05)] than that in Sham and Ad-GFP [(25.60 ± 4.09)vs(10.73 ± 2.42),(t = 16.77,P <0.05)],respectively.Compared to Control,Imatinib significantly decreased the level of CVF [(5.11 ± 0.29)vs(11.24 ± 0.31),(t = 3.892,P <0.05)].3.At PR4 h,compared with Sham,the expression of serum PDGF-D was greatly increased in Control,Imatinib,Ad-GFP and Ad-PDGFR(all P<0.05).At PR72 h,serum PDGF-D was continuously high in Ad-PDGFR when compared with Sham [(296.46 ± 30.82)pg/ml vs(93.74 ± 5.43)pg/ml,(t =7.755,P <0.05)].4.At PR72 h,the expression of Collagen I,?-SMA,Vimentin and PDGFR-? in Control and Ad-PDGFR were significantly increased than those in Sham and Ad-GFP,respectively(all P<0.05).However,compared with Control,Imatinib significantly decreased the expressions of the above proteins(all P<0.05).Conclusion:1.After cardiopulmonary resuscitation(CPR),the expression of PDGF-D in serum increased and PDGF-D/PDGFR-? signaling pathway activated fibroblasts.The conversion of fibroblasts into myofibroblasts to produce ECM,such as Collagen?,results in myocardial interstitial proliferation in rats.2.Imatinib can reduce myocardial interstitial hyperplasia induced by PDGF-D/PDGFR-? signal pathway after cardiopulmonary resuscitation(CPR).