Objective To investigate the effect of Pirfenidone(PFN)on respiratory syncytial virus(RSV)infection-induced damage to bronchial epithelial cells by regulating the high mobility group protein B1(HMGB1)/receptor for advanced glycation end products(RAGE)signaling pathway.Methods Human bronchial epithelial cells(HBE)were divided into Control group(cultured for 24 h under normal conditions),RSV group(inoculated with 4.65×106/mL RSV at 33℃for 2 h);low PFN(L-PFN)group(treated with 0.05 mg/mL PFN for 24 h),moderate PFN(M-PFN)group(treated with 0.10 mg/mL PFN for 24 h),high PFN(H-PFN)group(treated with 0.20 mg/mL PFN for 24 h)and recombinant HMGB1(rHMGB1)group(treated with 1 μg/mL rHMGB1+0.20 mg/mL PFN for 24 h).EdU method was applied to detect the proliferation rate of cells in each group,Hochest33258 staining method was applied to detect apoptosis status of cells in each group,and the migration of cells in each group was evaluated by the scratch experiment.Enzyme linked immunosorbent assay(ELISA)was applied to measure the levels of interferon(IFN)-α,IFN-γ,tumor necrosis factor-α(TNF-α),interleukin(IL)-1α,IL-6 and IL-4 in each group of cells,and Western blot was applied to detect the protein expression of HMGB1,RAGE,B lymphoblastoma-2-associated X protein(Bax),cysteine aspartic protease-3(Caspase-3),and B lymphoblastoma-2(Bcl-2).Results Compared with the RSV group,the cell proliferation rate,scratch closure rate,IL-4 levels,and expression of Bcl-2 in L-,M-,and H-PFN groups increased,while the apoptosis rate,the levels of IFN-α,IFN-γ,TNF-α,IL-1α,IL-6,and the expression of HMGB1,RAGE,Bax,and Caspase-3 reduced(P<0.05);rHMGB1 weakened the effect of H-PFN on the above-mentioned indicators(P<0.05).Conclusion PFN may suppress the apoptosis and inflammatory damage of RSV-infected bronchial epithelial cells by inhibiting the HMGB1/RAGE pathway.Conclusion PFN may suppress the apoptosis and inflammatory damage of RSV-infected bronchial epithelial cells by inhibiting the HMGB1/RAGE pathway.

Objective:To evaluate the role of exosomes in propofol-induced elimination of cardioprotective effect of remote ischemic preconditioning (RIPC) in rats.Methods:This experiment was performed in 2 parts. In vivo experiment Forty-eight healthy SPF male Sprague-Dawley rats, aged 8-10 weeks, weighing 250-300 g, were divided into 5 groups using the random number table method: sham operation group (Sham group, n=12), ischemia-reperfusion (I/R) group ( n=12), RIPC group ( n=8), RIPC+ propofol group (RIPC+ P group, n=8), and propofol+ I/R group (P+ I/R group, n=8). The model of myocardial I/R injury was developed by ligating the left anterior descending branch of coronary artery for 30 min followed by 120 min reperfusion in anesthetized animals. Four cycles of 5-min ischemia induced by occlusion of the bilateral hind limbs with a tourniquet/5-min reperfusion served as the RIPC stimulus. Propofol was intravenously infused at a rate of 12 mg·kg -1·h -1 in RIPC+ P group (during RIPC) and in P+ I/R group (for 40 min). Exosomes from RIPC-treated and RIPC+ propofol-treated rats were extracted (RIPC-EXO and RIPC+ P-EXO respectively) for determination of the expression of surface markers of exosomes CD9 and HSP70. Another 24 rats were randomly selected, and the aforementioned exosomes were injected at 15 min before myocardial ischemia, resulting in RIPC-EXO+ I/R group ( n=12) and RIPC+ P-EXO+ I/R group ( n=12). At the end of reperfusion, the area of myocardial infarction was determined, the concentration of serum cardiac troponin I (cTnI) was measured by the enzyme-linked immunosorbent assay, and the expression of B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) in myocardial tissues was detected by Western blot. Cell experiment H9c2 cells were cultured in vitro and divided into 4 groups ( n=6 each) using a random number table method: control group (C group), hypoxia-reoxygenation group (H/R group), RIPC-EXOc group and RIPC+ P-EXOc group. The cells were exposed to hypoxia for 4 h followed by reoxygenation for 16 h in H/R group. RIPC-EXO and RIPC+ P-EXO were added at a final concentration of 300 μg/ml before hypoxia in RIPC-EXOc group and RIPC+ P-EXOc group, respectively. The cell viability was determined using a cell counting kit-8 assay and the expression of Bax and Bcl-2 expression was detected by Western blot. Results:In vivo experiment Compared with RIPC-EXO group, the expression of CD9 and HSP70 was significantly down-regulated in RIPC+ P-EXO group ( P<0.05). Compared with Sham group, the percentage of the area of myocardial infarction was significantly increased, and the serum cTnI concentration and Bax/Bcl-2 ratio in myocardial tissues were increased in I/R group ( P<0.05). Compared with I/R group, the percentage of the area of myocardial infarction was significantly decreased in RIPC group and RIPC-EXO+ I/R group, the serum cTnI concentration and Bax/Bcl-2 ratio in myocardial tissues were significantly decreased in RIPC-EXO+ I/R group ( P<0.05), and no significant change was found in the percentage of the area of myocardial infarction in RIPC+ P group ( P>0.05). The percentage of the area of myocardial infarction was significantly larger in RIPC+ P group than in RIPC group ( P<0.05). Compared with RIPC-EXO+ I/R group, the percentage of the area of myocardial infarction was significantly increased, and the serum cTnI concentration and Bax/Bcl-2 ratio were increased in RIPC+ P-EXO+ I/R group ( P<0.05). Cell experiment Compared with C group, the cell viability was significantly decreased, and the Bax/Bcl-2 ratio was increased in H/R group ( P<0.05). Compared with H/R group, the cell viability was significantly increased, and the Bax/Bcl-2 ratio was decreased in RIPC-EXOc group ( P<0.05). Compared with RIPC+ EXOc group, the cell viability was significantly decreased, and the Bax/Bcl-2 ratio was increased in RIPC+ P-EXOc group ( P<0.05). Conclusions:Propofol may abolish the myocardial protective effect of RIPC by decreasing the production and release of serum exosomes in rats.

Objective:To evaluate the role of exosomes in reduction of myocardial ischemia-reperfusion (I/R) injury (MIRI) by remote preconditioning of trauma (RPCT) in rats.Methods:This experiment was performed in 2 parts. In vivo experiment Adult male Sprague-Dawley rats, aged 8 weeks, weighing 250-300 g, were used. Six rats were selected and randomly divided into 2 groups ( n=3 each): control group and RPCT group. Rats in control group underwent thoracotomy only, while rats in RPCT group were subjected to an additional 4 cm transverse skin incision along the abdominal midline after thoracotomy. Blood samples were collected, and serum exosomes were isolated from blood samples and labeled as control exosomes and RPCT exosomes. The expression of exosomal surface marker proteins CD9 and heat shock protein 70 (HSP70) was determined by Western blot, and the serum exosome concentration was measured. Another 30 rats were selected and randomly assigned to 5 groups ( n=6 each): sham operation group (Sham group), I/R group, I/R+ RPCT group, I/R+ control exosomes group (I/R+ EXO-CON group), and I/R+ RPCT exosomes group (I/R+ EXO-RPCT group). The MIRI model was established by ligating the left anterior descending coronary artery for 30 min followed by 120 min of reperfusion in anesthetized animals. In I/R+ RPCT group, the MIRI model was prepared at 15 min after the end of RPCT. In I/R+ EXO-CON and I/R+ EXO-RPCT groups, control exosomes and RPCT exosomes 100 μg were administered via the jugular vein at 15 min before ischemia respectively. At the end of reperfusion, the myocardial infarct size was measured, serum concentrations of cardiac troponin T (cTnT) and lactate dehydrogenase (LDH) were determined, and the contents of malondialdehyde (MDA) and superoxide dismutase (SOD) in myocardial tissues were measured. The expression of B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), caspase-3 and cleaved caspase-3 was detected. In vitro experiment H9c2 cells were cultured in vitro and randomly divided into 4 groups ( n=6 each): control group (Con group), hypoxia/reoxygenation (H/R) group, H/R+ control exosomes group (H/R+ EXO-CON group), and H/R+ RPCT exosomes group (H/R+ EXO-RPCT group). The rats were subjected to 4 h of hypoxia followed by 16 h of reoxygenation to establish the H/R injury model. In H/R+ EXO-CON and H/R+ EXO-RPCT groups, control exosomes and RPCT exosomes 4 μg were added at 15 min before hypoxia respectively. The cell survival rate and concentration of lactate dehydrogenase (LDH) in the supernatant were measured, and the expression of Bax, Bcl-2, cleaved caspase-3 and caspase-3 was detected. Results:In vivo experiment Compared with control group, the expression of serum CD9 and HSP70 was significantly up-regulated, and the exosome concentration was increased in RPCT group ( P<0.05). Compared with Sham group, the serum concentrations of cTnT and LDH, percentage of myocardial infarct size, content of MDA in myocardial tissues, Bax/Bcl-2 ratio, and cleaved caspase-3/caspase-3 ratio were significantly increased, and the activity of SOD was decreased in I/R group ( P<0.05). Compared with I/R group, the serum cTnT and LDH concentrations, percentage of myocardial infarct size, content of MDA in myocardial tissues, Bax/Bcl-2 ratio and cleaved caspase-3/caspase-3 ratio were significantly decreased, and the activity of SOD was increased in I/R+ RPCT group ( P<0.05), and no significant changes were observed in the aforementioned parameters in I/R+ EXO-CON group ( P>0.05). There were no significant differences in the aforementioned parameters between I/R+ RPCT group and I/R+ EXO-RPCT group ( P>0.05). In vitro experiment Compared with Con group, the cell survival rate was significantly decreased, and the LDH concentration in the supernatant and Bax/Bcl-2 and cleaved caspase-3/caspase-3 ratios were increased in H/R group ( P<0.05). Compared with H/R group, the cell survival rate was significantly increased, the LDH concentration in the supernatant, and Bax/Bcl-2 and cleaved caspase-3/caspase-3 ratios were decreased in H/R+ EXO-CON group ( P<0.05), and no significant changes were found in the aforementioned parameters in H/R+ EXO-RPCT group ( P>0.05). Conclusions:The mechanism by which RPCT reduces MIRI may be related to the increased release of serum exosomes in rats.

Objective:To explore the influence of Stat1 on Foxp3 expression and production of Treg.Methods:C57BL/6 mice were used and separated into normal control group and Stat1 specific inhibitor Fludarabine(Flud)treatment group.Ratio of CD4+Foxp3+Treg and expression of Foxp3 in spleen,lymph nodes and peripheral blood of mice in each group were detected by flow cy-tometry.Human Stat1 overexpression plasmid was constructed and transfected into human breast cancer MCF-7 cells,and expression changes of Foxp3 was detected by RT-qPCR and Western blot.Results:Compared with mice in normal control group,proportion of Treg and expression of Foxp3 in lymph nodes and peripheral blood of mice in Flud treatment group were increased,while Stat1 overex-pression resulted in decreased Foxp3 mRNA and protein expression in MCF-7 cells.Conclusion:Stat1 inhibits expression of Foxp3 and production of Tregs.

OBJECTIVE To investigate the mechanism through which Danggui buxue decoction regulates neutrophil extracellular traps （NETs） to improve osteoporosis （OP） in rats with premature ovarian failure （POF）. METHODS Female SD rats were randomly divided into normal group， model group， calcitriol group， and Danggui buxue decoction low-dose， medium-dose and high-dose groups， with 9 rats in each group. Except for the normal group， all other groups were administered cisplatin via intraperitoneal injection on days 1 and 8 to establish a POF complicated with OP model. Each group received the corresponding drugs or normal saline intragastrically starting from day 5， once a day， for 4 consecutive weeks. After the last medication， serum levels of estradiol （E2）， NETs， 25-hydroxyvitamin D3 [25（OH）D3]， receptor activator of nuclear factor-κB ligand （RANKL）， and osteocalcin （BGP） were measured. The histopathological changes in bone tissue were observed. The expressions of vitamin D receptor （VDR）， myeloperoxidase （MPO）， neutrophil elastase （NE） and citrullinated histone H3 （CitH3） in bone tissue were detected； the protein expressions of 25-hydroxyvitamin D-1α-hydroxylase （CYP27B1） and 1α，25-dihydroxyvitamin D3-24-hydroxylase （CYP24A1） were also determined. RESULTS Compared with the normal group， the bone tissue of rats in the model group showed a significant reduction in the number of trabeculae， which was thinner broken and poorly connected， with significant destruction of the reticular structure， and an enlarged marrow cavity. Serum levels of NETs and RANKL， the protein expressions of MPO， NE， CitH3 and CYP24A1 in bone tissue were significantly increased or upregulated， while serum levels of E2， 25（OH）D3 and BGP as well as protein expressions of VDR and CYP27B1 were significantly decreased or downregulated （P＜0.05）. Compared with the model group， the histopathological changes in the bone tissue of rats in each administration group showed some degree of recovery， with significant improvements observed in most quantitative indicators （P＜0.05）. CONCLUSIONS Danggui buxue decoction can restore the E2 level in POF complicated with OP rats， and improve OP. The mechanism may be related to its ability to upregulate VD level and inhibit the formation of NETs.

Objective To investigate the effect of Pirfenidone(PFN)on respiratory syncytial virus(RSV)infection-induced damage to bronchial epithelial cells by regulating the high mobility group protein B1(HMGB1)/receptor for advanced glycation end products(RAGE)signaling pathway.Methods Human bronchial epithelial cells(HBE)were divided into Control group(cultured for 24 h under normal conditions),RSV group(inoculated with 4.65×106/mL RSV at 33℃for 2 h);low PFN(L-PFN)group(treated with 0.05 mg/mL PFN for 24 h),moderate PFN(M-PFN)group(treated with 0.10 mg/mL PFN for 24 h),high PFN(H-PFN)group(treated with 0.20 mg/mL PFN for 24 h)and recombinant HMGB1(rHMGB1)group(treated with 1 μg/mL rHMGB1+0.20 mg/mL PFN for 24 h).EdU method was applied to detect the proliferation rate of cells in each group,Hochest33258 staining method was applied to detect apoptosis status of cells in each group,and the migration of cells in each group was evaluated by the scratch experiment.Enzyme linked immunosorbent assay(ELISA)was applied to measure the levels of interferon(IFN)-α,IFN-γ,tumor necrosis factor-α(TNF-α),interleukin(IL)-1α,IL-6 and IL-4 in each group of cells,and Western blot was applied to detect the protein expression of HMGB1,RAGE,B lymphoblastoma-2-associated X protein(Bax),cysteine aspartic protease-3(Caspase-3),and B lymphoblastoma-2(Bcl-2).Results Compared with the RSV group,the cell proliferation rate,scratch closure rate,IL-4 levels,and expression of Bcl-2 in L-,M-,and H-PFN groups increased,while the apoptosis rate,the levels of IFN-α,IFN-γ,TNF-α,IL-1α,IL-6,and the expression of HMGB1,RAGE,Bax,and Caspase-3 reduced(P<0.05);rHMGB1 weakened the effect of H-PFN on the above-mentioned indicators(P<0.05).Conclusion PFN may suppress the apoptosis and inflammatory damage of RSV-infected bronchial epithelial cells by inhibiting the HMGB1/RAGE pathway.Conclusion PFN may suppress the apoptosis and inflammatory damage of RSV-infected bronchial epithelial cells by inhibiting the HMGB1/RAGE pathway.

Objective:To develop and validate clinical predictive models for identifying poor short-term response to recombinant human growth hormone(rhGH) treatment in children with short stature.Methods:A retrospective analysis was conducted on 118 children diagnosed with growth hormone deficiency or idiopathic short stature who were treated at the First Affiliated Hospital of Zhengzhou University and two other hospitals between January 1, 2020, and January 1, 2024. A poor response to rhGH was defined as a height increase of less than 0.2 standard deviation score(SDS) after 6 months of rhGH treatment. LASSO regression was used to identify predictive variables from baseline and follow-up data. Two logistic regression models were conducted: Model A(incorporating baseline variables only) and model B(incorporating both baseline and follow-up variables), and nomograms were created for visualization. External data and internal resampling were used for dual validation of the models, and their performance was compared.Results:A total of 118 children with short stature were included. Six baseline predictive variables(diagnosis, initial height SDS, bone age, bone age-chronological age difference, rhGH dose, and gender) and one follow-up variable(height SDS after 3 months of rhGH treatment) were identified. Area under the curve values for Model A and Model B were 0.753(95% CI 0.696-0.811) and 0.930(95% CI 0.891-0.975), respectively. Calibration curves, decision curve analysis, and other evaluation metrics demonstrated good discrimination and clinical utility for both models. Model B, incorporating the 3-month follow-up variable, showed superior predictive performance compared to Model A. Conclusions:The clinical prediction models developed in this study(Model A and Model B) are practical and reliable tools for quantitatively, conveniently, and intuitively identifying children with short stature at risk of poor response to rhGH treatment.

Objective:To develop and validate clinical predictive models for identifying poor short-term response to recombinant human growth hormone(rhGH) treatment in children with short stature.Methods:A retrospective analysis was conducted on 118 children diagnosed with growth hormone deficiency or idiopathic short stature who were treated at the First Affiliated Hospital of Zhengzhou University and two other hospitals between January 1, 2020, and January 1, 2024. A poor response to rhGH was defined as a height increase of less than 0.2 standard deviation score(SDS) after 6 months of rhGH treatment. LASSO regression was used to identify predictive variables from baseline and follow-up data. Two logistic regression models were conducted: Model A(incorporating baseline variables only) and model B(incorporating both baseline and follow-up variables), and nomograms were created for visualization. External data and internal resampling were used for dual validation of the models, and their performance was compared.Results:A total of 118 children with short stature were included. Six baseline predictive variables(diagnosis, initial height SDS, bone age, bone age-chronological age difference, rhGH dose, and gender) and one follow-up variable(height SDS after 3 months of rhGH treatment) were identified. Area under the curve values for Model A and Model B were 0.753(95% CI 0.696-0.811) and 0.930(95% CI 0.891-0.975), respectively. Calibration curves, decision curve analysis, and other evaluation metrics demonstrated good discrimination and clinical utility for both models. Model B, incorporating the 3-month follow-up variable, showed superior predictive performance compared to Model A. Conclusions:The clinical prediction models developed in this study(Model A and Model B) are practical and reliable tools for quantitatively, conveniently, and intuitively identifying children with short stature at risk of poor response to rhGH treatment.

Objective:To evaluate the role of exosomes in propofol-induced elimination of cardioprotective effect of remote ischemic preconditioning (RIPC) in rats.Methods:This experiment was performed in 2 parts. In vivo experiment Forty-eight healthy SPF male Sprague-Dawley rats, aged 8-10 weeks, weighing 250-300 g, were divided into 5 groups using the random number table method: sham operation group (Sham group, n=12), ischemia-reperfusion (I/R) group ( n=12), RIPC group ( n=8), RIPC+ propofol group (RIPC+ P group, n=8), and propofol+ I/R group (P+ I/R group, n=8). The model of myocardial I/R injury was developed by ligating the left anterior descending branch of coronary artery for 30 min followed by 120 min reperfusion in anesthetized animals. Four cycles of 5-min ischemia induced by occlusion of the bilateral hind limbs with a tourniquet/5-min reperfusion served as the RIPC stimulus. Propofol was intravenously infused at a rate of 12 mg·kg -1·h -1 in RIPC+ P group (during RIPC) and in P+ I/R group (for 40 min). Exosomes from RIPC-treated and RIPC+ propofol-treated rats were extracted (RIPC-EXO and RIPC+ P-EXO respectively) for determination of the expression of surface markers of exosomes CD9 and HSP70. Another 24 rats were randomly selected, and the aforementioned exosomes were injected at 15 min before myocardial ischemia, resulting in RIPC-EXO+ I/R group ( n=12) and RIPC+ P-EXO+ I/R group ( n=12). At the end of reperfusion, the area of myocardial infarction was determined, the concentration of serum cardiac troponin I (cTnI) was measured by the enzyme-linked immunosorbent assay, and the expression of B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) in myocardial tissues was detected by Western blot. Cell experiment H9c2 cells were cultured in vitro and divided into 4 groups ( n=6 each) using a random number table method: control group (C group), hypoxia-reoxygenation group (H/R group), RIPC-EXOc group and RIPC+ P-EXOc group. The cells were exposed to hypoxia for 4 h followed by reoxygenation for 16 h in H/R group. RIPC-EXO and RIPC+ P-EXO were added at a final concentration of 300 μg/ml before hypoxia in RIPC-EXOc group and RIPC+ P-EXOc group, respectively. The cell viability was determined using a cell counting kit-8 assay and the expression of Bax and Bcl-2 expression was detected by Western blot. Results:In vivo experiment Compared with RIPC-EXO group, the expression of CD9 and HSP70 was significantly down-regulated in RIPC+ P-EXO group ( P<0.05). Compared with Sham group, the percentage of the area of myocardial infarction was significantly increased, and the serum cTnI concentration and Bax/Bcl-2 ratio in myocardial tissues were increased in I/R group ( P<0.05). Compared with I/R group, the percentage of the area of myocardial infarction was significantly decreased in RIPC group and RIPC-EXO+ I/R group, the serum cTnI concentration and Bax/Bcl-2 ratio in myocardial tissues were significantly decreased in RIPC-EXO+ I/R group ( P<0.05), and no significant change was found in the percentage of the area of myocardial infarction in RIPC+ P group ( P>0.05). The percentage of the area of myocardial infarction was significantly larger in RIPC+ P group than in RIPC group ( P<0.05). Compared with RIPC-EXO+ I/R group, the percentage of the area of myocardial infarction was significantly increased, and the serum cTnI concentration and Bax/Bcl-2 ratio were increased in RIPC+ P-EXO+ I/R group ( P<0.05). Cell experiment Compared with C group, the cell viability was significantly decreased, and the Bax/Bcl-2 ratio was increased in H/R group ( P<0.05). Compared with H/R group, the cell viability was significantly increased, and the Bax/Bcl-2 ratio was decreased in RIPC-EXOc group ( P<0.05). Compared with RIPC+ EXOc group, the cell viability was significantly decreased, and the Bax/Bcl-2 ratio was increased in RIPC+ P-EXOc group ( P<0.05). Conclusions:Propofol may abolish the myocardial protective effect of RIPC by decreasing the production and release of serum exosomes in rats.

Objective:To evaluate the role of exosomes in reduction of myocardial ischemia-reperfusion (I/R) injury (MIRI) by remote preconditioning of trauma (RPCT) in rats.Methods:This experiment was performed in 2 parts. In vivo experiment Adult male Sprague-Dawley rats, aged 8 weeks, weighing 250-300 g, were used. Six rats were selected and randomly divided into 2 groups ( n=3 each): control group and RPCT group. Rats in control group underwent thoracotomy only, while rats in RPCT group were subjected to an additional 4 cm transverse skin incision along the abdominal midline after thoracotomy. Blood samples were collected, and serum exosomes were isolated from blood samples and labeled as control exosomes and RPCT exosomes. The expression of exosomal surface marker proteins CD9 and heat shock protein 70 (HSP70) was determined by Western blot, and the serum exosome concentration was measured. Another 30 rats were selected and randomly assigned to 5 groups ( n=6 each): sham operation group (Sham group), I/R group, I/R+ RPCT group, I/R+ control exosomes group (I/R+ EXO-CON group), and I/R+ RPCT exosomes group (I/R+ EXO-RPCT group). The MIRI model was established by ligating the left anterior descending coronary artery for 30 min followed by 120 min of reperfusion in anesthetized animals. In I/R+ RPCT group, the MIRI model was prepared at 15 min after the end of RPCT. In I/R+ EXO-CON and I/R+ EXO-RPCT groups, control exosomes and RPCT exosomes 100 μg were administered via the jugular vein at 15 min before ischemia respectively. At the end of reperfusion, the myocardial infarct size was measured, serum concentrations of cardiac troponin T (cTnT) and lactate dehydrogenase (LDH) were determined, and the contents of malondialdehyde (MDA) and superoxide dismutase (SOD) in myocardial tissues were measured. The expression of B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), caspase-3 and cleaved caspase-3 was detected. In vitro experiment H9c2 cells were cultured in vitro and randomly divided into 4 groups ( n=6 each): control group (Con group), hypoxia/reoxygenation (H/R) group, H/R+ control exosomes group (H/R+ EXO-CON group), and H/R+ RPCT exosomes group (H/R+ EXO-RPCT group). The rats were subjected to 4 h of hypoxia followed by 16 h of reoxygenation to establish the H/R injury model. In H/R+ EXO-CON and H/R+ EXO-RPCT groups, control exosomes and RPCT exosomes 4 μg were added at 15 min before hypoxia respectively. The cell survival rate and concentration of lactate dehydrogenase (LDH) in the supernatant were measured, and the expression of Bax, Bcl-2, cleaved caspase-3 and caspase-3 was detected. Results:In vivo experiment Compared with control group, the expression of serum CD9 and HSP70 was significantly up-regulated, and the exosome concentration was increased in RPCT group ( P<0.05). Compared with Sham group, the serum concentrations of cTnT and LDH, percentage of myocardial infarct size, content of MDA in myocardial tissues, Bax/Bcl-2 ratio, and cleaved caspase-3/caspase-3 ratio were significantly increased, and the activity of SOD was decreased in I/R group ( P<0.05). Compared with I/R group, the serum cTnT and LDH concentrations, percentage of myocardial infarct size, content of MDA in myocardial tissues, Bax/Bcl-2 ratio and cleaved caspase-3/caspase-3 ratio were significantly decreased, and the activity of SOD was increased in I/R+ RPCT group ( P<0.05), and no significant changes were observed in the aforementioned parameters in I/R+ EXO-CON group ( P>0.05). There were no significant differences in the aforementioned parameters between I/R+ RPCT group and I/R+ EXO-RPCT group ( P>0.05). In vitro experiment Compared with Con group, the cell survival rate was significantly decreased, and the LDH concentration in the supernatant and Bax/Bcl-2 and cleaved caspase-3/caspase-3 ratios were increased in H/R group ( P<0.05). Compared with H/R group, the cell survival rate was significantly increased, the LDH concentration in the supernatant, and Bax/Bcl-2 and cleaved caspase-3/caspase-3 ratios were decreased in H/R+ EXO-CON group ( P<0.05), and no significant changes were found in the aforementioned parameters in H/R+ EXO-RPCT group ( P>0.05). Conclusions:The mechanism by which RPCT reduces MIRI may be related to the increased release of serum exosomes in rats.