Purpose To study the thrombolytic effect and safety of cRGD urokinase liposomes (cRGD-UK-LIP) in rats with acute pulmonary microthromboembolism (APMTE), and explore the application value of echocardiography (ECHO) in animal models. Patients and Methods Ninety-six SD rats were randomized into 6 groups (16/group): normal control, sham operation, APMTE, normal saline (NS), free urokinase (UK), cRGD-UK-LIP. Four groups (APMTE, NS, UK, cRGD-UK-LIP) of rats were injected with autologous thrombus to induce APMTE. Samples were injected into 3 groups (NS, UK, cRGD-UK-LIP) of rats after modeling. Echocardiography was used to assess right ventricle (RV) function and morphology in rats. Six rats in each group were randomly selected and pulmonary artery pressure (PAP) of them was measured through ECHO-guided transthoracic puncture. Finally, the rats were killed and their tissues were taken for pathological examination. Results Compared with normal control or sham operation group, rats in APMTE group had enlarged RV, decreased RV function, increased PAP, and lung tissue of them showed postthromboembolic appearance. There was no significant difference between NS group and APMTE group. RV morphology and function of rats in the UK group and cRGD-UK-LIP group were better and vessels with residual thrombus in these 2 groups were less than APMTE group, especially in the cRGD-UK-LIP group. In terms of PAP, only cRGD-UK-LIP group was significantly lower than APMTE group. No hyperemia, bleeding and swelling were observed in heart, liver and kidney of rats in each group. Conclusion A rat model of APMTE was successfully established. cRGD-UK-LIP has better thrombolytic effect than free urokinase and it is safe. Echocardiography is not merely an important way to evaluate the morphology and function of RV, transthoracic puncture measurement under the guidance of it can be an effective way to monitor PAP in animal models.

Backgroud:In-situ thrombosis is a significant pathophysiological basis for the development of pulmonary hypertension (PH). However, thrombolytic therapy for in-situ thrombus in PH was often hampered by the apparent side effects and the low bioavailability of common thrombolytic medications. Nanoscale cyclic RGD (cRGD)-decorated liposomes have received much attention thanks to their thrombus-targeting and biodegradability properties. As a result, we synthesized urokinase-loaded cRGD-decorated liposome (UK-cRGD-Liposome) for therapy of in-situ thrombosis as an exploration of pulmonary hypertensive novel therapeutic approaches.Purpose: To evaluate the utilize of UK-cRGD-Liposome for targeted thrombolysis of in-situ thrombus in PH and to explore the potential mechanisms of in-situ thrombus involved in the development of PH.Methods: UK-cRGD-Liposome nanoscale drug delivery system was prepared using combined methods of thin-film hydration and sonication. Induced PH via subcutaneous injection of monocrotaline (MCT). Fibrin staining (modified MSB method) was applied to detect the number of vessels within-situ thrombi in PH. Echocardiography, hematoxylin-eosin (H & E) staining, and Masson’s trichrome staining were used to analyze right ventricular (RV) function, pulmonary vascular remodeling, as well as RV remodeling.Results: The number of vessels with in-situ thrombi revealed that UK-cRGD-Liposome could actively target urokinase to in-situ thrombi and release its payload in a controlled manner in the in vivo environment, thereby enhancing the thrombolytic effect of urokinase. Pulmonary artery hemodynamics and echocardiography indicated a dramatical decrease in pulmonary artery pressure and a significant improvement in RV function post targeted thrombolytic therapy. Moreover, pulmonary vascular remodeling and RV remodeling were significantly restricted post targeted thrombolytic therapy.Conclusion: UK-cRGD-Liposome can restrict the progression of PH and improve RV function by targeting the dissolution of pulmonary hypertensive in-situ thrombi, which may provide promising therapeutic approaches for PH.

Objectives: Pulmonary artery pressure measurement is key to verifying the success of a rat model of pulmonary hypertension(PH). Herein, a novel method for measuring pulmonary artery pressure through high-frequency ultrasound-guided transthoracic puncture was demonstrated in rats. The efficacy and time of this novel method were also discussed. Methods: A single subcutaneous injection of monocrotaline was used to establish a rat model of PH. The tip of that puncture cannula was maintained at a certain angle after the needle core was removed through heat shaping method. In the short-axis section of the parasternal aorta, in-plane real-time guided trocar puncture of the right ventricular outflow tract was performed. The external pressure sensor was used to record the real-time waveform, right ventricular systolic pressure, pulmonary artery systolic pressure, and diastolic pressure. Results: The success rates of using this novel method in the model group and the control group were 88.5% and 86.7%, respectively, and the puncture pressure measurement times were 164 ± 31s and 235 ± 50s, respectively. The model group’s right ventricular systolic blood pressure, pulmonary systolic blood pressure, and diastolic blood pressure were higher than those of the control group. Conclusions: The modified method for trocar is helpful for accurately positioning pulmonary artery manometry. The method described in this paper has a high success rate and short operation time. It has a broad application prospect in verifying rat PH model and pulmonary artery pressure monitoring.