A model of chronic thromboembolic pulmonary hypertension with the use of microencapsulated fibrin particles

Aim. To develop a model of chronic thromboembolic pulmonary hypertension (CTEPH) in rats by embolization of the pulmonary vascular bed with microencapsulated fibrin (MF).

Materials and methods. Microencapsulated fibrin (MF) was prepared by encapsulating fibrin particles smaller than 71 μm in sodium alginate. Non-encapsulated fibrin with a particle size of 71–200 µm was used as an alternative embolic particle. Modeling was performed on male Wistar rats. The animals were divided into 4 groups. Intact (INT) animals (n = 7) were administered normal saline intravenously. In the NF8 group (n = 14), non-encapsulated fibrin was injected as embolic particles 8 times every 4 days. In the MF5 group (n = 14), 0.5 ml MF (9,047 ± 430 particles) was administered intravenously 5 times every 5 days. In the MF8 group (n = 14), MF was administered 8 times every 4 days. Six weeks after the last injection of embolic particles, cardiac catheterization with manometry and histologic examination of the lungs were performed.

Results. According to cardiac catheterization, right ventricular systolic pressure (RVSP) in the MF8 group was significantly higher compared to rats from the INT and NF8 groups (p < 0.05). The hypertrophy index and the percentage of collagen fibers in the structure of the vascular wall of the pulmonary artery branches were significantly higher in the MF5 and MF8 groups than in the INT and NF8 groups (p < 0.01). There were no significant differences between the MF5 and MF8 groups.

Conclusion. A representative CTEPH model in rats was developed, characterized by a stable increase in RVSP and pronounced structural changes in the branches of the pulmonary artery.

1. Konstantinides S.V., Meyer G., Becattini C., Bueno H., Geersing G.J., Harjola V.P. et al. 2019 ESC guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur. Heart J. 2020;41(4):543–603. DOI: 10.1093/eurheartj/ehz405.

2. Simonneau G., Dorfmüller P., Guignabert C., Mercier O., Humbert M. Chronic thromboembolic pulmonary hypertension: the magic of pathophysiology. Ann. Cardiothorac. Surg. 2022;11(2):106–119. DOI: 10.21037/acs-2021-pte-10.

3. Riedel M., Stanek V., Widimsky J., Prerovsky I. Longterm follow-up of patients with pulmonary thromboembolism. Late prognosis and evolution of hemodynamic and respiratory data. Chest. 1982;81(2):151–158. DOI: 10.1378/chest.81.2.151.

4. Karpov A.A., Vaulina D.D., Smirnov S.S., Moiseeva O.M., Galagudza M.M. Rodent models of pulmonary embolism and chronic thromboembolic pulmonary hypertension. Heliyon. 2022;8(3):e09014. DOI: 10.1016/j.heliyon.2022.e09014.

5. Deng C., Wu D., Yang M., Chen Y., Wang C., Zhong Z. et al. Expression of tissue factor and forkhead box transcription factor O-1 in a rat model for chronic thromboembolic pulmonary hypertension. J. Thromb. Thrombolysis. 2016;42(4):520–528. DOI: 10.1007/s11239-016-1413-9.

6. Deng C., Zhong Z., Wu D., Chen Y., Lian N., Ding H. et al. Role of FoxO1 and apoptosis in pulmonary vascular remolding in a rat model of chronic thromboembolic pulmonary hypertension. Sci. Rep. 2017;7(1):2270. DOI: 10.1038/s41598-017-02007-5.

7. Runyon M.S., Gellar M.A., Sanapareddy N., Kline J.A., Watts J.A. Development and comparison of a minimally-in vasive model of autologous clot pulmonary embolism in Sprague-Dawley and Copenhagen rats. Thromb. J. 2010;8:3. DOI: 10.1186/1477-9560-8-3.

8. Wu D., Chen Y., Wang W., Li H., Yang M., Ding H. et al. The role of inflammation in a rat model of chronic thromboembolic pulmonary hypertension induced by carrageenan. Ann. Transl. Med. 2020;8(7):492. DOI: 10.21037/atm.2020.02.86.

9. Karpov A.A., Mihailova A.M., Cherepanov D.E., Chefu S.G., Shilenko L.A., Vaulina D.D. et al. The use of microencapsulated autologous thrombi for modelling chronic thromboembolic pulmonary hypertension in rats. Bull. Exp. Biol. Med. 2023;175(5):616–619. DOI: 10.1007/s10517-023- 05912-0.

10. Zagorski J., Neto-Neves E., Alves N.J., Fisher A.J., Kline J.A. Modulation of soluble guanylate cyclase ameliorates pulmonary hypertension in a rat model of chronic thromboembolic pulmonary hypertension by stimulating angiogenesis. Physiol. Rep. 2022;10(1):e15156. DOI: 10.14814/phy2.15156.

11. Toba M., Nagaoka T., Morio Y., Sato K., Uchida K., Homma N. et al. Involvement of Rho kinase in the pathogenesis of acute pulmonary embolism-induced polystyrene microspheres in rats. Am. J. Physiol. Lung Cell Mol. Physiol. 2010;298(3):L297–303. DOI: 10.1152/ajplung.90237.2008.

12. Watts J.A., Marchick M.R., Gellar M.A., Kline J.A. Up-regulation of arginase II contributes to pulmonary vascular endothelial cell dysfunction during experimental pulmonary em bolism. Pulm. Pharmacol. Ther. 2011;24(4):407–413. DOI: 10.1016/j.pupt.2011.01.009.

13. Arias-Loza P.A., Jung P., Abeßer M., Umbenhauer S., Williams T., Frantz S. et al. Development and characterization of an inducible rat model of chronic thromboembolic pulmonary hypertension. Hypertension. 2016;67(5):1000–1005. DOI: 10.1161/HYPERTENSIONAHA.116.07247.

14. Karpov A.A., Anikin N.A., Mihailova A.M., Smirnov S.S., Vaulina D.D., Shilenko L.A. et al. Model of chronic thromboembolic pulmonary hypertension in rats caused by repeated intravenous administration of partially biodegradable sodium alginate microspheres. Int. J. Mol. Sci. 2021;22(3):1149. DOI: 10.3390/ijms22031149.

15. Jennewein C., Tran N., Paulus P., Ellinghaus P., Eble J.A., Zacharowski K. Novel aspects of fibrin(ogen) fragments during inflammation. Mol. Med. 2011;17(5-6):568–573. DOI: 10.2119/molmed.2010.00146.

16. Ippolito C., Colucci R., Segnani C., Errede M., Girolamo F., Virgintino D. et al. Fibrotic and vascular remodelling of colonic wall in patients with active ulcerative colitis. J. Crohns Colitis. 2016;10(10):1194–1204. DOI: 10.1093/ecco-jcc/jjw076.

17. Kitagawa M.G., Reynolds J.O., Wehrens X.H.T., Bryan R.M. Jr., Pandit L.M. Hemodynamic and pathologic characterization of the TASK-1-/-mouse does not demonstrate pulmonary hypertension. Front. Med. (Lausanne). 2017;4:177. DOI: 10.3389/fmed.2017.00177.

18. Barnhart M.I., Riddle J.M., Bluhm G.B., Quintana C. Fibrin promotion and lysis in arthritic joints. Ann. Rheum. Dis. 1967;26(3):206–218. DOI: 10.1136/ard.26.3.206.

19. Colvin R.B., Johnson R.A., Mihm M.C. Jr., Dvorak H.F. Role of the clotting system in cell-mediated hypersensitivity. I. Fibrin deposition in delayed skin reactions in man. J. Exp. Med. 1973 138(3):686–698. DOI: 10.1084/jem.138.3.686.