Annals of Nuclear Medicine

, 6:177 | Cite as

In vivo distribution of Tc-99m labeled recombinant tissue-type plasminogen activator in control and thrombus-bearing rats

  • Eriko Tsukamoto
Original Article


In vivo distribution of Tc-99m labeled recombinant tissue-type plasminogen activator (Tc-99m-rt-PA) was studied in control rats and thrombus-bearing rats. To compare fibrin bindingin vivo with thatin vitro, Tc-99m-rt-PA binding to fibrin gelin vitro was also imaged.

Rapid blood clearance and accumulation into the liver and kidneys were observed in both control and thrombus-bearing rats. Accumulation in the stomach, which indicates instability of labeled rt-PAin vivo, was very low until two hours after injection. Tc-99m-rt-PA accumulation in the clots was higher than that in skeletal and heart muscles, although it was lower than in blood, liver, and kidneys. Administration of aprotinin, an antifibrinolytic agent, significantly prolonged clot accumulation of Tc-99m-rt-PA at 30 minutes after injection. These results suggest that fibrinolysis is responsible for the low rt-PA concentration in the clots. A scintigram of a thrombus-bearing rat demonstrated increased radioactivity at the clot forming site. On the other hand, Tc-99m-labeled human albumin, which was used as a control, was not accumulated in the clot. Tc-99m-rt-PA binding to fibrin gelin vitro was clearly imaged.

By comparison,in vivo fibrin binding of Tc-99m-rt-PA was much lower thanin vitro. The reasons for low thrombus uptakein vivo may be: 1. biochemical inactivation of extrinsically administered rt-PA by t-PA inhibitor. 2. fibrinolysis by rt-PA activated plasminogen. Overcoming these limitations will enable Tc-99m-rt-PA to reach the stage of clinical trials.

Key words

recombinant tissue-type plasminogen activator (rt-PA) Tc-99m labeling biodistribution thrombus imaging 


  1. 1.
    Health and Welfare Statistics Association: Dynamic statistics of population (Jinkou doutai toukei).J Health and Welfare Statistics 37(9): 388–411, 1990 (in Japanese)Google Scholar
  2. 2.
    Gallus AS, Hirsh J, Hull R, et al: Diagnosis of venous thromboembolism.Semin Throm Hem 2: 203–231, 1976Google Scholar
  3. 3.
    Knight LC: Radiopharmaceuticals for thrombus detection.Semin Nucl Med 20: 52–67, 1990CrossRefPubMedGoogle Scholar
  4. 4.
    Oster ZH, Som P: New perspectives in thrombus-specific imaging: radiolabeled monoclonal antibodies.AJR 152: 253–260, 1989PubMedGoogle Scholar
  5. 5.
    Thakur ML, Welch MJ, Joist JH, et al: Indium-111 labeled platelets: studies on preparation and evaluation ofin vitro andin vivo function.Thromb Res 9: 345–357, 1976CrossRefPubMedGoogle Scholar
  6. 6.
    Davis HH, Siegel BA, Sherman LA, et al: Scintigraphy with In-111 labeled autologous platelets in venous thromboembolism.Radiology 136: 203–207, 1980PubMedGoogle Scholar
  7. 7.
    De Faucal P, Peltier P, Planchon B, et al: Evaluation of111In-labeled antifibrin monoclonal antibody for the diagnosis of venous thrombotic disease.J Nucl Med 32: 785–791, 1991PubMedGoogle Scholar
  8. 8.
    Knight LC, Maurer AH, Ammar IA, et al: Evaluation of indium-111-labeled anti-fibrin antibody for imaging vascular thrombi.J Nucl Med 29: 494–502, 1988PubMedGoogle Scholar
  9. 9.
    Som P, Oster ZH, Zamora PO, et al: Radioimmunoimaging of experimental thrombi in dogs using technetium-99m-labeled monoclonal antibody fragments reactive with human platelets.J Nucl Med 27: 1315–1320, 1986PubMedGoogle Scholar
  10. 10.
    Knight LC: Do we finally have a radiopharmaceutical for rapid, specific imaging of venous thrombosis?J Nucl Med 33: 791–795, 1991Google Scholar
  11. 11.
    Itoh K, Tsukamoto E, Nishibe T, et al: Tc-99m labeled tissue-type plasminogen activator: preparation, stability and preliminary imaging of thrombus bearing rats.Ann Nucl Med 5: 59–64, 1991CrossRefPubMedGoogle Scholar
  12. 12.
    Hoylayaerts M, Rijken DC, Lijnen HR, et al: Kinetics of the activation of plasminogen by human tissue plasminogen activator. Role of fibrin.J Biol Chem 257: 2912–2919, 1982Google Scholar
  13. 13.
    DeBoer AC, Pauluama JH, Cox PH, et al: Tc-99m labeled plasminogen activator (PA) for the diagnosis of deep vein thrombosis [Abstract].Thromb Haemostas 50: 159, 1983Google Scholar
  14. 14.
    Uehara A, Isaka Y, Etani H, et al: Binding of I-131-labeled tissue-type plasminogen activator on de-endothelialized lesions in rabbits.Nuklearmedizin 26: 224–228, 1987PubMedGoogle Scholar
  15. 15.
    Hnatowith DJ, Virzi F, Doherty PW, et al: Characterization of indium-111-labeled recombinant tissue plasminogen activator for the imaging of thrombi. EurJ Nucl Med 13: 467–473, 1987Google Scholar
  16. 16.
    Butler SP, Kader KL, Owen J, et al: Rapid Localization of Indium-111-labeled inhibited recombinant tissue plasminogen activator in rabbit thrombus model.J Nucl Med 32: 461–467, 1991PubMedGoogle Scholar
  17. 17.
    Korninger C, Stassen JM, Collen D: Turnover of human extrinsic (tissue-type) plasminogen activator in rabbits.Thromb Haemosta 46: 658–661, 1981Google Scholar
  18. 18.
    Nilsson T, Wallen P, Mellbring G:In vivo metabolism of human tissue plasminogen activator.Scan J Haematol 33: 49–53, 1984Google Scholar
  19. 19.
    Fuchs HE, Berger H, Pizzo SV: Catabolism of human tissue plasminogen activator in mice.Blood 65: 539–544, 1985PubMedGoogle Scholar
  20. 20.
    Emeis JJ, van den Hoogen CM, Jense D: Hepatic clearance of tissue-type plasminogen activator in rats.Thromb Haemosta 54: 661–664, 1985Google Scholar
  21. 21.
    Closel JP, Banken L, Roux S: Aprotinin: An anti- dote for recombinant tissue-type plasminogen activator (rt-PA) activein vivo.JACC 16: 507–510, 1990Google Scholar
  22. 22.
    Hunt B, Cottam S, Segal H, et al: Inhibition by aprotinin of t-PA-mediated fibrinolysis during orthotopic liver transplantation.Lancet 336: 381, 1990CrossRefPubMedGoogle Scholar
  23. 23.
    Verheijen JH, Chang GTG, Kluft C: Evidence for the occurrence of a fast-acting inhibitor for tissue-type plasminogen activator in human plasma.Throm Haemostas 51: 392–395, 1984Google Scholar
  24. 24.
    Wiman B, Chemielewska J, Randy M: Inactivation of tissue type plasminogen activator in plasma. Demonstration of a complex with a rapid inhibitor.J Biol Chem 259: 3644–3647, 1984PubMedGoogle Scholar
  25. 25.
    Kruithof EKO, Tran-Thang C, Ransijn A, et al: Demonstration of a fast-acting inhibitor of plasminogen activators in human plasma.Blood 64: 907–913, 1984PubMedGoogle Scholar
  26. 26.
    Fry ETA, Mack DL, Monge JC, et al: Labeling of human clotsin vitro with an active-site mutant of t-PA.J Nucl Med 30: 187–191, 1990Google Scholar
  27. 27.
    Pohl G, Sterky C, Nyberg E, et al: Tissue plasminogen activator mutants lacking the growth factor domain and the first kringle domain: I DNA constructions, expression in mammalian cells, protein structure, fibrin affinity and enzyme properties.Fibrinolysis 5: 17–29, 1991CrossRefGoogle Scholar
  28. 28.
    Wikstrom K, Mattsson C, Sterky C, et al: Tissue plasminogen activator mutants lacking the growth factor domain and the first kringle domain: II Enzymatic properties in plasma andin vitro thrombolytic activity and clearance rates in rabbits.Fibrinolysis 5: 31–41, 1991CrossRefGoogle Scholar
  29. 29.
    Coleman P, Kettner C, Shaw E: Inactivation of the plasminogen activator from HeCa cells by peptides of arginine chloromethyl ketoneBiochem Biolphys Acta 569: 41–51, 1979Google Scholar
  30. 30.
    Monge JC, Lucore CL, Fry ET, et al: Characterization of interaction of active-site serine mutants of tissue-type plasminogen activator with plasminogen activator inhibitor-1.J Biol Chem 264: 10922–10925, 1989PubMedGoogle Scholar
  31. 31.
    Russell ME, Quertermoust T, Declerck PJ: Binding of tissue-type plasminogen activator with human endothelial cell monolayers characterization of high affinity interaction with plasminogen activator inhibitor-1.J Biol Chem 265: 2569–2575, 1990PubMedGoogle Scholar
  32. 32.
    Korninger C, Collewn D: Studies on the specific fibrinolytic effect of human extrinsic (tissue-type) plasminogen activator in human blood and in various animal speciesin vitro.Thromb Haemostas 46: 561–565, 1981Google Scholar
  33. 33.
    Haggroth L, Mattsson CH, Fryberg J: Inhibition of the human tissue plasminogen activator in plasma from various species.Thromb Res 33: 583–594, 1984CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • Eriko Tsukamoto
    • 1
  1. 1.Department of Nuclear MedicineHokkaido University School of MedicineSapporoJapan

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