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Cyclophilin A: a Novel Radioprotector


Cyclophilin A: a Novel Granulocute-Stimulating Factor and a Radioprotector

Tech Area / Field

  • MED-DRG/Drug Discovery/Medicine
  • MED-RAD/Radiomedicine/Medicine

3 Approved without Funding

Registration date

Leading Institute
Cancer Research Center, Russia, Moscow

Supporting institutes

  • Institute of Immunological Engineering, Russia, Moscow reg., Lyubuchany


  • University of Pittsburgh Medical Center / Division of Clinical Immunopathology, USA, PA, Pittsburgh\nUniversity of Turku / Finnish-Russian Joint Biotechnology Laboratory, Finland, Turku\nCNRS / Institute Gustave Roussy (IGR) / Interactions Moleculaires et Cancer, France, Villejuif\nGeorge Washington University / George Washington University Medical Center / Department of Microbiology, Immunology and Tropical Medicine, USA, DC, Washington

Project summary

The aim of the Project is: to estimate haemopoietic properties and possible clinical application of recombinant human Cyclophilin A as a novel granulocyte-stimulating and radioprotective factor.

Cyclophilin A is a protein with molecular mass of 18 kD and participates in the processes of intracellular protein transport acting as an ubiquitinious protein with cis–trans-isomerase activity. Moreover, Cyclophilin A participates in the signal transduction from T-cell receptor and is a ligand for Cyclosporin A, thus determining the immunosuppressing properties of the latter.

Earlier we revealed that thymus cells are able to secret Cyclophilin A spontaneously into the environment. It was found that Cyclophilin A enhances the migration of mouse stem cells from bone marrow to the blood. In particular, singular injection of Cyclophilin A into sub-lethally irradiated mice (4,5 Gr) in a dosage of 50 mkg per mouse increased the number of spleen stem cell colonies 2-3 fold on the day 7 after irradiation (20,06,5 against 6,01,0 in control). The detailed analysis of Cyclophilin A marrow target cells revealed the precursors of dendritic cells and granulocytes as well as precursors of T- and B- cells. Thus, we have demonstrated that Cyclophilin A acts as the chemoattractant for the precursor cells from various bone marrow growths of differentiation and it is potentially involved in the blood and immune system restoration normally and after different stresses.

Due to the practically full homology between human and mouse Cyclophilin A (one aminoacid difference), the effects of this protein are not specie specific. We found that natural Cyclophilin A produced by mouse thymocytes and human recombinant protein from E. coli equally enhance the level of hematopoietic stem cell migration from bone marrow to peripheral blood in sublethally irradiated mice. In addition, the treatment of such mice with human recombinant Cyclophilin A increased mass of their spleens in 1.5-2 times comparing to control animals with irradiation reduced spleens.

We showed that human recombinant Cyclophilin A promotes blood cells restoration after the treatment by high dose chemotherapeutic anti-tumor drugs (cyclophosphamide, 200 mg/kg). It was found that the quantity of leukocytes of cyclophosphamide treated animals increased 3 times exceeding normal numbers under the influence of Cyclophilin A (25-100 mkg/mouse). Morphological examination of blood cells from the mice indicated to predominant increase of granulocytes in a response to human recombinant Cyclophilin A injection. The effect of Cyclophilin A hematopoiesis stimulation after high dose anti-tumor drug treatment was found alike the action of granulocyte colony stimulating factor. Comparative estimation of human recombinant proteins Cyclophilin A and granulocyte colony stimulating factor hematopoietic activities confirmed their analogy in dynamics and activity levels in given model.

The described human recombinant Cyclophilin A properties are revealed for the first time and may prerequisite the clinical trial of the protein in patient with compromised immune and hematopoietic systems, such as tumors and cell static drug therapy, irradiation, immunodeficiencies. The obtained data served a basis to forward an application for Russian Federation patent for invention.

In the project we propose to continue the estimation of therapeutic properties of human recombinant Cyclophilin A, examination the effects of this protein in the mouse models of secondary and innate immune system knockdown: lethal and sublethal irradiation, cytostatic drug treatment, immunodeficient thymus depleted Nude mice e.t.c. Comparative analysis of Cyclophilin A and granulocyte colony stimulating factor influence on growth, differentiation and migration of human blood stem cells in cancer patients after completed course of radio- or chemo- therapy and in healthy donors is also planned.


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