Tissue Factor (TF) Nanodisc

 

This technology marries the Recombinant Human Tissue Factor (TF) with Membrane Scaffold Protein (MSP) Nanodiscs, resulting in an efficient and easy to administer blood coagulation agent that has the potential for major advances in medicine.

Tissue factor initiates blood clotting by selectively binding one of the soluble plasma proteins, either factor VII or the activated form, factor VIIa, with high affinity. This results in the formation of TF:VIIa complexes on the cell surface. Factor VIIa, the first enzyme in the blood clotting cascade, is a serine protease that circulates as a soluble protein in the plasma. Factor VIIa is an extremely weak enzyme unless it is bound to its protein cofactor, TF. Factor VIIa is allosterically activated when it binds to TF, creating an extremely potent, two-subunit enzyme - TF:VIIa. The complex then triggers blood clotting by proteolytically activating two plasma serine protease zymogens, which then propagate the clotting cascade.

The result is the formation of blood clots composed of polymerized fibrin and activated platelets. Tissue factor can be successfully incorporated into Nanodiscs (TF-Nanodiscs), where it is highly functional at assembling the TF:VIIa enzyme complex. The enzyme kinetic properties of TF:VIIa complexes assembled on TF-Nanodiscs are very comparable to such complexes assembled on conventional phospholipid vesicles.

Applications

  • Topical clotting agent: TF-Nanodiscs could be assembled into matrices that would allow for them to be applied to the surface of a wound, rather than injected into the patient's blood supply, to encourage accelerated clotting locally. Such topical methods of application would be beneficial in emergency situations or surgeries in areas typically associated with heavy bleeding.
  • Internal blood-loss control: In clinical situations where there is excessive bleeding, such as invasive surgery on hemophiliacs or patients being treated with blood thinners, TF-Nanodiscs may be able to be hypodermically injected into a patient, and allowed to bind to proteins that are exposed only at sites of trauma.
  • Kill Tumors: By tethering antibodies or other targeting molecules to TF-Nanodiscs, the compound could be injected into the blood stream and allowed to bind to the surface of a tumor. Once attached, the TF-Nanodiscs would trigger local blood clotting, infarcting the tumor bed and resulting in death of the tumor due to restricted blood supply.
  • Prothrombin time assays: The TF-Nanodisc could be used in a lab to rapidly screen for clotting problems or to monitor patients taking oral blood thinners.

Benefits

  • Small structure & high stability: TF molecules have shown a high affinity for Nanodisc chemistry. As the Nanodisc is formed, TF is embedded into the Nanodisc in a conformation that preserves the clotting agent's natural structure and functionality.
  • More reliable than soluble TF: Tissue Factor built into Nanodiscs can be up to 90% more potent than TF solutions, decreasing the necessary dosage.
  • Fewer side effects than soluble TF: Application of soluble TF has resulted in disseminated intravascular coagulation (DIC). TF-Nanodiscs could reduce or eliminate the risks associated with this