Autologous Human Thrombin: Production from Whole Blood.

Introduction: Thrombin is routinely combined in surgical practice with a fibrinogen source to prepare fibrin sealant to promote hemostasis or with platelet concentrates to prepare platelet gels to enhance wound healing and reduce infections. Currently, thrombin is derived either from bovine tissue or “pooled” human plasma. The purpose of this study was to evaluate the robustness and reproducibility of a new sterile handheld disposable TPD™ (Thrombin Processing Device) to generate autologous human thrombin in the intra-operative setting, using whole blood as the starting source material. By using whole blood instead of plasma as the starting material, it is possible to eliminate the plasma separation step from whole blood and reduce the thrombin production time and increase its availability to the surgical team intra-operatively. The performance of the disposable set was evaluated at the low and high end of operating room temperatures.

Materials and Methods: Active thrombin was prepared by combining 4 ml of thrombin reagent (a mixture of calcium chloride and ethanol) to 11 ml of blood in a reaction chamber containing negatively charged particles. The whole blood, reagent and particle mixture was incubated for 25 minutes at either 18°C or 24°C (n=25/group) to assess stability of the thrombin activity.

Results: The average activity of the thrombin produced at 18°C and 24°C was 52 ± 14 IU/ml (n=25) and 61 ± 12.2 IU/ml (n=25), respectively. The average volume of thrombin harvested from each aliquot of blood was 9 ± 0.6 ml in both groups. The thrombin concentration generated was demonstrated to rapidly (<5 seconds) coagulate fibrinogen concentrate and retained clotting activity for 1 hr at room temperature (18 - 26 ^oC) and up to 4 hours when stored on ice.

Conclusions: The results demonstrate that the TPD is able to consistently generate high thrombin activity from human whole blood. The device offers a robust and rapid approach for preparing active thrombin from whole blood. By eliminating the risk for allergic reactions and blood borne pathogen transmission, autologous human thrombin can be considered as a safer alternative to bovine or “pooled” plasma sourced thrombin.