In Vitro Evaluation of the Procoagulant Properties of Autologous Peripheral Blood Stem Cell Transplant

Autologous transplantation is a treatment option for bone marrow toxicity induced by chemotherapy and/or radiotherapy in cancer patients. Although it improves patient survival, autologous transplantation is associated with thrombotic complications. The procoagulant properties of autologous peripheral blood stem cell transplant (APBSCT) have never been characterized.

The aim of this study was to determine in vitro the procoagulant properties of APBSCT transfused in patients with solid tumors.

Samples of APBSCT from 10 consecutive patients eligible for autologous transplantation were studied. The ability of APBSCT to induce in vitro thrombin generation in normal platelet poor or rich plasma (PPP or PRP respectively) was evaluated. The APBSCT was diluted 1/10 in PPP or PRP. Thrombin generation was measured using the Calibrated Automated Thrombogram (Thrombinoscope bv Stago France). In control experiments the APBSCT was replaced by saline. Platelet- and erythrocyte-derived microparticles (PdMP and EdMP respectively) were determined by flow cytometry using monoclonal antibodies anti-CD41-PE and anti-CD235a-PE respectively. Five out of 10 samples of APBSCT were also studied for tissue factor (TF) and phosphatidylserine (PS) expression. The TF was revealed by the monoclonal antibody anti-CD142-PE and PS by annexin V-FITC.

In both PPP and PRP experiments, APBSCT increased thrombin generation compared with the controls. In the presence of the APBSCT, the chronometric parameters of the thrombogram (lag time and time-to-peak) were significantly shorter and the peak and mean rate index (MRI) were significantly increased as compared to the experiment controls. The endogenous thrombin potential (ETP) was the only parameter of the thrombogram that was not influenced (Table). Increased expression of PdMP was noticed in APBSCT samples as compared to the control group (23979 ± 29 204 versus 752 ± 432, p <0.001). No significant difference was found in EdMP (55 ± 67 versus 69 ± 49, p> 0.05). In the five samples PS had a greater mean fluorescence intensity as compared to the control group (PS = 25 ± 6 versus 9 ± 4, p <0.01). In contrast, TF was not significantly different (FT = 5 ± 4 versus 4 ± 2, p> 0.05).

The APBSCT used for autologous transplatation in patients with solid cancer accelerate in vitro thrombin generation in PPP and PRP and presents significant procoagulant properties. These procoagulant properties of APBSC are related to an important expression of PdMP and PS. Whether the transfusion of the APBSCT induces a hypercoagulable state in vivo that merits further investigation.

Table: Parameters of thrombogram. * p<0.05, ** p<0.01 APBSCT induced thrombin generation was compared to saline experiments. APBSCT: autologous peripheral blood stem cell transplant, PPP: Plasma poor in platelets, PRP: plasma rich in platelets, ETP: endogenous thrombin potential, MRI: mean rate index.

No relevant conflicts of interest to declare.