Novel, high incidence exercise-induced muscle bleeding model in hemophilia B mice: rationale, development and prophylactic intervention

Promoting Sports Practice in Persons with Hemophilia: A Survey of Clinicians' Perspective

Historically, people with hemophilia have been warned to avoid physical activities as a possible cause of bleeding; however, currently, sport is considered necessary, especially in the developmental age, for providing a good quality of life. A survey was proposed to a group of hematologists and sports physicians working in Puglia, Italy, to explore their approach to physical activities for their patients with hemophilia and to obtain suggestions about possible interventions to promote the access of patients to sports. The survey was answered by 6 hematologists and 15 sports physicians. In total, 71% (about six patients/year/physician) of patients with hemophilia seen by sports physicians asked for counseling about sports, and 67% (about five patients/year/physician) actually practiced sports. On the other hand, only 31% (about 16 patients/year/hematologist) of patients asked hematologists questions on sports, and only 16% (about seven patients/year/hematologist) of patients with hemophilia and that were followed-up by hematologists practiced sports. The sports most often recommended to patients with hemophilia by physicians included swimming, athletics, tennis, running and gymnastics. According to hematologists, physical activity was very efficient in improving the quality of life of patients; stability of joints; their psychological, social and musculoskeletal wellbeing; and in reducing the risk of bleedings. On the other hand, physical activity was considered less important in all these areas by sport physicians. In conclusion, answers to this survey suggested that sports could be promoted among hemophilic patients by increasing the sports physicians' knowledge about hemophilia and their special role in this area. In addition, interviewed clinicians were of the opinion that increased awareness of specific guidelines and clinical practice protocols among both hematologists and sports physicians could be beneficial. Finally, answers suggested that access to fitness certification should be facilitated.

Recombinant human prothrombin (MEDI8111) prevents bleeding in haemophilia A and B mice

BACKGROUND

Haemophilia A and B are treated with FVIII and FIX replacement therapy. Treatment may be complicated by inhibitory antibodies that require bypass therapy such as FEIBA(®) in which prothrombin (FII) is suggested to be the main active component.

METHODS

To evaluate the effect of FII on haemophilia recombinant human (rh) FII (MEDI8111) or plasma-derived human FII (pdhFII) was given as single doses to anaesthetized haemophilia A and B mice 3 min before tail transection and rhFVIII or rhFIX was used for comparison. After tail transection, automatic bleeding registration was used to continuously measure blood loss (BL) and bleeding time (BT). Thrombin generation and plasma concentrations of human FVIII, FIX, FII and thrombin-antithrombin complex (TAT) were measured.

RESULTS

Blood loss and BT were dose-dependently decreased by rhFVIII or rhFIX. The concentrations that decreased BL and BT for rhFVIII by 50% (EC50) were 0.06 and 0.01 IU mL(-1) and for rhFIX 0.07 and 0.07 IU mL(-1) , respectively. Administration of rhFVIII and rhFIX dose-dependently increased thrombin generation potential but did not affect TAT. MEDI8111 and pdhFII dose-dependently decreased BL and BT in haemophilia A mice, EC50 37 and 87 and 100 and 155 mg L(-1) respectively. In haemophilia B mice given MEDI8111 EC50 was for BL 56 mg L(-1) and for BT 67 mg L(-1) . TAT and thrombin generation increased dose-dependently for MEDI8111 and pdhFII.

CONCLUSION

MEDI8111 dose-dependently decreased bleeding and increased procoagulant activity in haemophilia A and B mice and suggest that MEDI8111 may be useful for preventing bleeding in patients with haemophilia A and B.