Currently, haemophilia A cannot be cured. To prevent major bleeding episodes in haemophilia, human Factor VIII (FVIII) protein must be frequently administered as prophylaxis or on demand. This treatment is complicated by its high cost and development of antibodies that neutralize FVIII activity in 20 to 30% of the patients. Therefore, permanent solutions in the form of cell and gene therapy are very attractive for haemophilia A. Recently, we demonstrated in a murine model that liver sinusoidal endothelial cells (LSEC) produce and secrete FVIII, although not exclusively. We have also found that these mice can be treated by reconstitution with wild-type bone marrow, indicating that bone marrow-derived cells, of hematopoietic, mesenchymal or even endothelial origin, can produce and secrete FVIII. Based on these findings in mice, I propose that human LSEC, umbilical cord blood cells, and bone marrow cells might be suitable sources of FVIII to be used for cell replacement therapy for haemophilia A. To advance opportunities for cell and gene therapies in haemophilia A and for identifying additional cell sources of FVIII, I intend to explore whether replacement of liver endothelium and bone marrow in immnocompromised Haemophilia A mice with healthy human cells will provide therapeutic correction. Recently, the possibility of reprogramming mature somatic cells to generate induced pluripotent stem (iPS) cells has enabled the derivation of disease-specific pluripotent cells, thus providing unprecedented experimental platforms to treat human diseases. Therefore, I intend to study whether the generation of patient-specific iPS cells may be applied to cell and gene therapy of coagulation disorders and in particular for the treatment of Haemophilia A. Studies with these novel target cells may impact significantly the future course of Haemophilia A by providing proof-of feasibility of a novel therapy strategies.