**4. Platelets in hemophilia**

Platelets are key components of primary coagulation system [50]. TF released from the damaged endothelial cells activates the platelets [51].Activated platelets get adhere to the site of damage with help of vWF [52]. Upon activation platelets expose phosphatidylserine which gives the lipid surface to the coagulation cascade [51]. Recent studies elucidate that platelets can play a major role in hemophilia, as hemophilia patients with same FIX or FVIII antigen levels has different clotting time due to variations in the platelet mediated coagulation activity [53–55]. Platelets store FVIII in the alpha granules therefore, platelets are being used as therapeutic components for hemophilia treatment, majorly in gene therapy. In a recent study, hemophilic dogs were transfused with genetically modified platelets (which can over express FVIII gene). Bleeding events were stopped in the hemophilic dogs after transfusing them with genetically altered platelets [53].
