Factor VIII is produced primarily by which cells?

Factor VIII is produced primarily by which cells?

• A. Liver
• B. Spleen
• C. Vascular endothelial cells
• D. Platelets

Answer: (C)

The main idea here is where Factor VIII is produced and how it stays in circulation. Factor VIII is a coagulation cofactor that helps the intrinsic pathway convert prothrombin to thrombin. It is mainly produced by the cells lining the blood vessels—the vascular endothelium. Endothelial cells secrete Factor VIII into the bloodstream, where it remains bound to von Willebrand factor, a partner also produced by endothelial cells that protects and stabilizes FVIII in circulation. While the liver makes many coagulation factors, it is not the primary source of Factor VIII. Platelets do not synthesize Factor VIII, though they carry von Willebrand factor. Spleen is not a major source either. So, the best answer is that vascular endothelial cells are the primary producers of Factor VIII.

The main idea here is where Factor VIII is produced and how it stays in circulation. Factor VIII is a coagulation cofactor that helps the intrinsic pathway convert prothrombin to thrombin. It is mainly produced by the cells lining the blood vessels—the vascular endothelium. Endothelial cells secrete Factor VIII into the bloodstream, where it remains bound to von Willebrand factor, a partner also produced by endothelial cells that protects and stabilizes FVIII in circulation. While the liver makes many coagulation factors, it is not the primary source of Factor VIII. Platelets do not synthesize Factor VIII, though they carry von Willebrand factor. Spleen is not a major source either. So, the best answer is that vascular endothelial cells are the primary producers of Factor VIII.