Human endothelial cells synthesize and release ADAMTS-13

Area of Science:

• Biochemistry
• Cell Biology
• Hematology

Background:

• Hepatic stellate cells were previously thought to be the main source of ADAMTS-13.
• ADAMTS-13 is a metalloprotease that cleaves von Willebrand factor (VWF).

Purpose of the Study:

• To investigate whether human endothelial cells synthesize and release ADAMTS-13.
• To determine the source of plasma ADAMTS-13.

Main Methods:

• Immunofluorescence and antibody staining to detect ADAMTS-13 antigen in endothelial cells.
• Reverse transcription-polymerase chain reaction (RT-PCR) to detect ADAMTS13 mRNA.
• Immunoprecipitation and enzymatic assays to confirm protein presence and activity.

Main Results:

• ADAMTS-13 antigen was found intracellularly in human umbilical vein (HUVECs) and arterial endothelial cells (HUAECs), distinct from VWF.
• ADAMTS13 mRNA was detected, indicating synthesis within these cells.
• Enzymatically active ADAMTS-13 protein (approx. 170 kDa) was immunoprecipitated and released from endothelial cells.

Conclusions:

• Human endothelial cells synthesize ADAMTS-13.
• ADAMTS-13 is constitutively released from endothelial cells.
• Endothelial cells represent a potentially significant source of plasma ADAMTS-13.