Plasma fibronectin contributes to fibronectin in tissues

Area of Science:

• Connective tissue biology
• Plasma protein dynamics

Background:

• Hepatocytes are the primary source of plasma fibronectin.
• Mesenchymal cells produce fibronectin in vitro and potentially in vivo.
• The origin of tissue fibronectin remains unclear.

Purpose of the Study:

• To investigate the distribution and origin of fibronectin in rat connective tissue.
• To determine the contribution of plasma fibronectin to tissue fibronectin.

Main Methods:

• Direct and indirect immunofluorescence to detect fibronectin in rat tissues.
• Intravenous injection of 125I-labelled fibronectin to track its distribution and clearance.
• Measurement of fibronectin half-life in circulation.

Main Results:

• Fibronectin was found ubiquitously in rat connective tissue.
• Significant uptake of injected fibronectin into tissues was observed.
• The half-time for circulating fibronectin removal was approximately 15 hours.

Conclusions:

• A continuous flux of fibronectin occurs from plasma into tissues.
• Plasma fibronectin is a significant contributor to tissue fibronectin under normal physiological conditions.