Short summary of Tamaki, K et al; Fibrocytes and fibrovascular membrane formation in proliferative diabetic retinopathy. Invest Ophthalmol Vis Sci 2016, 57(11). Full article can be found here.

Diabetic retinopathy is classified in four stages of which proliferative diabetic retinopathy (PDR) is the most advanced stage. It is characterized by the formation of a fibrovascular membrane (FVM), which is the result of chronic inflammation and ischemia.

A circulating bone marrow-derived population of fibroblast-like cells, termed fibrocytes, has recently been suggested to have a role in the pathogenesis of fibrosis in various organs. Serum amyloid P component (SAP) is a highly conserved protein and is a soluble pattern recognition receptor involved in the innate immune system that regulates monocyte activation and differentiation. SAP inhibits the differentiation of circulating monocytes into fibrocytes. There have been several reports asserting that the circulating level of SAP may have an important role in fibrosis.

The SAP concentration was significantly higher in vitreous fluid samples from PDR patients than in those from control samples (77.5 ± 53.3 ng/ml versus 1.4. ± 1.1 ng/ml, P < 0.05). These results suggest that the pathogenesis of FVM may be related to infiltration of fibrocytes into the vitreous fluid, which may be regulated by SAP. Accordingly, fibrocytes may be a novel therapeutic target for treatment of PDR.