Fibrocytes and Fibrovascular Membrane Formation in Proliferative Diabetic Retinopathy

Abstract The purpose of this study was to investigate whether fibrocytes participate in formation of the fibrovascular membrane (FVM) in patients with proliferative diabetic retinopathy (PDR). Vitreous fluid and FVM samples were obtained during vitrectomy in patients with PDR. Samples from patients with macular hole or epiretinal membrane were used as controls. Vitreous fluid and FVM samples were subjected to immunohistochemical analysis. In addition, cells isolated from the vitreous fluid of PDR and control patients were cultured in serum-free medium. Fibrocytes were identified among these cells by morphological and immunohistochemical analyses. We examined the number of fibrocytes in PDR patients and control patients. Also, the concentrations of monocyte chemoattractant protein-1 (MCP-1), pentraxin3, and serum amyloid P (SAP) in vitreous fluid samples from PDR patients and control patients were determined by enzyme-linked immunosorbent assay. Fibrocytes were observed in the vitreous and FVM samples from PDR patients. Cells cultured from the vitreous samples of PDR patients were spindle shaped and expressed fibrocyte markers. TGF-β1 induced differentiation of these cells into myofibroblasts. The number of fibrocytes was higher in samples from PDR patients than in samples from control patient. The vitreous fluid concentration of MCP-1 was significantly higher in PDR patients than in controls and showed a significant positive correlation with the number of fibrocytes from the vitreous fluid. Vitreous fluid concentrations of pentraxin3 and SAP were also higher in PDR patients than in control patients. These findings indicate that fibrocytes may be involved in development of the FVM in PDR.