Microparticles are small vesicles that are released by budding of the plasma membrane during cellular activation and apoptotic cell breakdown. A spectrum of cell types can release microparticles including endothelial cells, platelets, macrophages, lymphocytes and tumor cells. Biological effects of microparticles mainly include procoagulant activity, inhibition of inflammation and cancer progression. The present study shows that vitreous microparticles isolated from proliferative diabetic retinopathy (PDR) stimulated endothelial cell proliferation and increased new vessel formation, promoting the pathological neovascularization in PDR patients. Oxidative stress induces the formation of retina pigment epithelium-derived microparticles carrying membrane complement regulatory proteins, which is associated with drusen formation and age related macular degeneration. Microparticles from lymphocyte (LMP) play an important role in anti-angiogenesis by altering the gene expression pattern of angiogenesis-related factors in macrophages. Besides, LMP are important proapoptotic regulators for retinoblastoma cells through reduction of spleen tyrosine kinase expression and upregulation of the p53-p21 pathway which ultimately activates caspase-3. However, how to apply the microparticles in the prevention and treatment of retinal diseases is a major challenge, because the study of the microparticles in the fundus diseases is still limited. Further studies conducted would certainly enhance the application of microparticles in the fundus diseases.
Purpose To clarify the relationship between diabetic retinopathy (DR) and maculopathy (DM) and explore the clinical implication of independent graduation of DM. Methods Fundus fluorescein angiography and routine ophthalmological examination were performed on 582 cases of diabetes.Their ocular fundi and macular impairments were graded. Results In general,the severity of diabetic macular impairment was accompanied by retinal involvement,but discrepancy existed between DM and DR.Degree I DM occurred in 5.4% (16/294) among cases without DR,in stage IV DR,degree Ⅲ DM accounted for the most part ,54.5% (116/213).There were still 5.1% (2/39) cases without DM in stage Ⅴ DR. Conclusion The degree of the macular lesions in DM is often not in parallel with the gradation of general affections in retinal tissue other than in macular region in DR,therefore,independentg radation of diabetic maculopathy has its clinical significance for choosing the optimal period of treating maculopathy and preserving the macular function. (Chin J Ocul Fundus Dis,2000,16:153-154)