Abstract
Purpose: :
Storage granules containing biologically active proteins and lipids are secreted from platelets following activation. Increased platelet activation status in diabetic patients, and in particular those with proliferative retinopathy, may contribute towards an altered balance of circulating pro– and anti–angiogenic mediators. The current study aims to identify the cytokine and growth factors present in the platelet releasate, and its effect on human retinal endothelial cell migration, a key component of pathological retinal neovascularisation.
Methods: :
Platelets were isolated from whole blood taken from healthy donors. Platelets were stimulated with collagen for three minutes while stirring in order to induce platelet aggregation. Platelet releasates were prepared by centrifugation of aggregated platelets and retention of the supernatant. A human cytokine array was used to analyse the cytokines released from platelets during aggregation. Human retinal endothelial cells employed in a Boyden chamber assay were treated with platelet releasates and cell migration was quantified.
Results: :
The human cytokine array of platelet releasates revealed the presence of many cytokines and growth factors, including interleukin–8 (IL–8), interleukin–10 (IL–10), RANTES, epidermal growth factor (EGF), angiogenin, vascular endothelial growth factor (VEGF), and platelet derived growth factor–BB (PDGF–BB). Collagen stimulated platelet releasate increased retinal endothelial cell migration 2.5–fold over vehicle controls (P<0.05, N=3).
Conclusions: :
Human platelets secrete a number of growth factors and cytokines following stimulation with agonists such as collagen. Retinal endothelial cell migration can be stimulated by substances released by activated platelets, which may ultimately contribute to pathological retinal neovascularisation in proliferative retinopathies.
Keywords: cytokines/chemokines • growth factors/growth factor receptors • vascular cells