Early onset of podocytes apoptosis - a TEM study in streptozotocin-induced diabetic rats

Cell death types are usually defined by morphological criteria. Even though podocyte loss is associated with various cell death mechanisms, podocyte apoptosis is rarely detected. The purpose of this study is to evaluate whether morphological signs of apoptotic cell death could be detected in early streptozotocin-induced diabetes in rats kidneys. There were used five Wistar rats, and renal tissue samples were drawn after three weeks of disease and further evaluated in transmission electron microscopy (TEM). Podocytes damage was indicated by two major findings: foot processes effacement, viewed as loss of cell processes, and chromatin condensation and margination (partial karyopyknosis: peculiar nuclear morphologies - partly normal, euchromatic, and partly positive for karyopyknosis and nuclear shrinkage). Mitotic glomerular endotheliocytes were also encountered. Podocytes cell death commitment and detachment appeared as concomitant events. However, karyopyknosis is not a specific feature of apoptosis. Thus, further biochemical evaluations are needed to distinguish between different pathways of podocytes death.