The Application of Organotypic Brain Slice Culture to Study Microglial Differentiation by Lycopersicon esculentum and Sambucus nigra Lectin Histochemistry

Microglial cells are the subset of macrophages in the central nervous system (CNS). Changes in the CNS such as injury or developmental events cause morphological and physiological changes in microglial cells. In this study organotypic brain slice cultures under serum free condition were used to investigate the morphology and lectin histochemistry of microglia and macrophages in the CNS in vitro. Microglial cells exhibited dramatic morphological changes in the organotypic brain slice culture. Immediately after slicing microglias were seen to have the same morphology as they do in the intact brain: they had small cell bodies from which radiated several highly ramified processes. After 1 day in vitro (DIV) all microglia transformed into an active form with round soma and no processes. At 5 days in vitro, and especially at 9 days in vitro, many of the microglia had tended to return to the ramified phenotype. The expression of different carbohydrates was examined at the 0, 1, 5 and 9 days in vitro time periods by employing Lycopersicon esculentum tomato lectin (LEA lectin) and Sambucus nigra (SNA). Microglial cells with different morphology intensely stained with the LEA. SNA stained the ramified microglia only after they re-ramified at 5 DIV and 9 DIV. The results of this study confirmed that the expression of carbohydrate structures in these cells would undergo changes corresponding to the changes in morphology.