Exogenous administration of microsomes-associated alpha-synuclein aggregates to primary neurons as a powerful cell model of fibrils formation

For years, the inability of replicating formation of insoluble alpha-synuclein (αS) inclusions in cell cultures has been a great limitation in the study of αS aggregation in Parkinson's Disease (PD). Recently, the development of new animal models through the exogenous inoculation of brain extracts from diseased αS transgenic mice or PD patients has given new hopes to the possibility of creating more adequate cell models of αS aggregation. Unfortunately, when it comes to cells in cultures, administration of raw brain extracts has not proven as successful as in mice and the source of choice of exogenous aggregates is still in vitro preformed αS fibrils. We have developed a method to induce the formation of intracellular αS inclusions in primary neurons through the exogenous administration of native microsomes-associated αS aggregates, a highly toxic αS species isolated from diseased areas of transgenic mice. This fraction of αS aggregates that is associated with the microsomes vesicles, is efficiently internalized and induces the formation of intracellular inclusions positive for aggregated and phosphorylated αS. Compared to in vitro-preformed fibrils which are made from recombinant αS, our method is faster and guarantees that the pathogenic seeding is made with authentic αS aggregates extracted from diseased animal models of PD, mimicking more closely the type of inclusions obtained in vivo. As a result, availability of tissues rich in αS inclusions is mandatory. We believe that this method will provide a versatile cell-based model to study the microscopic aspects of αS aggregation and the related cellular pathophysiology in vivo and will be a starting point for the creation of more accurate and sophisticated cell paradigm of PD.