We developed a siRNA-mediated knockdown protocol to study how the loss of endogenous GRN expression in human iPSC neurons relates to GRN haploinsufficiency in human FTD patients and studied how the treatment of the used human iPSC neuronal cultures with recombinant PGRN impacts neuronal outgrowth dynamics, resilience towards neurotoxic stress and neuronal function. This evidence concerns the gene GRN and frontotemporal dementia.