Messenger RNA (mRNA) presents itself as an efficient and effective therapeutical tool, especially due to its global and commercial rise in the past few years. As there are various rare and genetic disorders, the demand for novel treatments is at its highest. A promising approach to this problem is gene therapy, specifically using non-viral vectors, such as lipids, polymers and nanoparticles. One such disease is neurofibromatosis type 1 (NF1), which affects roughly 1 in 3000 people through mutations into the NF1 gene. Apart from aesthetic and physical ailments, it is characterized by benign and malignant tumors. Causing the development of NF1 related malignant tumors, but also heightening the risk of developing other types of cancers, the disease poses a serious life-threat to patients. In this project, a lipoplex made of a liposome vector and modified GRD mRNA encoding an important functional domain of Nf1 protein was used to transfect mutated Schwann cells (NF1 -/-). The GRD protein synthesized from the mRNA was analysed on a biochemical level, focusing on its functional activity, half-life and proteasome degradation. Another focus of the project was establishing a 3D culture model in the form of spheroids. As monolayer cultures cannot grasp the complexity of interactions and the metabolism of cells in physiological in vivo conditions, it is crucial to expand experiments onto 3D models like spheroids and organoids. Altogether, the experiments carried out offer insight into a possible mRNA gene therapy method. They demonstrated the functional activity of the GRD protein and how its half-life and proteasome activity influence its expression. A valuable protocol to form and transfect spheroids has been made, which will be helpful in further experiments.