Here, we describe a simple protocol for neurogenesis using the P19 cell line. Although many reports have been published in this regard, a detailed methodology for neurogenesis induction using P19 cell line remains unclear. Moreover, we utilized a simple high glucose (4,500 mg/L) DMEM medium with 10% FBS for the entire experiment. This allowed us to perform the neurogenic experiment in a user-friendly manner and expand the usage of this method for the future.
The most critical points within this protocol are the RA concentration as well as the generation of cell aggregates in the suspension culture. The stimulation of neurogenesis in the P19 cell line can be carried out without the formation of aggregates, but the number of neuronal cells produced will be reduced by two-thirds in the cell culture22. Monzo et al. have shown neurogenesis induction in P19 cell line by culturing them in monolayer15. Although their method is quite convenient as we can eliminate suspension culture process, further studies are required to compare their method with other well-described methods.The RA concentration of 0.5 µM in the medium produced a high number of cell aggregates as well as neurons after plating as compared to 1 µM of RA. It is also important to note that we could not observe an efficient neurogenesis when most of the aggregates are attached to the bottom of the suspension culture dish during RA treatment. The optimal number of the P19 cell line to be used at the beginning of the procedure is 1 x 106 for every 10 mL of Differentiation Medium. During the induction of neurogenesis, the P19 cell line forms varying sized aggregates and even single cells are found in the culture. To overcome this problem, we collected the cell aggregates after 1.5 min of free fall in a 15 mL tube. We found that this approach allows the exclusion of contamination of single cells. It is also recommended to perform neuronal enrichment with the cell culture using anti-mitotic drugs (e.g., cytosine arabinoside) for long term culture to inhibit extensive proliferation of glial cells23.
Neurons derived from the P19 cell line express ionotropic glutamate receptors of both N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)/kainite (KA) types24,25, as well as functional γ-aminobutyric acid (GABA) receptors25. Therefore, the P19 cell line is widely used in the studies on molecular mechanisms governing neuronal differentiation26,27,28. More importantly, the tumor development was not observed after cell transplantation29,30.
To this end, research on neurodegenerative diseases such as Alzheimer's disease17,18 is also conducted using P19 cell line, and we believe that the method developed in this study will thus play a part in elucidating the molecular mechanisms in neurodevelopmental abnormalities and neurodegenerative diseases.