Melissa officinalis extract nanoemulsion, Caffeic acid and Quercetin as a novel inducer for investigating neural differentiation of human Wharton's jelly mesenchymal stem cells.

Background: Cell therapy utilizing mesenchymal stem cells, which have the ability to differentiate into different lineages, has garnered significant attention in recent years. Melissa officinalis is rich in biologically active compounds and exhibits antioxidant activity, antimicrobial properties, and sedative effects. Nanoemulsions can facilitate the effective transfer of substances and also protect drugs and biological materials from environmental factors. The aim of the present study is to investigate the role of Melissa officinalis extract nanoemulsion and the active ingredients of caffeic acid and quercetin as inducers in increasing the efficiency of differentiation of mesenchymal stem cells into neural cells in a laboratory environment.

Materials And Methods: Human WJMSCs were cultured in the basic culture medium consisting of: Hight glucose DMEM, 10 % FBS and 1 % penicillin/streptomycin. The alcoholic extract of Melissa officinalis was extracted and its nanoemulsion was prepared along with two other effective substances. Next, zeta potential and size of nanoparticles were measured by Dynamic light scattering (DLS) technique. The optimal dose of all three material was calculated by MTT (3-4,5-dimethylthiazol-2-yl-2, 5-diphenyl tetrazolium bromide) assay and Acridine orange-ethidium bromide (AO/EB) staining. In the following, neural differentiation was investigated using Real-time Reverse Transcription Polymerase Chain Reaction (RT-PCR) and immunocytochemistry (ICC) techniques on days 7 and 14.

Results: The results obtained from MTT and AO/EB assays showed that the optimal dose of nanoemulsion M. officinalis, caffeic acid and quercetin is 150 μg/ml, 75 μg/ml and 25 μg/ml, respectively. The ideal particle size for nanoemulsion is below 100 nm. The zeta potential of the M. officinalis extract nanoemulsion was reported to be -9.45 and the average particle size was 17.76 nm. The results of this study indicated that the expression of neural marker genes (MAP-2, β-tubulin III and NSE) and proteins (MAP-2, β-tubulin III and Gamma-enolase) increased in differentiated cells treated with the synthesized nanoemulsion compared to the control group on days 7 and 14 (P ≤ 0.05).

Conclusion: In general, our results showed that M. officinalis extract nanoemulsion, caffeic acid and quercetin caused induction of neural differentiation mechanism in human WJ-MSCs.