**4. Resistance and stability of plant miRNAs to harsh conditions**

In 2017, Luo et al. [31] revealed the abundance of miRNAs in *Zea mays* (maize), obtaining 18 highly represented miRNAs, fresh maize samples were subjected to different treatments (elevated temperature and pressure, starch dextrinization, and protein denaturation), observing that all miRNAs resisted the treatments with only decrease in their concentrations. Subsequently, the resistance of miRNAs from maize was analyzed in pigs, due to their attractive biomedical model and organ size similar to humans, they were fed for 7 days with fresh maize-based diet, and evaluated the presence of the 18 previously selected miRNAs, finding 16 in tissue and serum. They verified the crossing of the gastrointestinal barrier of synthetic miRNAs and evaluated by bioinformatic analysis the possible regulation of pig genes by miRNAs from maize, obtaining as a result that MIR164a-5p has CSPG4, OTX1, and PLAGL2 genes as a potential target, with a reduction in the gene activity compared with control. This suggests the likelihood that exogenous miRNAs regulate gene expression in endogenous mRNAs in a similar way to mammalian miRNAs.
