Proteins have variable half-lives depending on their primary structure. mRNA administration for protein replacement has multiple advantages. First by mRNA engineering we can adjust the half-life and translation efficiency of the mRNA. Thus, we can determine the duration and the amount of the protein expression. Second, most proteins function inside the cell. It is extremely hard to transfer synthetic proteins inside the cell membrane. IN Addition, unlike lentiviral vectors, mRNA does not have genomic integration risk. Furthermore, unlike AAV vectors, mRNA does not have a payload size limit or surface immunogenicity (when delivered via non-viral systems such as lipid nanoparticles). Finally, because mRNA expression is transient, any potential adverse effects (e.g. adaptive immune responses against the payload or idiosyncratic drug reactions) can be limited temporally by treatment cessation.