Tetrahydrouridine aqueous solution is primarily used in research and clinical settings to inhibit the enzyme cytidine deaminase. This inhibition helps stabilize certain nucleoside analogs, such as decitabine and azacitidine, which are used in the treatment of hematological malignancies like myelodysplastic syndromes and acute myeloid leukemia. By preventing their rapid breakdown in the body, tetrahydrouridine enhances the bioavailability and therapeutic effectiveness of these drugs. It is also employed in experimental gene therapy and epigenetic studies where maintaining the integrity of deoxycytidine analogs is critical. Its use in aqueous solution form allows for easier handling and compatibility in biological systems.