Acute Respiratory Distress Syndrome (ARDS), characterized by diffuse alveolar damage and severe hypoxemia, remains a major clinical challenge with limited treatment options and uncertain therapeutic efficacy. Mesenchymal stem cells (MSCs) derived from human umbilical cord tissue hold significant therapeutic potential due to their immunomodulatory properties and ease of non-invasive collection. While most studies have focused on the therapeutic use of MSCs, prophylactic applications are underexplored, particularly in the context of reducing initial lung inflammation severity. This study evaluates both prophylactic and therapeutic administration of MSCs in mitigating LPS-induced lung injury in a murine model, aiming to provide insights into the feasibility and efficacy of MSCs as a preemptive treatment modality for ARDS. A total of 29 BALB/c mice were randomly assigned to five groups: Healthy Control, MSCs only, LPS only, Prophylactic, and Therapeutic. MSCs were administered intravenously 48 hours before LPS induction in the prophylactic group and post-induction in the therapeutic group. Histopathological and clinicopathological assessments revealed that therapeutic MSCs significantly reduced markers of inflammation and lung injury, while prophylactic MSCs showed limited but notable effects on early inflammatory parameters. BALF and blood analyses, including cytokine analysis, revealed both therapeutic and prophylactic MSC treatments reduced inflammatory cytokines such as Mouse TNF, Mouse MCP-1, and Mouse IL-6. These findings suggest MSCs offer therapeutic benefits but further research is needed for prophylactic use in ARDS.