Protective Effects Of Keratinocyte Growth Factor Gene Modified Bone Mesenchymal Stem Cells Transplantion On Lipopolysaccharide Induced Acute Lung Injury In Mice

Background and objectives:Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) are progressiveacute respiratory failure mainly caused by pulmonary infection. The injury of alveolarepithelial cells and alveolar-capillary membrane barrier has been implicated in thepathogenesis of ALI/ARDS. However, despite decades of research, the therapeuticstrategy can not improve the prognosis, with the mortality as high as40%.Bone mesenchymal stem cells (MSCs) as multi-potential stem cells could be easilyacquired and cultured. They can engraft in the injured lung and induce immunetolerance. MSCs are not only ideal source of tissue repair and but good vectors for thegene transfection. Therefore, they have important values in the treatment ofALI/ARDS.Keratinocyte growth factor (KGF), also known as a member of fibroblast growthfactors (FGFs), is a potent mitogenic factor for epithelial cells. Additionally, it hasmany beneficial effects on ALI, such as regulating the cell differentiation, stimulatingsurfactant synthesis, decreasing apoptosis, etc. Thus, KGF may have expansiveapplication prospect in the treatment of ALI.The aim of this study was investigating the protective effects of KGF genemodified bone MSCs transplantation on ALI, exploring the underlying mechanismsand providing experimental basis for the gene therapy of ALI.Methods and results:MSCs were isolated and purified by means of adherent culture, and verified byflow cytometry analysis and differentiation assays. MSCs were infected withrecombinant lentivirus constructed with KGF. The expression of KGF gene wasdetected by real-time PCR and western blot, both of which showed that KGF expression in the MSCs-KGF group were higher than that of the control groupsrespectively. After an hour of LPS intratracheal instillation to induce lung injury, micereceived saline, MSCs alone, empty lentivirus vector-engineered MSCs (MSCs-vec)or KGF-engineered MSCs (MSCs-KGF) via the tail vein, respectively. In theMSCs-KGF group, the level of KGF expression was significantly increased. TheMSCs mediated KGF administration not only improved lung microvascularpermeability, but also mediated a down-regulation of proinflammatory responses(reducing IL-1β and TNF-α) and up-regulation of anti-inflammatoryresponses(increasing cytokine IL-10). Furthermore, the total severity scores of lunginjury were significantly reduced in the MSCs-KGF group compared with the otherthree groups. Kaplan-Meier survival assay showed that the MSCs-KGFtransplantation have a trend of improving the survival rate. The levels of SPB andSPC mRNA in the MSCs-KGF group were higher than that of the three control groupsat24h and3d (P<0.05). Also immunohistochemistry analysis displayed that thenumber of positive PCNA cells in MSCs-KGF group was more than that of the threecontrol groups.Conclusions:MSCs were not only proved to be good vectors for gene therapy but alsotherapeutic cells in this study. KGF combined the MSCs could ameliorate the lungpermeability, restrain the inflammatory response, attenuate the severity of lung injuryinduced by LPS and have a trend of improving the survival rate, which providedexperimental evidences for gene therapy of ALI. And the underlying mechanism ofthe protective effects of KGF on ALI might be attributed to the promotion of lungepithelial cell proliferation and enhancement of surfactant synthesis.