C57BL/6 lungs were stored for 18 hours in low-potassium dextran glucose solution at 4¡ãC prior to transplantation. The left lung grafts were orthotopically transplanted into C57BL/6 mice. A frozen vial of human MSCs (isolated from healthy male, courtesy of Dr. Darwin Prockop, Texas A&M Health Science Center) was thawed and expanded. MSCs or PBS were slowly infused into the left lung graft via left pulmonary artery before lung transplantation. The recipient mice were killed at 6 hours after transplantation. PBS (400¦ÌL x 2) was injected into trachea after a clamp was placed on the right hilum, and bronchioalveolar lavage fluid (BALF) was collected. The total protein level and cell counts of the BALF were measured. The levels of cytokines in the BALF were quantified by multiplex assay kit. Another mice were killed and the lung was fixed in parafolmaldehyde and stained by hematoxyn eosin. Immunohistochemical analysis was used to determine the location of the human MSC in the lung graft.
Protein level and cell counts in BALF were significantly less in MSCs administered mice compared with PBS administered mice (total protein; 1.095 vs 1.965 mg/ml, p=0.037, cell count; 0.61x10^5 vs 1.09x10^5 cells, p=0.011). IL-1¦Â, IL17A and TNF¦Á levels in BALF showed a trend toward a decrease in MSCs administered mice compared with PBS administered mice (IL-1¦Â; 26.6 vs 38.7 pg/ml, p=0.13, IL17A; 284 vs 655 pg/ml, p=0.097, TNF¦Á; 234 vs 500 pg/ml, p=0.073). Human MSCs were found in the lung graft 6 hours after lung transplantation by immunohistochemistry against human HLA class I.
MSCs attenuated ischemia reperfusion injury, which was accompanied by a trend toward decreased levels of proinflammatory cytokines in the graft after lung transplantation in a mouse model.