OBJECTIVETo investigate the effect of intravenous infusion of rat bone marrow-derived mesenchymal stem cells (MSCs) against lung injuries in neonatal exposed to hyperoxia.

METHODSRat bone marrow-derived MSCs were separated, cultured, amplified, and labeled with BrdU. Thirty-two 3-day-old SD rats were randomized into 4 equal groups (groups A, B, C and D), and the rats in groups A and B were exposed to 7-day 95% oxygen, while those in groups C and D were not. In groups A and C, the rats received injection with 5x10(4) MSCs via the tail vein, and those in groups B and D were given PBS only. Seventy-two hours after housing in normal air, all the rats were killed to determine the radial alveolar count (RAC) under light microscope. Immunohistochemistry was used to detect BrdU expression in the lung tissue, where the levels of tumor necrosis factoralpha(TNFalpha) and transforming growth factor beta1 (TGFbeta1) were detected using enzyme-linked immunosorbent assay.

RESULTSCompared to air exposure groups, the levels of TNFalpha and TGFbeta1 in the homogenate of the lungs increased while RACs decreased significantly in the two hyperoxia exposure groups. Groups A and B showed significant differences in the fields of RACs and the levels of TNFalpha and TGFbeta1 in the lung tissue homogenate, and BrdU-positive cells were detected only in the lungs of groups A and C, between which a significant quantitative difference was seen.

CONCLUSIONIntravenously injected MSCs may reside in the lungs of neonatal rats, which is subject to influences by the exposure conditions, and the transplanted MSCs may offer effective protection against lung injuries induced by hyperoxia.