Various source-derived mesenchymal stem cells (MSCs) have been considered for cell therapeutics in incurable diseases. To characterize MSCs from different sources, we compared human bone marrow (BM), adipose tissue (AT), and umbilical cord blood-derived MSCs (UCB-MSCs) for surface antigen expression, differentiation ability, proliferation capacity, clonality, tolerance for aging, and paracrine activity. Although MSCs from different tissues have similar levels of surface antigen expression, immunosuppressive activity, and differentiation ability, UCB-MSCs had the highest rate of cell proliferation and clonality, and significantly lower expression of p53, p21, and p16, well known markers of senescence. Since paracrine action is the main action of MSCs, we examined the anti-inflammatory activity of each MSC under lipopolysaccharide (LPS)-induced inflammation. Co-culture of UCB-MSCs with LPS-treated rat alveolar macrophage, reduced expression of inflammatory cytokines including interleukin-1α (IL-1α), IL-6, and IL-8 via angiopoietin-1 (Ang-1). Using recombinant Ang-1 as potential soluble paracrine factor or its small interference RNA (siRNA), we found that Ang-1 secretion was responsible for this beneficial effect in part by preventing inflammation. Our results demonstrate that primitive UCB-MSCs have biological advantages in comparison to adult sources, making UCB-MSCs a useful model for clinical applications of cell therapy.

Recent evidence suggests mesenchymal stem cells (MSCs) can downmodulate bleomycin-induced lung injury, and umbilical cord blood (UCB) is a promising source for human MSCs. This study examined whether intratracheal or intraperitoneal transplantation of human UCB-derived MSCs can attenuate hyperoxia-induced lung injury in immunocompetent newborn rats. Wild-type Sprague-Dawley rats were randomly exposed to 95% oxygen or air from birth. In the transplantation groups, a single dose of PKH26-labeled human UCBderived MSCs was administered either intratracheally (2 × 10 6 cells) or intraperitoneally (5 × 10 5 cells) at postnatal day (P) 5. At P14, the harvested lungs were examined for morphometric analyses of alveolarization and TUNEL staining, as well as the myeoloperoxidase activity, the level of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and transforming growth factor (TGF)-β mRNA, α-smooth muscle actin (SMA) protein, and collagen levels. Differentiation of MSCs to the respiratory epithelium was also evaluated both in vitro before transplantation and in vivo after transplantation. Despite one fourth dosage of MSCs, significantly more PKH26-labeled donor cells were recovered with intratracheal administration than with intraperitoneal administration both during normoxia and hyperoxia. The hyperoxia-induced increase in the number of TUNELpositive cells, myeloperoixdase activity, and the level of IL-6 mRNA were significantly attenuated with both intratracheal and intraperitoneal MSCs transplantation. However, the hyperoxia-induced impaired alveolarization and increased the level of TNF-α and TGF-β mRNA, α-SMA protein, and collagen were significantly attenuated only with intratracheal MSCs transplantation. MSCs differentiated into respiratory epithelium in vitro and a few PKH26-positive donor cells were colocalized with pro surfactant protein C in the damaged lungs. In conclusion, intratracheal transplantation of human UCB-derived MSCs is more effective than intraperitoneal transplantation in attenuating the hyperoxia-induced lung injury in neonatal rats.Key words: Hyperoxic lung injury; Transplantation; Animal; Newborn; Inflammation; Cell differentiation INTRODUCTION development of hyperoxic neonatal lung injury and BPD (42).Recently, the exogenous administration of bone marBronchopulmonary dysplasia (BPD) is a chronic pulmonary disease that usually occurs in premature infants row (BM)-derived mesenchymal stem cells (MSCs) significantly attenuated the bleomycin-induced lung injury receiving prolonged ventilatory support and oxygen supplementation. It is also an important cause of mortality by downmodulating the inflammatory responses and ameliorating their fibrotic effects (33). In addition, the transand long-term respiratory morbidity with few effective treatments (3,6). The histopathological characteristics of planted cells assumed the lung parenchymal cell phenotypes (34). The anti-inflammatory effect of MSCs has BPD include impaired alveolarization and interstitial fibrosis (30). Prolonged exposure of neonata...

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Intratracheal transplantation of human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) attenuates the hyperoxia-induced neonatal lung injury. The aim of this preclinical translation study was to optimize the dose of human UCB-derived MSCs in attenuating hyperoxia-induced lung injury in newborn rats. Newborn Sprague-Dawley rats were randomly exposed to hyperoxia (95% oxygen) or normoxia after birth for 14 days. Three different doses of human UCB-derived MSCs, 5 × 103 (HT1), 5 × 104 (HT2), and 5 × 105 (HT3), were delivered intratracheally at postnatal day (P) 5. At P14, lungs were harvested for analyses including morphometry for alveolarization, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) staining, myeoloperoxidase activity, mRNA level of tumor necross factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and transforming growth factor-β (TGF-β), human glyceradehyde-3-phosphate dehydrogenase (GAPDH), and p47phox, and collagen levels. Increases in TUNEL-positive cells were attenuated in all transplantation groups. However, hyperoxia-induced lung injuries, such as reduced alveolarization, as evidenced by increased mean linear intercept and mean alveolar volume, and increased collagen levels were significantly attenuated in both HT2 and HT3, but not in HT1, with better attenuation in HT3 than in HT2. Dose-dependent human GAPDH expression, indicative of the presence of human RNA in lung tissue, was observed only in the transplantation groups, with higher expression in HT3 than in HT2, and higher expression in HT2 than in HT1. Hyperoxia-induced inflammatory responses such as increased myeloperoxidase acitivity, mRNA levels of TNF-α, IL-1β, IL-6, and TGF-β of the lung tissue, and upregulation of both cytosolic and membrane p47phox, indicative of oxidative stress, were significantly attenuated in both HT2 and HT3 but not in HT1. These results demonstrate that intratracheal transplantation of human UCB-derived MSCs with appropriate doses may attenuate hyperoxia-induced lung injury through active involvement of these cells in modulating host inflammatory responses and oxidative stress in neonatal rats.

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