Mesenchymal Stromal Cells from Neonatal Tracheal Aspirates Demonstrate a Pattern of Lung-Specific Gene Expression

We have previously isolated mesenchymal stromal cells (MSCs) from the tracheal aspirates of premature neonates with respiratory distress. Although isolation of MSCs correlates with the development of bronchopulmonary dysplasia, the physiologic role of these cells remains unclear. To address this, we further characterized the cells, focusing on the issues of gene expression, origin, and cytokine expression. Microarray comparison of early passage neonatal lung MSC gene expression to cord blood MSCs and human fetal and neonatal lung fibroblast lines demonstrated that the neonatal lung MSCs differentially expressed 971 gene probes compared with cord blood MSCs, including the transcription factors Tbx2, Tbx3, Wnt5a, FoxF1, and Gli2, each of which has been associated with lung development. Compared with lung fibroblasts, 710 gene probe transcripts were differentially expressed by the lung MSCs, including IL-6 and IL-8/CXCL8. Differential chemokine expression was confirmed by protein analysis. Further, neonatal lung MSCs exhibited a pattern of Hox gene expression distinct from cord blood MSCs but similar to human fetal lung fibroblasts, consistent with a lung origin. On the other hand, limiting dilution analysis showed that fetal lung fibroblasts form colonies at a significantly lower rate than MSCs, and fibroblasts failed to undergo differentiation along adipogenic, osteogenic, and chondrogenic lineages. In conclusion, MSCs isolated from neonatal tracheal aspirates demonstrate a pattern of lung-specific gene expression, are distinct from lung fibroblasts, and secrete pro-inflammatory cytokines.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90487/1/scd-2E2010-2E0494.pd

Stem/progenitor cell populations resident in the lung and the role of stromal support in their maintenance and differentiation

Lungs are vital organs for respiration, being enabled by their complex three-dimensional organization [1]. Airway tubes bifurcate into millions of highly vascularized alveolar sacs, the alveoli, which are responsible for gas exchange. The gas exchange surface of the lungs makes up one of the largest surface areas of the human body. The alveoli receive air from the conducting airways, starting in the trachea, bifurcating into the bronchi and bronchioles, and ending in the terminal bronchioles, which divide into the alveolar ducts from which the alveoli arise. The aim of this chapter is to provide an overview of the progenitors in adult lung tissue and the regulation of their maintenance and differentiation by the microenvironment during lung developmental as well as repair processes, when developmental pathways are often reactivated. As most work has been done in mouse studies, the current knowledge from animal studies will be summarized and translated to what is known from human lungs. In order to understand the regenerative processes in the lung, we will first provide insight into the complex three-dimensional organization and composition of the lung, its function, and the processes involved in lung development.</p

Nuclear receptors Nur77 and Nurr1 modulate mesenchymal stromal cell migration

Item does not contain fulltextDetailed understanding of mesenchymal stromal cells (MSC) migration is imperative for future cellular therapies. To identify genes involved in the process of MSC migration, we generated gene expression profiles of migrating and nonmigrating fetal bone marrow MSC (FBMSC). Only 12 genes showed differential expression in migrating versus nonmigrating FBMSC. The nuclear receptors Nur77 and Nurr1 showed the highest expression in migratory MSC. Nur77 and Nurr1 are members of NR4A nuclear orphan receptor family, and we found that their expression is rapidly increased upon exposure of FBMSC to the migratory stimuli stromal-derived factor-1alpha (SDF-1alpha) and platelet-derived growth factor-BB. Lentiviral expression of Nur77 or Nurr1 resulted in enhanced migration of FBMSC toward SDF-1alpha compared with mock-transduced FBMSC. Analysis of the cell cycle, known to be involved in MSC migration, revealed that expression of Nur77 and Nurr1 decreases the proportion of cells in S-phase compared with control cells. Further, gain-of-function experiments showed increased hepatocyte growth factor expression and interleukin (IL)-6 and IL-8 production in MSC. Despite the altered cytokine profile, FBMSC expressing Nur77 or Nurr1 maintained the capacity to inhibit T-cell proliferation in a mixed lymphocyte reaction. Our results demonstrate that Nur77 and Nurr1 promote FBMSC migration. Modulation of Nur77 and Nurr1 activity may therefore offer perspectives to enhance the migratory potential of FBMSC which may specifically regulate the local immune response