Autocrine production of TGF-β1 promotes myofibroblastic differentiation of neonatal lung mesenchymal stem cells

Abstract

We have isolated mesenchymal stem cells (MSCs) from tracheal aspirates of premature infants with respiratory distress. We examined the capacity of MSCs to differentiate into myofibroblasts, cells that participate in lung development, injury, and repair. Gene expression was measured by array, qPCR, immunoblot, and immunocytochemistry. Unstimulated MSCs expressed mRNAs encoding contractile (e.g., ACTA2, TAGLN), extracellular matrix (COL1A1 and ELN), and actin-binding (DBN1, PXN) proteins, consistent with a myofibroblast phenotype, although there was little translation into immunoreactive protein. Incubation in serum-free medium increased contractile protein (ACTA2, MYH11) gene expression. MSC-conditioned medium showed substantial levels of TGF-beta1, and treatment of serum-deprived cells with a type I activin receptor-like kinase inhibitor, SB-431542, attenuated the expression of genes encoding contractile and extracellular matrix proteins. Treatment of MSCs with TGF-beta1 further induced the expression of mRNAs encoding contractile (ACTA2, MYH11, TAGLN, DES) and extracellular matrix proteins (FN1, ELN, COL1A1, COL1A2), and increased the protein expression of alpha-smooth muscle actin, myosin heavy chain, and SM22. In contrast, human bone marrow-derived MSCs failed to undergo TGF-beta1-induced myofibroblastic differentiation. Finally, primary cells from tracheal aspirates behaved in an identical manner as later passage cells. We conclude that human neonatal lung MSCs demonstrate an mRNA expression pattern characteristic of myofibroblast progenitor cells. Autocrine production of TGF-beta1 further drives myofibroblastic differentiation, suggesting that, in the absence of other signals, fibrosis represents the "default program" for neonatal lung MSC gene expression. These data are consistent with the notion that MSCs play a key role in neonatal lung injury and repair.

Isolation of Tracheal Aspirate Mesenchymal Stromal Cells Predicts Bronchopulmonary Dysplasia

“…There was no difference in latent TGF-β between groups (no BPD, 223±133 pg/ml, 0.24±0.13 pg/ng scIgA; BPD, 255±183 pg/ml, 0.30±0.26 pg/ng scIgA; mean±SD). On the other hand, normalized TGF-β levels were higher in patients with MSCs (cell-negative, 162± 113 pg/ml, 0.129±0.096 pg/ng scIgA; cell-positive, 263±163 pg/ml, 0.317±0.209 pg/ng scIgA, p=0.038), consistent with our finding that MSCs produce TGF-β 11 .…”

“…We also observed that MSCs express mRNAs encoding contractile and extracellular matrix proteins, consistent with a myofibroblast progenitor phenotype. Treatment of MSCs with TGF-β induced myofibroblastic differentiation 11 . We therefore reasoned that MSCs are more likely to be isolated from the tracheal aspirates of premature infants who develop BPD than those who do not.…”

“…Since we have not thoroughly tested the clonogenicity or selfrenewal of neonatal lung mesenchymal cells, we now refer to them as mesenchymal stromal cells (MSCs), which have a more restricted differentiation potential. Based on their potential to differentiate into myofibroblasts 11 , we tested whether isolation of MSCs from tracheal aspirates of premature infants with respiratory distress during the first week of life would correlate with development of BPD.…”

The transcriptome of nitrofen-induced pulmonary hypoplasia in the rat model of congenital diaphragmatic hernia

“…MiR-384-5p is a marker of neurotoxicity and regulates apoptotic cell death in myocardial ischemia by modulating PIK3CD pathway (26). Myosin heavy chain 11 is a component of the contractile apparatus of aortic smooth muscle cells and is expressed in neonatal lung smooth muscle cells (27). RNF44 is a poorly understood protein that is encoded by a gene and contains a RING finger motif, a motif often present on proteins involved in protein-protein and protein-DNA interactions.…”

The Robyn Barst Memorial Lecture: Differences between the Fetal, Newborn, and Adult Pulmonary Circulations: Relevance for Age‐Specific Therapies (2013 Grover Conference Series)

“…117,118 Conflicting reports also exist about mesenchymal stromal cells, depending on the source. [119][120][121] These findings highlight the importance of appropriately defining these progenitor cells and whether their function is altered because of their origin (lung, umbilical cord, bone marrow). Yet therapeutic administration of progenitor cells for the prevention or treatment of BPD holds significant promise, as several studies have shown benefit in experimental models.…”