Attenuating Effect of Long-term Culture of Umbilical Cord Vein Mesenchymal Stromal Cells on Pulmonary Fibrosis in C57BL/6 Mice.

In recent studies, mesenchymal stromal cells (MSCs) have been increasingly employed to treat various diseases like pulmonary fibrosis (PF). There are very few MSCs in tissues so in order to obtain their sufficient numbers for therapeutic applications, their in vitro expansion is necessary. The aim of this study was to investigate the effects of long-term culture of the human umbilical cord vein MSCs (hUCV-MSCs) on pulmonary fibrosis in mice. MSCs were first isolated from human umbilical cord vein and cultured up to 18 passages. In C57BL/6 mice, 15 min after belomycin instillation, UCV-MSCs at passages (P) 0, 4, 8, 12, and 18 (long-term culture) were transplanted intratracheally. Mice were weighted every 5 days and were euthanized on day 21. For histopathological examination, the lung sections were stained with hematoxylin-eosin (HE) and Masson's trichrome. The mRNA expression of TGF-β1, alpha-smooth muscle actin (α-SMA), and collagen type I alpha 1 (COL1A1) in lung tissues were assessed using RT-PCR. For cell tracking, human cytochrome B DNA was detected in mice lung tissues by PCR. The weight of mice receiving long-term culture of UCV-MSCs increased compared to other mice (p=0.056). Also, transplantation of UCV-MSCs at P18 led to increased alveolar space and decreased connective tissue and collagen deposition of the lung tissues. The mRNA expression of TGF-β1, α-SMA, and COL1A1 also decreased in this group. The results showed that intratracheally transplanted long-term culture of the UCV-MSCs attenuated lung fibrosis in mice.