Reversal of bleomycin-induced rat pulmonary fibrosis by a xenograft of human umbilical mesenchymal stem cells from Wharton's jelly

Abstract

Pulmonary fibrosis (PF) is a progressive and irreversible condition with various causes, and no effective treatment has been found to rescue fibrotic lungs. Successful recovery from PF requires inhibiting inflammation, promoting collagen degradation and stimulating alveolar regeneration. Human umbilical mesenchymal stem cells (HUMSCs) not only regulate immune responses but also synthesize and release hyaluronan to improve lung regeneration. This study investigated the feasibility of HUMSC engraftment into rats with bleomycin (BLM)-induced PF to explore HUMSC therapeutic effects/outcomes.Methods: A unique BLM-induced left-lung-dominated PF animal model was established. Rats were transplanted with low-dose (5×106) or high-dose (2.5×107) HUMSCs on Day 21 after BLM injection. Combinations in co-culture of pulmonary macrophages, fibroblasts, HUMSCs treated with BLM and the same conditions on alveolar epithelia versus HUMSCs were evaluated.Results: Rats with high-dose HUMSC engraftment displayed significant recovery, including improved blood oxygen saturation levels and respiratory rates. High-dose HUMSC transplantation reversed alveolar injury, reduced cell infiltration and ameliorated collagen deposition. One month posttransplantation, HUMSCs in the rats' lungs remained viable and secreted cytokines without differentiating into alveolar or vascular epithelial cells. Moreover, HUMSCs decreased epithelial-mesenchymal transition in pulmonary inflammation, enhanced macrophage matrix-metallopeptidase-9 (MMP-9) expression for collagen degradation, and promoted toll-like receptor-4 (TLR-4) expression in the lung for alveolar regeneration. In coculture studies, HUMSCs elevated the MMP-9 level in pulmonary macrophages, released hyaluronan into the medium and stimulated the TLR-4 quantity in the alveolar epithelium.Principal Conclusions: Transplanted HUMSCs exhibit long-term viability in rat lungs and can effectively reverse rat PF.

Comparison of Reversal of Rat Pulmonary Fibrosis of Nintedanib, Pirfenidone and Human Umbilical Mesenchymal Stem Cells from Wharton’s Jelly

“…Immunostaining using anti-ED1 antibody showed that HUMSCs transplantation triggered a large number of macrophage activation. We previously found that the transplantation of HUMSCs promotes M2 macrophage to synthesize and secrete MMP-9 to facilitate the degradation of extracellular matrix collagen [9]. Cabrera et al also had the same opinion regarding macrophage [35].…”

“…Eight-week-old Sprague-Dawley (SD) rats weighed 250 g were provided by the Laboratory Animal Center (LAC) of National Yang-Ming University. Following con rmation of anesthesia depth, male SD rats received 5 Unit/5 mg BLM/250 g body weight (Nippon Kayaku Co., Ltd.) in µL phosphate buffered saline by intratracheal injection and were then rotated to the left side by 60° for 90 min to establish a severe, reproducible, left-lung PF animal model [9].…”

“…The above reasons bring di culties in applying this model for the evaluation of the therapeutic effects of stem cell transplantation. In order to precisely evaluate the effect of medications or xenografted stem cells in treating PF in rat, our laboratory has previously established a severe, reproducible, consistent, one-sided left-lung brosis animal model, which provides advantages in keeping the rat alive and allowing accurate evaluations of the therapeutic effects of human umbilical mesenchymal stem cells from wharton's jelly (HUMSCs) for rat PF [9].…”

“…Our laboratory previously established a severe, reproducible, consistent, onesided left-lung PF animal model. While intratracheal transplantation of 2.5 × 10 7 HUMSCs was performed on Day 21 after BLM injection, signi cant therapeutic effects on lung functionality and tissue morphology were observed at one month post-transplantation [9]. Therefore, we applied the severe, reproducible, consistent, one-sided left-lung PF animal model in this study.…”

Lights and Shadows in the Use of Mesenchymal Stem Cells in Lung Inflammation, a Poorly Investigated Topic in Cystic Fibrosis

“…Concerning pulmonary tissues, increasing evidences support MSCs regenerative properties. Indeed, they were able to engraft and to differentiate into lung epithelial cells under experimental conditions such as irradiation, bleomycin, or LPS-induced injury [86][87][88]. A systematic review of seventeen studies on rodents models of bleomycin-induced pulmonary fibrosis, describes the beneficial effects of MSCs, mostly derived from bone marrow, in improving alveolar injury and in decreasing lung fibrosis and collagen content [86].…”