Reply to “Comment on ‘Reactive Oxygen Species-Responsive Polypeptide Drug Delivery System Targeted Activated Hepatic Stellate Cells to Ameliorate Liver Fibrosis’”

Abstract

Metrics & MoreArticle Recommendations S un et al. made reasonable suggestions for some of the results of our recent article. 1 As follows: (i) the expression levels of α-SMA and collagen I in the RES/ CRGD-PMK-MCs group, (ii) the ability of resveratrol and CRGD to alleviate the progression of liver fibrosis, and (iii) the effect of RES/CRGD-PMK-MCs on the lung tissue of healthy mice, etc. As described in this Reply, we interpreted the results of our article by reviewing and referring to other published articles.A Note on the Expression Levels of α-SMA and Collagen I in the RES/CRGD-PMK-MCs Group. Actually, the in vitro cell model used in Figure 6 is HSC-T6, which is an immortalized cell established in year 1998 by transforming primary HSC from Sprague−Dawley rats with the large Tantigen from Simian virus 40 2,3 and is widely used as an important experimental tool for studies of hepatic metabolism. Recently, Nanda et al. 4 analyzed the transcriptome of HSC-T6 cells grown under basal conditions by mRNA sequencing (mRNA-Seq) using next generation sequencing (NGS). Their results demonstrated that HSC-T6 cultured under normal conditions showed high expression of characteristic HSC markers, including, for example, α-smooth muscle actin (α-SMA), vimentin, fibronectin, and collagen type I, among others. Most of these markers are reliable markers indicative of HSC cellular activation. 5 In addition, it has been reported that another immortalized hepatic stellate cell line, the human cell line LX-2, also retains key features of activated/transdifferentiated HSCs. 6,7 Strictly speaking, therefore, HSC-T6 and LX-2 are mildly activated cell types that do not represent fully healthy hepatic stellate cells in animals. Therefore, the expression levels of α-SMA and collagen type I of normally cultured immortalized HSC-T6 and LX-2 are theoretically higher than those of completely healthy hepatic stellate cells. In addition, refs 8−10 show that the expressions of α-SMA and collagen type I in HSC-T6 and LX-2 are significantly increased after being stimulated by TGF-β1 or LPS. 8−10 Therefore, after RES/CRGD-PMK-MCs treated TGF-β1-stimulated HSC-T6, it is understandable that the expression levels of α-SMA and collagen type I were lower than those of normal cultured HSC-T6 (control group). Other studies 8,9,11−13 also showed that the albumin (ALB) levels, we found that the overall toxicity of the RES/CRGD-PMK-MCs group to healthy mice was acceptable.