Intestinal Adipocytes Transdifferentiate into Myofibroblast-like Cells and Contribute to Fibrosis in Crohn's Disease.

BACKGROUND AND AIMS: Intestinal fibrotic stenosis is a major reason for surgery in Crohn's disease [CD], but the mechanism is unknown. Thus, we asked whether intestinal adipocytes contribute to intestinal fibrosis. Adipocytes were found to transdifferentiate into myofibroblasts and confirmed to be involved in mesenteric fibrosis in our recent study. Here, we investigated the role and possible mechanisms of intestinal adipocytes in intestinal fibrosis in CD. METHODS: The intestinal tissue of patients with CD with or without fibrotic stenosis [CDS or CDN] and normal intestinal tissue from individuals without CD were obtained to assess alterations in submucosal adipocytes in CDS and whether these cells transdifferentiated into myofibroblasts and participated in the fibrotic process. Human primary adipocytes and adipose organoids were used to evaluate whether adipocytes could be induced to transdifferentiate into myofibroblasts and to investigate the fibrotic behaviour of adipocytes. LPS/TLR4/TGF-ß signalling was also studied to explore the underlying mechanism. RESULTS: Submucosal adipocytes were reduced in number or even absent in CDS tissue, and the extent of the reduction correlated negatively with the degree of submucosal fibrosis. Interestingly, submucosal adipocytes in CDS tissue transdifferentiated into myofibroblast-like cells and expressed collagenous components, possibly due to stimulation by submucosally translocated bacteria. Lipopolysaccharide [LPS]-stimulated human primary adipocytes and adipose organoids also exhibited transdifferentiation and profibrotic behaviour. Mechanistically, TLR4-mediated TGF-ß signalling was associated with the transdifferentiation and profibrotic behaviour of intestinal adipocytes in CDS tissue. CONCLUSIONS: Intestinal adipocytes transdifferentiate into myofibroblasts and participate in the intestinal fibrosis process in CD, possibly through LPS/TLR4/TGF-ß signalling.

Ceiling culture of human mature white adipocytes with a browning agent: A novel approach to induce transdifferentiation into beige adipocytes.

Excess and dysfunctional adipose tissue plays an important role in metabolic diseases, including obesity, atherosclerosis and type 2 diabetes mellitus. In mammals, adipose tissue is categorized into two types: white and brown. Adult brown tissue is mainly composed of beige adipocytes, which dispose of stored energy as heat and have become increasingly popular as a therapeutic target for obesity. However, there is still a paucity of cell models that allow transdifferentiation of mature white adipocytes into beige adipocytes, as seen in vivo. Here, we describe a novel, ceiling culture-based model of human mature white adipocytes, which transdifferentiate into beige adipocytes under the mechanical force and hypoxia of ceiling culture. We also show that the use of rosiglitazone and rapamycin can modulate transdifferentiation, up and down regulating expression of beige adipocyte-specific genes, respectively. Rosiglitazone additionally facilitated the upregulation of fatty acid lipolysis and oxidation genes. Finally, these beige adipocytes derived from dedifferentiated adipocytes exhibited a progenitor-specific phenotype, with higher expression of mature adipocyte-specific genes than adipocyte-derived stem cells. Overall, we report a novel approach to conveniently cultivate beige adipocytes from white adipocytes in vitro, suitable for mechanistic studies of adipose biology and development of cell and drug therapies in the future.

Coaxially Bioprinted Cell-Laden Tubular-Like Structure for Studying Glioma Angiogenesis.

Glioblastomas are the most frequently diagnosed and one of the most lethal primary brain tumors, and one of their key features is a dysplastic vascular network. However, because the origin of the tumor blood vessels remains controversial, an optimal preclinical tumor model must be established to elucidate the tumor angiogenesis mechanism, especially the role of tumor cells themselves in angiogenesis. Therefore, shell-glioma cell (U118)-red fluorescent protein (RFP)/core-human umbilical vein endothelial cell (HUVEC)-green fluorescent protein (GFP) hydrogel microfibers were coaxially bioprinted. U118-RFP and HUVEC-GFP cells both exhibited good proliferation in a three-dimensional (3D) microenvironment. The secretability of both vascular endothelial growth factor A and basic fibroblast growth factor was remarkably enhanced when both types of cells were cocultured in 3D models. Moreover, U118 cells promoted the vascularization of the surrounding HUVECs by secreting vascular growth factors. More importantly, U118-HUVEC-fused cells were found in U118-RFP/HUVEC-GFP hydrogel microfibers. Most importantly, our results indicated that U118 cells can not only recruit the blood vessels of the surrounding host but also directly transdifferentiate into or fuse with endothelial cells to participate in tumor angiogenesis in vivo. The coaxially bioprinted U118-RFP/HUVEC-GFP hydrogel microfiber is a model suitable for mimicking the glioma microenvironment and for investigating tumor angiogenesis.

The recruitment mechanisms and potential therapeutic targets of podocytes from parietal epithelial cells.

Podocytes are differentiated postmitotic cells which cannot be replaced after podocyte injury. The mechanism of podocyte repopulation after injury has aroused wide concern. Parietal epithelial cells (PECs) are heterogeneous and only a specific subpopulation of PECs has the capacity to replace podocytes. Major progress has been achieved in recent years regarding the role and function of a subset of PECs which could transdifferentiate toward podocytes. Additionally, several factors, such as Notch, Wnt/ß-catenin, Wilms' tumor-1, miR-193a and growth arrest-specific protein 1, have been shown to be involved in these processes. Finally, PECs serve as a potential therapeutic target in the conditions of podocyte loss. In this review, we discuss the latest observations and concepts about the recruitment of podocytes from PECs in glomerular diseases as well as newly identified mechanisms and the most recent treatments for this process.