Fat depot-specific gene signature and ECM remodeling of Sca1high adipose-derived stem cells

Abstract

Stem Cell Antigen-1 (Sca1 or Ly6A/E) is a cell surface marker that is widely expressed in mesenchymal stem cells, including adipose-derived stem cells (ASCs). We hypothesized that the fat depot-specific gene signature of Sca1high ASCs may play the major role in defining adipose tissue function and extracellular matrix (ECM) remodeling in a depot-specific manner. Herein we aimed to characterize the unique gene signature and ECM remodeling of Sca1high ASCs isolated from subcutaneous (inguinal) and visceral (epididymal) adipose tissues. Sca1high ASCs are found in the adventitia and perivascular area of adipose tissues. Sca1high ASCs purified with magnetic-activated cell sorting (MACS) demonstrate dendrite or round shape with the higher expression of cytokines and chemokines (e.g., Il6, Cxcl1) and the lower expression of a glucose transporter (Glut1). Subcutaneous and visceral fat-derived Sca1high ASCs particularly differ in the gene expressions of adhesion and ECM molecules. While the expression of the major membrane-type collagenase (MMP14) is comparable between the groups, the expressions of secreted collagenases (MMP8 and MMP13) are higher in visceral Sca1high ASCs than subcutaneous ASCs. Consistently, slow but focal MMP-dependent collagenolysis was observed with subcutaneous Sca1high ASCs, whereas rapid and bulk collagenolysis was observed with visceral Sca1high ASCs in MMP-dependent and –independent manners. These results suggest that the fat depot-specific gene signatures of ASCs may contribute to the distinct patterns of ECM remodeling and adipose function in different fat depots.

Proinflammatory Phenotype of Perivascular Adipocytes

“…However, as compared to subcutaneous and perirenal adipocytes derived from the same subjects, these PV adipocytes are smaller in size, less efficient at storing lipid, and express lower levels of adipocyte-specific genes, suggesting a reduced state of adipogenic differentiation. 17 Global gene expression analyses indicate that these features of PV adipocytes map to early developmental differences, consistent with their origination from a distinct precursor cell, 30 as has been proposed for adipose-derived stem cells surrounding perivascular regions of subcutaneous and visceral adipose tissues of mice 33 . In contrast, in vitro differentiated PV adipocytes derived from human radial arteries are larger in size and exhibit a high capacity to form lipid droplets, suggesting that the origin and/or differentiation state of human PV adipocytes is variable depending on the vascular bed.…”

Immunomagnetic Separation of Fat Depot-specific Sca1^high Adipose-derived Stem Cells (ASCs)

“…When these cells were assessed with flow cytometry, most of the GFP positive cells were confirmed to express Sca1 proteins on the cell surface as detected with Anti-Sca1 antibody (Figure 1C). Sca1 high cells derived from inguinal fat pad maintain increased capacity of adipocyte differentiation whereas eWAT-derived Sca1 high cells are more difficult to differentiate into adipocyte with conventional adipogenic mix 10 .…”

“…Genome-wide transcriptome analyses with RNA sequencing demonstrated the enrichment of genes related to extracellular matrix proteins and modifiers (GO:0031012, GO:0005578) in those Sca1 high ASCs 10 . Coupled with real-time PCR analyses, we were able to demonstrate the differential expression of the collagenolytic MMPs (MMP2, MMP8, MMP13, MMP14) between iWAT- and eWAT-derived Sca1 high ASCs.…”

“…Recently, Tokunaga et al . showed that Sca1 high cells isolated from inguinal (or subcutaneous, SQ) and perigonadal (or visceral, VIS) C57BL6/J fat depots exhibited different gene signatures and ECM remodeling in vitro 10 . MMP14 (MT1-MMP), a prototypical member of the membrane-type matrix metalloproteinase (MMP) family mediates the development of white adipose tissue (WAT) through its collagenolytic activity 1 .…”

“…Examples of experiments that may be conducted with the cells isolated and enriched through the following protocol include three-dimensional culture, differentiation studies, collagen degradation assays, and RNA sequencing 10,11 . Degradation assays should be conducted with acid-extracted collagen to ensure the preservation of telopeptide 11,12 {Rajan, 2006 #40}.…”