Abstract-It has been shown that stromal-vascular fraction isolated from adipose tissues contains an abundance of CD34 ϩ cells. Histological analysis of adipose tissue revealed that CD34 ϩ cells are widely distributed among adipocytes and are predominantly associated with vascular structures. The majority of CD34 ϩ cells from freshly isolated stromal-vascular fraction were CD31 Ϫ /CD144 Ϫ and could be separated from a distinct population of CD34 ϩ /CD31 ϩ /CD144 ϩ (endothelial) cells by differential attachment on uncoated plastic. The localization of CD34 ϩ cells within adipose tissue suggested that the nonendothelial population of these cells occupied a pericytic position. Analysis of surface and intracellular markers of the freshly isolated CD34 ϩ /CD31 Ϫ /CD144 Ϫ adipose-derived stromal cells (ASCs) showed that Ͼ90% coexpress mesenchymal (CD10, CD13, and CD90), pericytic (chondroitin sulfate proteoglycan, CD140a, and CD140b), and smooth muscle (␣-actin, caldesmon, and calponin) markers. ASCs demonstrated polygonal self-assembly on Matrigel, as did human microvascular endothelial cells. Coculture of ASCs with human microvascular endothelial cells on Matrigel led to cooperative network assembly, with enhanced stability of endothelial networks and preferential localization of ASCs on the abluminal side of cords. Bidirectional paracrine interaction between these cells was supported by identification of angiogenic factors (vascular endothelial growth factor, hepatocyte growth factor, basic fibroblast growth factor), inflammatory factors (interleukin-6 and -8 and monocyte chemoattractant protein-1 and -2), and mobilization factors (macrophage colony-stimulating factor and granulocyte/macrophage colony-stimulating factor) in media conditioned by CD34 ϩ ASCs, as well a robust mitogenic response of ASCs to basic fibroblast growth factor, epidermal growth factor, and platelet-derived growth factor-BB, factors produced by endothelial cells. These results demonstrate for the first time that the majority of adipose-derived adherent CD34

Obesity is an increasingly prevalent human condition in developed societies. Despite major progress in the understanding of the molecular mechanisms leading to obesity, no safe and effective treatment has yet been found. Here, we report an antiobesity therapy based on targeted induction of apoptosis in the vasculature of adipose tissue. We used in vivo phage display to isolate a peptide motif (sequence CKGGRAKDC) that homes to white fat vasculature. We show that the CKGGRAKDC peptide associates with prohibitin, a multifunctional membrane protein, and establish prohibitin as a vascular marker of adipose tissue. Targeting a proapoptotic peptide to prohibitin in the adipose vasculature caused ablation of white fat. Resorption of established white adipose tissue and normalization of metabolism resulted in rapid obesity reversal without detectable adverse effects. Because prohibitin is also expressed in blood vessels of human white fat, this work may lead to the development of targeted drugs for treatment of obese patients.

The molecular diversity of receptors in human blood vessels remains largely unexplored. We developed a selection method in which peptides that home to specific vascular beds are identified after administration of a peptide library. Here we report the first in vivo screening of a peptide library in a patient. We surveyed 47,160 motifs that localized to different organs. This large-scale screening indicates that the tissue distribution of circulating peptides is nonrandom. High-throughput analysis of the motifs revealed similarities to ligands for differentially expressed cell-surface proteins, and a candidate ligand-receptor pair was validated. These data represent a step toward the construction of a molecular map of human vasculature and may have broad implications for the development of targeted therapies.

The connection between obesity and accelerated cancer progression has been established, but the mediating mechanisms are not well understood. We have shown that stromal cells from white adipose tissue (WAT) cooperate with the endothelium to promote blood vessel formation through the secretion of soluble trophic factors. Here, we hypothesize that WAT directly mediates cancer progression by serving as a source of cells that migrate to tumors and promote neovascularization. To test this hypothesis, we have evaluated the recruitment of WAT-derived cells by tumors and the effect of their engraftment on tumor growth by integrating a transgenic mouse strain engineered for expansion of traceable cells with established allograft and xenograft cancer models. Our studies show that entry of adipose stromal and endothelial cells into systemic circulation leads to their homing to and engraftment into tumor stroma and vasculature, respectively. We show that recruitment of adipose stromal cells by tumors is sufficient to promote tumor growth. Finally, we show that migration of stromal and vascular progenitor cells from WAT grafts to tumors is also associated with acceleration of cancer progression. These results provide a biological insight for the clinical association between obesity and cancer, thus outlining potential avenues for preventive and therapeutic strategies.

Epidemiologic studies associate cancer with obesity, but the pathophysiologic connections remain obscure. In this study, we show that obesity facilitates tumor growth in mice irrespective of concurrent diet, suggesting a direct effect of excess white adipose tissue (WAT). When transplanted into mice, adipose stromal cells (ASC) can serve as perivascular adipocyte progenitors that promote tumor growth, perhaps helping explain the obesitycancer link. In developing this hypothesis, we showed that ASCs are expanded in obesity and that they traffic from endogenous WAT to tumors in several mouse models of cancer. Strikingly, a comparison of circulating and tumorinfiltrating cell populations in lean, and obese mice revealed that cancer induces a six-fold increase of ASC frequency in the systemic circulation. We obtained evidence that ASCs mobilized in this way can be recruited into tumors, where they can be incorporated into blood vessels as pericytes and they can differentiate into adipocytes in an obesity-dependent manner. Extending this evidence, we found that increased tumor vascularization (reflected by changes in tumor vascular morphology and a two-fold increase in vascular density) was associated with intratumoral adipocytes and elevated proliferation of neighboring malignant cells. Taken together, our results suggest that ASCs recruited from endogenous adipose tissue can be recruited by tumors to potentiate the supportive properties of the tumor microenvironment. Cancer Res; 72(20); 5198-208. Ó2012 AACR.

Adipose stromal cells (ASCs) serve as mesenchymal progenitors in white adipose tissue (WAT). Intercellular interactions involving ASCs have remained obscure. By merging phage display technology with fluorescence-activated cell sorting (FACS), we screened a combinatorial library for peptides that target mouse ASCs in vivo. We isolated peptide CSWKYWFGEC that specifically homes to ASCs, used it as bait to purify the corresponding ASC surface receptor, and identified it as a previously unreported cleavage product of decorin (DCN) lacking the glycanation site (termed ΔDCN). We demonstrate that ΔDCN is differentially expressed on ASC surface. In a screen for ΔDCN-binding proteins, we identified resistin, an adipokine for which the receptor has been unknown. Expression of ΔDCN in 3T3-L1 cells promoted proliferation and migration but suppressed lipid accumulation upon adipogenesis induction, which was resistin dependent. We conclude that ΔDCN serves as a functional receptor of resistin in adipocyte progenitors and may regulate WAT expansion.

Recognition of molecular diversity of cell surface proteomes in disease is essential for the development of targeted therapies. Progress in targeted therapeutics requires establishing effective approaches for high-throughput identification of agents specific for clinically relevant cell surface markers. Over the past decade, a number of platform strategies have been developed to screen polypeptide libraries for ligands targeting receptors selectively expressed in the context of various cell surface proteomes. Streamlined procedures for identification of ligand-receptor pairs that could serve as targets in disease diagnosis, profiling, imaging and therapy have relied on the display technologies, in which polypeptides with desired binding profiles can be serially selected, in a process called biopanning, based on their physical linkage with the encoding nucleic acid. These technologies include virus/phage display, cell display, ribosomal display, mRNA display and covalent DNA display (CDT), with phage display being by far the most utilized. The scope of this review is the recent advancements in the display technologies with a particular emphasis on molecular mapping of cell surface proteomes with peptide phage display. Prospective applications of targeted compounds derived from display libraries in the discovery of targeted drugs and gene therapy vectors are discussed.

Purpose Adipose tissue contains a population of tumor-tropic mesenchymal progenitors, termed adipose stromal cells (ASC), which engraft in neighboring tumors to form supportive tumor stroma. We hypothesized that intra-abdominal visceral adipose tissue may contain a uniquely tumor promoting population of ASC to account for the relationship between excess visceral adipose tissue and mortality of intra-abdominal cancers. Experimental Design To investigate this, we isolated and characterized ASC from intra-abdominal omental adipose tissue (O-ASC) and characterized their effects on endometrial cancer progression as compared to subcutaneous adipose derived mesenchymal stromal cells (SC-ASC), bone marrow derived mesenchymal stromal cells (BM-MSC) and lung fibroblasts. To model chronic recruitment of ASC by tumors, cells were injected metronomically into mice bearing Hec1a xenografts. Results O-ASC expressed cell surface markers characteristic of BM-MSC and differentiated into mesenchymal lineages. Co-culture with O-ASC increased endometrial cancer cell proliferation in-vitro. Tumor tropism of O-ASC and SC-ASC for human Hec1a endometrial tumor xenografts was comparable, but O-ASC more potently promoted tumor growth. Compared with tumors in SC-ASC-injected mice, tumors in O-ASC-injected mice contained higher numbers of large tortuous desmin-positive blood vessels, which correlated with decreased central tumor necrosis and increased tumor cell proliferation. O-ASC-exhibited enhanced motility as compared to SC-ASC in response to Hec1a secreted factors. Conclusions Visceral adipose contains a population of multipotent MSC that promote endometrial tumor growth more potently than MSC from subcutaneous adipose tissue. We propose that O-ASC recruited to tumors express specific factors that enhance tumor vascularization, promoting survival and proliferation of tumor cells.