Tumor angiogenesis is of paramount importance in solid tumor development. Elevated serum levels of YKL-40, a secreted heparin-binding glycoprotein have been associated with a worse prognosis from a variety of advanced human cancers. Yet the role of YKL-40 activity in these cancers is still missing. Here, we have shown that ectopic expression of YKL-40 in MDA-MB-231 breast cancer cells and HCT-116 colon cancer cells led to larger tumor formation with an extensive angiogenic phenotype than did control cancer cells in mice. Affinity purified recombinant YKL-40 protein promoted vascular endothelial cell angiogenesis in vitro, the effects similar to the activities observed using MDA-MB-231 and HCT-116 cell conditioned medium after transfection with YKL-40. Further, YKL-40 was found to induce the coordination of membrane-bound receptor syndecan-1 and integrin αvβ3 and activate an intracellular signaling cascade including focal adhesion kinase and MAP kinase Erk1/2 in endothelial cells. Also, blockade of YKL-40 using siRNA gene knockdown suppressed tumor angiogenesis in vitro and in vivo. Immunohistochemical analysis of human breast cancer revealed a correlation between YKL-40 expression and blood vessel density. These findings provide novel insights into angiogenic activities and molecular mechanisms of YKL-40 in cancer development.

Since inflammatory mechanisms have been postulated to link obesity to osteoarthritis, the current study evaluated the ratio of immune cells to multipotent stromal cells within the infrapatellar fat pad (IPFP) and subcutaneous adipose tissue (SQ) of the knee; each depot has potential as a source of regenerative cells. The immunophenotypes of stromal vascular fraction (SVF) and adipose‐derived stem cells (ASCs) of the IPFP and SQ were determined in tissues from osteoarthritic subjects (n = 7) undergoing total knee replacement. Based on a subset of surface antigens, the immunophenotype of ASCs from SQ of OA subjects was not significantly different from that of relatively healthy and leaner subjects undergoing elective liposuction surgery. Flow‐cytometry comparison of SVF cell populations in the IPFP of OA subjects resembled those within the subject's own matched SQ, with the exception of the endothelial marker CD31+, which was significantly greater in cells from SQ. In the OA subjects, lower numbers of capillary‐like structures and higher numbers of stromal and alkaline phosphatase colony‐forming units in the IPFP vs SQ were consistent with this finding; however, ASCs from both depots in OA subjects exhibited comparable adipogenic and osteogenic differentiation potential. Thus, the IPFP contains an ASC and immune cell population similar to that of donor‐matched SQ, making it an alternative ASC source for tissue regeneration. Further studies will be needed to determine whether IPFP immune cell infiltrates play an aetiological role in osteoarthritis equivalent to that shown in diabetes associated with obesity. Copyright © 2012 John Wiley & Sons, Ltd.

Three-dimensional matrices of collagen type I (Col I) are widely used in tissue engineering applications for its abundance in many tissues, bioactivity with many cell types, and excellent biocompatibility. Inspired by the structural role of lignin in a plant tissue, we found that sodium lignosulfonate (SLS) and an alkali-extracted lignin from switchgrass (SG) increased the stiffness of Col I gels. SLS and SG enhanced the stiffness of Col I gels from 52 to 670 Pa and 52 to 320 Pa, respectively, and attenuated shear-thinning properties, with the formulation of 1.8 mg/mL Col I and 5.0 mg/mL SLS or SG. In 2D cultures, the cytotoxicity of collagen–SLS to adipose-derived stromal cells was not observed and the cell viability was maintained over 7 days in 3D cultures. Collagen–SLS composites did not elicit immunogenicity when compared to SLS-only groups. Our collagen–SLS composites present a case that exploits lignins as an enhancer of mechanical properties of Col I without adverse cytotoxicity and immunogenicity for in vitro scaffolds or in vivo tissue repairs.

Monitoring wound progression over time is a critical aspect for studies focused on in-depth molecular analysis or on evaluating the efficacy of potential novel therapies. Histopathological analysis of wound biopsies can provide significant insight into healing dynamics, yet there is no standardized and reproducible scoring system currently available. The purpose of this study was to develop and statistically validate a scoring system based on parameters in each phase of healing that can be easily and accurately assessed using either Hematoxylin & Eosin (H&E) or Masson's Trichrome (MT) staining. These parameters included re-epithelization, epithelial thickness index, keratinization, granulation tissue thickness, remodeling, and the scar elevation index. The initial phase of the study was to (1) optimize and clarify healing parameters to limit investigator bias and variability; (2) compare the consistency of parameters assessed using H&E versus MT staining. During the validation phase of this study, the accuracy and reproducibility of this scoring system was independently iterated upon and validated in four different types of murine skin wound models (Excisional; punch biopsy; pressure ulcers; burn wounds). A total of n = 54 histology sections were randomized, blinded, and assigned to two groups of independent investigators (n = 5 per group) for analysis. The sensitivity of each parameter (ranging between 80% and 95%) is reported with illustrations on the appropriate assessment method using ImageJ software. In the validated scoring system, the lowest score (score:0) is associated with an open/unhealed wound as is evident immediately and within the first day postinjury, whereas the highest score (score:12) is associated with a completely closed and healed wound without excessive scarring. This study defines and describes the minimum recommended criteria for assessing wound healing dynamics using the SPOT skin wound score. The acronym SPOT refers to the academic and scientific institutions that were involved in the development of the scoring system, namely

Biological aging alters the metabolism and volume of adipose tissue depots. Recent evidence suggests that circadian mechanisms play a role in promoting adipogenesis, obesity, and lipodystrophy.The current study compared cohorts of younger (5-9 months) and older (24-28 months) C57BL/6 mice as a function of biological age and circadian time. Advanced age significantly reduced the weight of the AGE (2013) 35:533-547 DOI 10.1007 Electronic supplementary material The online version of this article (doi:10.1007/s11357-012-9389-7) contains supplementary material, which is available to authorized users. brown, epididymal, inguinal, and retroperitoneal adipose depots but not total body weight. The older mice reduced their physical activity by >50% and delayed their activity initiation after light offset. The expressed transcriptome in brown and white adipose depots and liver of both cohorts displayed evidence of circadian rhythmicity; however, the oscillating mRNAs differed significantly between age groups and across tissues. The amplitude of Cry1, a component of the negative arm of the circadian apparatus, and downstream regulators such as Rev-erbα were elevated in the older relative to the younger cohorts as a function of circadian time. Overall, transcript levels differed significantly for 557 (inguinal adipose), 1,016 (liver), and 1,021 (brown adipose) expressed sequences between the cohorts as a function of age. These included transcripts encoding proteins within the canonical and non-canonical Wnt pathways. Since the Wnt pathway regulates adipose stem cell differentiation and shares a critical enzyme, glycogen synthase kinase 3β, with the circadian mechanism, the intersection between these two fundamental regulatory mechanisms merits further investigation with respect to biological aging of adipose tissues.

Human adipose-derived stromal/stem cells (hASC) are widely used for in vitro modeling of physiologically relevant human adipose tissue. These models are useful for the development of tissue constructs for soft tissue regeneration and 3-dimensional (3D) microphysiological systems (MPS) for drug discovery. In this systematic review, we report on the current state of hASC culture and assessment methods for adipose tissue engineering using 3D MPS. Our search efforts resulted in the identification of 184 independent records, of which 27 were determined to be most relevant to the goals of the present review. Our results demonstrate a lack of consensus on methods for hASC culture and assessment for the production of physiologically relevant in vitro models of human adipose tissue. Few studies have assessed the impact of different 3D culture conditions on hASC adipogenesis. Additionally, there has been a limited use of assays for characterizing the functionality of adipose tissue in vitro. Results from this study suggest the need for more standardized culture methods and further analysis on in vitro tissue functionality. These will be necessary to validate the utility of 3D MPS as an in vitro model to reduce, refine, and replace in vivo experiments in the drug discovery regulatory process.

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The development of resistance to therapy is a significant obstacle to effective therapeutic regimens. Evaluating the effects of oncology drugs in the laboratory setting is limited by the lack of translational models that accurately recapitulate cell-microenvironment interactions present in tumors. Acquisition of resistance to therapy is facilitated, in part, by the composition of the tumor extracellular matrix (ECM), with the primary current in vitro model using collagen I (COL I). Here we seek to identify the prevalence of COL I-enhanced expression in the triple-negative breast cancer (TNBC) subtype. Furthermore, we identify if methods of response to therapy are altered depending on matrix composition. We demonstrated that collagen content varies in patient tumor samples across subtypes, with COL I expression dramatically increased in typically less aggressive estrogen receptor (ER)-positive(ER + )/progesterone receptor (PGR)-positive (PGR + ) cancers irrespective of patient age or race. These findings are of significance considering how frequently COL I is implicated in tumor progression. In vitro analyses of ER + and ER-negative (ER -) cell lines were used to determine the effects of ECM content (collagen I, collagen IV, fibronectin, and laminin) on proliferation, cellular phenotype, and survival. Neither ER + nor ERcells demonstrated significant increases in proliferation when cultured on these ECM substrates. ERcells cultured on these substrates were sensitized to both chemotherapy and targeted therapy. In addition, MDA-MB-231 cells expressed different morphologies, binding affinities, and stiffness across these substrates. We also demonstrated that ECM composition significantly alters transcription of senescence-associated pathways across ER + and ERcell lines. Together, these results suggest that complex matrix composites should be incorporated into in vitro tumor models, especially for the drug-resistant TNBC subtype.