Uncontrolled expansion of adipose tissue leads to obesity, a public health epidemic affecting >30% of adult Americans. Adipose mass increases in part through the recruitment and differentiation of an existing pool of preadipocytes (PA) into adipocytes (AD). Most studies investigating adipogenesis used primarily murine cell lines; much less is known about the relevant processes that occur in humans. Therefore, characterization of genes associated with adipocyte development is key to understanding the pathogenesis of obesity and developing treatments for this disorder. To address this issue, we performed large-scale analyses of human adipose gene expression using microarray technology. Differential gene expression between PA and AD was analyzed in 6 female patients using human cDNA microarray slides and data analyzed using the Stanford Microarray Database. Statistical analysis for the gene expression was performed using the SAS mixed models. Compared with PA, several genes involved in lipid metabolism were overexpressed in AD, including fatty acid binding protein, adipose differentiation-related protein, lipoprotein lipase, perilipin, and adipose most abundant transcript 1. Novel genes expressed in adipocytes included E2F5 transcriptional factor and SMARC (SWI/SNF-related, matrix associated, actin-dependent regulator of chromatin). PA predominantly expressed genes encoding extracellular matrix components such as fibronectin, matrix metalloprotein, and novel proteins such as lysyl oxidase. Despite the high differential expression of some of these genes, many did not differ significantly likely due to high variability and limited statistical power. A comprehensive list of differential gene expression is presented according to cellular function. In conclusion, these studies offer an overview of the gene expression profiles in PA and AD and identify new genes with potentially important functions in adipose tissue development and obesity that merit further investigation.

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Hydrogels serve as three-dimensional scaffolds whose composition can be customized to allow attachment and proliferation of several different cell types. Extracellular matrix-derived hydrogels are considered close replicates of the tissue microenvironment. They can serve as scaffolds for in vitro tissue engineering and are a useful tool to study cell-scaffold interaction. The aim of the present study was to analyze the effect of adipose-derived stromal/stem cells (ASCs) and decellularized adipose tissue-derived (DAT) hydrogel interaction on ASC morphology, proliferation, differentiation, and DAT hydrogel microstructure. First, the ASCs were characterized using flow cytometry, adipogenic/osteogenic differentiation, colony-forming unit fibroblast assay and doubling time. The viability and proliferation assays showed that ASCs seeded in DAT hydrogel at different concentrations and cultured for 21 days remained viable and displayed proliferation. ASCs were seeded on DAT hydrogel and cultured in stromal, adipogenic, or osteogenic media for 14 or 28 days. The analysis of adipogenic differentiation demonstrated the upregulation of adipogenic marker genes and accumulation of oil droplets in the cells. Osteogenic differentiation demonstrated the upregulation of osteogenic marker genes and mineral deposition in the DAT hydrogel. The analysis of DAT hydrogel fiber metrics revealed that ASC seeding, and differentiation altered both the diameter and arrangement of fibers in the matrix. Matrix metalloproteinase-2 (MMP-2) activity was assessed to determine the possible mechanism for DAT hydrogel remodeling. MMP-2 activity was observed in all ASC seeded samples, with the osteogenic samples displaying the highest MMP-2 activity. These findings indicate that DAT hydrogel is a cytocompatible scaffold that supports the adipogenic and osteogenic differentiation of ASCs. Furthermore, the attachment of ASCs and differentiation along adipogenic and osteogenic lineages remodels the microstructure of DAT hydrogel.

Critical-sized bone defects fail to heal and often cause non-union. Standard treatments employ autologous bone grafting, which can cause donor tissue loss/pain. Although several scaffold types can enhance bone regeneration, multiple factors limit their level of success. To address this issue, this study evaluated a novel decellularized human adipose tissue (DAT) hydrogel as an alternative. In this study, DAT hydrogel alone, or in combination with adipose-derived stromal/stem cells (ASC), osteo-induced ASCs (OIASC), and hydroxyapatite were tested for their ability to mediate repair of a critical-sized (3 mm) femoral defect created in C57BL/6 mice. Micro-computed tomography results showed that all DAT hydrogel treated groups significantly enhanced bone regeneration, with OIASC + hydroxyapatite treated group displaying the most robust bone regeneration. Histological analyses revealed that all treatments resulted in significantly higher tissue areas with the relative mineralized tissue area significantly increased at 12 weeks; however, cartilaginous content was lowest among treatment groups with OIASC. Immunohistochemical analyses showed that DAT hydrogel enhanced collagen I and osteopontin expression, while the addition of OIASCs to the hydrogel reduced collagen II levels. Thus, DAT hydrogel promotes bone regeneration in a critical-sized femoral defect model that is further enhanced in the presence of OIASCs and hydroxyapatite.

Purpose: The aim of this study is to further examine the associations of race, socioeconomic factors, and comorbidity with COVID-19 health outcomes. Methods: This is a retrospective cohort study of 309 PCR confirmed COVID-19 positive adults who presented to Tulane Medical Center in New Orleans, LA, from March 9 to May 29, 2020. The primary outcomes investigated were need for invasive mechanical ventilation (IMV) and in-hospital mortality. A multivariate analysis was performed to determine socioeconomic and medical risk factors for IMV and in-hospital mortality. Results: Compared to white patients, Black patients were more likely to present younger, female, obese, unemployed, and underinsured. However, when controlled for common risk factors, Black and white patients had similar risk for IMV and mortality. Increased age (≥65 years), obesity, and increased comorbidity were associated with increased risk for IMV and mortality. Conclusions: Race and socioeconomic factors may increase risk for COVID-19 infection but did not affect health outcomes within the hospital setting. Therefore, the higher rates of COVID-19 infection and mortality in vulnerable populations may be better explained by lower socioeconomic status, with subsequent higher comorbidity, in these populations. Community health initiatives should be prioritized in response to the COVID-19 pandemic.

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