PubMed · 11293084
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M DiGirolamo, J B Fine. 2001. Cellularity measurements.. https://doi.org/10.1385/1-59259-231-7%3A065
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Decellularized tissues provide biological cues owing to the wealth of structural and regulatory factors that promote angiogenesis, adipogenesis, and myogenesis and facilitate neurite outgrowth. Here, we demonstrated the advantages of decellularized adipose tissue (adipoECM) over defined collagen-based biomaterials for host tissue integration. Three batches of human adipose tissue were decellularized using a rapid decellularization protocol and analyzed using mass spectrometry. To assess the biological activity of the decellularized materials, adipoECM and a reference standard of care biomaterial (Integra®DRT, also containing collagen I and glycosaminoglycans) were implanted subcutaneously, but far from the wound bed (in anatomical potential spaces) of immunocompetent BALB/c mice. The mice were euthanized in the acute (1 day) and chronic (day 60) inflammatory reaction phases, followed by biomaterial excision and Masson’s trichrome immunohistofluorescence imaging of the paraffin-embedded specimens. Each batch of processed tissue passed a quality control check, showing a low level of donor genomic DNA, lack of nuclei, lipids, endotoxins, and bacterial contamination. Mass spectrometry revealed that all batches of decellularized tissue mainly contained collagen I and, to a lesser degree, collagen III, collagen IV, collagen V, laminin, fibrillin, fibronectin, tenascin, and elastin. No acute inflammatory reaction was observed in either material one day post-transplantation. At 60 days post-implantation, different cell types were detected in adipoECM specimens, whereas Integra®DRT remained acellular. Additional immunohistochemical staining of adipoECM revealed CD31-positive cells in the blood vessels. Mesenchymal (CD90 positive) and myeloid (CD14 positive) cells were also detected. Primary cell types involved in soft tissue healing and remodeling were found in the adipoECM-treated group. The ingrowth of blood vessels and mesenchymal cells confirmed the effective integration of adipoECM with host tissues. Our results demonstrate that decellularized adipose tissue implanted away from the wound bed possesses contextual biological activities that promote efficient integration with host tissues.
Current data suggest that phospholipid transfer protein (PLTP) has multiple metabolic functions, however, its physiological significance in humans remains to be clarified. To provide further insight into the role of PLTP in lipoprotein metabolism, plasma PLTP activity was measured, and lipoproteins were analyzed in 134 non-diabetic individuals on a controlled diet. Insulin sensitivity index (Si) and body fat composition were also determined. Plasma PLTP activity was comparable between men (n=56) and women (n=78). However, in women but not in men, plasma PLTP activity was positively correlated with cholesterol, triglyceride, low density lipoprotein (LDL) cholesterol, and apolipoprotein (apo) B (r=0.38-0.45, P< or =0.001), and with body mass index (BMI), subcutaneous and intra-abdominal fat (SCF, IAF) (r=0.27-0.29, P<0.02). Among the different apo B-containing lipoproteins (LpB) in women, PLTP was most highly correlated with intermediate density lipoproteins (IDL) and buoyant LDL (r=0.45-0.46, P<0.001). The correlation with IDL was significant only in women with BMI < or =27.5 kg/m(2) (n=56). In men with BMI < or =27.5 kg/m(2) (n=35), PLTP activity was significantly correlated with buoyant LDL (r=0.40, P<0.02) and high density lipoprotein (HDL) (r=0.43, P<0.01). These data provide evidence for a role of PLTP in LpB metabolism, particularly IDL and buoyant LDL. They also suggest that gender and obesity-related factors can modulate the impact of PLTP on LpB.
Sterol regulatory element binding proteins (SREBPs) are transcription factors that are involved in adipogenesis and regulate the expression of genes controlling cholesterol and fatty acid biosynthesis. Animal experiments indicate that SREBP-1a, -1c, and -2 have distinct functions despite overlapping specificities for target genes. To study the possible relationships of SREBPs with obesity, we determined their expression levels in intra- and extraperitoneal adipose tissue samples of obese, post-obese and never-obese humans. We furthermore investigated possible associations of SREBP gene expression with mRNA levels of key enzymes of fatty acid and cholesterol biosynthesis. SREBP-1c was the most abundant SREBP mRNA isoform in human adipose tissue. mRNA levels of SREBP-1a and -1c correlated within tissues whereas no correlations were observed between SREBP-1a or -1c and SREBP-2 mRNA abundance. SREBP-1c and -2 mRNA levels were significantly lower in obese than in never-obese and post-obese subjects. SREBP-1c, but not -1a or -2 gene expression was associated with fatty acid synthase and acetyl-CoA carboxylase alpha gene expression in the intraperitoneal adipose tissue of obese humans. Our results suggest that common mechanisms are involved in the regulation of SREBP-1a and -1c expression in human adipose tissues and imply distinct functions of SREBP isoforms in the regulation of lipid and cholesterol biosynthesis. The reduction in SREBP-1c and -2 mRNA expression in obese humans and their upregulation after weight loss provides new insight into the relationship of these transcription factors with obesity in humans.