Biomedical subjects

G Entenmann

Publications and source records attributed to G Entenmann.

4 recordsLinked to original sources

PubMed1996

Relationship between replication and differentiation in cultured human adipocyte precursor cells.

The aim of this study was to investigate the role of cell replication for the differentiation of human adipocyte precursor cells in primary culture. When cells were seeded in a medium supplemented with 10% fetal bovine serum, they started to proliferate within 48 h after exposure, as assessed by cell counting and [3H]thymidine autoradiography. When cells were inoculated in the absence of serum, a significant degree of cell proliferation was not detectable. Histochemical investigations using bromodeoxyuridine incorporation demonstrated that cells replicating their DNA did not accumulate lipid droplets. Inoculating adipocyte precursor cells under completely serum-free conditions resulted in a 30-50% higher expression of lipogenic enzymes such as glycerol-3-phosphate dehydrogenase and lipoprotein lipase than keeping cells in serum-supplemented medium for the initial 16 h. Addition of cytosine arabinoside at concentrations that effectively block mitosis did not interfere with adipocyte development. In conclusion, adipocyte precursor cells from human adipose tissue do not require cell division to enter the differentiation process in vitro. These cells may have already undergone possibly critical cell divisions in vivo and may be in a late stage of adipocyte development.

Adipocytes↗

PubMed1992

Resorbable polyesters: composition, properties, applications.

Synthetic polymers, in particular polyesters based on lactic acid, glycolic acid and other raw materials are described for medical and technical applications. Their main advantages are compatibility and safety. As they are degradable in the human body they are particularly suitable for implants needed only temporarily for the healing process. Resorbable polyesters are produced by direct polycondensation or ring opening polymerization resulting in a broad range of polymers with different features. The main properties such as degradation (hydrolytic and thermal), crystallinity and mechanical strengths are discussed. These polyesters, which can be processed like other thermo-plastic polymers by extrusion and injection moulding, are used mainly for wound closure products (sutures, staples, clips), fracture fixation devices (nails, screws, plates) and parenteral depot systems for the sustained release of drugs. Possibilities for polymer and process improvement to develop better implants and additional applications are presented.

Biocompatible Materials↗

PubMed1991

Regional variation of adipose differentiation in cultured stromal-vascular cells from the abdominal and femoral adipose tissue of obese women.

The capacities of the adipocyte precursor pools to form new fat cells were compared in the abdominal and femoral adipose tissue regions of obese women. Adipose tissue samples were obtained from 24 females by needle biopsy. The stromal-vascular cells isolated by collagenase digestion were cultured in a chemically defined medium supplemented with 0.5 mumol/l insulin and 0.1 mumol/l cortisol. The extent of adipose differentiation was assessed by determination of glycerol-3-phosphate dehydrogenase (GPDH) activity after 18 days in culture. No significant differences were found between the two depots with regard to mean fat cell diameter and the number of stromal-vascular cells (abdominal vs femoral site: 134,800 +/- 7900 vs 138,800 +/- 6700 cells/g wet adipose tissue, n.s.). However, GPDH activities were significantly higher in cultured cells from the abdominal region as compared to those from the femoral depot (253.1 +/- 40.9 vs 155.8 +/- 21.4 mU/mg protein, P less than 0.01). These results suggest that regional differences exist in the capacity of adipose tissue depots to form new fat cells. This finding may help to understand changes in adipose tissue distribution during adult life.

Abdomen↗

PubMed1989

Promoting effect of glucocorticoids on the differentiation of human adipocyte precursor cells cultured in a chemically defined medium.

Stromal-vascular cells obtained from adult human subcutaneous adipose tissue were cultured in a chemically defined serum-free medium. In the presence of 0.2 nM triiodothyronine and 0.5 microM insulin, up to 25% of the cells were able to undergo terminal adipose differentiation within 18 d, as assessed by lipid accumulation and the expression of lipoprotein lipase (LPL) and glycerol-3-phosphate dehydrogenase (GPDH) activities. Addition of cortisol resulted in a potent dose-dependent stimulation of the adipose differentiation process. Cortisol could be replaced by dexamethasone and partly by aldosterone, but not by sex steroids. The proportion of differentiated cells was dependent upon the age of the donor; when isolated from young adults, up to 70% of the stromal-vascular cells expressed the adipocyte phenotype as compared with 5-10% when the cells were isolated from the oldest subjects. An inverse relationship was observed between the age of the 27 normal-weight donors and the extent of GPDH expression after maintenance of the cells for 18 d in chemically defined medium supplemented with insulin, triiodothyronine, and cortisol (r = -0.787, P less than 0.001). It is concluded that adult human adipose tissue still contains precursor cells that are able to undergo adipose differentiation in vitro. This improved culture system may offer the opportunity to characterize other adipogenic factors as well as antiadipogenic factors involved in the control of adipose tissue growth.

Adipose Tissue↗