Polymeric Microspheres/Cells/Extracellular Matrix Constructs Produced by Auto-Assembly for Bone Modular Tissue Engineering

Modular tissue engineering (MTE) is a novel “bottom-up” approach to create engineered biological tissues from microscale repeating units. Our aim was to obtain microtissue constructs, based on polymer microspheres (MSs) populated with cells, which can be further assembled into larger tissue blocks and used in bone MTE. Poly(L-lactide-co-glycolide) MS of 165 ± 47 µm in diameter were produced by oil-in-water emulsification and treated with 0.1 M NaOH. To improve cell adhesion, MSs were coated with poly-L-lysine (PLL) or human recombinant collagen type I (COL). The presence of oxygenated functionalities and PLL/COL coating on MS was confirmed by X-ray photoelectron spectroscopy (XPS). To assess the influence of medium composition on adhesion, proliferation, and osteogenic differentiation, preosteoblast MC3T3-E1 cells were cultured on MS in minimal essential medium (MEM) and osteogenic differentiation medium (OSG). Moreover, to assess the potential osteoblast–osteoclast cross-talk phenomenon and the influence of signaling molecules released by osteoclasts on osteoblast cell culture, a medium obtained from osteoclast culture (OSC) was also used. To impel the cells to adhere and grow on the MS, anti-adhesive cell culture plates were utilized. The results show that MS coated with PLL and COL significantly favor the adhesion and growth of MC3T3-E1 cells on days 1 and 7, respectively, in all experimental conditions tested. On day 7, three-dimensional MS/cell/extracellular matrix constructs were created owing to auto-assembly. The cells grown in such constructs exhibited high activity of early osteogenic differentiation marker, namely, alkaline phosphatase. Superior cell growth on PLL- and COL-coated MS on day 14 was observed in the OSG medium. Interestingly, deposition of extracellular matrix and its mineralization was particularly enhanced on COL-coated MS in OSG medium on day 14. In our study, we developed a method of spontaneous formation of organoid-like MS-based cell/ECM constructs with a few millimeters in size. Such constructs may be regarded as building blocks in bone MTE.     

A matheuristic approach for optimizing mineral value chains under uncertainty

Optimization and Engineering - Mineral value chains, also known as mining complexes, involve mining, processing, stockpiling, waste management and transportation activities. Their optimization is...     

Effect of rancidity of Lupinus albus protein-concentrate-based diets on food intake and growth of Wistar rats

The organoleptic properties of a diet are influenced by technological processes and have to be taken into account in food intake studies. The authors studied the food intake suppression associated with rancidity occurring during the storage of diets based on casein or heated or lyophilised lupin protein concentrates, and with or without ascorbic acid supplementation in five groups of 10 weanling Wistar rats for 21 or 26 days. After 15 days of storage, the unsaturated fatty acids were oxidised in heated lupin-protein-based diet without ascorbic acid. Compared to casein, food intake was decreased slightly during the first 10, 16 or 20 days for, respectively, heated lupin protein diet without ascorbic acid, heated lupin protein diet with ascorbic acid, and lyophilised lupin protein diet with or without ascorbic acid. After these periods, food intake decreased strongly. Body weight gain variations did not exactly follow food intake variations. The storage at 20°C could induce first an accumulation of free radicals, which were not detectable in measurement of fatty acids but perceived by rats, and then a fast oxidation of unsaturated fatty acids that increased rancid smell, modified nutritional quality and caused a dramatic decrease of rat food intake. Supplementing ascorbic acid into the diet could diminish the formation of free radicals at the beginning of storage, and consequently could delay food intake decrease. © 1997 SCI.     

Gene Doping with Peroxisome-Proliferator-Activated Receptor Beta/Delta Agonists Alters Immunity but Exercise Training Mitigates the Detection of Effects in Blood Samples

Synthetic ligands of peroxisome-proliferator-activated receptor beta/delta (PPARβ/δ) are being used as performance-enhancing drugs by athletes. Since we previously showed that PPARβ/δ activation affects T cell biology, we wanted to investigate whether a specific blood T cell signature could be employed as a method to detect the use of PPARβ/δ agonists. We analyzed in primary human T cells the in vitro effect of PPARβ/δ activation on fatty acid oxidation (FAO) and on their differentiation into regulatory T cells (Tregs). Furthermore, we conducted studies in mice assigned to groups according to an 8-week exercise training program and/or a 6-week treatment with 3 mg/kg/day of GW0742, a PPARβ/δ agonist, in order to (1) determine the immune impact of the treatment on secondary lymphoid organs and to (2) validate a blood signature. Our results show that PPARβ/δ activation increases FAO potential in human and mouse T cells and mouse secondary lymphoid organs. This was accompanied by increased Treg polarization of human primary T cells. Moreover, Treg prevalence in mouse lymph nodes was increased when PPARβ/δ activation was combined with exercise training. Lastly, PPARβ/δ activation increased FAO potential in mouse blood T cells. Unfortunately, this signature was masked by training in mice. In conclusion, beyond the fact that it is unlikely that this signature could be used as a doping-control strategy, our results suggest that the use of PPARβ/δ agonists could have potential detrimental immune effects that may not be detectable in blood samples.     

Comparison of effects of prickly pear (Opuntia ficus indica sp) fruit,arabic gum,carrageenan, alginic acid,locust bean gum and citrus pectin on viscosity and in vitro digestibility of casein

The consumption of high levels of fibres can induce a decrease in both food digestibility and nutrient availability. Prickly pear is a pectin‐rich fruit and it is possible to use it to decrease plasma cholesterol levels. Its effect on food digestibility deserves attention. This effect was determined by using a mixture of a constant quantity of casein and an increasing quantity (10, 20, 25% of the casein) of prickly pear pulp, skin and seed. In parallel, the effect of similar mixtures of carrageenan, gum arabic, locust bean gum, alginic acid and citrus pectin with casein was also studied. The flow behaviour of the different mixtures was determined and their digestibilities were measured using an in vitro digestion cell device. The apparent viscosities of the mixtures with prickly pear components and gum arabic were similar. The nature and level of fibres in the diet modified nitrogen release in the in vitro digestion cell model. The pulp of the prickly pear decreased the digestibility of the casein‐based diet to a greater extent than the other soluble fibres, whatever the percentage used. The results suggest that the decrease in N release in the digestion cell model is due to the interaction of the fibres with the enzymes or casein rather than to the apparent viscosity of the mixtures. © 2000 Society of Chemical Industry