2015 Journal of tissue engineering and regenerative medicine
* Ex vivo expansion of cord blood haematopoietic stem/progenitor cells under physiological oxygen tensions: clear-cut effects on cell proliferation, differentiation and metabolism.
- Physiologically low O(2) tensions are believed to regulate haematopoietic stem cell (HSC) functions in the bone marrow (BM; 0-5%). In turn, placenta and umbilical cord are characterized by slightly higher physiological O(2) tensions (3-10%). We hypothesized that O(2) concentrations within this range may be exploited to augment the ex vivo expansion/maintenance of HSCs from umbilical cord (placental) blood (UCB). The expansion of UCB CD34(+) -enriched cells was studied in co-culture with BM mesenchymal stem/stromal cells (MSCs) under 2%, 5%, 10% and 21% O(2). 2% O(2) resulted in a significantly lower CD34(+) cell expansion (25-fold vs 60-, 64- and 92-fold at day 10 for 5%, 21%, 10% O(2), respectively). In turn, 10% O(2) promoted the highest CD34(+) CD90(+) cell expansion, reaching 22 ± 5.4- vs 5.6 ± 2.4- and 5.7 ± 2.0-fold for 2%, 5% and 21% O(2), respectively, after 14 days. Similar differentiation patterns were observed under different O(2) tensions, being primarily shifted towards the neutrophil lineage. Cell division kinetics revealed a higher proliferative status of cells cultured under 10% and 21% vs 2% O(2). Expectedly, higher specific glucose consumption and lactate production rates were determined at 2% O(2) when compared to higher O(2) concentrations (5-21%). Overall, these results suggest that physiological oxygen tensions, in particular 10% O(2), can maximize the ex vivo expansion of UCB stem/progenitor cells in co-culture with BM MSCs. Importantly, these studies highlight the importance of exploiting knowledge of the intricate microenvironment of the haematopoietic niche towards the definition of efficient and controlled ex vivo culture systems capable of generating large HSCs numbers for clinical applications.
=>1.低くする/なる, 下げる/下がる, 卑しめる, 2.しかめっ面, 3.lowの比較級
Overview of noun lower
The noun lower has 1 sense (no senses from tagged texts)
1. lower berth, lower -- (the lower of two berths)
Overview of verb lower
The verb lower has 5 senses (first 3 from tagged texts)
1. (15) lower, take down, let down, get down, bring down -- (move something or somebody to a lower
position; "take down the vase from the shelf")
2. (6) lower, lour -- (set lower; "lower a rating"; "lower expectations")
3. (1) turn down, lower, lour -- (make lower or quieter; "turn down the volume of a radio")
4. lower, depress -- (cause to drop or sink; "The lack of rain had depressed the water level in the
reservoir")
5. frown, glower, lour, lower -- (look angry or sullen, wrinkle one's forehead, as if to signal
disapproval)
Overview of adj low
The adj low has 10 senses (first 6 from tagged texts)
1. (55) low -- (less than normal in degree or intensity or amount; "low prices"; "the reservoir is
low")
2. (23) low -- (literal meanings; being at or having a relatively small elevation or upward
extension; "low ceilings"; "low clouds"; "low hills"; "the sun is low"; "low furniture"; "a low
bow")
3. (11) low, low-toned -- (very low in volume; "a low murmur"; "the low-toned murmur of the surf")
4. (6) low -- (unrefined in character; "low comedy")
5. (4) low, low-pitched -- (used of sounds and voices; low in pitch or frequency)
6. (3) abject, low, low-down, miserable, scummy, scurvy -- (of the most contemptible kind; "abject
cowardice"; "a low stunt to pull"; "a low-down sneak"; "his miserable treatment of his family"; "You
miserable skunk!"; "a scummy rabble"; "a scurvy trick")
7. humble, low, lowly, modest, small -- (low or inferior in station or quality; "a humble cottage";
"a lowly parish priest"; "a modest man of the people"; "small beginnings")
8. depleted, low -- (no longer sufficient; "supplies are low"; "our funds are depleted")
9. broken, crushed, humbled, humiliated, low -- (subdued or brought low in condition or status;
"brought low"; "a broken man"; "his broken spirit")
10. gloomy, grim, blue, depressed, dispirited, down, downcast, downhearted, down in the mouth, low,
low-spirited -- (filled with melancholy and despondency ; "gloomy at the thought of what he had to
face"; "gloomy predictions"; "a gloomy silence"; "took a grim view of the economy"; "the darkening
mood"; "lonely and blue in a strange city"; "depressed by the loss of his job"; "a dispirited and
resigned expression on her face"; "downcast after his defeat"; "feeling discouraged and
downhearted")
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