We explore the status of quiescence, stemness and adipogenic differentiation capacity in adipose stem/progenitor cells (ASCs) ex vivo, immediately after isolation from human subcutaneous white adipose tissue, by sorting the stromal vascular fraction into cell-surface DLK1⁺/CD34⁻, DLK1⁺/CD34^dim and DLK1⁻/CD34⁺ cells. We demonstrate that DLK1⁻/CD34⁺ cells, the only population exhibiting proliferative and adipogenic capacity, express ex vivo the bonafide quiescence markers p21^Cip1, p27^Kip1 and p57^Kip2 but neither proliferation markers nor the senescence marker p16^Ink4a. The pluripotency markers NANOG, SOX2 and OCT4 are barely detectable in ex vivo ASCs while the somatic stemness factors, c-MYC and KLF4 and the early adipogenic factor C/EBPβ are highly expressed. Further sorting of ASCs into DLK1⁻/CD34⁺/CD24⁻ and DLK1⁻/CD34⁺/CD24⁺ fractions shows that KLF4 and c-MYC are higher expressed in DLK1⁻/CD34⁺/CD24⁺ cells correlating with higher colony formation capacity and considerably lower adipogenic activity. Proliferation capacity is similar in both populations. Next, we show that ASCs routinely isolated by plastic-adherence are DLK1⁻/CD34⁺/CD24⁺. Intriguingly, CD24 knock-down in these cells reduces proliferation and adipogenesis. In conclusion, DLK1⁻/CD34⁺ ASCs in human sWAT exist in a quiescent state, express high levels of somatic stemness factors and the early adipogenic transcription factor C/EBPβ but senescence and pluripotency markers are barely detectable. Moreover, our data indicate that CD24 is necessary for adequate ASC proliferation and adipogenesis and that stemness is higher and adipogenic capacity lower in DLK1⁻/CD34⁺/CD24⁺ relative to DLK1⁻/CD34⁺/CD24⁻ subpopulations.

中文翻译：

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人 DLK1-/CD34+/CD24+ 脂肪干细胞/祖细胞的静止、干性和成脂分化能力

我们通过将基质血管部分分选到细胞表面 DLK1 ⁺ /CD34 ^{- 中}，在从人皮下白色脂肪组织中分离后立即探索离体脂肪干/祖细胞 (ASC) 的静止状态、干性和成脂分化能力状态， DLK1 ⁺ /CD34^暗淡和 DLK1 ^- /CD34 ⁺细胞。我们证明 DLK1 ^- /CD34 ⁺细胞是唯一表现出增殖和成脂能力的细胞群，在体外表达真正的静止标记 p21 ^Cip1、p27 ^Kip1和 p57 ^Kip2但增殖标记和衰老标记 p16 ^{Ink4a 都没有}。多能性标记 NANOG、SOX2 和 OCT4 在离体 ASC 中几乎检测不到，而体细胞干细胞因子、c-MYC 和 KLF4 以及早期成脂因子 C/EBPβ 高度表达。进一步将 ASC 分为 DLK1 ^- /CD34 ⁺ /CD24 ^-和 DLK1 ^- /CD34 ⁺ /CD24 ⁺部分表明 KLF4 和 c-MYC 在 DLK1 ^- /CD34 ⁺ /CD24 ^{+ 中}表达更高与较高的集落形成能力和显着较低的脂肪生成活性相关的细胞。两个种群的增殖能力相似。接下来，我们展示了通过塑料粘附常规分离的 ASCs 是 DLK1 ^- /CD34 ⁺ /CD24 ⁺。有趣的是，这些细胞中的 CD24 敲低会减少增殖和脂肪生成。总之，DLK1 ^- /CD34 ⁺人类 sWAT 中的 ASC 以静止状态存在，表达高水平的体干细胞因子和早期成脂转录因子 C/EBPβ，但几乎检测不到衰老和多能性标记物。此外，我们的数据表明，CD24 是足够的 ASC 增殖和脂肪生成所必需的，并且相对于 DLK1 ^- /CD34 ⁺ /CD24 ^-亚群，DLK1 ^- /CD34 ⁺ /CD24 ^{+ 的}干性更高，脂肪生成能力更低。