The Department of Cardiovascular Medicine, State Key Laboratory of Medical Genomics, Shanghai Key Laboratory of Hypertension, Ruijin Hospital, Shanghai Institute of Hypertension, Shanghai Jiao Tong University School of Medicine, No. 197, Ruijin 2nd Road, Shanghai, 200025, China.
Department of Digestion, Huaihe Hospital of Henan University, Kaifeng, 475000, China.
Stem Cell Res Ther. 2021 Mar 10;12(1):167. doi: 10.1186/s13287-021-02169-0.
Brown adipocytes (BAs) are major components of brown adipose tissue (BAT), which is involved in blood pressure regulation. BAs are derived from multiple progenitors, including PDGFRα adipose-derived stem cells (ASCs). Skin-derived mesenchymal stem cells (S-MSCs) have the capacity to differentiate into adipocytes; however, their ability to differentiate into BAs remains unexplored. We aim to study the ability and regulatory mechanism of the differentiation of S-MSCs into BAs and the direct role of BAT in blood pressure regulation.
Protein expression was measured by flow cytometry or Western blotting, and gene mRNA levels were quantified by real-time quantitative PCR (RT-PCR). To induce the differentiation of S-MSCs into BAs, S-MSCs were stimulated with a brown adipogenic cocktail comprising insulin, IBMX, dexamethasone, triiodothyronine (T3), and rosiglitazone for the indicated periods. The oxygen consumption rate (OCR) was measured with an XF24 Extracellular Flux Analyzer. Mitochondrial mass was determined by flow cytometry and fluorescence staining. Hypertension was induced in WT mice by infusion of angiotensin II (Ang II), and systolic blood pressure (SBP) was measured using a tail cuff. Interscapular brown adipose tissue (iBAT)-deficient mice were generated by surgical removal of the iBAT depot, after which the animals were allowed to recover for 6 days. Aortic, iBAT, and heart tissue sections were analyzed by hematoxylin and eosin (HE) staining.
We found that in vitro, S-MSCs isolated from the mouse dermis expressed the stem cell markers CD90/105 and PDGFRα and readily differentiated into BAs. Mitochondrial biogenesis and oxygen consumption were markedly increased during differentiation of S-MSCs into BAs. In vivo, iBAT was converted to white adipose tissue (WAT) in Ang II-induced hypertensive mice. We assessed the direct role of BAT in blood pressure (BP) regulation by using iBAT-deficient mice (generated by surgical removal of iBAT) and C57BL/6 (wild-type (WT)) mice and found that Ang II-induced BP elevation and vascular damage were markedly aggravated in iBAT-deficient mice compared with WT mice.
This study demonstrates that PDGFRα S-MSCs are able to differentiate into BAs and that this differentiation is regulated by mitochondrial activity. We also show that BAT plays a direct role in ameliorating Ang II-induced hypertension. The therapeutic potential of BAT for the prevention of hypertension-induced organ remodeling thus warrants further investigation.
棕色脂肪细胞（BAs）是棕色脂肪组织（BAT）的主要组成部分，参与血压调节。BAs 来源于多个祖细胞，包括 PDGFRα 脂肪源性干细胞（ASCs）。皮肤衍生的间充质干细胞（S-MSCs）具有分化为脂肪细胞的能力；然而，它们分化为 BAs 的能力仍未得到探索。我们旨在研究 S-MSCs 向 BAs 分化的能力和调节机制，以及 BAT 在血压调节中的直接作用。
通过流式细胞术或 Western blot 测量蛋白质表达，通过实时定量 PCR（RT-PCR）定量基因 mRNA 水平。为了诱导 S-MSCs 向 BAs 分化，用包含胰岛素、IBMX、地塞米松、三碘甲状腺原氨酸（T3）和罗格列酮的棕色脂肪生成鸡尾酒刺激 S-MSCs 进行了指定时间的分化。用 XF24 细胞外通量分析仪测量耗氧量（OCR）。通过流式细胞术和荧光染色测定线粒体质量。通过输注血管紧张素 II（Ang II）在 WT 小鼠中诱导高血压，并使用尾套测量收缩压（SBP）。通过手术切除 iBAT 储存库生成 iBAT 缺陷型小鼠，然后允许动物恢复 6 天。用苏木精和伊红（HE）染色分析主动脉、iBAT 和心脏组织切片。
我们发现，在体外，从小鼠真皮分离的 S-MSCs 表达干细胞标志物 CD90/105 和 PDGFRα，并且易于分化为 BAs。S-MSCs 向 BAs 分化过程中线粒体生物发生和耗氧量明显增加。在体内，Ang II 诱导的高血压小鼠中 iBAT 转化为白色脂肪组织（WAT）。我们通过使用 iBAT 缺陷型（通过手术切除 iBAT 生成）和 C57BL/6（野生型（WT））小鼠评估了 BAT 在血压（BP）调节中的直接作用，发现与 WT 小鼠相比，iBAT 缺陷型小鼠的 Ang II 诱导的血压升高和血管损伤明显加重。
这项研究表明，PDGFRα S-MSCs 能够分化为 BAs，这种分化受线粒体活性调节。我们还表明，BAT 在改善 Ang II 诱导的高血压中起直接作用。BAT 预防高血压引起的器官重塑的治疗潜力因此值得进一步研究。
