The efficacy of adiponectin (APN) in regulating bone metabolism remains controversial. This study aimed to investigate the role of APN secreted from adipose-derived stem cells on adipogenesis and osteogenesis. Human APN gene was transfected via recombinant adenovirus into adipose derived stem cells (ASCs) in vitro and were cocultured with bone marrow mesenchymal stem cells (BMSCs) in using a transwell chamber. Adipogenesis was inhibited in APN-transfected ASCs; in BMSCs, adipogenesis was inhibited, but osteogenesis was promoted in coculture with APN-transfected ASCs. Next, the same adenovirus construct was transfected into the abdominal adipose tissue of a Sprague Dawley rat in vivo, and then a tibia defect was established in the same rat. We confirmed there was higher gene and protein expression of APN in ASCs and the abdominal adipose tissue of these rat models. Development of adipocytes in abdominal adipose tissue was suppressed, and less new bone was formed in the bone defect area. In conclusion, APN secreted from ASCs could directly inhibit adipogenesis in ASCs and BMSCs and promote osteogenesis in the latter. However, APN overexpression in adipose tissue was inversely associated with bone formation in tibia defects potentially due to decreased levels of circulating bone-activating hormones.

中文翻译：

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脂肪干细胞分泌的脂联素对骨脂平衡和骨缺损愈合的影响。

脂联素（APN）在调节骨代谢中的功效仍存在争议。这项研究旨在调查从脂肪干细胞分泌的APN在脂肪形成和成骨中的作用。将人APN基因通过重组腺病毒体外转染到脂肪来源的干细胞（ASC）中，并在一个transwell室中与骨髓间充质干细胞（BMSCs）共培养。在APN转染的ASC中，脂肪形成受到抑制。在BMSCs中，脂肪形成受到抑制，但与APN转染的ASC共培养可促进成骨作用。接下来，将相同的腺病毒构建体体内转染到Sprague Dawley大鼠的腹部脂肪组织中，然后在同一只大鼠中建立胫骨缺损。我们证实，在这些大鼠模型的ASC和腹部脂肪组织中，APN的基因和蛋白表达较高。腹部脂肪组织中脂肪细胞的发育受到抑制，并且在骨缺损区域形成的新骨更少。总之，从ASC分泌的APN可以直接抑制ASC和BMSC中的脂肪形成，并促进后者的成骨作用。但是，脂肪组织中APN的过表达与胫骨缺损中的骨形成呈负相关，这可能是由于循环中的骨激活激素水平降低所致。