Department of Bioengineering and QB3 Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
Acta Pharmacol Sin. 2013 Aug;34(8):1052-60. doi: 10.1038/aps.2013.67. Epub 2013 Jun 17.
To study the influence of acute experimental diabetes on the regenerative potential of muscle stem (satellite) cells in mice.
Male C57BL/6 young mice were injected with a single dose of streptozotocin (STZ, 180 mg/kg, ip) to induce diabetes. The diabetic mice were treated with insulin (0.75 U/kg, ip), follistatin (12 μg/kg, im) or Alk5 inhibitor (5 μmol/L per kg, sc) once a day. On the first day when high glucose levels were found, cardiotoxin (CTX) was focally injected into tibialis anterior and gastronemius muscles of the mice. The muscles were harvested 3 d and 5 d after CTX injection, and myofibers and satellite cells were isolated. Quantitative ex-vivo and in-vivo assays of myogenic potential were used to evaluate the muscle regenerative responses.
The satellite cells from the diabetic mice 3 d after CTX injection fail to activate, and the repair of muscle deteriorates, resembling that observed in old control mice. Furthermore, the satellite cells have excessive levels of myostatin, TGF-β receptor 1, pSmad3 and the cell cycle inhibitor p15, while the level of TGF-β1 remain unchanged. Treatment of the diabetic mice with insulin rescued muscle regenerative responses, and restored the expression levels of myostatin, TGF-β receptor 1, pSmad3, and p15 to those similar of healthy controls. Treatment of the diabetic mice with the myostatin antagonist follistatin, or with the Alk5 inhibitor of TGF-β receptor 1 (which did not diminish the blood glucose levels) rescued muscle regenerative responses and attenuated the myostatin/TGFβ receptor/pSmad3 signaling.
The muscle regenerative responses are incapacitated and repair of the tissue fails within hours after the initiation of hyperglycemia in a mouse model of type 1 diabetes, but stem cell function is rescued by insulin, as well as follistatin or an Alk5 inhibitor that blocks TGF-β receptor signaling.
研究急性实验性糖尿病对小鼠肌肉干细胞（卫星细胞）再生潜能的影响。
雄性 C57BL/6 幼鼠单次腹腔注射链脲佐菌素（STZ，180mg/kg）诱导糖尿病。糖尿病小鼠每天用胰岛素（0.75U/kg，腹腔注射）、卵泡抑素（12μg/kg，肌肉注射）或 Alk5 抑制剂（5μmol/L/kg，皮下注射）治疗。在发现高血糖的第一天，将心脏毒素（CTX）局部注射到小鼠的胫骨前肌和比目鱼肌。CTX 注射后 3 天和 5 天采集肌肉，分离肌纤维和卫星细胞。采用定量的体外和体内肌生成潜能检测方法评估肌肉再生反应。
CTX 注射后 3 天，糖尿病小鼠的卫星细胞无法激活，肌肉修复恶化，类似于老年对照组小鼠。此外，卫星细胞中肌肉生长抑制素、TGF-β 受体 1、pSmad3 和细胞周期抑制剂 p15 的水平过高，而 TGF-β1 的水平不变。用胰岛素治疗糖尿病小鼠可挽救肌肉再生反应，并将肌肉生长抑制素、TGF-β 受体 1、pSmad3 和 p15 的表达水平恢复到与健康对照组相似的水平。用肌肉生长抑制素拮抗剂卵泡抑素或 TGF-β 受体 1 的 Alk5 抑制剂（不降低血糖水平）治疗糖尿病小鼠可挽救肌肉再生反应，并减弱肌肉生长抑制素/TGFβ 受体/pSmad3 信号通路。
在 1 型糖尿病小鼠模型中，高血糖开始后数小时内，肌肉再生反应丧失，组织修复失败，但胰岛素以及卵泡抑素或阻断 TGF-β 受体信号的 Alk5 抑制剂可挽救干细胞功能。
