Department of Respiratory Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, 1095, Jie Fang Road, Han Kou District, Wuhan, Hubei 430030, China.
Respir Res. 2014 Mar 25;15(1):33. doi: 10.1186/1465-9921-15-33.
Stem cell transplantation is a promising method for the treatment of chronic obstructive pulmonary disease (COPD), and mesenchymal stem cells (MSCs) have clinical potential for lung repair/regeneration. However, the rates of engraftment and differentiation are generally low following MSC therapy for lung injury. In previous studies, we constructed a pulmonary surfactant-associated protein A (SPA) suicide gene system, rAAV-SPA-TK, which induced apoptosis in alveolar epithelial type II (AT II) cells and vacated the AT II cell niche. We hypothesized that this system would increase the rates of MSC engraftment and repair in COPD rats.
The MSC engraftment rate and morphometric changes in lung tissue in vivo were investigated by in situ hybridization, hematoxylin and eosin staining, Masson's trichrome staining, immunohistochemistry, and real-time PCR. The expression of hypoxia inducible factor (HIF-1α) and stromal cell-derived factor-1 (SDF-1), and relationship between HIF-1α and SDF-1 in a hypoxic cell model were analyzed by real-time PCR, western blotting, and enzyme-linked immunosorbent assay.
rAAV-SPA-TK transfection increased the recruitment of MSCs but induced pulmonary fibrosis in COPD rats. HIF-1α and SDF-1 expression were enhanced after rAAV-SPA-TK transfection. Hypoxia increased the expression of HIF-1α and SDF-1 in the hypoxic cell model, and SDF-1 expression was augmented by HIF-1α under hypoxic conditions.
Vacant AT II cell niches increase the homing and recruitment of MSCs to the lung in COPD rats. MSCs play an important role in lung repair and promote collagen fiber deposition after induction of secondary damage in AT II cells by rAAV-SPA-TK, which involves HIF-1α and SDF-1 signaling.
干细胞移植是治疗慢性阻塞性肺疾病（COPD）的一种有前途的方法，间充质干细胞（MSCs）在肺修复/再生方面具有临床潜力。然而，在 MSC 治疗肺损伤后，其植入和分化的比例通常较低。在之前的研究中，我们构建了肺表面活性剂相关蛋白 A（SPA）自杀基因系统 rAAV-SPA-TK，该系统可诱导肺泡上皮 II 型（AT II）细胞凋亡并排空 AT II 细胞龛。我们假设该系统会增加 COPD 大鼠中 MSC 植入和修复的比例。
通过原位杂交、苏木精和伊红染色、Masson 三色染色、免疫组织化学和实时 PCR 研究了 MSC 在体内的植入率和肺组织的形态学变化。通过实时 PCR、Western blot 和酶联免疫吸附试验分析了缺氧诱导因子（HIF-1α）和基质细胞衍生因子-1（SDF-1）在缺氧细胞模型中的表达以及 HIF-1α与 SDF-1 之间的关系。
rAAV-SPA-TK 转染增加了 MSC 的募集，但在 COPD 大鼠中诱导了肺纤维化。rAAV-SPA-TK 转染后 HIF-1α 和 SDF-1 的表达增强。缺氧增加了缺氧细胞模型中 HIF-1α 和 SDF-1 的表达，并且在缺氧条件下 HIF-1α 增强了 SDF-1 的表达。
排空的 AT II 细胞龛增加了 COPD 大鼠肺中 MSC 的归巢和募集。MSCs 在肺修复中发挥重要作用，并在 rAAV-SPA-TK 诱导 AT II 细胞继发损伤后促进胶原纤维沉积，涉及 HIF-1α 和 SDF-1 信号通路。
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