DEVELOPMENT OF CULTURE METHODS FOR EXOCRINE GLAND STEM CELLS USING GENE-TRANSDUCED FEEDER CELLS AND THEIR APPLICATION FOR TREATMENT

基于干细胞的治疗已被提出作为一个有前途的战略再生组织失去了通过不治之症。虽然纯化干细胞的技术在很大程度上取决于特定的表面标记，但侧群（SP）细胞在没有干细胞标记的情况下也是适用的。然而，SP细胞的功能仍然存在争议。为了探索SP细胞的精确功能，我们评估了它们在小鼠外分泌腺，即唾液腺中的功能，因为这些腺体作为方便的模型，其能力可以通过测量它们的泪液和唾液分泌物来容易地评估。在这里，我们表明，SP细胞移植恢复的功能，这两个腺体功能减退的辐射，并澄清一个假定的基板，保护细胞免受氧化应激损伤。我们从泪腺和唾液腺中分离SP细胞，并将其移植到辐射诱导的每个腺体功能减退的小鼠体内。结果表明，移植后两个月内，受体小鼠的两个腺体的分泌物都恢复了，尽管移植的细胞只是稀疏分布，没有产生副产物，这表明SP细胞分泌的可溶性因子，而不是重建的细胞，可能恢复了残留腺体的功能。已被鉴定为SP细胞特异性基因之一的白藜芦醇苷是一种分泌性糖蛋白，并且被证明抑制由氧化应激诱导的细胞死亡和活性氧（ROS）积累。我们的研究结果表明，SP细胞移植的好处是由于不细胞移植介导的腺体重建，但SP细胞衍生的可溶性因子，包括clusterin的功能。

Stem cell-based therapy has been proposed as a promising strategy for regenerating tissues lost through incurable diseases. Although the technology to purify stem cells largely depends on specific surface markers, side population (SP) cells are applicable without stem cell markers. However, the functions of SP cells still remain controversial. To explore the precise functions of SP cells, we assessed their functions in mouse exocrine glands, namely, salivary glands, because these glands serve as convenient models whose ability can be easily evaluated by measurement of their tear and saliva secretions, respectively. Here we show that SP cell transplantation restores the functions of both the glands rendered hypofunctional by irradiation, and clarify a putative substrate that protects the cells from damage by oxidative stress. We isolated SP cells from the lachrymal and salivary glands and transplanted them into mice with irradiation-induced hypofunction in each gland. The results revealed that the secretions from both glands in the recipient mice were restored within two months after the transplantation, although transplanted cells were only sparsely distributed and produced no outgrowths, indicating that soluble factors secreted by SP cells, and not reconstituted cells, possibly restored the functions of the residual glands. Clusterin, which has been identified as one of the SP cell-specific genes, is a secretory glycoprotein, and been shown to inhibit cell death and reactive oxygen species (ROS) accumulation induced by oxidative stress. Our results indicate that the benefits of SP cell transplantation are attributable to not cell transplantation-mediated reconstitution of the glands but the functions of SP cell-derived soluble factors including clusterin.