3月25日，國際著名學(xué)術(shù)期刊《The Journal of Clinical Investigation》在線發(fā)表了交通大學(xué)醫(yī)學(xué)院基礎(chǔ)研究院分子發(fā)育生物學(xué)研究室金穎課題組與同濟大學(xué)醫(yī)學(xué)院徐國彤課題組合作完成的題為“WNT signaling determines tumorigenicity and function of ESC-derived retinal progenitors”的最新研究成果,。論文首次報道了canonical Wnt信號通路通過調(diào)控Tcf7,影響Sox2和Nestin的表達水平,，最終決定胚胎干細胞來源的視網(wǎng)膜前體細胞眼內(nèi)移植后的療效和腫瘤形成。
視網(wǎng)膜變性疾病,，是一類以光感受器和視網(wǎng)膜色素上皮細胞變性和功能喪失導(dǎo)致視功能損害為共同表現(xiàn),，以視網(wǎng)膜細胞的凋亡為重要病理特征的致盲性眼病,。據(jù)統(tǒng)計，目前世界上約有超過2千萬人患有各種視網(wǎng)膜變性類疾病,，是成年人的主要致盲原因,。但目前,這類疾病尚沒有有效的治療手段。雖然已有的報道證實了來自小鼠新生兒的視網(wǎng)膜前體細胞(retinal progenitor cells, RPCs)移植治療視網(wǎng)膜變性類疾病的安全性和有效性,但是來源虧缺限制了其應(yīng)用,。胚胎干細胞(embryonic stem cells, ESCs)是胚胎著床前囊胚期的內(nèi)細胞團在體外特定培養(yǎng)條件下建立的細胞系,能夠分化成為各種類型的細胞,這使得它們具有巨大的研究價值,并可為臨床提供充足的細胞來源,。但是,ESCs的發(fā)育全能性和持續(xù)的自我更新能力,也使得細胞移植的安全性特別引起人們的關(guān)注。如何將ESC在體外誘導(dǎo)分化為既能有效地修復(fù)損傷,，又不具有成瘤危險的狀態(tài)是成功地應(yīng)用干細胞治療疾病所面臨的關(guān)鍵問題,。
博士研究生崔璐、管圓利用視網(wǎng)膜變性小鼠模型移植實驗,，結(jié)合全轉(zhuǎn)錄本芯片的檢測,發(fā)現(xiàn) canonical Wnt 通路在胚胎干細胞來源的視網(wǎng)膜前體細胞（ESC-RPCs）中的異常激活及在調(diào)控治療效果和腫瘤形成中的關(guān)鍵作用,。他們的研究證明，在細胞移植前,，應(yīng)用Wnt抑制劑處理ESC-RPC能顯著地提高移植細胞對動物視力的保護作用和減少移植細胞引起的腫瘤形成,。在針對 canonical Wnt 通路對 ESC-RPCs 的分化和致瘤性的調(diào)控作用及其機制的深入研究中, 他們發(fā)現(xiàn)canonical Wnt 通路的下游Tcf7,直接調(diào)控Sox2和Nestin的表達水平從而參與調(diào)控神經(jīng)分化和腫瘤形成的過程。當在ESC-RPCs中,沉默Tcf7 或Sox2 或Nestin都能夠有效地降低腫瘤的發(fā)生率,同時提高供體細胞的整合及宿主視功能的恢復(fù),。該研究首次證明Wnt-Tcf7-Sox2-Nestin信號通路在調(diào)控ESC-RPC移植后的整合和腫瘤形成中的重要作用,，也為臨床上移植 ESC 來源的細胞治療視網(wǎng)膜變性類疾病和其它神經(jīng)退行性疾病奠定了重要的基石。該研究被JCI選為封面論文,，并有評論文章在同期發(fā)表,。
該課題獲得國家科技部、國家自然科學(xué)基金委及中國科學(xué)院先導(dǎo)項目的經(jīng)費資助,。（生物谷Bioon.com)
doi:10.1172/JCI65048
PMC:
PMID:
WNT signaling determines tumorigenicity and function of ESC-derived retinal progenitors
Lu Cui1,2,3, Yuan Guan1,2, Zepeng Qu1,3, Jingfa Zhang2, Bing Liao1,3, Bo Ma4, Jiang Qian4, Dangsheng Li5, Weiye Li6, Guo-Tong Xu2 and Ying Jin1,3
The unique properties of embryonic stem cells (ESCs), unlimited self-renewal and pluripotency, make them an attractive cell source for the treatment of various degenerative diseases. However, the same properties also present a major hurdle for their clinical application. Tumor formation has been reported in the transplantation of ESC derivatives despite predifferentiation or presorting (1–6), raising a safety concern for the therapeutic use of ESC-derived cell products in humans. On the other hand, transplantation of photoreceptor precursors in neonatal mice repaired retinal defect efficiently without development of any tumors (7, 8), which emphasizes the critical role of the developmental stage of donor cells in determining the cell fate following transplantation. Thus, steering ESCs to an appropriate state could be an important step for safe and effective cell therapies.
To date, ESCs from the mouse, monkey, and human have been successfully differentiated into retinal cells in vitro (9–13). Sasai’s group developed an efficient induction of retinal precursors by culturing mouse ESCs under a serum-free suspension condition (SFEB culture) and obtained high percentages of differentiated cells expressing key eye-field transcription factors (12–14). However, mechanisms governing efficient generation of various types of retinal cells and the optical cups from ESCs in vitro as well as their application potential in vivo, in regards to the functional integration and safety, are not clearly elucidated.
In an attempt to find major extracellular signaling and intrinsic factors controlling tumorigenicity and therapeutic effects of ocular transplanted ESC-derived retinal progenitor cells (ESC-RPCs), we identified the canonical WNT signaling-activated TCF7-SOX2-NESTIN cascade as a critical determinant for the consequence of ESC-RPC transplantation: whether tumors would form as well as whether successful integration into the host retina and prevention of the visual defect would be achieved. Canonical WNT signaling is known to play a key role in cell fate determination for various cell lineages, and its inappropriate activation is frequently associated with cancers (15–17). It has also been shown to promote proliferation of isolated retinal stem cells (18) and retina regeneration in adult mammals (19). However, the correlation between WNT signaling in ESC-derived donor cells and their therapeutic effect as well as tumorigenicity after transplantation in a disease model remains unexamined. In addition, factor(s) that mediate the function of WNT signaling in the control of cell fate commitment remain elusive. In this study, we link the activity of WNT signaling to the tumorigenic potential of ESC-RPCs and provide the experimental evidence for transcriptional factor TCF7 to regulate expression of SOX2 and NESTIN, two important genes actively engaged in the neural development and tumor formation. The tumorigenic and therapeutic effect of transplanted ESC-RPCs is determined in a well-studied sodium iodate–induced (SI-induced) mouse retinal degeneration model (20, 21). We also show that the expression of TCF7, SOX2, and NESTIN is closely associated in mouse neonatal retinae. These findings open new avenues to define and manipulate ESC-derived donor cells prior to transplantation for safe and effective cell therapies.
