美國科學(xué)家將實驗老鼠的4個遺傳因子轉(zhuǎn)化成了成纖維細胞，并由此制造出類似于人體造血干細胞的細胞，這些造血干細胞每天會在人體內(nèi)制造出數(shù)百萬個新鮮的血液細胞。

這項研究有助于科學(xué)家們未來為血液病癥患者量身打造造血干/祖細胞，用于細胞替代療法中。相關(guān)研究發(fā)表在6月13日出版的《細胞·干細胞》雜志上。

美國西奈山醫(yī)院伊坎醫(yī)學(xué)院的研究人員對18個誘導(dǎo)血液形成活動的遺傳因子進行了篩查，找出了其中的4個轉(zhuǎn)錄因子 Gata2、Gfi1b、cFos、Etv6，并進行了正確的組合，培育出了血管前體細胞以及隨后的成纖維細胞。這些前體細胞表達了一個人類的CD34分子（其會選擇性地表達于人類及其他哺乳動物的造血干/祖細胞表面，并隨細胞的成熟逐漸減弱至消失）、一個Sca1（干細胞抗原-1）以及一個Prominin1（一種造血干細胞和神經(jīng)干細胞的表面標志物）。

該論文的第一作者、伊坎醫(yī)學(xué)院發(fā)育和再生生物學(xué)博士研究員卡洛斯·菲利普－佩雷拉表示：“我們在培養(yǎng)皿中培育出來的這些細胞與我們在老鼠的胚胎中發(fā)現(xiàn)的細胞在基因表達方面一模一樣，最終，我們有望借此制造出成熟的血液細胞?！?/p>

伊坎醫(yī)學(xué)院發(fā)育和再生生物學(xué)教授艾霍爾·雷米斯奇卡表示：“有很多研究人員一直在嘗試用胚胎干細胞來培育造血干細胞，但我們另辟蹊徑，使用成熟老鼠的成纖維細胞，再加上正確的蛋白質(zhì)組合取得了成功?！?/p>

西奈山醫(yī)院伊坎醫(yī)學(xué)院院長丹尼斯·查尼表示：“這一發(fā)現(xiàn)或許僅僅是一個開始，將有助于我們?yōu)檠翰』颊哒业街委煼椒?。?/p>

佩雷拉說，在血液干細胞移植手術(shù)中，獲得合適的捐贈一直是個大問題。捐贈者必須滿足罹患白血病（血癌）、再生障礙性貧血、淋巴瘤、多發(fā)性骨髓瘤以及免疫系統(tǒng)缺陷等病癥的病患的需要。佩雷拉表示：“培育出造血干細胞是一種非常好的替代方法?！?/p>

該研究的另一名作者、伊坎醫(yī)學(xué)院發(fā)育和再生生物學(xué)副教授凱特瑞·摩爾表示：“我們能在一個培養(yǎng)皿中培育出如此多的成血細胞真是一件令人興奮的事情。希望新方法應(yīng)用于人體細胞可以取得同樣的成功?！?/p>

Researchers Succeed in Programming Blood Forming Stem Cells

By transferring four genes into mouse fibroblast cells,researchers at the Icahn School of Medicine at Mount Sinai have produced cells that resemble hematopoietic stem cells,which produce millions of new blood cells in the human body every day.These findings provide a platform for future development of patient-specific stem/progenitor cells,and more differentiated blood products,for cell-replacement therapy.

The study,titled,“Induction of a Hemogenic Program in Mouse Fibroblasts,”was published online in CELL STEM CELL on June 13.Mount Sinai researchers screened a panel of 18 genetic factors for inducing blood-forming activity and identified a combination of four transcription factors,Gata2,Gfi1b,cFos,and Etv6 as sufficient to generate blood vessel precursor cells with the subsequent appearance of hematopoietic cells.The precursor cells express a human CD34 reporter,Sca1 and Prominin1 within a global endothelial transcription program.

“The cells that we grew in a petri dish are identical in gene expression to those found in the mouse embryo and could eventually generate colonies of mature blood cells,”said the first author of the study,Carlos Filipe Pereira,PhD,Postdoctoral Fellow of Developmental and Regenerative Biology at the Icahn School of Medicine.Other leaders of the research team that screened the genetic factors to find the right combination included Kateri Moore,DVM,Associate Professor of Developmental and Regenerative Biology at the Icahn School and Ihor R.Lemischka,PhD,Professor of Developmental and Regenerative Biology,Pharmacology and Systems Therapeutics and Director of The Black Family Stem Cell Institute at The Mount Sinai Medical Center.

“The combination of gene factors that we used was not composed entirely of the most obvious or expected proteins,”said Dr.Lemischka.“Many investigators have been trying to grow hematopoietic stem cells from embryonic stem cells,but this process has been problematic.Instead,we used mature mouse fibroblasts,picked the right combination of proteins,and it worked.”

“This discovery is just the beginning of something new and exciting and can hopefully be used to identify a treatment for blood disorders,”said Dennis S.Charney,MD,Anne and Joel Ehrenkranz Dean of the Icahn School of Medicine at Mount Sinai and Executive Vice President for Academic Affairs at The Mount Sinai Medical Center.

According to Dr.Pereira,there is a critical shortage of suitable donors for blood stem cell transplants.Donors are currently necessary to meet the needs of patients suffering from blood diseases such as leukemia,aplastic anemia,lymphomas,multiple myeloma and immune deficiency disorders.“Programming of hematopoietic stem cells represents an exciting alternative,”said Pereira.

“Dr.Lemischka and I have been working together for over 20 years in the fields of hematopoiesis and stem cell biology,”said Dr.Moore,senior author of the study.“It is truly exciting to be able to grow these blood forming cells in a culture dish and learn so much from them.We have already started applying this new approach to human cells and anticipate similar success.”

Mount Sinai Innovation Partners is managing the intellectual property for this cellreplacement technology on behalf of the Mount Sinai researchers and is actively engaged with commercial collaboration opportunities.

Summary

Definitive hematopoiesis emerges during embryogenesis via an endothelial-to-hematopoietic transition.We attempted to induce this process in mouse fibroblasts by screening a panel of factors for hemogenic activity.We identified a combination of four transcription factors,Gata2,Gfi1b,cFos,and Etv6,that efficiently induces endothelial-like precursor cells,with the subsequent appearance of hematopoietic cells.The precursor cells express a human CD34 reporter,Sca1,and Prominin1 within a global endothelial transcription program.Emergent hematopoietic cells possess nascent hematopoietic stem cell gene-expression profiles and cell-surface phenotypes.After transgene silencing and reaggregation culture,the specified cells generate hematopoietic colonies in vitro.