利用人造血干細(xì)胞(human hematopoietic stem cells, hHSCs)治療一系列疾病所面臨的一個(gè)主要的障礙就是科學(xué)家們很難在體外培養(yǎng)它們.它們?cè)隗w外要么很快死亡,要么分化為其他類型的細(xì)胞.在一項(xiàng)新的研究中,來(lái)自美國(guó)塔夫斯大學(xué)工程學(xué)院生物醫(yī)學(xué)工程系的Dean Liang Glettig和David Kaplan通過(guò)一系列實(shí)驗(yàn)證實(shí)含有脂肪細(xì)胞的飼養(yǎng)層(feeder layer)能夠成功地促進(jìn)體外培養(yǎng)的hHSCs長(zhǎng)期存活.相關(guān)研究結(jié)果于2013年3月12日在線發(fā)表在BioResearch Open Access期刊上,論文標(biāo)題為"Extending Human Hematopoietic Stem Cell Survival In Vitro with Adipocytes".
為了在體外延長(zhǎng)hHSCs的存活時(shí)間,研究人員一直試圖利用人間充質(zhì)干細(xì)胞(human mesenchymal stem cells, hMSCs)產(chǎn)生模擬造血干細(xì)胞微環(huán)境(hHSC niche)的飼養(yǎng)層.
在這項(xiàng)新的研究中,研究人員利用這些含有脂肪細(xì)胞的飼養(yǎng)層抑制hHSCs分化來(lái)開(kāi)展一系列實(shí)驗(yàn),以便驗(yàn)證hHSCs在體外的存活時(shí)間是否得到提高,并且在每項(xiàng)實(shí)驗(yàn)中,存活的hHSCs數(shù)量通過(guò)流式細(xì)胞儀進(jìn)行定量.
在第一項(xiàng)實(shí)驗(yàn)中,研究人員比較了含有未分化的hMSCs的飼養(yǎng)層和利用基本培養(yǎng)基讓hMSCs已分化為成骨細(xì)胞或脂肪細(xì)胞的飼養(yǎng)層,結(jié)果證實(shí)當(dāng)飼養(yǎng)層含有脂肪細(xì)胞時(shí),hHSCs擁有最高的存活率.在第二項(xiàng)實(shí)驗(yàn)中,研究人員比較了hMSCs飼養(yǎng)層和利用添加有hHSC生長(zhǎng)因子混合物的培養(yǎng)基讓hMSCs分化為脂肪細(xì)胞的飼養(yǎng)層,他們得出了同樣的結(jié)論.
在第三項(xiàng)實(shí)驗(yàn)中,研究人員證實(shí)細(xì)胞之間直接接觸是這些飼養(yǎng)層發(fā)揮支持性作用所必需的.在第四項(xiàng)和第五項(xiàng)實(shí)驗(yàn)中,研究人員改變飼養(yǎng)層中的脂肪細(xì)胞數(shù)量,而且在這兩項(xiàng)實(shí)驗(yàn)中,他們都證實(shí)飼養(yǎng)層中含有較高數(shù)量的脂肪細(xì)胞讓hHSCs數(shù)量在隨后的時(shí)間中更不容易快速下降.
基于這一系列實(shí)驗(yàn),研究人員作出結(jié)論：脂肪細(xì)胞有助于抑制hHSCs分化,從而有助于提高它們?cè)隗w外的存活時(shí)間.
BioResearch Open Access期刊編輯Jane Taylor博士說(shuō),"提高體外培養(yǎng)的hHSCs的存活能力不僅有助于基礎(chǔ)性干細(xì)胞研究,而且它也是開(kāi)發(fā)先進(jìn)的細(xì)胞療法用于未來(lái)的臨床應(yīng)用所取得的重要一步."（生物谷Bioon.com）
doi:10.1089/biores.2013.0006
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Extending Human Hematopoietic Stem Cell Survival In Vitro with Adipocytes
Dean Liang Glettig and David L. Kaplan
Human hematopoietic stem cells (hHSCs) cannot be maintained in vitro for extended time periods because they rapidly differentiate or die. To extend in vitro culture time, researchers have made attempts to use human mesenchymal stem cells (hMSCs) to create feeder layers that mimic the stem cell niche. We have conducted an array of experiments including adipocytes in these feeder layers that inhibit hHSC differentiation and by that prolong stem cell survival in vitro. The amount of CD34+ cells was quantified using flow cytometry. In a first experiment, feeder layers of undifferentiated hMSCs were compared with feeder layers differentiated toward osteoblasts or adipocytes using minimal medium, showing the highest survival rate where adipocytes were included. The same conclusion was drawn in a second experiment in comparing hMSCs with adipogenic feeder cells, using a culture medium supplemented with a cocktail of hHSC growth factors. In a third experiment, it was shown that direct cell–cell contact is necessary for the supportive effect of the feeder layers. In a fourth and fifth experiment the amount of adipocytes in the feeder layers were varied, and in all experiments a higher amount of adipocytes in the feeder layers showed a less rapid decay of CD34+ cells at later time points. We therefore concluded that adipocytes assist in suppressing hHSC differentiation and aid in prolonging their survival in vitro.
