科技日報(bào)訊據(jù)物理學(xué)家組織網(wǎng)7月17日報(bào)道，美國埃默里大學(xué)和佐治亞理工大學(xué)研究人員合作,，證明讓干細(xì)胞攜帶氧化鐵納米粒子,，通過靜脈注射到小鼠體內(nèi)后，用磁鐵能吸引這些細(xì)胞到達(dá)身體特定位置,。相關(guān)論文近期將發(fā)表在納米科技雜志《Small》上,。
以往研究中也曾用過納米粒子，但那些粒子涂層有毒,，或者會(huì)改變干細(xì)胞性質(zhì),。新粒子的涂層是聚乙二醇，內(nèi)部為直徑約15納米的氧化鐵核，能保護(hù)細(xì)胞免受傷害,。“納米粒子的涂層是獨(dú)特的,，因此細(xì)胞生存能力不受影響；我們也沒有發(fā)現(xiàn)干細(xì)胞的分化能力等特征有任何改變,。”論文第一作者,、埃默里大學(xué)醫(yī)學(xué)院醫(yī)學(xué)與生物醫(yī)學(xué)工程教授、心臟病學(xué)分部主管羅伯特·泰勒說,。
實(shí)驗(yàn)所用細(xì)胞是間葉干細(xì)胞,。它能很容易地從成熟組織中取得，如骨髓或脂肪,，能變成骨髓,、脂肪和軟骨細(xì)胞，但不能變成肌肉,、腦等類型的細(xì)胞,。它們能分泌多種營養(yǎng)和抗炎癥因子，在治療心血管病或自身免疫紊亂方面是極有價(jià)值的工具,。
在細(xì)胞的溶酶體中,，粒子會(huì)變黏，能停駐在細(xì)胞中至少一個(gè)星期而不被覺察,。研究人員檢測了細(xì)胞中攜帶的鐵成分,，確定每個(gè)細(xì)胞吸收了大約150萬個(gè)粒子。給干細(xì)胞“裝入”氧化鐵粒子后,，他們分別在培養(yǎng)細(xì)胞和活動(dòng)物身上測試了用磁力驅(qū)動(dòng)細(xì)胞的能力,。
在小鼠實(shí)驗(yàn)中，研究人員將條形稀土磁鐵放在尾部靠近身體的地方,，吸引注射的干細(xì)胞到達(dá)小鼠尾部,，并給干細(xì)胞做了熒光染色標(biāo)記用于跟蹤。一般情況下,，大部分間葉干細(xì)胞會(huì)在肺部或肝臟沉積下來,，而使用磁鐵時(shí)，到達(dá)小鼠尾部的干細(xì)胞數(shù)量是原來的6倍,。此外,，氧化鐵粒子本身也可用于跟蹤細(xì)胞在體內(nèi)的進(jìn)程。
“這是關(guān)鍵的原理實(shí)驗(yàn)證據(jù),。最終，我們將把這些專門用于特定肢體,、異常血管,，甚至心臟。”泰勒說，“下一步,，我們打算重點(diǎn)研究在動(dòng)物模型上的治療應(yīng)用,，用磁鐵引導(dǎo)這些細(xì)胞到達(dá)精確部位，影響新血管的修復(fù)和再生,。”
總編輯圈點(diǎn)
生活中,，鮮活農(nóng)產(chǎn)品要通過長途運(yùn)輸而不變質(zhì)，就必須對運(yùn)輸車輛進(jìn)行改造,，加裝制冷或輸氧等設(shè)備,。醫(yī)學(xué)上，納米氧化鐵粒子就是一種備受關(guān)注的運(yùn)輸工具,，作為一種新型靶向給藥系統(tǒng),，它可在外加磁場控制下，將藥物準(zhǔn)確運(yùn)到患處,，實(shí)現(xiàn)使命必達(dá),。然而，如果把死的藥物變成了活的干細(xì)胞,，并讓干細(xì)胞在生物體內(nèi)的長途旅行中保持活力,，就必須對載體進(jìn)行表面改性，以增強(qiáng)其穩(wěn)定性和生物相容性等,，這便是本成果的核心價(jià)值所在,。（生物谷 Bioon.com）
生物谷推薦的英文摘要
Small DOI: 10.1002/smll.201300570
Magnetic Targeting of Human Mesenchymal Stem Cells with Internalized Superparamagnetic Iron Oxide Nanoparticles
Natalia Landázuri, Sheng Tong, Jin Suo, Giji Joseph, Daiana Weiss, Diane J. Sutcliffe, Don P. Giddens, Gang Bao, W. Robert Taylor
Cell therapies offer exciting new opportunities for effectively treating many human diseases. However, delivery of therapeutic cells by intravenous injection, while convenient, relies on the relatively inefficient process of homing of cells to sites of injury. To address this limitation, a novel strategy has been developed to load cells with superparamagnetic iron oxide nanoparticles (SPIOs), and to attract them to specific sites within the body by applying an external magnetic field. The feasibility of this approach is demonstrated using human mesenchymal stem cells (hMSCs), which may have a significant potential for regenerative cell therapies due to their ease of isolation from autologous tissues, and their ability to differentiate into various lineages and modulate their paracrine activity in response to the microenvironment. The efficient loading of hMSCs with polyethylene glycol-coated SPIOs is achieved, and it is found that SPIOs are localized primarily in secondary lysosomes of hMSCs and are not toxic to the cells. Further, the key stem cell characteristics, including the immunophenotype of hMSCs and their ability to differentiate, are not altered by SPIO loading. Through both experimentation and mathematical modeling, it is shown that, under applied magnetic field gradients, SPIO-containing cells can be localized both in vitro and in vivo. The results suggest that, by loading SPIOs into hMSCs and applying appropriate magnetic field gradients, it is possible to target hMSCs to particular vascular networks.
