基質(zhì)細(xì)胞，有別于造血細(xì)胞,，為骨髓微環(huán)境中的必要組成,，并且是長(zhǎng)期維持生物體內(nèi)造血干細(xì)胞所不可或缺的。先前的研究指出,，基質(zhì)細(xì)胞藉由產(chǎn)生造血調(diào)節(jié)因子與胞外基質(zhì),，以及藉由調(diào)控細(xì)胞間的物理性接觸和黏合分子與細(xì)縫連結(jié)為基礎(chǔ)的細(xì)胞間訊息傳導(dǎo)來(lái)控制造血細(xì)胞的生長(zhǎng)及分化。然而,，大多數(shù)關(guān)于基質(zhì)細(xì)胞調(diào)控造血細(xì)胞生長(zhǎng)及自我更新能力的研究都是利用平面骨髓培養(yǎng)系統(tǒng)所進(jìn)行的,，而且大部分的結(jié)果顯示培養(yǎng)四至八周后，造血細(xì)胞即會(huì)開(kāi)始減少,。
Hirabayashi與來(lái)自日本大學(xué)醫(yī)學(xué)院,、大阪府立大學(xué)與挪威科技大學(xué)的共同研究者們，于2011年11月的《實(shí)驗(yàn)生物與醫(yī)學(xué)》期刊中發(fā)表了立體骨髓培養(yǎng)系統(tǒng)的論文,。正如同文章的共同作者Isao Tsuboi所述：“平面骨髓培養(yǎng)系統(tǒng)無(wú)法長(zhǎng)期培養(yǎng)造血細(xì)胞,，因此無(wú)法用來(lái)進(jìn)行基質(zhì)細(xì)胞的功能性研究。所以,，我們發(fā)展了三維立體的骨髓培養(yǎng)系統(tǒng),，并且可以成功地長(zhǎng)期培養(yǎng)造血細(xì)胞。”
此一新型態(tài)的立體培養(yǎng)系統(tǒng)由特殊的粒子所構(gòu)成,。論文的共同作者Yukio Hirabayashi解釋?zhuān)?ldquo;此一由接合環(huán)氧樹(shù)脂所組成聚合物粒子為立體骨髓培養(yǎng)系統(tǒng)中最重要的一部分。我們由二十多種具有不同接合聚合物鏈長(zhǎng)度,、表面密度,、聚合物網(wǎng)狀結(jié)構(gòu)以及接合聚合物側(cè)鏈的粒子中，選出了最適合用于細(xì)胞培養(yǎng)的一種,，我們將其命名為G-02,。”另一位共同作者Tomonori Harada亦指出：“除了老鼠纖維母細(xì)胞株（MS-5 cell）外，表皮細(xì)胞株（HeLa cell）,、骨源母細(xì)胞株（MC3T3E1 cell）與軟骨細(xì)胞株（ch-8 cell）皆可附著于G-02粒子并于其表面上快速生長(zhǎng),。此一優(yōu)勢(shì)使的我們可以將G-02粒子用于三維立體骨髓培養(yǎng)系統(tǒng)，亦可應(yīng)用于中央神經(jīng)系統(tǒng),、心臟與肝臟的立體組織培養(yǎng),。
CD34是一個(gè)廣為人知的人類(lèi)造血先驅(qū)細(xì)胞表面標(biāo)志分子,，不過(guò)帶有CD34分子的細(xì)胞亦可分化成基質(zhì)細(xì)胞。因此,，當(dāng)帶有CD34標(biāo)志分子的細(xì)胞與基質(zhì)細(xì)胞共同培養(yǎng)時(shí),，對(duì)于事先建立的基質(zhì)細(xì)胞層的功能將十分難以厘清?；|(zhì)細(xì)胞研究專(zhuān)家Shin Aizawa教授指出：“于此研究中我們利用老鼠基質(zhì)細(xì)胞株（MS-5）而非人類(lèi)的基質(zhì)細(xì)胞,，因此可以排除帶有CD34標(biāo)志分子的基質(zhì)細(xì)胞所造成的影響。此一共培養(yǎng)系統(tǒng)使的我們可以清楚的區(qū)分MS-5基質(zhì)細(xì)胞層與帶有CD34基質(zhì)細(xì)胞的功能,。我們的研究團(tuán)隊(duì)正利用具有特異性的引子與探針來(lái)研究多種人類(lèi)與老鼠細(xì)胞生長(zhǎng)素在基質(zhì)細(xì)胞中的基因表現(xiàn),。
《實(shí)驗(yàn)生物與醫(yī)學(xué)》期刊主編Steven R. Goodman博士指出，由Hirabayashi與共同作者們所發(fā)展的立體骨髓培養(yǎng)系統(tǒng)為基質(zhì)細(xì)胞功能性研究中的杰出且影響深遠(yuǎn)的工具,。（生物谷 Bioon.com）
doi:10.1258/ebm.2011.011075
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Novel three-dimensional long-term bone marrow culture system using polymer particles with grafted epoxy-polymer-chains supports the proliferation and differentiation of hematopoietic stem cells
Yukio Hirabayashi, Yoshihiro Hatta, Jin Takeuchi, Isao Tsuboi, Tomonori Harada, Kentaro Ono, Wilhelm Robert Glomm, Masahiro Yasuda and Shin Aizawa
Hematopoiesis occurs in the bone marrow, where primitive hematopoietic cells proliferate and differentiate in close association with a three-dimensional (3D) hematopoietic microenvironment composed of stromal cells. We examined the hematopoietic supportive ability of stromal cells in a 3D culture system using polymer particles with grafted epoxy polymer chains. Umbilical cord blood-derived CD34+ cells were co-cultivated with MS-5 stromal cells. They formed a 3D structure in the culture dish in the presence of particles, and the total numbers of cells and the numbers of hematopoietic progenitor cells, including colony-forming unit (CFU)-Mix, CFU-granulocyte-macrophage, CFU-megakaryocyte and burst-forming unit-erythroid, were measured every seven days. The hematopoietic supportive activity of the 3D culture containing polymer particles and stromal cells was superior to that of 2D culture, and allowed the expansion and maintenance of hematopoietic progenitor cells for more than 12 weeks. Various types of hematopoietic cells, including granulocytes, macrophages and megakaryocytes at different maturation stages, appeared in the 3D culture, suggesting that the CD34+ cells were able to differentiate into a range of blood cell types. Morphological examination showed that MS-5 stromal cells grew on the surface of the particles and bridged the gaps between them to form a 3D structure. Hematopoietic cells slipped into the 3D layer and proliferated within it, relying on the presence of the MS-5 cells. These results suggest that this 3D culture system using polymer particles reproduced the hematopoietic phenomenon in vitro, and might thus provide a new tool for investigating hematopoietic stem cell–stromal cell interactions.
