细胞支架研究进展

目前细胞培养通常采用二维平面培养技术,但由于在培养板和培养瓶二维细胞培养并不能完全模拟体内细胞的三维生长环境,因此所得的试验数据与在体情况有偏差。然而细胞支架材料却能为细胞提供一个良好的三维生长环境,更利于细胞粘附、生长和增殖。目前可用于细胞支架材料的来源有天然和人工两大类,现将细胞支架研究进展综述如下。     

三维细胞培养技术应用于肿瘤细胞的研究进展

三维细胞培养是一种模拟细胞在体内微环境生长的新兴培养技术。在三维支架中细胞能以三维空间的方式生长,并以三维方式与周围的微环境交互作用,能充分体现肿瘤细胞的黏附、侵袭及远端转移过程,可作为动物模型和二维培养模型之间的桥梁。三维细胞培养技术广泛应用于肿瘤模型构建、肿瘤细胞生理学研究以及肿瘤耐药机制分析等的研究。     

采用三维模型探索香烟烟雾提取物(CSE)对A549细胞的影响

本研究采用D-型和L-型自组装短肽作为纳米纤维支架材料进行细胞三维培养体系平台,探索香烟烟雾提取物(CSE)诱导人类Ⅱ型肺泡上皮(A549)细胞氧化损伤后,考察其细胞行为在二维和三维微环境下的差异。A549细胞分别在二维和三维环境中用不同浓度的CSE溶液诱导24 h、48 h或72 h之后,进行细胞增殖活力,乳酸脱氢酶(LDH),细胞周期,细胞凋亡检测,以及运用吖啶橙/溴化乙锭(AO/EB)和4',6-二脒基-2-苯基吲哚二盐酸盐(DAPI)染色观察A549细胞形态。结果表明,与二维环境相比,在三维环境中细胞活力更高,LDH释放量较少,细胞凋亡减少。细胞的周期分布检测表明,随着CSE浓度的增大,发生G1期阻滞;当15%,50%CSE作用时,与二维环境相比,三维培养环境中的G1期细胞比例更低,G2期和S期更高,G1期阻滞减弱。上述结果均表明D-型和L-型肽手性自组装短肽能够构建出适于A549细胞生长、增殖的三维微环境,并能模拟细胞胞外基质,对细胞形态、增殖、周期及凋亡等有重要影响。     

微米阵列结构聚合物薄膜的制备及其对细胞三维培养的影响

二维 (Two-dimensional,2D) 细胞实验模型是目前研究人类疾病的细胞过程和药物筛选的主流方法。然而,生物细胞的生长受到众多因素的影响,传统的2D细胞培养在精确再现三维组织内细胞的功能方面存在一些障碍。与2D细胞培养相比,三维 (Three-dimensional,3D) 细胞培养体系注重细胞间的接触及细胞-基质间的接触,更接近于生物体的生长环境,更适合于药物筛选、细胞培植等研究。文中通过纳米压印技术制备了不同结构微米阵列聚合物薄膜,并将其应用于293T细胞的培养,通过调节薄膜表面结构、表面接触角成功实现了对生物细胞生长形貌的调控。利用扫描电镜等方法,对比了聚合物薄膜不同微结构、不同表面润湿性对细胞生长形貌的影响,重点关注细胞团的形态变化。结果表明,细胞在亲水性10 μm柱形阵列薄膜上呈现三维生长状态,这种薄膜可能更适用于制备生物细胞3D培养基;疏水性3 μm柱形阵列薄膜适用于体积小、表皮硬的组织细胞的3D培养,对于体积较大的细胞效果差。另外,对于疏水性较强的薄膜,细胞倾向于球状生长,而亲水性较强的薄膜则易贴壁生长。研究结果为微结构薄膜在生物细胞3D培养方面的应用作了初步探索。     

前列腺癌DU145细胞相关蛋白在构建体内三维空间模型中的表达研究

目的探讨前列腺癌相关蛋白在胶原、琼脂糖、基质胶、海藻酸钠加明胶4种支架材料培养的前列腺癌DU145细胞中的表达水平。方法将前列腺癌DU145细胞按照一定比例接种至胶原、琼脂糖、基质胶、海藻酸钠加明胶4种支架材料中,分别分组进行移植瘤模型的三维培养,然后采用免疫组化方法检测MMP9、FN1、Laminin等3个前列腺癌相关蛋白在3种支架材料中培养的DU145细胞构建移植瘤模型后培养的组织中表达情况。结果 MMP9在有支架材料培养的前列腺癌DU145中蛋白表达高于无支架材料培养的组织;FN1在海藻酸钠加明胶组中蛋白表达阴性,在琼脂糖与胶原组中蛋白表达阳性且明显强于空白组;Lamininm在空白组与海藻酸钠加明胶组中均表达阳性,但明显低于胶原、琼脂糖、基质胶组的强阳性。结论采用支架材料的三维培养体系优于无支架材料的二维培养体系。胶原为体内前列腺癌DU145细胞三维培养的最优支架材料。     

模拟微重力条件下大鼠肝细胞三维培养支架材料的筛选(简报)

组织工程是一门新兴的边缘学科,它是利用体外培养的人体功能细胞与适当的细胞外基质或支架材料相结合,然后将其移植到体内病损部位以期达到修复目的。微重力组织工程(Microgravity Tis-sue Engineering)是近年来由美国空间生物技术研究人员开创的一个独特研究领域,其核心技术是建立微重力条件下哺乳动物细胞三维(Three Dimen-sion)培养体系。利用外壁转动生物反应器(RotatingWall Vessel Bioreactor,RWVB)模拟微重力培养环境,减少培养液对细胞产生的机械剪切力,增加细胞营养的补充,加速代谢产物的排除,因此可以大大改善离体细胞的培养条件,使在普通重力培养条件下只能二维贴壁生长的哺乳动物细胞表现出三维增殖与分化,这类分化的细胞团可进一步形成有功能的     

雪旺氏细胞与同种异体骨支架的体外共培养研究

目的:探讨雪旺细胞(Schwann’s cells,SCs)在同种异体骨支架上的生物相容性,体外构建组织工程骨神经化模型。方法:利用新鲜人体骨骼制备同种异体骨支架材料,检测其物理性能;采用优化方法提取新生SD大鼠坐骨、臂丛神经培养SCs,实验分为三维培养实验组(SCs+同种异体骨)、二维培养对照组(SCs+胶原玻片),S-100抗体免疫荧光染色鉴定SCs纯度;细胞计数法检测两组细胞增殖特点;细胞接种后第3、7天取样,扫描电镜观察。结果:同种异体骨支架具有良好的三维孔隙结构,适宜细胞贴附生长;S-100免疫荧光染色证实SCs纯度95%;扫描电镜检测显示两组SCs均可正常粘附增殖,细胞间排布规律相似,培养早期实验组SCs胞体更加细长,伪足更加明显,随着培养时间的延长表现出较强的迁移能力;细胞增殖检测:两组SCs生长曲线特征基本一致,支架材料对SCs无毒性作用。结论:同种异体骨支架SCs具有良好的生物相容性,其三维立体多孔结构有利于SCs的粘附与迁移,初步构建了体外组织工程骨神经化模型。     

三维培养在肿瘤细胞生物学研究中的应用

近年来,三维培养技术逐渐成为肿瘤细胞培养领域研究的热点,其利用各种方法及材料,在体外模拟体内微环境培养细胞,使肿瘤细胞呈空间立体方式生长,表现出很多不同于传统二维培养的特点。三维培养为深入研究肿瘤的细胞生物学特性,尤其是药物敏感性这个转化医学的关键点提供了良好的平台,有望成为生物医学体外实验中,传统二维培养和动物实验中的一个桥梁。本文综述了近年来三维培养在肿瘤细胞生物学和药敏试验研究中的应用和进展。     

自组装短肽水凝胶支架三维培养环境对骨髓间充质干细胞生物学特性及心肌方向分化的影响

目的:探究短肽GFS-4自组装形成的水凝胶作为支架材料构建三维微环境对BMSCs生物学特性及向心肌细胞方向诱导分化过程的影响。方法:刚果红染色、红细胞膜裂解实验检测短肽GFS-4自组装效果及对细胞膜是否具有裂解作用;CCK8和AO/EB染色分别检测对BMSCs活性和凋亡的影响;Real-time PCR分析BMSCs诱导分化后MLC-2v、GATA-4基因表达情况。结果:GFS-4自组装后形成致密凝胶,自组装前后对细胞膜无损伤;三维培养环境细胞呈球形生长,细胞活力和凋亡速度均低于二维培养环境。三维培养组在诱导分化过程中的第5天和第7天MLC-2v、GATA-4基因表达均显著高于二维组(P0.05)。结论:短肽GFS-4自组装水凝胶构建的三维微环境延缓了BMSCs的增殖速度和凋亡速度,并促进向心肌方向诱导分化过程中MLC-2v、GATA-4基因的表达。     

三维细胞培养与肿瘤细胞恶性表型研究

了解肿瘤细胞与微环境的相互作用,对研究肿瘤的发生、发展及抗癌药物的筛选具有重要意义。三维细胞培养技术近年被用于研究肿瘤细胞恶性表型,与传统二维细胞培养相比．它可以模拟体内细胞生长的微环境,是研究肿瘤细胞恶性表型、细胞与细胞外基质信号传递的有力工具。     

Osteogenic differentiation of human periosteal-derived cells in a three-dimensional collagen scaffold

This study examined the osteogenic differentiation of cultured human periosteal-derived cells grown in a three dimensional collagen-based scaffold. Periosteal explants with the appropriate dimensions were harvested from the mandible during surgical extraction of lower impacted third molar. Periosteal-derived cells were introduced into cell culture. After passage 3, the cells were divided into two groups and cultured for 28 days. In one group, the cells were cultured in two-dimensional culture dishes with osteogenic inductive medium containing dexamethasone, ascorbic acid, and β-glycerophosphate. In the other group, the cells were seeded onto a three-dimensional collagen scaffold and cultured under the same conditions. We examined the bioactivity of alkaline phosphatase (ALP), the RT-PCR analysis for ALP and osteocalcin, and measurements of the calcium content in the periosteal-derived cells of two groups. Periosteal-derived cells were successfully differentiated into osteoblasts in the collagen-based scaffold. The ALP activity in the periosteal-derived cells was appreciably higher in the three-dimensional collagen scaffolds than in the two-dimensional culture dishes. The levels of ALP and osteocalcin mRNA in the periosteal-derived cells was also higher in the three-dimensional collagen scaffolds than in the two-dimensional culture dishes. The calcium level in the periosteal-derived cells seeded onto three-dimensional collagen scaffolds showed a 5.92-fold increase on day 7, 3.28-fold increase on day 14, 4.15-fold increase on day 21, and 2.91-fold increase on day 28, respectively, compared with that observed in two-dimensional culture dishes. These results suggest that periosteal-derived cells have good osteogenic capacity in a three-dimensional collagen scaffold, which provides a suitable environment for the osteoblastic differentiation of these cells.     

The benzo[c]phenanthridine alkaloid, sanguinarine, is a selective, cell-active inhibitor of mitogen-activated protein kinase phosphatase-1

Mitogen-activated protein kinase phosphatase-1 (MKP-1) is a dual specificity phosphatase that is overexpressed in many human tumors and can protect cells from apoptosis caused by DNA-damaging agents or cellular stress. Small molecule inhibitors of MKP-1 have not been reported, in part because of the lack of structural guidance for inhibitor design and definitive assays for MKP-1 inhibition in intact cells. Herein we have exploited a high content chemical complementation assay to analyze a diverse collection of pure natural products for cellular MKP-1 inhibition. Using two-dimensional Kolmogorov-Smirnov statistics, we identified sanguinarine, a plant alkaloid with known antibiotic and antitumor activity but no primary cellular target, as a potent and selective inhibitor of MKP-1. Sanguinarine inhibited cellular MKP-1 with an IC50 of 10 microM and showed selectivity for MKP-1 over MKP-3. Sanguinarine also inhibited MKP-1 and the MKP-1 like phosphatase, MKP-L, in vitro with IC50 values of 17.3 and 12.5 microM, respectively, and showed 5-10-fold selectivity for MKP-3 and MKP-1 over VH-1-related phosphatase, Cdc25B2, or protein-tyrosine phosphatase 1B. In a human tumor cell line with high MKP-1 levels, sanguinarine caused enhanced ERK and JNK/SAPK phosphorylation. A close congener of sanguinarine, chelerythrine, also inhibited MKP-1 in vitro and in whole cells, and activated ERK and JNK/SAPK. In contrast, sanguinarine analogs lacking the benzophenanthridine scaffold did not inhibit MKP-1 in vitro or in cells nor did they cause ERK or JNK/SAPK phosphorylation. These data illustrate the utility of a chemical complementation assay linked with multiparameter high content cellular screening.     

Three‐dimensional nanocharacterization of porous hydrogel with ion and electron beams

Porous hydrogels provide an excellent environment for cell growth and tissue regeneration, with high permeability for oxygen, nutrients, and other water‐soluble metabolites through their high water‐content matrix. The ability to image three‐dimensional (3D) cell growth is crucial for understanding and studying various cellular activities in 3D context, particularly for designing new tissue engineering scaffold, but it is still challenging to study cell‐biomaterial interfaces with high resolution imaging. We demonstrate using focused ion beam (FIB) milling, electron imaging, and associated microanalysis techniques that novel 3D characterizations can be performed effectively on cells growing inside 3D hydrogel scaffold. With FIB‐tomography, the porous microstructures were revealed at nanometer resolution, and the cells grown inside. The results provide a unique 3D measurement of hydrogel porosity, as compared with those from porosimetry, and offer crucial insights into material factors affecting cell proliferation at specific regions within the scaffold. We also proved that high throughput correlative imaging of cell growth is viable through a silicon membrane based environment. The proposed approaches, together with the protocols developed, provide a unique platform for analysis of the microstructures of novel biomaterials, and for exploration of their interactions with the cells as well. Biotechnol. Bioeng. 2013; 110: 318–326. © 2012 Wiley Periodicals, Inc.     

Proliferation of Myoblast Skeletal Cells on Three-Dimensional Supermacroporous Cryogels

Cardiac and skeletal muscle tissue engineering provides a smart approach to overcome problems associated with organ transplantation and cardiac tissue and also lays a platform for superior alternative approaches in muscle regeneration. The aim of the study was to demonstrate cryogel scaffold potential in the field of skeletal muscle and cardiac tissue engineering. Poly-hydroxyethyl methacrylate (pHEMA)-gelatin cryogel scaffold was synthesized using cryogelation technique and such a designed material is being reported first time. Rheology study of the pHEMA-gelatin (HG) suggested that the cryogel scaffolds were stable at different temperatures and phase angle remained constant in both dry and wet state. HG cryogel was able to bear increased stress without leading to deformation. Monitoring the hydration of HG scaffold showed shift from a stiff to a more pliable material and upon continuing hydration, shear modulus remained constant with no further change observed. However, the change in phase angle <0.24º indicates a gradual increase in stiffness of the material over time. Scaffold synthesised using such polymer combinations gave cells a native environment for proliferation and surface stiffness have shown to help in differentiation of the cells. Myoskeletal cell lines were cultured on these scaffolds to check the biocompatibility and cell proliferation. Alamar blue assay performed over a period of 3 weeks analysed the metabolic activity of cells which showed more than 60% increase in the total cellular activity. DNA content of cells was found to be directly related to number of cells present at a given time point and this was found to have increased by more than 50% in 3 weeks. Since in 3-D scaffold the surface area is more in comparison to 2-D, hence better cell proliferation is observed. Hoechst and DAPI staining showed tubular structure and alignment of the cells during formation of the tubules shows promising cellular response to the cryogel matrix. The mechanical strength, stiffness and elastic measurements of the scaffold indicated potential application of these materials for skeletal and cardiac tissue engineering.     

Rac-MEKK3-MKK3 scaffolding for p38 MAPK activation during hyperosmotic shock

Sensing the osmolarity of the environment is a critical response for all organisms. Whereas bacteria will migrate away from high osmotic conditions, most eukaryotic cells are not motile and use adaptive metabolic responses for survival. The p38 MAPK pathway is a crucial mediator of survival during cellular stress. We have discovered a novel scaffold protein that binds to actin, the GTPase Rac, and the upstream kinases MEKK3 and MKK3 in the p38 MAPK phospho-relay module. RNA interference (RNAi) demonstrates that MEKK3 and the scaffold protein are required for p38 activation in response to sorbitol-induced hyperosmolarity. FRET identifies a cytoplasmic complex of the MEKK3 scaffold protein that is recruited to dynamic actin structures in response to sorbitol treatment. Through its ability to bind actin, relocalize to Rac-containing membrane ruffles and its obligate requirement for p38 activation in response to sorbitol, we have termed this protein osmosensing scaffold for MEKK3 (OSM). The Rac-OSM-MEKK3-MKK3 complex is the mammalian counterpart of the CDC42-STE50-STE11-Pbs2 complex in Saccharomyces cerevisiae that is required for the regulation of p38 activity.     

The ECM moves during primitive streak formation--computation of ECM versus cellular motion

Galileo described the concept of motion relativity--motion with respect to a reference frame--in 1632. He noted that a person below deck would be unable to discern whether the boat was moving. Embryologists, while recognizing that embryonic tissues undergo large-scale deformations, have failed to account for relative motion when analyzing cell motility data. A century of scientific articles has advanced the concept that embryonic cells move ("migrate") in an autonomous fashion such that, as time progresses, the cells and their progeny assemble an embryo. In sharp contrast, the motion of the surrounding extracellular matrix scaffold has been largely ignored/overlooked. We developed computational/optical methods that measure the extent embryonic cells move relative to the extracellular matrix. Our time-lapse data show that epiblastic cells largely move in concert with a sub-epiblastic extracellular matrix during stages 2 and 3 in primitive streak quail embryos. In other words, there is little cellular motion relative to the extracellular matrix scaffold--both components move together as a tissue. The extracellular matrix displacements exhibit bilateral vortical motion, convergence to the midline, and extension along the presumptive vertebral axis--all patterns previously attributed solely to cellular "migration." Our time-resolved data pose new challenges for understanding how extracellular chemical (morphogen) gradients, widely hypothesized to guide cellular trajectories at early gastrulation stages, are maintained in this dynamic extracellular environment. We conclude that models describing primitive streak cellular guidance mechanisms must be able to account for sub-epiblastic extracellular matrix displacements.     

Apple Derived Cellulose Scaffolds for 3D Mammalian Cell Culture

There are numerous approaches for producing natural and synthetic 3D scaffolds that support the proliferation of mammalian cells. 3D scaffolds better represent the natural cellular microenvironment and have many potential applications in vitro and in vivo. Here, we demonstrate that 3D cellulose scaffolds produced by decellularizing apple hypanthium tissue can be employed for in vitro 3D culture of NIH3T3 fibroblasts, mouse C2C12 muscle myoblasts and human HeLa epithelial cells. We show that these cells can adhere, invade and proliferate in the cellulose scaffolds. In addition, biochemical functionalization or chemical cross-linking can be employed to control the surface biochemistry and/or mechanical properties of the scaffold. The cells retain high viability even after 12 continuous weeks of culture and can achieve cell densities comparable with other natural and synthetic scaffold materials. Apple derived cellulose scaffolds are easily produced, inexpensive and originate from a renewable source. Taken together, these results demonstrate that naturally derived cellulose scaffolds offer a complementary approach to existing techniques for the in vitro culture of mammalian cells in a 3D environment.     

Ex vivo Mimicry of Normal and Abnormal Human Hematopoiesis

Hematopoietic stem cells require a unique microenvironment in order to sustain blood cell formation¹; the bone marrow (BM) is a complex three-dimensional (3D) tissue wherein hematopoiesis is regulated by spatially organized cellular microenvironments termed niches^2-4. The organization of the BM niches is critical for the function or dysfunction of normal or malignant BM⁵. Therefore a better understanding of the in vivo microenvironment using an ex vivo mimicry would help us elucidate the molecular, cellular and microenvironmental determinants of leukemogenesis⁶.Currently, hematopoietic cells are cultured in vitro in two-dimensional (2D) tissue culture flasks/well-plates⁷ requiring either co-culture with allogenic or xenogenic stromal cells or addition of exogenous cytokines⁸. These conditions are artificial and differ from the in vivo microenvironment in that they lack the 3D cellular niches and expose the cells to abnormally high cytokine concentrations which can result in differentiation and loss of pluripotency^9,10.Herein, we present a novel 3D bone marrow culture system that simulates the in vivo 3D growth environment and supports multilineage hematopoiesis in the absence of exogenous growth factors. The highly porous scaffold used in this system made of polyurethane (PU), facilitates high-density cell growth across a higher specific surface area than the conventional monolayer culture in 2D¹¹. Our work has indicated that this model supported the growth of human cord blood (CB) mononuclear cells (MNC)¹² and primary leukemic cells in the absence of exogenous cytokines. This novel 3D mimicry provides a viable platform for the development of a human experimental model to study hematopoiesis and to explore novel treatments for leukemia.