旋转生物反应器用于提高组织工程气管软骨力学强度的实验研究

针对体外静态培养方法的缺点,采用旋转生物反应器培养组织工程气管软骨,探讨工程化软骨合适的体外培养条件.选用大鼠剑突软骨细胞种植到DegraPol管状支架上,然后分别于传统静态培养和生物反应器内培养.于体外培养3周和6周后,取出软骨细胞-DegraPol支架复合物,以噻唑蓝(MTT)法测定细胞增殖活性,GAG浓度测定细胞外基质分泌情况,应力-应变机械力学方法测定最大应变和应力的变化,并制备扫描电镜标本观察软骨细胞在DegraP01支架中培养后的超微结构.体外培养3周应用MTT法测定A值分别为:静态培养的细胞-支架复合物组0.12±0.01,生物反应器组0.17±0.05(每组n=6).GAG浓度测定静态培养组为(0.14±0.03) μg/mg,生物反应器组为(0.22±O.03) μg/mg(每组n=6).应力-应变机械力学测定结果为,体外培养3周应变值:生物反应器组为(3.53±0.91),静态培养组为(1.71±0.13).应力值生物反应器组为(0.33±0.04) MPa,静态培养组为(0.26±0.01) MPa.体外培养6周应变值:生物反应器组为(0.57±0.10),静态培养组为(0.48±0.07),应力值生物反应器组为(0.16±0.02) MPa,静态培养组为(0.09±0.02) MPa(每组n=4).扫描电镜观察显示生物反应器组获得更好的软骨样结构和更多的细胞外基质.应用旋转生物反应器能够提供适宜的机械应力刺激,可作为体外构建组织工程化气管软骨的可行的培养方法.     

DegraPol支架上培养人气管软骨细胞体外合成组织工程软骨

 目的　探讨以人气管软骨细胞（HTC）为种子细胞在新型生物材料DegraPol泡沫支架上体外合成组织工程气管软骨的可行性。方法　从肺移植供体（9例）取人气管软骨片段，胶原酶消化，将所获软骨细胞传代培养，将传代至6～8代的HTC种植到DegraPol支架上体外静态培养。种植前行II型胶原免疫组织化学染色。于体外静态培养第2 小时末和第 3、7、21、42 天取HTC-DegraPol复合物用噻唑蓝（MTT）法测定细胞增殖活性；培养3周后取HTC-DegraPol复合物制备组织学检测标本行阿辛蓝染色观察硫酸软骨素分泌情况，并制备扫描电镜标本观察HTC在DegraPol支架中培养后的超微结构。结果 HTC在传代培养中显示稳定的增殖活性并分泌II型胶原。种植到DegraPol支架中后培养2 h和3、7、21、42 d时MTT法测定的A值分别为0.112±0.004、0.151±0.021、0.170±0.035、0.176±0.023和0. 213±0.023（每个时点n=4）。培养21、42 d与培养2 h比较， 活性HTC数量差异均有统计学意义（P<0.05）。阿辛蓝染色显示HTC-DegraPol复合物的基质分泌硫酸软骨素，证实HTC- DegraPol复合物具有软骨样结构。扫描电镜观察显示新生软骨在DegraPol材料表面和中央均有形成，但以表面为主。结论　HTC可以在体外良好扩增并以多孔生物材料DegraPol为支架体外合成组织工程气管软骨，但培养条件应进一步优化。     

气管软骨细胞和羧乙基壳聚糖-羟基磷灰石泡沫支架复合及裸鼠皮下植入

目的 探讨以兔气管软骨细胞为种子细胞在自制羧乙基壳聚糖-羟基磷灰石泡沫(NCECS-HA)支架合成组织工程气管软骨的可行性.方法 通过真空冷冻干燥法制得NCECS-HA泡沫支架.从6个月大的大耳白兔取气管软骨片段,Ⅱ型胶原酶消化,将所获得第3代软骨细胞种植于NCECS-HA三维支架上.细胞-支架复合物在24孔板中培养5 d以后,将其植入裸鼠皮下8周.然后取出分别进行HE染色、Ⅱ型胶原免疫组化染色和甲苯胺蓝染色,观察软骨细胞基质分泌情况.结果 8周后,构建出组织工程气管软骨示光泽良好,甲苯胺蓝染色、Ⅱ型胶原免疫组化染色显示细胞-支架复合物中的软骨细胞可以像天然软骨一样分泌糖氨多糖和Ⅱ型胶原.结论 生物材料NCECS-HA对于兔软骨细胞有良好的生物相容性,可作为生物组织工程支架.     

旋转反应器胶原支架的制备及复合软骨细胞修复骨软骨损伤的初步研究

目的以胶原为原料开发一种小型胶原支架材料,尝试是否适合旋转反应器来复合软骨细胞,并探讨复合细胞后修复软骨损伤的效果。方法成年猪跟腱中提取胶原,制备胶原支架,进行细胞毒性检测和生物相容性分析。将其切成1 mm~3小块,置于旋转培养器中与软骨细胞共培养,倒置相差显微镜观察细胞贴附效果。建立兔关节软骨缺损模型,编号后,将14只新西兰大白兔随机分为2组:支架材料组(n=8),兔膝关节软骨缺损区植入胶原支架材料和软骨细胞;空白对照组(n=6),不进行任何植入处理。进行HE染色后观察。结果胶原支架呈瓷白色,表面空隙均匀,无细胞毒性,生物相容性良好,但在体内降解较快。在旋转反应器中,支架可以与软骨细胞良好结合。胶原支架植入动物体内12周,虽未完全修复缺损,但已有少量软骨细胞在缺损处出现,修复效果优于对照组。结论制备的胶原支架复合软骨细胞短期内有一定的修复软骨缺损的能力,长期效果欠佳,可能与胶原支架在体内过快降解有关,尚需对制备方法进行改进。     

软骨组织工程研究的新进展

软骨组织的再生能力有限，组织工程软骨的构建对修复软骨缺损意义理大。本从四方面介绍了软骨组织工程的研究的新进展，包括软骨种子细胞的研究，软骨细胞与支架的体外培养，细胞支架复合物植入体内的研究及软骨细胞移植的临床应用。     

自制双腔生物反应器构建组织工程骨软骨复合体的体外性能

背景:关节软骨损伤往往并发软骨下骨损伤形成骨软骨复合缺损,其治疗仍为骨科急待解决的问题,利用组织工程学构建骨软骨复合体为治疗该类疾患提供了新思路。目的:探讨利用自行设计制造的双腔搅拌式生物反应器构建一体化组织工程骨软骨复合体的可行性。方法:在双腔搅拌式生物反应器内对复合于β-磷酸三钙支架材料的羊骨髓间充质干细胞同时进行成骨和成软骨诱导,并根据施加剪切应力分为动态培养组和静态培养组。利用MTT试验、RT-PCR和扫描电镜检测骨髓间充质干细胞体外增殖和诱导分化情况。结果与结论:MTT试验和扫描电镜结果显示,骨髓间充质干细胞增殖良好。成骨和成软骨相关基因RT-PCR检测结果表明,骨髓间充质干细胞诱导分化良好,动态培养组要优于静态培养组。提示利用自行设计制作的双腔搅拌式生物反应器进行骨软骨复合体的体外构建是可行的,力学刺激环境下的构建效果要优于静态环境。     

软骨组织工程中力学因素的影响及应用

力学因素是软骨组织工程中的重要影响因素之一。近年来的研究表明，力学作用可以刺激细胞因子及激素的分泌，改变三维支架上培养的软骨细胞的新陈代谢，从而促进软骨组织的生长与重建。目前已经有诸多关于体外构建软骨组织的报道，但对于其中的力学因素的影响（包括力学因素对软骨细胞增殖的促进及力学刺激的传导机制等）还没有完全认识。就以上几方面做一综述，并简单介绍生物反应器在软骨组织工程中的应用。     

软骨组织工程研究的新进展

软骨组织的再生能力有限 ,组织工程软骨的构建对修复软骨缺损意义重大。本文从四方面介绍了软骨组织工程的研究的新进展 ,包括软骨种子细胞的研究、软骨细胞与支架的体外培养、细胞支架复合物植入体内的研究及软骨细胞移植的临床应用。     

用组织工程学方法探讨兔佐剂性关节炎关节软骨修复的实验研究

目的探讨海藻酸盐支架超微结构及软骨形态变化与组织工程修复佐剂性关节炎软骨缺损的关系,为临床应用组织工程方法治疗类风湿性关节炎(rheumatoid arthritis,RA)提供一定的实验依据。方法将24只新西兰兔随机均分为假手术对照组,关节炎模型组和软骨细胞-海藻酸钙支架复合物治疗组。对模型组和治疗组膝关节处注射0.5 m L完全弗氏佐剂诱导关节炎,假手术组注射等量生理盐水。抽取治疗组骨髓5 m L,Percoll密度梯度分离出自体骨髓间充质干细胞,体外培养纯化,并诱导分化成软骨细胞。与海藻酸钙支架混合培养,对支架进行扫描电镜观察,并将混合物回注相应关节腔内治疗1个月。对各组兔膝关节进行组织学评分检测软骨缺损修复结果。结果海藻酸盐支架电镜扫描显示支架具有一定的孔隙,有利于营养物质的进入,便于细胞的增殖分化。软骨组织评分结果显示软骨纤维化减轻,关节腔内积液消失,软骨缺损得到一定修复。结论软骨组织评分显示海藻酸钙复合工程化软骨细胞对兔佐剂性关节炎软骨缺损有一定的修复作用,其机制可能与支架有利于软骨细胞生长发育有关。     

以交联透明质酸钠为支架体外构建组织工程软骨

背景:采用组织工程技术再生和重建软骨是目前修复软骨组织缺损效果最好、最有应用前景的方法。目的:以体外培养的软骨细胞和交联透明质酸钠为支架材料,开发一套体外构建组织工程软骨的完整方案。方法:分离新西兰兔膝关节软骨细胞,制成细胞悬液滴加于交联透明质酸钠支架上,体外复合培养21 d,提取RNA进行RT-PCR检测,制备冰冻切片进行显微观察和免疫组织化学观察。结果与结论:软骨细胞接种于交联透明质酸钠支架材料后,可贴附于支架上生长,并且大量细胞聚集成团,在支架材料的纤维间隙中生长或呈单层细胞附着于支架材料纤维。细胞-支架复合物表达软骨组织特异性蛋白聚糖基因和Ⅱ型胶原α1基因,以及软骨组织特异性蛋白Ⅱ型胶原蛋白,可维持软骨细胞表型。表明培养的细胞-支架复合物在体外培养可形成软骨细胞外基质,有望获得组织工程软骨组织。     

颈椎旋转手法对兔颈动脉粥样硬化血管 拉伸力学特性的影响

目的 研究颈椎旋转手法对兔颈动脉粥样硬化血管拉伸力学特性的影响,为颈椎旋转手法的安全性提供依据。方法 20只雄性新西兰兔随机分为2组,每组各10只,均饲高脂饮食12周建立动脉粥样硬化动物模型。12周后对实验组兔行颈椎旋转手法,每日左、右各旋转1次,共4周;对照组不作手法处理。手法结束后处死兔,取双侧颈动脉,利用生物组织材料力学试验机测定颈动脉拉伸最大载荷、最大形变、平均载荷、弹性模量和断裂延伸率等指标以及输出应力—应变曲线。结果 实验组颈动脉拉伸最大载荷(1.36±0.35) N,最大形变(6.84±2.08) mm,平均载荷(0.44±0.30) N,弹性模量(4.30±2.66) MPa,断裂延伸率(83.08±51.32)%;对照组颈动脉拉伸最大载荷(2.92±0.65) N,最大形变(9.23±2.62) mm,平均载荷(1.17±0.63) N,弹性模量(3.71±0.60) MPa,断裂延伸率(154.19±34.32)%。其中,实验组颈动脉拉伸的最大载荷、平均载荷和断裂延伸率明显小于对照组（P<0.05）;而最大形变以及弹性模量在两组中差异无统计学意义（P>0.05）。结论 经颈椎旋转手法后,颈动脉粥样硬化血管的拉伸力学特性下降,应注意颈椎旋转手法操作的力度和幅度,以免伤及颈动脉。     

Engineering of rat articular cartilage on porous sponges: effects of tgf-beta 1 and microgravity bioreactor culture

The objective of this study was to develop an engineered rat hyaline cartilage by culturing articular chondrocytes on three-dimensional (3D) macroporous poly(DL-lactic-co-glycolic acid) (PLGA) sponges under chondrogenic induction and microgravity bioreactor conditions. Experimental groups consisted of 3D static and dynamic cultures, while a single cell monolayer (2D) served as the control. The effect of seeding conditions (static vs. dynamic) on cellularization of the scaffolds was investigated. MTT assay was used to evaluate the number of viable cells in each group at different time points. Formation of a hyaline-like cartilage was evaluated for up to 4 weeks in vitro. While 2D culture resulted in cell sheets with very poor matrix production, 3D culture was in the favor of tissue formation. A higher yield of cell attachment and spatially uniform cell distribution was achieved when dynamic seeding technique was used. Dynamic culture promoted cell growth and infiltration throughout the sponge structure and showed the formation of cartilage tissue, while chondrogenesis appeared attenuated more towards the outer region of the constructs in the static culture group. Medium supplemented with TGF-beta 1 (5 ng/ml) had a positive impact on proteoglycan production as confirmed by histochemical analyses with Alcian blue and Safranin-O stainings. Formation of hyaline-like tissue was demonstrated by immunohistochemistry performed with antibodies against type II collagen and aggrecan. SEM confirmed higher level of cellularization and cartilage tissue formation in bioreactor cultures induced by TGF-beta 1. The data suggest that PLGA sponge inside rotating bioreactor with chondrogenic medium provides an environment that mediates isolated rat chondrocytes to redifferentiate and form hyaline-like rat cartilage, in vitro.     

The importance of bicarbonate and nonbicarbonate buffer systems in batch and continuous flow bioreactors for articular cartilage tissue engineering

In cartilage tissue engineering an optimized culture system, maintaining an appropriate extracellular environment (e.g., pH of media), can increase cell proliferation and extracellular matrix (ECM) accumulation. We have previously reported on a continuous-flow bioreactor that improves tissue growth by supplying the cells with a near infinite supply of medium. Previous studies have observed that acidic environments reduce ECM synthesis and chondrocyte proliferation. Hence, in this study we investigated the combined effects of a continuous culture system (bioreactor) together with additional buffering agents (e.g., sodium bicarbonate [NaHCO?]) on cartilaginous tissue growth in vitro. Isolated bovine chondrocytes were grown in three-dimensional cultures, either in static conditions or in a continuous-flow bioreactor, in media with or without NaHCO?. Tissue constructs cultivated in the bioreactor with NaHCO?-supplemented media were characterized with significantly increased (p<0.05) ECM accumulation (glycosaminoglycans a 98-fold increase; collagen a 25-fold increase) and a 13-fold increase in cell proliferation, in comparison with static cultures. Additionally, constructs grown in the bioreactor with NaHCO?-supplemented media were significantly thicker than all other constructs (p<0.05). Further, the chondrocytes from the primary construct expanded and synthesized ECM, forming a secondary construct without a separate expansion phase, with a diameter and thickness of 4?mm and 0.72?mm respectively. Tissue outgrowth was negligible in all other culturing conditions. Thus this study demonstrates the advantage of employing a continuous flow bioreactor coupled with NaHCO? supplemented media for articular cartilage tissue engineering.     

Fluid flow increases type II collagen deposition and tensile mechanical properties in bioreactor-grown tissue-engineered cartilage

A novel parallel-plate bioreactor has been designed to apply a consistent level of fluid flow-induced shear stress to tissue-engineered articular cartilage in order to improve the matrix composition and mechanical properties and more nearly approximate to that of native tissue. Primary bovine articular chondrocytes were seeded into the bioreactor at high densities (1.7 x 10(6) cell/cm2) without a scaffold and cultured for two weeks under static, no-flow conditions. A mean fluid flow-induced shear stress of 1 dyne/cm2 was then applied continuously for 3 days. The application of flow produced constructs with significantly (p < 0.05) higher amounts of total collagen (via hydroxyproline) and specifically type II collagen (via ELISA) (25.3 +/- 2.5% and 22.1 +/- 4.7% of native tissue, respectively) compared to static controls (22.4 +/- 1.7% and 9.5 +/- 2.3%, respectively). Concurrently, the tensile Young's modulus and ultimate strength were significantly increased in flow samples (2.28 +/- 0.19 MPa and 0.81 +/- 0.07 MPa, respectively) compared to static controls (1.55 +/- 0.10 MPa and 0.62 +/- 0.05 MPa, respectively). This study suggests that flow-induced shear stresses and/or enhanced mass transport associated with the hydrodynamic environment of our novel bioreactor may be an effective functional tissue-engineering strategy for improving matrix composition and mechanical properties in vitro.     

Cartilage engineering from ovine umbilical cord blood mesenchymal progenitor cells

We aimed to determine whether three-dimensional (3D) cartilage could be engineered from umbilical cord blood (CB) cells and compare it with both engineered fetal cartilage and native tissue. Ovine mesenchymal progenitor cells were isolated from CB samples (n=4) harvested at 80-120 days of gestation by low-density fractionation, expanded, and seeded onto polyglycolic acid scaffolds. Constructs (n=28) were maintained in a rotating bioreactor with serum-free medium supplemented with transforming growth factor-beta1 for 4-12 weeks. Similar constructs seeded with fetal chondrocytes (n=13) were cultured in parallel for 8 weeks. All specimens were analyzed and compared with native fetal cartilage samples (n=10). Statistical analysis was by analysis of variance and Student's t-test (p<.01). At 12 weeks, CB constructs exhibited chondrogenic differentiation by both standard and matrix-specific staining. In the CB constructs, there was a significant time-dependent increase in extracellular matrix levels of glycosaminoglycans (GAGs) and type-II collagen (C-II) but not of elastin (EL). Fetal chondrocyte and CB constructs had similar GAG and C-II contents, but CB constructs had less EL. Compared with both hyaline and elastic native fetal cartilage, C-II and EL levels were, respectively, similar and lower in the CB constructs, which had correspondingly lower and similar GAG levels than native hyaline and elastic fetal cartilage. We conclude that CB mesenchymal progenitor cells can be successfully used for the engineering of 3D cartilaginous tissue in vitro, displaying select histological and functional properties of both native and engineered fetal cartilage. Cartilage engineered from CB may prove useful for the treatment of select congenital anomalies.     

Fetal cartilage engineering from amniotic mesenchymal progenitor cells

We determined whether cartilage could be engineered from mesenchymal progenitor cells (MPCs) normally found in amniotic fluid. Mesenchymal amniocytes were isolated from ovine amniotic fluid samples (n = 5) and had their identity confirmed by immunocytochemistry. Cells were expanded and then cultured as micromass pellets (n = 5) in a chondrogenic medium containing transforming growth factor-beta2 (TGF-beta2) and insulin growth factor-1 (IGF-1) for 6-12 weeks. Pellets derived from fetal dermal fibroblasts (n = 4) were cultured under identical conditions. Additionally, expanded mesenchymal amniocytes were seeded onto biodegradable polyglycolic acid scaffolds (n = 5) and maintained in the same chondrogenic medium within a rotating bioreactor for 10-15 weeks. Engineered specimens were analyzed quantitatively and compared with native fetal hyaline cartilage samples (n = 5). Statistical analysis was by the unpaired Student's t-test (p < 0.05). The isolated cells stained positively for vimentin and cytokeratins-8 and -18, but negatively for CD31. Micromass pellets derived from mesenchymal amniocytes exhibited chondrogenic differentiation by both standard and matrix-specific staining. In contrast, these findings could not be replicated in dermal fibroblast-based pellets. The engineered constructs derived from mesenchymal amniocytes similarly displayed histological evidence of chondrogenic differentiation and maintained their original size and three-dimensional architecture. Quantitative assays of the engineered constructs revealed lower concentrations of collagen type II, but similar amounts of glycosaminoglycans, elastin, and DNA, when compared to native fetal hyaline cartilage. We conclude that mesenchymal amniocytes can be used for the engineering of cartilaginous tissue in vitro. Cartilage engineering from the amniotic fluid may become a practical approach for the surgical treatment of select congenital anomalies.     

Use of a rotating bioreactor toward tissue engineering the temporomandibular joint disc

This objective of this study was to determine the effects of a rotating bioreactor in temporomandibular joint (TMJ) disc tissue engineering. Porcine TMJ disc cells were seeded at a density of 20 million cells/mL onto nonwoven poly(glycolic acid) (PGA) scaffolds in spinner flasks for 1 week and then cultured either under static conditions or in a rotating bioreactor for a period of 6 weeks. A series of analyses was performed, including mechanical testing, measurement of cellularity, quantification of matrix biosynthesis with a hydroxyproline assay and enzyme-linked immunosorbent assays, and observation of matrix distribution with immunohistochemistry. Between the bioreactor and static cultures, there were marked differences in gross appearance, histological structure, and distribution of collagen types I and II. Engineered constructs from the bioreactor contracted earlier and to a greater extent, resulting in a denser matrix and cell composition. In addition, immunostaining intensity was generally uniform in static constructs, in contrast to higher intensity around the periphery of bioreactor constructs. Moreover, bioreactor constructs had higher amounts of collagen II than did static constructs. However, differences in total matrix content and compressive stiffness were generally not significant. On the basis of the results of this study there is no clear benefit from use of the rotating bioreactor, although a sequence of static culture followed by rotating bioreactor culture may prove in the future to be more beneficial than either alone.     

pGenesil-siHBV X 对 HepG2.2.15 细胞 HBV 表达和复制的抑制效果研究

 目的 研究针对HBV X基因区设计的小干扰RNA（siRNA）表达载体质粒pGenesil-siHBV X 对HepG2.2.15细胞HBV表达和复制的抑制效果及特异性。方法 针对HBV X区设计siRNA表达载体质粒pGenesil- siHBV X。分别用培养液（空白对照）、脂质体Metafectene、pGenesil 空载体、pGenesil-siHK（阴性对照）、pGenesil-siAFP（特异性对照）、pGenesil-siHBV X处理或转染HepG2.2.15细胞各3次。于每次转染后24 h，取各组细胞培养上清液，用时间分辨荧光免疫测定技术检测上清液中HBsAg和HBeAg含量，用化学发光法检测AFP含量，用PCR荧光定量技术检测HBV-DNA复制水平。 结果 pGenesil-siHBV X转染能抑制HepG2.2.15细胞对HBV标志物的表达，且抑制作用随转染次数增加而增强。第3次转染后，pGenesil-siHBV X组细胞上清液中 HBsAg、 HBeAg和HBV-DNA检测结果分别为（6.26 ± 1.07）ng/ml 、（0.13 ± 0.05）Ncu/ml和（3.01 ± 0.40）×107拷贝/ml，与空白对照组的（22.50 ± 1.39）ng/ml、（1.12 ± 0.11）Ncu/ml和（12.33 ± 1.28）×107拷贝/ml比较，差异有统计学意义（t值分别为12.80、12.21、9.71，P < 0.05）；pGenesil-siHBV X 转染不影响细胞对AFP的表达（t = 0.18，P = 0.86）。结论 pGenesil-siHBV X可以有效和特异地抑制HepG 2.2. 15细胞HBV-DNA的复制及HBsAg和HBeAg表达。