Determination of specific oxygen uptake rates in human hematopoietic cultures and implications for bioreactor design

Oxygen plays an important role in the cultivation of primary cellsex vivo. In this study, we used hermetically sealed tissue culture well inserts equipped with oxygen electrodes to measure the oxygen utilization of cultured human bone marrow mononuclear cells (BM MNCs). The oxygen uptake rate (OUR) of BM MNCs was determined during a 14-day culture in which both adherent and nonadherent cells were present. Early in the culture, the cells exhibited very low OURs. The specific OURs (uptake rate per cell) were at approximately 0.005 μmol/10⁶ cells/hr shortly after the initiation of culture. The OUR then increased as the cultures developed. After about 8 to 10 days of cultivation the specific OURs had increased to 0.038±0.006 and 0.025±0.005 μmol/10⁶ cells/hr for adherent and nonadherent cells, respectively, after which no further increase was observed. Based on these oxygen uptake rate data, a mathematical model of oxygen diffusion was formulated and use to investigate issues associated with hematopoietic bioreactor design, including initial cell density, medium depth, reactor configuration, and oxygen partial pressure.In situ OUR measurements confirmed predicted oxygen limitations based on the mathematical model and the experimentally determined OURs. High-density hematopoietic cultures present design challenges in terms of sufficient and uniform delivery of oxygen to an active hematopoietic culture. These challenges can be met by using parallelplate bioreactors with thin liquid layers.     

转壁生物反应器中动态分化组织工程软骨的实验研究

目的 :在转壁生物反应器动态环境中分化骨髓间充质干细胞 (bMSC) ,制备立体组织工程软骨。方法 :穿刺吸取成年兔骨髓 ,分离扩增bMSC ,复合于纤维蛋白凝胶制成圆柱状三维组织 (细胞密度2 0× 10 7/ml) ,置于转壁生物反应器中进行分化培养 ,同时设单纯静止培养组。 5周后观测大体形态和组织学形态、Ⅰ和Ⅱ型胶原免疫组织化学表达 ,测量分化组织的细胞活力。结果 :动态培养可以有效保持材料大体形态 ,甲苯胺兰染色阳性 ,无明显Ⅰ型胶原表达 ,大量表达Ⅱ型胶原 ,人工组织的细胞活力显著高于单纯静止培养方法。结论 :转壁生物反应器培养明显改善组织工程软骨的活力 ,有利于进行三维材料体外软骨分化。     

Alginate‐encapsulated HepG2 Cells in a Fluidized Bed Bioreactor Maintain Function in Human Liver Failure Plasma

Alginate‐encapsulated HepG2 cells cultured in microgravity have the potential to serve as the cellular component of a bioartificial liver. This study investigates their performance in normal and liver failure (LF) human plasma over 6–8 h in a fluidized bed bioreactor. After 8 days of microgravity culture, beads containing 1.5 × 10⁹ cells were perfused for up to 8 h at 48 mL/min with 300 mL of plasma. After exposure to 90% LF plasma, vital dye staining showed maintained cell viability, while a 7% increase in lactate dehydrogenase activity indicated minimal cell damage. Glucose consumption, lactate production, and a 4.3‐fold linear increase in alpha‐fetoprotein levels were observed. Detoxificatory function was demonstrated by quantification of bilirubin conjugation, urea synthesis, and Cyp450 1A activity. These data show that in LF plasma, alginate‐encapsulated HepG2 cells can maintain viability, and metabolic, synthetic, and detoxificatory activities, indicating that the system can be scaled‐up to form the biological component of a bioartificial liver.     

用超速玻璃化冻存人肝组织微团构建人工肝生物反应器的初步研究

本研究用胶原酶有限消化法将手术切除的小块成人肝组织消化成肝组织微团,用超速玻璃化法冻存,解冻后继续消化成较小组织微团并与胶原培养液混合灌注中空纤维反应器管外腔,在外腔中形成凝胶将肝组织微团悬浮其中,构建人工肝生物反应器,体外灌注检测了该反应器代谢合成功能,现报道如下.     

Trends and targets of various types of stem cell derived transfusable RBC substitution therapy: Obstacles that need to be converted to opportunity

A shortage of blood during the pandemic outbreak of COVID-19 is a typical example in which the maintenance of a safe and adequate blood supply becomes difficult and highly demanding. So far, human RBCs have been produced in vitro using diverse sources: hematopoietic stem cells (SCs), embryonic SCs and induced pluripotent SCs. The existing, even safest core of conventional cellular bioproducts destined for transfusion have some shortcoming in respects to: donor –dependency variability in terms of hematological /immunological and process/ storage period issues. SCs–derived transfusable RBC bioproducts, as one blood group type for all, were highly complex to work out. Moreover, the strategies for their successful production are often dependent upon the right selection of starting source materials and the composition and the stability of the right expansion media and the strict compliance to GMP regulatory processes. In this mini-review we highlight some model studies, which showed that the efficiency and the functionality of RBCs that could be produced by the various types of SCs, in relation to the in-vitro culture procedures are such that they may, potentially, be used at an industrial level. However, all cultured products do not have an unlimited life due to the critical metabolic pathways or the metabolites produced. New bioreactors are needed to remove these shortcomings and the development of a new mouse model is required. Modern clinical trials based on the employment of regenerative medicine approaches in combination with novel large-scale bioengineering tools, could overcome the current obstacles in artificial RBC substitution, possibly allowing an efficient RBC industrial production.     

应用生物反应器体外培养骨软骨复合体修复犬关节软骨损伤

目的 探讨应用灌注型生物反应器体外培养骨软骨复合体修复关节软骨损伤的可行性. 方法 体外分离犬骨髓间充质干细胞(MSCs),流式细胞仪鉴定.经过生长因子诱导生成软骨细胞和成骨细胞后,免疫组化及碱性磷酸酶等染色鉴定.将软骨细胞、成骨细胞接种到三维多孔β-磷酸三钙(β-TCP)陶瓷支架材料上,置于灌注型生物反应器中复合培养21 d,构建骨软骨复合体,扫描电镜观察细胞在支架材料上的黏附、伸展和增殖情况,并模仿马赛克骨软骨移植术用塑形良好的骨软骨复合体修复犬软骨缺损,切片染色观察其修复情况. 结果 扫描电镜显示软骨细胞、成骨细胞在β-TCP支架上的黏附、伸展和增殖良好,实验组缺损区软骨厚度与正常软骨组织接近.实验组与阴性时照组比较,差异有统计学意义(q=12.337 0,P＜0.01);与空白对照组比较,差异有统计学意义(q=31.5393,P＜0.01). 结论 灌注型生物反应器使软骨和成骨细胞在三维载体内存活并增殖,提高细胞在载体内的复合效率.     

旋转式动态三维培养结合可控管道结构支架体外节段性骨的构建

目的探讨应用可控管道结构支架接种成骨细胞并行旋转式动态三维培养作为一种新的节段性组织工程骨体外构建方法的可行性、效果和机制。方法设计、制备可控管道结构自固化磷酸钙（CPC）支架,并设计开发新型旋转式生物反应器。分离、扩增兔颅骨成骨细胞接种支架后分别行旋转培养和静态培养7、14、21d后,行四甲基偶氮唑蓝（MTT）比色法、细胞葡萄糖日耗量、细胞碱性磷酸酶（ALP）活性的检测及扫描电镜（SEM）观察、X射线能谱（EDX）分析。结果旋转培养组细胞的增殖、代谢、成骨分化等均显著优于静态培养（F=144．187、F=491．603、F=34．913,均P〈0．01、P〈0．01）;旋转培养组细胞支架内分布的均匀性优于静态培养,EDX分析显示细胞分泌磷酸钙基质。结论可控管道结构CPC支架结合旋转式动态三维培养有效促进成骨细胞的增殖、代谢、分化和支架内合理分布,可成为一种新的节段性组织工程骨体外构建方法。     

Increasing Vero viable cell densities for yellow fever virus production in stirred-tank bioreactors using serum-free medium

In this work, changes in Vero cell cultivation methods have been employed in order to improve cell growth conditions to obtain higher viable cell densities and to increase viral titers. The propagation of the 17DD yellow fever virus (YFV) in Vero cells grown on Cytodex I microcarriers was evaluated in 3-L bioreactor vessels. Prior to the current changes, Vero cells were repeatedly displaying insufficient microcarrier colonization. A modified cultivation process with four changes has resulted in higher cell densities and higher virus titers than previously observed for 17DD YFV.