Activation of microcarrier-attached lymphocytes in microgravity

A technology has been developed to achieve optimal attachment of adhesion-independent lymphocytes to microcarrier beads. The activation of T-lymphocytes by concanavalin A was tested under microgravity conditions in an experiment carried out in space during the first Spacelab Life Science Mission. Activation, measured as the synthesis of deoxyribonucleic acid (DNA) and the production of interferon-gamma, more than doubled in attached lymphocytes in microgravity. The depression of the activation discovered in previous space experiments is due to an impairment not of the lymphocyte but of the macrophage function. The system described here may be useful for radiobiological investigations on the effect of high-energy particles and for testing the efficiency of the immune system in humans during the long-duration space flight planned in the future. The biotechnological significance of the increased lymphokine production in space remains to be assessed.     

Adult rat pancreatic islet cells adherent to microcarrier beads: Evaluation of function and morphology

Summary Dispersed adult rat pancreatic islet cells were incubated with Cytodex-3 microcarrier beads for 72 h, during which time single cells adhered firmly to bead surfaces. Electron microscopy revealed well-preserved ultrastructure of attached A, B, and D cells. Perifusion of these cultures showed stable basal insulin release, brisk, biphasic insulin responses to 30-min glucose stimulation, and consistent, monophasic spikes of insulin release in response to repeated, brief pulses of glucose. These results indicate that adult rat islet cells attach to microcarriers and remain viable in culture. This preparation offers advantages for studies of hormone secretory dynamics of differentiated single islet cells, free from cell-to-cell interactions. This study was supported by grants from the Medical Research Council of New Zealand. D.W.H. was the recipient of a Novo Diabetes Research Scholarship.     

Skeletal muscle satellite cells cultured in simulated microgravity

Summary Satellite cells are postnatal myoblasts responsible for providing additional nuclei to growing or regenerating muscle cells. Satellite cells retain the capacity to proliferate and differentiate in vitro and, therefore, provide a useful model to study postnatal muscle development. Most culture systems used to study postnatal muscle development are limited by the two-dimensional (2-D) confines of the culture dish. Limiting proliferation and differentiation of satellite cells in 2-D could potentially limit cell-cell contacts important for developing the level of organization in skeletal muscle obtained in vivo. Culturing satellite cells on microcarrier beads suspended in the High-Aspect-Ratio-Vessel (HARV) designed by NASA provides a low shear, three-dimensional (3-D) environment to study muscle development. Primary cultures established from anterior tibialis muscles of growing rats (∼ 200 gm) were used for all studies and were composed of greater than 75% satellite cells. Different inoculation densities did not affect the proliferative potential of satellite cells in the HARV. Plating efficiency, proliferation, and glucose utilization were compared between 2-D culture and 3-D HARV culture. Plating efficiency (cells attached ÷ cells plated ×100) was similar between the two culture systems. Proliferation was reduced in HARV cultures and this reduction was apparent for both satellite cells and nonsatellite cells. Furthermore, reduction in proliferation within the HARV could not be attributed to reduced substrate availability because glucose levels in medium from HARV and 2-D cell culture were similar. Morphologically, microcarrier beads within the HARV were joined together by cells into 3-D aggregates composed of greater than 10 beads/aggregate. Aggregation of beads did not occur in the absence of cells. Myotubes were often seen on individual beads or spanning the surface of two beads. In summary, proliferation and differentiation of satellite cells on microcarrier beads within the HARV bioreactor results in a 3-D level of organization that could provide a more suitable model to study postnatal muscle development than is currently available with standard culture methods.     

Bioprocessing automation in cell therapy manufacturing: Outcomes of special interest group automation workshop

Phacilitate held a Special Interest Group workshop event in Edinburgh, UK, in May 2017. The event brought together leading stakeholders in the cell therapy bioprocessing field to identify present and future challenges and propose potential solutions to automation in cell therapy bioprocessing. Here, we review and summarize discussions from the event. Deep biological understanding of a product, its mechanism of action and indication pathogenesis underpin many factors relating to bioprocessing and automation. To fully exploit the opportunities of bioprocess automation, therapeutics developers must closely consider whether an automation strategy is applicable, how to design an ‘automatable’ bioprocess and how to implement process modifications with minimal disruption. Major decisions around bioprocess automation strategy should involve all relevant stakeholders; communication between technical and business strategy decision-makers is of particular importance. Developers should leverage automation to implement in-process testing, in turn applicable to process optimization, quality assurance (QA)/ quality control (QC), batch failure control, adaptive manufacturing and regulatory demands, but a lack of precedent and technical opportunities can complicate such efforts. Sparse standardization across product characterization, hardware components and software platforms is perceived to complicate efforts to implement automation. The use of advanced algorithmic approaches such as machine learning may have application to bioprocess and supply chain optimization. Automation can substantially de-risk the wider supply chain, including tracking and traceability, cryopreservation and thawing and logistics. The regulatory implications of automation are currently unclear because few hardware options exist and novel solutions require case-by-case validation, but automation can present attractive regulatory incentives.     

大规模动物细胞培养技术研究进展

利用动物细胞大规模培养技术可生产多种生物制品,为提高细胞活力和表达水平及有利于表达产物的纯化,采用有多种添加成分的无血清培养基培养细胞,选择更有利于细胞生长又可提高培养细胞密度的微载体和条件温和、易操作、气体交换速度快的生物反应器,在线监控细胞生存环境和生理活动,减少培养过程培养基中的抑制因素,可创造更适合细胞生存的环境,提高表达水平,向细胞中导入抗凋亡基因,可提高细胞活性和蛋白产量。利用多也微载体以球转球方式大规模培养动物细胞有很好的发展前景。     

Production of erythropoietin by BHK cells growing on the microcarriers trapped in alginate gel beads

Baby hamster kidney (BHK) cells engineered to produce recombinant human erythropoietin (EPO) were cultured at high density on microcarriers entrapped by calcium alginate gel particles. In this system, the BHK cells proliferated not only on the microcarriers but also in vacant spaces in the alginate gel particles. These spaces contributed greatly to high-density cultivation of the cells and a high productivity of EPO.Abbreviations BHK Baby Hamster Kidney - EPO Erythropoietin     

Secondary metabolism in simulated microgravity and space flight

Space flight experiments have suggested that microgravity can affect cellular processes in microorganisms. To simulate the microgravity environment on earth, several models have been developed and applied to examine the effect of microgravity on secondary metabolism. In this paper, studies of effects of space flight on secondary metabolism are exemplified and reviewed along with the advantages and disadvantages of the current models used for simulating microgravity. This discussion is both signi?cant and timely to researchers considering the use of simulated microgravity or space flight to explore effects of weightlessness on secondary metabolism.     

Scale-up of suspension and anchorage-dependent animal cells

Alternative culture processes for laboratory scale-up (to 20 L) are described for both suspension and anchorage-dependent cells. Systems range from simple multiple culture units such as the roller bottle, through stirred suspension and microcarrier unit bioreactors, to highly sophisticated perfusion culture capable of maintaining cells at densities of about 10⁸/mL. Critical parameters in scale-up are discussed, and the advantages and disadvantages of each culture system are critically evaluated.     

Effect of a mass of lead in the incubator space of growing cells

Mouse fibroblasts (3T3 line) growing in vitro in an incubator were subjected to inclusion in the incubator space of different masses and different arrangements of metallic lead. It was found that the mass of lead was positively correlated with death of a percentage of the 3T3 cells. Aside from mass, a second property of the lead, that of shape, was also found to be related to the percentage cell death. Progeny of 3T3 cells whose parents had been previously exposed to lead during their growth were found to have developed a resistance to its cytocidal effect on subsequent exposure. Such progeny cells showed no increase in cell death over the period of time which proved lethal to cells which had not had prior exposure to lead in their environment.     

利用报告基因比较悬浮细胞与贴壁细胞对HIV-1假病毒感染效率的差异

【目的】研究用人免疫缺陷病毒(Human immunodeficiency virus,HIV)-1假病毒感染带有β-半乳糖苷酶(β-galactosidase,β-gal)报告基因和HIV受体CD4+CCR5+的Tzmbl细胞,分析悬浮状态与贴壁状态对HIV-1假病毒感染Tzmbl细胞的影响,为进一步进行HIV生物学研究与中和抗体实验室评价提供实验基础。【方法】通过将pNL43 R-E-与编码HIV膜蛋白的质粒共转染293T细胞,收集上清,获得HIV假病毒。该假病毒感染悬浮的和贴壁的Tzmbl细胞后可表达β-gal报告蛋白,通过X-gal染色和仪器分析可测定表达β-gal报告基因的细胞数与细胞感染率。【结果】HIV假病毒感染悬浮细胞的效率高于其对贴壁的Tzmbl细胞感染的效率,且细胞的感染率的改变与病毒的型相关。【结论】该研究结果可为进一步利用具有单轮感染活性的HIV假病毒进行生物研究和中和抗体实验提供研究方法。     

Real microgravity condition promoted regeneration capacity of induced pluripotent stem cells during the TZ‐1 space mission

Induced pluripotent stem cells (iPSCs) are reprogrammed somatic cells that gained self‐renewal and differentiation capacity similar to embryonic stem cells. Taking the precious opportunity of the TianZhou‐1 spacecraft mission, we studied the effect of space microgravity (µg) on the self‐renewal capacity of iPSCs. Murine iPSCs carrying pluripotency reporter Oct4‐GFP were used. The Oct4‐EGFP‐iPSCs clones were loaded into the bioreactor and exposed to μg in outer space for 14 days. The control experiment was performed in identical device but on the ground in earth gravity (1 g). iPSCs clones were compact and highly expressed Oct4 before launch. In μg condition, cells in iPSC clones spread out more rapidly than those in ground 1 g condition during the first 3 days after launch. However, in 1 g condition, as the cell density increases, the Oct4‐GFP signal dropped significantly during the following 3 days. Interestingly, in μg condition, iPSCs originated from the spread‐out clones during the first 3 days appeared to cluster together and reform colonies that activated strong Oct4 expression. On the other hand, iPSC clones in 1 g condition were not able to recover Oct4 expression after overgrown. Our study for the first time performed real‐time imaging on the proliferation process of iPSCs in space and found that in μg condition, cell behaviour appeared to be more dynamic than on the ground.     

Effects of long-term microgravity exposure in space on circadian rhythms of heart rate variability

We evaluated their circadian rhythms using data from electrocardiographic records and examined the change in circadian period related to normal RR intervals for astronauts who completed a long-term (≥6-month) mission in space. The examinees were seven astronauts, five men and two women, from 2009 to 2010. Their mean?±?SD age was 52.0?±?4.2 years (47–59?yr). Each stayed in space for more than 160 days; their average length of stay was 172.6?±?14.6 days (163–199 days). We conducted a 24-h Holter electrocardiography before launch (Pre), at one month after launch (DF1), at two months after launch (DF2), at two weeks before return (DF3), and at three months after landing (Post), comparing each index of frequency-domain analysis and 24-h biological rhythms of the NN intervals (normal RR intervals). Results show that the mean period of Normal Sinus (NN) intervals was within 24?±?4?h at each examination. Inter-individual variability differed among the stages, being significantly smaller at DF3 (Pre versus DF1 versus DF3 versus Post?=?22.36?±?2.50 versus 25.46?±?4.37 versus 22.46?±?1.75 versus 26.16?±?7.18?h, p?<?0.0001). The HF component increased in 2 of 7 astronauts, whereas it decreased in 3 of 7 astronauts and 1 was remained almost unchanged at DF1. During DF3, about 6 months after their stay in space, the HF component of 5 of 7 astronauts recovered from the decrease after launch, with prominent improvement to over 20% in 3 astronauts. Although autonomic nervous functions and circadian rhythms were disturbed until one month had passed in space, well-scheduled sleep and wake rhythms and meal times served as synchronizers.     

Initial culture conditions affect the sensitivity of HepG2 cells to excessive mechanical agitation

Hepatoma cells, HepG2, grew normally on microcarriers even at a relatively high agitation rate if sufficient time was allowed for cell attachment and adhesion. However, if a high agitation rate was applied shortly after initial cell attachment, the growth rate was retarded. This sensitivity to mechanical agitation appears to be dependent on the inoculation cell density.     

A countermeasure to ameliorate immune dysfunction in in vitro simulated microgravity environment: role of cellularnucleotide nutrition

Considerable evidence suggests that space travelers are immunosuppressed, presumably by microgravity environmental stresses, putting them at risk for adverse effects, such as opportunistic infections, poor wound healing, and cancer. The purpose of this study was to examine the role and mechanisms of nucleotide (NT) supplementation as a countermeasure to obviate immunosuppression during space travel. The in vitro rotary cell culture system, a bioreactor (BIO), was used to simulate the effect of microgravity and to isolate the neuroendocrine effects inherent to in vitro models. The splenocytes from normal mice were cultured in BIO and control tissue culture (TC) flasks with and without phytohemagglutinin (PHA) for mitogen assays. The culture medium was then supplemented with various concentrations of a nucleosides-nucleotides mixture (NS + NT), inosine, and uridine. Cytokines interleukin (IL)-1beta, IL-2, IL-3, tumor necrosis factor-alpha, and interferon (IFN)-gamma were measured from the supernatant by enzyme-linked immunosorbent assay. In the PHA-stimulated cultures the cellular proliferation in the BIO was significantly decreased as compared with the TC flask cells. BIO-cultured cells in the presence of NS + NT maintained mitogen responses similar to the control TC flask cells. The maintenance of the mitogen response in BIO was observed by the supplementation of uridine and not of inosine. These results are in agreement with our earlier results from unit gravity experiments that showed that pyrimidines are more effective in pleiogenic immunoprotection to hosts. Cytokines IL-1beta, IL-2, and IFN-gamma in the BIO supernatants of cells cultured in the presence of NS + NT had a significantly higher response than the control vessel. Thus, supplemental NT, especially pyrimidines, can confer immune protection and enhance cytokine responses during space travel.     

Surface transformation of bioactive glass in bioreactors simulating microgravity conditions. Part I: experimental study

Surface modified bioactive glass with surface properties akin to those of the bone mineral phase is an attractive candidate for use as a microcarrier material for 3-D growth of bone-like tissue in rotating wall vessel bioreactors (RWVs). The critical surface properties of this material are the result of reaction in solution. Because an RWV environment is completely different from conditions previously employed for bioactive glass testing, a detailed study of the surface reactions is warranted. Under properly chosen conditions, RWVs can also provide a simulated microgravity environment for the bioactive glass (BG) particles. In this sense, this study is also a report on the behavior of a bioactive material under microgravity conditions simulated on earth. A high aspect ratio vessel (HARV) and carefully selected experimental conditions enabled the simulation of microgravity in our laboratory. A complimentary numerical study was simultaneously conducted to ascertain the appropriateness of the experimental parameters (particle size, particle density, medium density, medium viscosity, and rotational speed) that ensure simulated microgravity conditions for the glass particles in the HARV. Physiological solutions (pH 7.4) with and without electrolytes, and also with serum proteins, were used to study the change in surface character resulting from simulated microgravity. Control tests at normal gravity, both static and dynamic, were also conducted. Solution and surface analyses revealed major effects of simulated microgravity. The rates of leaching of constituent ions (Si-, Ca-, and P-ions) were greatly increased in all solutions tested. The enhanced dissolution was followed by the enhanced formation of bone-like minerals at the BG surface. This enhancement is expected to affect adsorption of serum proteins and attachment molecules, which, in turn, may favorably affect bone cell adhesion and function. The findings of the study are important for the use of bioactive materials as microcarriers to generate and analyze 3-D bone-like tissue structures in bioreactors under microgravity conditions or otherwise. Copyright John Wiley & Sons, Inc.     

Oxygen transport and consumption by suspended cells in microgravity: a multiphase analysis

A rotating bioreactor for the cell/tissue culture should be operated to obtain sufficient nutrient transfer and avoid damage to the culture materials. Thus, the objective of the present study is to determine the appropriate suspension conditions for the bead/cell distribution and evaluate oxygen transport in the rotating wall vessel (RWV) bioreactor. A numerical analysis of the RWV bioreactor is conducted by incorporating the Eulerian-Eulerian multiphase and oxygen transport equations. The bead size and rotating speed are the control variables in the calculations. The present results show that the rotating speed for appropriate suspensions needs to be increased as the size of the bead/cell increases: 10 rpm for 200 microm; 12 rpm for 300 microm; 14 rpm for 400 microm; 18 rpm for 600 microm. As the rotating speed and the bead size increase from 10 rpm/200 microm to 18 rpm/600 microm, the mean oxygen concentration in the 80% midzone of the vessel is increased by approximately 85% after 1-h rotation due to the high convective flow for 18 rpm/600 microm case as compared to 10 rpm/200 microm case. The present results may serve as criteria to set the operating parameters for a RWV bioreactor, such as the size of beads and the rotating speed, according to the growth of cell aggregates. In addition, it might provide a design parameter for an advanced suspension bioreactor for 3-D engineered cell and tissue cultures.     

Proliferation of human hematopoietic bone marrow cells in simulated microgravity

Expansion and/or maintenance of hematopoietic stem cell (HSC) potential following in vitro culture remains a major obstacle in stem cell biology and bone marrow (BM) transplantation. Several studies suggest that culture of mammalian cells in microgravity (micro-g) may reduce proliferation and differentiation of these cells. We investigated the application of these findings to the field of stem cell biology in the hopes of expanding HSC with minimal loss of hematopoietic function. To this end, BM CD34+ cells were cultured for 4-6 d in rotating wall vessels for simulation of micro-g, and assessed for expansion, cell cycle activation, apoptosis, and hematopoietic potential. While CD34+ cells cultured in normal gravity (1-g) proliferated up to threefold by day 4-6, cells cultured in micro-g did not increase in number. As a possible explanation for this, cells cultured in simulated micro-g were found to exit G0/G1 phase of cell cycle at a slower rate than 1-g controls. When assayed for primitive hematopoietic potential in secondary conventional 1-g long-term cultures, cells from initial micro-g cultures produced greater numbers of cells and progenitors, and for a longer period of time, than cultures initiated with 1-g control cells. Similar low levels of apoptosis and adhesion molecule phenotype in micro-g and 1-g-cultured cells suggested similar growth patterns in the two settings. These data begin to elucidate the effects of micro-g on proliferation of human hematopoietic cells and may be potentially beneficial to the fields of stem cell biology and somatic gene therapy.     

Characteristics of human dendritic cells generated in a microgravity analog culture system

Summary Generation of an effective immune response requires that antigens be processed and presented to T lymphocytes by antigen-presenting cells, the most efficient of which are dendritic cells (DC). Because of their influence on both the innate and the acquired arms of immunity, a defect in DC would be expected, to result in a broad impairment of immune function, not unlike that observed in astronauts during or after space flight. In the study reported here, we investigated whether DC generation and function are altered in a culture environment that models microgravity, i.e., the rotary-cell culture system (RCCS). We observed that RCCS supported the generation of DC identified by morphology, phenotype (HLA-DR⁺ and lacking lineage-associated markers), and function (high allostimulatory activity). However, the yield of DC from RCCS was significantly lower than that from static cultures. RCCS-generated DC were less able to phagocytoseAspergillus fumigatus conidia and expressed a lower density of surface HLA-DR. The proportion of Dc expressing CD80 was also significantly reduced in RCCS compared to static cultures. When exposed to fungal antigens, RCCS-generated DC produced lower levels of interleukin-12 and failed to upregulate some costimulatory/adhesion molecules involved in antigen presentation. These data suggest that DC generation, and some functions needed to mount an effective immune response to pathogens, may be disturbed in the microgravity environment of space.     

Effect of microgravity on proliferation and differentiation of embryonic stem cells in an automated culturing system during the TZ‐1 space mission

Objective

Despite a great number of studies analysing the effects of microgravity on stem cell proliferation and differentiation, few of them have focused on real‐time imaging estimates in space. Herein, we utilized the TZ‐1 cargo spacecraft, automatic cell culture equipment and live cell imaging techniques to examine the effects of real microgravity on the proliferation and differentiation of mouse embryonic stem cells (mESCs).

Materials and methods

Oct4‐GFP, Brachyury‐GFP mESC and Oct4‐GFP mESC‐derived EBs were used as experimental samples in the TZ‐1 spaceflight mission. These samples were seeded into chambers, cultured in an automatic cell culture device and were transported into space during the TZ‐1 mission. Over 15 days of spaceflight, bright field and fluorescent images of cell growth were taken in micrography, and the medium was changed every day. Real‐time image data were transferred to the ground for analysis.

Results

Space microgravity maintains stemness and long‐term survival of mESCs, promising 3D aggregate formation. Although microgravity did not significantly prevent the migration of EBs on the ECM substrate, it did prevent terminal differentiation of cells.

Conclusions

This study demonstrates that space microgravity might play a potential role in supporting 3D cell growth and maintenance of stemness in embryonic stem cells, while it may negatively affect terminal differentiation.