Modeling and performance prediction of a conceptual bioprocess for mass production of suspended stem cells

Computational evaluation of light propagation in cylindrical bioreactors for optogenetic mammalian cell cultures

Light-inducible regulation of cellular pathways and gene circuits in mammalian cells is a new frontier in mammalian genetic engineering. Optogenetic mammalian cell cultures, which are light-sensitive engineered cells, utilize light to regulate gene expression and protein activity. As a low-cost, tunable, and reversible input, light is highly adept at spatiotemporal and orthogonal regulation of cellular behavior. However, light is absorbed and scattered as it travels through media and cells, and the applicability of optogenetics in larger mammalian bioreactors has not been determined. In this work, we computationally explore the size limit to which optogenetics can be applied in cylindrical bioreactors at relevant height-to-diameter ratios. We model the propagation of light using the radiative transfer equation and consider changes in reactor volume, absorption coefficient, scattering coefficient, and scattering anisotropy. We observe sufficient light penetration for activation in simulated bioreactors with sizes of up to 80,000 L at maximal cell densities. We performed supporting experiments and found that significant attenuation occurs at the boundaries of the system, but the relative change in intensity distribution within the reactor was consistent with simulation results. We conclude that optogenetics can be applied to bioreactors at an industrial scale and may be a valuable tool for specific biomanufacturing applications.

Influence of shear force on ex vivo expansion of hematopoietic model cells in a stirred tank bioreactor

To evaluate shear stress influence on ex vivo expansion of hematopoietic cell lineages for clinical application, in this study, human pro-monocytic cell (namely U937 cell line) was selected as a hematopoietic stem cell (HSC) model and cultured in suspension mode at two different agitation rates (50, 100 rpm) in the stirred bioreactor. At the agitation rate of 50 rpm, the cells achieved higher expansion folds (27.4 fold) with minimal morphological changes as well as apoptotic cell death, while at 100 rpm the expansion fold decreased after 5-day of culture in suspension culture in comparison with static culture and reached 24.5 fold at the end of the culture. The results of glucose consumption and lactate production were also in agreement with the data of fold expansion and indicated the preference of culture in the stirred bioreactor when agitated at 50 rpm. This study indicated the stirred bioreactor system with an agitation rate of 50 rpm and surface aeration may be used as a potential dynamic culture system for clinical applications of hematopoietic cell lineage. The current experiments shed data related to the effect of shear stress on human U937 cells, as a hematopoietic cell model, to set a protocol for expansion of HSCs for biomedical applications.

Touch-free optical technologies to streamline the production of T cell therapies

Currently approved adoptive T cell therapy relies on autologous (obtained from the same patient) T cells, which often suffer from poor quality that diminishes treatment efficacy. Due to the heterogeneous nature of T cell quality between and within patients, significant efforts are aimed at optimizing cell manipulation and growth conditions for potent T cell products. We believe that touch-free imaging and sensing technologies are critical to monitor single-cell features during T cell manufacturing to ensure consistent and optimally timed methods for cell manipulation and growth. Here, we discuss emerging label-free optical imaging and sensing methods, along with machine learning techniques that could enable in-line feedback to optimize T cell quality at multiple stages during manufacturing. These methods have the potential to streamline current workflow, accelerate the manufacture of safe high-quality T cell therapies, and improve our understanding of the dynamic, heterogeneous processes of T cell manufacturing.

Design of nutrient gas-phase bioreactors: a critical comprehensive review

To reach an efficient and economical gas-phase bioreactor is still one of the most critical challenges in biotechnology engineering. The numerous advantages of gas-phase bioreactors (GPBs) as well as disadvantages of these bioreactors should be exactly recognized, and efforts should be made to eliminate these defects. The first step in upgrading these bioreactors is to identify their types and the results of previous research. In the present work, a summary of the studies carried out in the field of cultivation in these bioreactors, their classification, their components, their principles and relations governing elements, modeling them, and some of their inherent engineering aspects are presented. Literature review showed that inoculation of shoots, roots, adventurous roots, callus, nodal explants, anther, nodal segment, somatic embryo, hairy roots, and fungus is reported in 15, 2, 2, 2, 3, 2, 1, 1, 37, and 5 cases, respectively.

Static and dynamic culture of human endothelial cells encapsulated inside alginate-gelatin microspheres

This study aimed to explore the angiogenesis potential of human endothelial cells encapsulated inside alginate-gelatin microspheres under static and dynamic culture systems after 7 days. Human umbilical vein endothelial cells were encapsulated inside alginate (1%) and gelatin (1.2%) using an electrostatic encapsulation method. Cells were incubated for 7 days in vitro. The cell survival rate was measured using the MTT assay. The expression of VEGFR-2 and von Willebrand factor genes was studied by real-time PCR assay. Using western blot analysis, we monitored the protein contents of VEGFR-2, vWF, and Caspase 3. The levels of SOD and GPx enzymes were calculated using biochemical kits. Angiogenesis potential was assessed using in vitro Matrigel assay. Data showed an increased survival rate in encapsulated cells cultured under the static condition compared to the conventional 2D condition (p < 0.05). The culture of encapsulated cells under a dynamic bioreactor system did not alter cell viability. Compared to the dynamic culture system, the incubation of encapsulated cells in the static culture system swelled the microspheres (p < 0.05). Both dynamic and static culture models increased the expression of VEGFR-2 and von Willebrand factor in encapsulated cells compared to 2D culture (p < 0.05), showing enhanced functional maturation. Data showed a significant increase of vWF and reduction of apoptosis marker Caspase in the dynamic culture system (p < 0.05). The levels of SOD and GPx were significantly increased in dynamic and static culture models as compared to the control 2D group (p < 0.05). In vitro tubulogenesis assay showed significant induction of angiogenesis in dynamic encapsulated HUVECs indicated with a large number of vascular tubes and arborized ECs compared to the control and static encapsulated HUVECs (p < 0.05). The current study suggests a bioreactor dynamic system is a reliable approach, similar to a static condition, for the expansion of encapsulated human ECs in a 3D milieu.

Performance evaluation of a novel conceptual bioprocess for clinically-required mass production of hematopoietic cells

OBJECTIVE

The novel engineered bioprocess, which was designed and modeled to provide the clinically relevant cell numbers for different therapies in our previous work (Kaleybar et al. Food Bioprod Process 122:254-268, https://doi.org/10.1016/j.fbp.2020.04.012 , 2020), was evaluated by using U937 as hematopoietic model cells.

RESULTS

The culture system showed a 30-fold expansion of U937 cells in one-step during a 10-day culture period. The cell growth profile, the substrate and oxygen consumptions, and byproduct formations were all in agreement with the model predications during 7 days. The cell proliferation decrease after 7 days was attributed to optional oxygen limiting condition in the last days of culture. The bioreactor culture system revealed also a slight enhancement of lactate dehydrogenase (LDH) production as compared to the 2D conventional culture system, indicating the low impact of shear stress on cellular damage in the dynamic system.

CONCLUSIONS

The results demonstrated that the conceptual bioprocess for suspended stem cell production has a great potential in practice although additional experiments are required to improve the system.