Scalable Expansion of Human Pluripotent Stem Cell-Derived Neural Progenitors in Stirred Suspension Bioreactor Under Xeno-free Condition

Impact of perfusion on neuronal development in human derived neuronal networks

Advanced in vitro models of the brain have evolved in recent years from traditional two-dimensional (2D) ones, based on rodent derived cells, to three-dimensional (3D) ones, based on human neurons derived from induced pluripotent stem cells. To address the dynamic changes of the tissue microenvironment, bioreactors are used to control the in vitro microenvironment for viability, repeatability, and standardization. However, in neuronal tissue engineering, bioreactors have primarily been used for cell expansion purposes, while microfluidic systems have mainly been employed for culturing organoids. In this study, we explored the use of a commercial perfusion bioreactor to control the culture microenvironment of neuronal cells in both 2D and 3D cultures. Namely, neurons differentiated from human induced pluripotent stem cells (iNeurons) were cultured in 2D under different constant flow rates for 72 h. The impact of different flow rates on early-stage neuronal development and synaptogenesis was assessed by morphometric characterization and synaptic analysis. Based on these results, two involving variable flow rates were developed and applied again in 2D culture. The most effective protocol, in terms of positive impact on neuronal development, was then used for a preliminary study on the application of dynamic culturing conditions to neuronal cells in 3D. To this purpose, both iNeurons, co-cultured with astrocytes, and the human neuroblastoma cells SH-SY5Y were embedded into a hydrogel and maintained under perfusion for up to 28 days. A qualitative evaluation by immunocytochemistry and confocal microscopy was carried out to assess cell morphology and the formation of a 3D neuronal network.

Neural stem cell therapies for spinal cord injury repair: an update on recent preclinical and clinical advances

Traumatic spinal cord injury (SCI) is a leading cause of lifelong disabilities. Permanent sensory, motor and autonomic impairments after SCI are substantially attributed to degeneration of spinal cord neurons and axons, and disintegration of neural network. To date, minimal regenerative treatments are available for SCI with an unmet need for new therapies to reconstruct the damaged spinal cord neuron-glia network and restore connectivity with the supraspinal pathways. Multipotent neural precursor cells (NPCs) have a unique capacity to generate neurons, oligodendrocytes and astrocytes. Due to this capacity, NPCs have been an attractive cell source for cellular therapies for SCI. Transplantation of NPCs has been extensively tested in preclinical models of SCI in the past two decades. These studies have identified opportunities and challenges associated with NPC therapies. While NPCs have the potential to promote neuroregeneration through various mechanisms, their low long-term survival and integration within the host injured spinal cord limit the functional benefits of NPC-based therapies for SCI. To address this challenge, combinatorial strategies have been developed to optimize the outcomes of NPC therapies by enriching SCI microenvironment through biomaterials, genetic and pharmacological therapies. In this review, we will provide an in-depth discussion on recent advances in preclinical NPC-based therapies for SCI. We will discuss modes of actions and mechanism by which engrafted NPCs contribute to the repair process and functional recovery. We will also provide an update on current clinical trials and new technologies that have facilitated preparation of medical-grade human NPCs suitable for transplantation in clinical studies.

Dissolved oxygen concentration regulates human hepatic organoid formation from pluripotent stem cells in a fully controlled bioreactor

Developing technologies for scalable production of human organoids has gained increased attention for "organoid medicine" and drug discovery. We developed a scalable and integrated differentiation process for generation of hepatic organoid from human pluripotent stem cells (hPSCs) in a fully controlled stirred tank bioreactor with 150 ml working volume by application of physiological oxygen concentrations in different liver tissue zones. We found that the 20-40% dissolved oxygen concentration [DO] (corresponded to 30-60 mmHg pO₂ within the liver tissue) significantly influences the process outcome via regulating the differentiation fate of hPSC aggregates by enhancing mesoderm induction. Regulation of the [DO] at 30% DO resulted in efficient generation of human fetal-like hepatic organoids that had a uniform size distribution and were comprised of red blood cells and functional hepatocytes, which exhibited improved liver-specific marker gene expressions, key liver metabolic functions, and, more important, higher inducible cytochrome P450 activity compared to the other trials. These hepatic organoids were successfully engrafted in an acute liver injury mouse model and produced albumin after implantation. These results demonstrated the significant impact of the dissolved oxygen concentration on hPSC hepatic differentiation fate and differentiation efficacy that should be considered ascritical translational aspect of established scalable liver organoid generation protocols for potential clinical and drug discovery applications.

Gene Expression Patterns of Royan Human Embryonic Stem Cells Correlate with Their Propensity and Culture Systems

OBJECTIVE

Human embryonic stem cells (hESCs) have the potential to give rise to all types of cells in the human body when appropriately induced to differentiate. Stem cells can differentiate spontaneously into the three-germ layer derivatives by embryoid bodies (EBs) formation. However, the two-dimensional (2D) adherent culture of hESCs under defined conditions is commonly used for directed differentiation toward a specific type of mature cells. In this study, we aimed to determine the propensity of the Royan hESC lines based on comparison of expression levels of 46 lineage specific markers.

MATERIALS AND METHODS

In this experimental study, we have compared the expression of lineage-specific markers in hESC lines during EB versus adherent-based spontaneous differentiation. We used quantitative real-time polymerase chain reaction (qRT-PCR) to assess expressions of 46 lineage-specific markers in 4 hESC lines, Royan H1 (RH1), RH2, RH5, and RH6, during spontaneous differentiation in both EB and adherent cultures at 0, 10, and 30 days after initiation of differentiation.

RESULTS

Based on qRT-PCR data analysis, the liver and neuronal markers had higher expression levels in EBs, whereas skin-specific markers expressed at higher levels in the adherent culture. The results showed differential expression patterns of some lineage-specific markers in EBs compared with the adherent cultures.

CONCLUSION

According to these results, possibly the spontaneous differentiation technique could be a useful method for optimization of culture conditions to differentiate stem cells into specific cell types such ectoderm, neuron, endoderm and hepatocyte. This approach might prove beneficial for further work on maximizing the efficiency of directed differentiation and development of novel differentiation protocols.

Advances in ex vivo models and lab-on-a-chip devices for neural tissue engineering

The technologies related to ex vivo models and lab-on-a-chip devices for studying the regeneration of brain, spinal cord, and peripheral nerve tissues are essential tools for neural tissue engineering and regenerative medicine research. The need for ex vivo systems, lab-on-a-chip technologies and disease models for neural tissue engineering applications are emerging to overcome the shortages and drawbacks of traditional in vitro systems and animal models. Ex vivo models have evolved from traditional 2D cell culture models to 3D tissue-engineered scaffold systems, bioreactors, and recently organoid test beds. In addition to ex vivo model systems, we discuss lab-on-a-chip devices and technologies specifically for neural tissue engineering applications. Finally, we review current commercial products that mimic diseased and normal neural tissues, and discuss the future directions in this field.

A Field-Portable Cell Analyzer without a Microscope and Reagents

This paper demonstrates a commercial-level field-portable lens-free cell analyzer called the NaviCell (No-stain and Automated Versatile Innovative cell analyzer) capable of automatically analyzing cell count and viability without employing an optical microscope and reagents. Based on the lens-free shadow imaging technique, the NaviCell (162 × 135 × 138 mm³ and 1.02 kg) has the advantage of providing analysis results with improved standard deviation between measurement results, owing to its large field of view. Importantly, the cell counting and viability testing can be analyzed without the use of any reagent, thereby simplifying the measurement procedure and reducing potential errors during sample preparation. In this study, the performance of the NaviCell for cell counting and viability testing was demonstrated using 13 and six cell lines, respectively. Based on the results of the hemocytometer (de facto standard), the error rate (ER) and coefficient of variation (CV) of the NaviCell are approximately 3.27 and 2.16 times better than the commercial cell counter, respectively. The cell viability testing of the NaviCell also showed an ER and CV performance improvement of 5.09 and 1.8 times, respectively, demonstrating sufficient potential in the field of cell analysis.

Allogeneic cell therapy manufacturing: process development technologies and facility design options

INTRODUCTION

Currently, promising outcomes from clinical trials of allogeneic cells, especially allogeneic mesenchymal stromal cells, fibroblasts, keratinocytes, and human cardiac stem cells, have encouraged research institutions, small and medium enterprises (SMEs), and big pharmaceutical companies to invest and focus on developing allogeneic cell therapy products. Commercial and large-scale production of allogeneic cell therapy products requires unique capabilities to develop technologies that generate safe and effective allogeneic cells/cell lines and their fully characterized master/working banks. In addition, it is necessary to design robust upstream and downstream manufacturing processes, and establish integrated, well-designed manufacturing facilities to produce high quality affordable products in accordance with current GMP regulations for the production of cell therapy products. Areas covered: The authors highlight: the recent advances in the development of allogeneic products, the available options to develop robust manufacturing processes, and facility design considerations. Expert opinion: Currently, there are multiple challenges in development of allogeneic cell therapy products. Indeed, the field is still in its infancy; with technologies and regulations still under development, as is our understanding of the mechanisms of action in the body and their interaction with the host immune system. Their characterization and testing is also an emerging and very complex area.