Extracellular vesicle biogenesis of three-dimensional human pluripotent stem cells in a novel Vertical-Wheel bioreactor

A roadmap towards manufacturing extracellular vesicles for cardiac repair

For the past two decades researchers have linked extracellular vesicle (EV)-mediated mechanisms to various physiological and pathological processes in the heart, such as immune response regulation, fibrosis, angiogenesis, and the survival and growth of cardiomyocytes. Although use of EVs has gathered momentum in the cardiac field, several obstacles in both upstream and downstream processes during EV manufacture need to be addressed before clinical success can be achieved. Low EV yields obtained in small-scale cultures deter clinical translation, as mass production is a prerequisite to meet therapeutic doses. Moreover, standardizing EV manufacture is critical given the inherent heterogeneity of EVs and the constraints of current isolation techniques. In this review, we discuss the critical steps for the large-scale manufacturing of high-potency EVs for cardiac therapies.

Viscoelasticity of Hyaluronic Acid Hydrogels Regulates Human Pluripotent Stem Cell-derived Spinal Cord Organoid Patterning and Vascularization

Recently, it has been recognized that natural extracellular matrix (ECM) and tissues are viscoelastic, while only elastic properties have been investigated in the past. How the viscoelastic matrix regulates stem cell patterning is critical for cell-ECM mechano-transduction. Here, this study fabricated different methacrylated hyaluronic acid (HA) hydrogels using covalent cross-linking, consisting of two gels with similar elasticity (stiffness) but different viscoelasticity, and two gels with similar viscoelasticity but different elasticity (stiffness). Meanwhile, a second set of dual network hydrogels are fabricated containing both covalent and coordinated cross-links. Human spinal cord organoid (hSCO) patterning in HA hydrogels and co-culture with isogenic human blood vessel organoids (hBVOs) are investigated. The viscoelastic hydrogels promote regional hSCO patterning compared to the elastic hydrogels. More viscoelastic hydrogels can promote dorsal marker expression, while softer hydrogels result in higher interneuron marker expression. The effects of viscoelastic properties of the hydrogels become more dominant than the stiffness effects in the co-culture of hSCOs and hBVOs. In addition, more viscoelastic hydrogels can lead to more Yes-associated protein nuclear translocation, revealing the mechanism of cell-ECM mechano-transduction. This research provides insights into viscoelastic behaviors of the hydrogels during human organoid patterning with ECM-mimicking in vitro microenvironments for applications in regenerative medicine.

Profiling biomanufactured extracellular vesicles of human forebrain spheroids in a Vertical-Wheel Bioreactor

Extracellular vesicles (EVs) secreted by human brain cells have great potential as cell-free therapies in various diseases, including stroke. However, because of the significant amount of EVs needed in preclinical and clinical trials, EV application is still challenging. Vertical-Wheel Bioreactors (VWBRs) have designed features that allow for scaling up the generation of human forebrain spheroid EVs under low shear stress. In this study, EV secretion by human forebrain spheroids derived from induced pluripotent stem cells as 3D aggregates and on Synthemax II microcarriers in VWBRs were investigated with static aggregate culture as a control. The spheroids were characterized by metabolite and transcriptome analysis. The isolated EVs were characterized by nanoparticle tracking analysis, electron microscopy, and Western blot. The EV cargo was analyzed using proteomics and miRNA sequencing. The in vitro functional assays of an oxygen and glucose-deprived stroke model were conducted. Proof of concept in vivo study was performed, too. Human forebrain spheroid differentiated on microcarriers showed a higher growth rate than 3D aggregates. Microcarrier culture had lower glucose consumption per million cells and lower glycolysis gene expression but higher EV biogenesis genes. EVs from the three culture conditions showed no differences in size, but the yields from high to low were microcarrier cultures, dynamic aggregates, and static aggregates. The cargo is enriched with proteins (proteomics) and miRNAs (miRNA-seq), promoting axon guidance, reducing apoptosis, scavenging reactive oxygen species, and regulating immune responses. Human forebrain spheroid EVs demonstrated the ability to improve recovery in an in vitro stroke model and in vivo. Human forebrain spheroid differentiation in VWBR significantly increased the EV yields (up to 240-750 fold) and EV biogenesis compared to static differentiation due to the dynamic microenvironment and metabolism change. The biomanufactured EVs from VWBRs have exosomal characteristics and more therapeutic cargo and are functional in in vitro assays, which paves the way for future in vivo stroke studies.

Exploring the potential of in vitro extracellular vesicle generation in reproductive biology

The interest in the growing field of extracellular vesicle (EV) research highlights their significance in intercellular signalling and the selective transfer of biological information between donor and recipient cells. EV studies have provided valuable insights into intercellular communication mechanisms, signal identification and their involvement in disease states, offering potential avenues for manipulating pathological conditions, detecting biomarkers and developing drug-delivery systems. While our understanding of EV functions in reproductive tissues has significantly progressed, exploring their potential as biomarkers for infertility, therapeutic interventions and enhancements in assisted reproductive technologies remains to be investigated. This knowledge gap stems partly from the difficulties associated with large-scale EV production relevant to clinical applications. Most existing studies on EV production rely on conventional 2D cell culture systems, characterized by suboptimal EV yields and a failure to replicate in vivo conditions. This results in the generation of EVs that differ from their in vivo counterparts. Hence, this review firstly delves into the importance of EVs in reproduction to then expand on current techniques for in vitro EV production, specifically examining diverse methods of culture and the potential of bioengineering technologies to establish innovative systems for enhanced EV production.

Systems Approaches to Cell Culture-Derived Extracellular Vesicles for Acute Kidney Injury Therapy: Prospects and Challenges

Acute kidney injury (AKI) is a heterogeneous syndrome, comprising diverse etiologies of kidney insults that result in high mortality and morbidity if not well managed. Although great efforts have been made to investigate underlying pathogenic mechanisms of AKI, there are limited therapeutic strategies available. Extracellular vesicles (EV) are membrane-bound vesicles secreted by various cell types, which can serve as cell-free therapy through transfer of bioactive molecules. In this review, we first overview the AKI syndrome and EV biology, with a particular focus on the technical aspects and therapeutic application of cell culture-derived EVs. Second, we illustrate how multi-omic approaches to EV miRNA, protein, and genomic cargo analysis can yield new insights into their mechanisms of action and address unresolved questions in the field. We then summarize major experimental evidence regarding the therapeutic potential of EVs in AKI, which we subdivide into stem cell and non-stem cell-derived EVs. Finally, we highlight the challenges and opportunities related to the clinical translation of animal studies into human patients.