Various Three-Dimensional Culture Methods and Cell Types for Exosome Production

Spherical Shell Bioprinting to Produce Uniform Spheroids with Controlled Sizes

Conventional cell spheroid production methods are largely manual, leading to variations in size and shape that compromise consistency and reliability for use in cell-based therapeutic applications. To enhance spheroid production, a spherical shell bioprinting system was implemented, enabling the high-throughput generation of uniform cell spheroids with precisely controlled sizes. The system encapsulates cells within thin alginate hydrogel shells formed through bioprinting and ion crosslinking reactions. Alginate-calcium ion crosslinking created alginate shells that contained gelatin-based bioinks with embedded cells, facilitating spontaneous cell aggregation within the shells and eliminating the need for plastic wells. By adjusting cell concentrations in the alginate-gelatin bioink, we achieved precise control over spheroid size, maintaining a sphericity above 0.94 and size deviations within ±10 µm. This method has been successfully applied to various cell types including cancer cells, fibroblasts, chondrocytes, and epithelial cells, demonstrating its versatility. This scalable approach enhances the reliability of cell therapy and drug screening, offering a robust platform for future biomedical applications.

Spheroid-Exosome-Based Bioprinting Technology in Regenerative Medicine

Since the discovery that exosomes can exchange genes, their potential use as tools for tissue regeneration, disease diagnosis, and therapeutic applications has drawn significant attention. Emerging three-dimensional (3D) printing technologies, such as bioprinting, which allows the printing of cells, proteins, DNA, and other biological materials, have demonstrated the potential to create complex body tissues or personalized 3D models. The use of 3D spheroids in bioprinting facilitates volumetric tissue reconstruction and accelerates tissue regeneration via exosome secretion. In this review, we discussed a convergence approach between two promising technologies for bioprinting and exosomes in regenerative medicine. Among the various 3D cell culture methods used for exosome production, we focused on spheroids, which are suitable for mass production by bioprinting. We then summarized the research results on cases of bioprinting applications using the spheroids and exosomes produced. If a large number of spheroids can be supplied through bioprinting, the spheroid-exosome-based bioprinting technology will provide new possibilities for application in tissue regeneration, disease diagnosis, and treatment.

Distribution and Incorporation of Extracellular Vesicles into Chondrocytes and Synoviocytes

Osteoarthritis (OA) is a chronic disease affecting over 500 million people worldwide. As the population ages and obesity rates rise, the societal burden of OA is increasing. Pro-inflammatory cytokines, particularly interleukin-1β, are implicated in the pathogenesis of OA. Recent studies suggest that crosstalk between cartilage and synovium contributes to OA development, but the mechanisms remain unclear. Extracellular vesicles (EVs) were purified from cell culture-conditioned medium via ultracentrifugation and confirmed using transmission electron microscopy, nanoparticle tracking analysis, and western blotting. We demonstrated that EVs were taken up by human synoviocytes and chondrocytes in vitro, while in vivo experiments revealed that fluorescent-labelled EVs injected into mouse joints were incorporated into chondrocytes and synoviocytes. EV uptake was significantly inhibited by dynamin-mediated endocytosis inhibitors, indicating that endocytosis plays a major role in this process. Additionally, co-culture experiments with HEK-293 cells expressing red fluorescent protein (RFP)-tagged CD9 and the chondrocytic cell line OUMS-27 confirmed the transfer of RFP-positive EVs across a 600-nm but not a 30-nm filter. These findings suggest that EVs from chondrocytes are released into joint fluid and taken up by cells within the cartilage, potentially facilitating communication between cartilage and synovium. The results underscore the importance of EVs in OA pathophysiology.

From bench to bedside: The promising value of exosomes in precision medicine for CNS tumors

Exosomes are naturally present extracellular vesicles (EVs) released into the surrounding body fluids upon the fusion of polycystic and plasma membranes. They facilitate intercellular communication by transporting DNA, mRNA, microRNA, long non-coding RNA, circular RNA, proteins, lipids, and nucleic acids. They contribute to the onset and progression of Central Nervous System (CNS) tumors. In addition, they can be used as biomarkers of tumor proliferation, migration, and blood vessel formation, thereby affecting the Tumor Microenvironment (TME). This paper reviews the recent advancements in the diagnosis and treatment of exosomes in various CNS tumors, the promise and challenges of exosomes as natural carriers of CNS tumors, and the therapeutic prospects of exosomes in CNS tumors. Furthermore, we hope this research can contribute to the development of more targeted and effective treatments for central nervous system tumors.

The Influence of Tacrolimus on Cellular Morphology, Cellular Viability, Osteogenic Differentiation, and mRNA Expression within Stem Cell Spheroids

Background and Objectives: Tacrolimus is a macrolide lactone compound derived from the bacterium Streptomyces tsukubensis, widely known as an immunosuppressant. In basic research, the effects of tacrolimus on osteogenic differentiation have been tested using mesenchymal stem cells. In this study, tacrolimus's effects on the cellular survival and osteogenic differentiation of stem cell spheroids were investigated. Materials and Methods: Concave microwells were used to form stem cell spheroids in the presence of tacrolimus at final concentrations of 0 μg/mL, 0.1 μg/mL, 1 μg/mL, 10 μg/mL, and 100 μg/mL. A microscope was used to test cellular vitality qualitatively, and an assay kit based on water-soluble tetrazolium salt was used to measure cellular viability quantitatively. Alkaline phosphatase activity and an anthraquinone dye test for measuring calcium deposits were used to assess osteogenic differentiation. To assess the expression of osteogenic differentiation, a quantitative polymerase chain reaction, Western blot, and RNA sequencing were performed. Results: Spheroids across all concentrations maintained a relatively uniform and spherical shape. Cell viability assay indicated that tacrolimus, up to a concentration of 100 μg/mL, did not significantly impair cell viability within spheroids cultured in osteogenic media. The increase in calcium deposition, particularly at lower concentrations of tacrolimus, points toward an enhancement in osteogenic differentiation. There was an increase in COL1A1 expression across all tacrolimus concentrations, as evidenced by the elevated mean and median values, which may indicate enhanced osteogenic activity. Conclusions: This study showed that tacrolimus does not significantly impact the viability of stem cell spheroids in osteogenic media, even at high concentrations. It also suggests that tacrolimus may enhance osteogenic differentiation, as indicated by increased calcium deposition and COL1A1 expression. These findings advance our understanding of tacrolimus's potential roles in tissue repair, regeneration, and stem cell-based therapeutic applications.

Recent advances in extracellular vesicle engineering and its applications to regenerative medicine

Extracellular vesicles (EVs) are nanosized particles that are released from cells and reflect the characteristics of the mother cell. Recently, the EVs have been used in several types of studies across many different fields. In the field of EV research, multiple cell culture and EV isolation techniques have been highlighted in importance. Various strategies, including exclusive component culture media, three-dimensional (3D) cultures, and hypoxic conditions, have been proposed for the cell culture to control function of the EVs. Ultracentrifugation, ultrafiltration, precipitation, and tangential flow filtration (TFF) have been utilized for EV isolation. Although isolated EVs have their own functionalities, several researchers are trying to functionalize EVs by applying various engineering approaches. Gene editing, exogenous, endogenous, and hybridization methods are the four well-known types of EV functionalization strategies. EV engineered through these processes has been applied in the field of regenerative medicine, including kidney diseases, osteoarthritis, rheumatoid arthritis, nervous system-related diseases, and others. In this review, it was focused on engineering approaches for EV functionalization and their applications in regenerative medicine.

Extracellular Vesicles Derived From 3D Cultured Antler Stem Cells Serve as a New Drug Vehicle in Osteosarcoma Treatment

Extracellular vesicles (EVs) from antler reserve mesenchymal (RM) cells play an important role in the paracrine regulation during rapid growth of antler without forming a tumor; therefore, RM-EVs become novel materials for anti-tumor studies, such as osteosarcoma treatment. However, the problem of low production of RM-EVs in traditional 2D culture limits its mechanism research and application. In this study, we established an optimal 3D culture system for antler RM cells to produce EVs (3D-RM-EVs). Morphology and property of harvested 3D-RM-EVs were normal compared with EVs from conventional 2D culture, and the miRNA profile in them was basically the same through transcriptome sequencing analysis. Based on the same number of RM cells, the volume of the culture medium collected by 3D cultural system concentrated nearly 30 times, making it more convenient for subsequent purification. In addition, EVs were harvested 30 times in 3D cultural system, greatly increasing the total amount of EVs (harvested a total of 2-3 times in 2D culture). Although 3D-RM-EVs had a limited inhibitory effect on the proliferation of K7M2 cells, the inhibition effect of 3D-RM-EVs loaded drugs (Ifosfamide + Etoposide) were more significant than that of positive drug group alone (P < 0.05). Furthermore, in vivo studies showed that 3D-RM-EVs loaded drugs (Ifosfamide + Etoposide) had the most significant tumor inhibition effect, with decreased tumor size, and could slow down body weight loss compared with Ifosfamide + Etoposide (IFO + ET) group. These results demonstrated that 3D-RM-EVs were efficiently prepared from antler RM cells and were effective as drug vehicles for the treatment of osteosarcoma.