3D Spheroid Cultures of Stem Cells and Exosome Applications for Cartilage Repair

Abstract

Cartilage is a connective tissue that constitutes the structure of the body and consists of chondrocytes that produce considerable collagenous extracellular matrix and plentiful ground substances, such as proteoglycan and elastin fibers. Self-repair is difficult when the cartilage is damaged because of insufficient blood supply, low cellularity, and limited progenitor cell numbers. Therefore, three-dimensional (3D) culture systems, including pellet culture, hanging droplets, liquid overlays, self-injury, and spinner culture, have attracted attention. In particular, 3D spheroid culture strategies can enhance the yield of exosome production of mesenchymal stem cells (MSCs) when compared to two-dimensional culture, and can improve cellular restorative function by enhancing the paracrine effects of MSCs. Exosomes are membrane-bound extracellular vesicles, which are intercellular communication systems that carry RNAs and proteins. Information transfer affects the phenotype of recipient cells. MSC-derived exosomes can facilitate cartilage repair by promoting chondrogenic differentiation and proliferation. In this article, we reviewed recent major advances in the application of 3D culture techniques, cartilage regeneration with stem cells using 3D spheroid culture system, the effect of exosomes on chondrogenic differentiation, and chondrogenic-specific markers related to stem cell derived exosomes. Furthermore, the utilization of MSC-derived exosomes to enhance chondrogenic differentiation for osteoarthritis is discussed. If more mechanistic studies at the molecular level are conducted, MSC-spheroid-derived exosomes will supply a better therapeutic option to improve osteoarthritis.

Different priming strategies improve distinct therapeutic capabilities of mesenchymal stromal/stem cells: Potential implications for their clinical use

“…In particular, EXOs derived from MSC 3D cultures have been shown to have higher yields and enhanced activity. Indeed, compared with 2D cultures, EXOs isolated from CM of MSC spheroids were able to inhibit T cell proliferation and stimulate angiogenesis in vitro [ 44 ], as well as attenuate inflammation and periodontitis in vivo [ 132 ], and stimulate tissue regeneration in both in vitro and in vivo models[ 133 ].…”

Production and Utility of Extracellular Vesicles with 3D Culture Methods

“…Another method of forming spheroids is placing cells in a spinner flask. This will agitate the cells to form spheroids, allowing for larger scale production [ 126 ]. Magnetic levitation involves labelling cells with magnetic nanoparticles and subsequently applying an external magnetic field, encouraging cells to self-assemble into multicellular spheroids.…”

Optimization strategies of mesenchymal stem cell-based therapy for acute kidney injury

“…A more recently developed technique for spheroid culture is magnetic levitation. The resultant spheroids can be easily manipulated and tracked via this means [ 130 ]. In general, with the help of 3D spheroid culture, MSCs could better maintain their distinct phenotypic and functional properties as well as secrete higher levels of cytokines or other factors, which as a result, improves the therapeutic effects of MSCs for AKI [ 131 , 132 ].…”