Toward Standardization of Mesenchymal Stromal Cell‐Derived Extracellular Vesicles for Therapeutic Use: A Call for Action

Abstract

Extracellular vesicles (EVs), which include a variety of nano‐sized membrane‐encapsulated particles, are released to the extracellular microenvironment by the vast majority of cells and carry lipids, proteins, mRNA, and miRNA or non‐coding RNA. Increasing evidence suggests the great versatility and potential of EV‐based applications in humans. In this issue, van Balkom et al. explore and compare the reported proteomic signature of mesenchymal stromal cell (MSC)‐derived small EVs. In particular, their paper offers a valuable approach and point of view on MSC‐EV manufacturing and therapeutic potential. Briefly, van Balkom et al. aimed to identify a common protein signature that may be useful in ensuring the homogeneity of therapeutic MSC‐EVs. In addition to excessive variability in EV‐producing cell sources and culture conditions, the harvesting time for the EV‐containing conditioned medium, and EV isolation procedure, the authors found a specific protein signature from the publicly available MSC‐EVs proteome. In light of their findings and those from the plentiful studies published in this continuously growing area of research, potential focus areas and issues are outlined for the more rational design and optimization of MSC‐EV production and potency for therapeutics.

Osteogenic commitment of Wharton’s jelly mesenchymal stromal cells: mechanisms and implications for bioprocess development and clinical application

“…Increasing evidence have shown that nanosized, membrane-encapsulated EVs are one of the most active MSCs' secreted factors [25]. Indeed, EVs can serve as powerful tools for cell-free therapy due to precise multifunctional molecular cargoes [57,58]. However, significant differences have been described in the content of EV purified from MSC cultures of different origins.…”

Functional assays to assess the therapeutic potential of extracellular vesicles

“…They have also introduced challenges in comparing data between different studies. Besides harmonization of EV nomenclature (Witwer & Théry, 2019) and characterization (Théry et al., 2018), the need for standardization of functional assays has become an important issue (Geeurickx et al., 2019; Roura & Bayes‐Genis, 2019; Witwer et al., 2019). For therapeutic EVs, potency assays are needed to fill this gap.…”

“…Despite demonstration of the preclinical and clinical positive effects of EVs, broad translation is still limited due to several hurdles (Witwer et al., 2019), including (1) heterogeneity in EV‐preparation procedures, (2) absence of uniform quality control (QC) criteria, and (3) necessity of alignment with national and international regulatory guidelines to reach clinical testing (Lener et al., 2015; Reiner et al., 2017). A recent ‘Call for Action’ underscored that an integrated international collaborative approach is required for successful translation of EVs to clinical application (Roura & Bayes‐Genis, 2019). In light of this call, we address the assessment of the quality, efficacy and therapeutic dose of EVs, and provide arguments for the use of harmonized assays to describe these aspects.…”

A Chemically Defined, Xeno- and Blood-Free Culture Medium Sustains Increased Production of Small Extracellular Vesicles From Mesenchymal Stem Cells

“…In order to reduce time and resources needed to produce a therapeutic dose, new compliant media are required as the central part of the GMP-compliant manufacturing strategy for increased and reproducible sEV production. A defined and consistent protocol devoid from contaminant and oxidative stress agents will fulfill the quality-control requirements necessary for batch releases, regulation fulfillment, and the taking of sEV’s advantages, such as low toxicity, biocompatibility, biological permeability/distribution, ease of handling and storage, and the possibility of loading them in order to use them as drug-delivery vehicles ( Roura and Bayes-Genis, 2019 ; Zipkin, 2019 ).…”