Mesenchymal stem cell-derived exosomes: Toward cell-free therapeutic strategies in regenerative medicine

Table 1 Characteristics of different types of extracellular vesicles

Feature	Exosomes	Microvesicles	Apoptotic bodies
Diameter and shape	30-100 nm, cup shape	100-1000 nm, irregular shape	1-5 μm, heterogeneous shape
Sucrose gradient	1.13-1.19 g/mL	1.04-1.07 g/mL	1.18-1.28 g/mL
Sedimentation	100000 g	10000 g	16000 g
Protein markers	CD63, CD81, CD9, Alix, Tsg101, annexins, heat-shock proteins	Integrins, selectins, CD40, flotillins, CD40, ARF6, VCAMP3	TSP, C3b, histones
Origin	Fusion of multivesicular bodies with cell membrane	Outward budding of cell membrane	Outward budding of apoptotic cell membrane
Lipid content	Ceramide	Phosphatidylserine	Phosphatidylserine
Nucleic acids	DNA, mRNA, miRNA, non-coding RNA	DNA, mRNA, miRNA, non-coding RNA	Fragmented DNA, mRNA, miRNA, non-coding RNA

Table 2 Summary of exosome isolation methods

Methods	Mechanism	Advantages	Disadvantages
Ultracentrifugation	Physical method	A golden standard; low cost; a wide range of volumes	Low yield; low purity; time-consuming
Membrane filtration	Physical method using filters	Simple; fast; high yield; keeps exosomes intact	Low purity; deformation of exosomes
Precipitation	Physical/chemical method	High yield; easy; high recoveries	Low purity; contaminants
Size exclusion chromatography	Use columns packed with pore beads	High yield; reduces exosome aggregation; keeps exosomes intact	A small number of bands; time-consuming
Immunoaffinity capture technology	Magnetic beads bound to specific antibodies	High yield; high purity; specialty	Time-consuming; high cost

Table 3 Clinical studies with mesenchymal stem cell-derived exosomes

Study title	Disease	Intervention	Phase	NCT
Allogenic mesenchymal stem cell derived exosome in patients with acute ischemic stroke	Cerebrovascular disorders	Biological: Exosome	Completed	NCT03384433
A pilot clinical study on inhalation of mesenchymal stem cells exosomes treating severe novel coronavirus pneumonia	Coronavirus	Biological: MSCs-derived exosomes	Phase 1	NCT04276987
Effect of microvesicles and exosomes therapy on β-cell mass in type I diabetes mellitus (T1DM)	Diabetes mellitus type 1	Biological: MSC Exosomes	Phase 2, Phase 3	NCT02138331
iExosomes in treating participants with metastatic pancreas cancer with KrasG12D mutation	Metastatic pancreatic adenocarcinoma	Drug: Mesenchymal stromal cells-derived exosomes with KRAS G12D siRNA	Phase 1	NCT03608631
Effect of UMSCs Derived exosomes on dry eye in patients with cGVHD	Dry eye	Drug: Umbilical mesenchymal stem cells derived exosomes	Phase 1, Phase 2	NCT04213248
Evaluation of adipose derived stem cells exo.in treatment of periodontitis	Periodontitis	Biological: Adipose derived stem cells exosomes	Early phase 1	NCT04270006
A tolerance clinical study on aerosol inhalation of mesenchymal stem cells exosomes in healthy volunteers	Healthy	Biological: Low level of MSCs-Exo Biological: High level of MSCs-Exo	Phase 1	NCT04313647
MSC-Exos promote healing of MHs	Macular holes	Biological: Exosomes derived from mesenchymal stem cells (MSC-Exo)	Early Phase 1	NCT03437759