Stem cell derived exosomes: Emerging cell-free therapeutics for neurodegenerative disorders

Table 1 Components of exosomes structure

Serial number	Structure	Compositions	Functions
1	Cytoskeletal elements	Actin, tubulin, cofilin, talin, vimentin	Structural support, vesicle formation, transport
2	Lysosomal protein	Lamp2b	Degradation, protein sorting, membrane trafficking
3	Exosome membrane	Sphingomyelin, phosphatidylserine, cholesterol, and ceramides	Encloses exosomal content, interacts with target cells
4	Tetraspanin family	CD63, CD9, CD37, CD81, and CD82	Membrane organization, protein interactions, cell adhesion
5	HSPs	HSP70, HSP90, HSP20, HSP27, HSP60, HSC70	Protein folding, stress response, cell protection
6	Intercellular adhesion molecule	ICAM-1, integrins, p-selectin, lactadhesion	Cell-cell interactions, signaling, immune responses
7	Fusion and membrane transport proteins	GTPases, flotillin, annexins, Rabs, dynamin, syntaxin	Vesicle fusion, content release, membrane trafficking
8	Transmembrane proteins	CD13, LAM1/2, PGRL	Signaling, cell-cell interactions, membrane anchoring
9	Immuno-regulator molecules	CD80, CD86	Modulate immune responses, tolerance, inflammation
10	Antigen presentation	MHC class I and II molecules	Activate immune cells, antigen display
11	Nucleic acids	mRNA, DNA, and non-coding RNAs	Genetic information transfer, gene regulation
12	Enzymes	Glycosidases, GAPDH, nitric oxide synthase, catalase, phosphatases, lipases, pgk1, ATPase	Catalyze biochemical reactions, metabolic processes
13	Growth factors and cytokines	TRAIL, TNF-α, TGF-β	Cell growth, differentiation, signaling
14	ESCRT-dependent exosomal biogenesis	ALIX, TSG101, clathrin	Exosome formation, sorting, release

Lamp: Lysosomal associated membrane protein; CD: Cluster of differentiation; HSP: Heat shock proteins; HSC70: Heat shock cognate protein 70; ICAM: Intercellular adhesion molecule; MHC: Major histocompatibility complex; GAPDH: Glyceraldehyde-3-phosphate dehydrogenase; pgk1: Phosphoglycerate kinase 1; TRAIL: Tumor necrosis factor-related apoptosis-inducing ligand; TNF-α: Tumor necrosis factor α; TGF-β: Transforming growth factor β; ALIX: Apoptosis-linked gene 2-interacting protein X; TSG101: Tumor susceptibility gene 101.