Page 38 - Mesenchymal Stem Cell-Derived Exosomes as an Emerging Paradigm for Regenerative Therapy and Nano-Medicine

Li et al. Stem Cell Research & Therapy (2019) 10:278
https://doi.org/10.1186/s13287-019-1372-0

REVIEW Open Access

Recent advances of exosomes in immune-

mediated eye diseases

*
Na Li, Lu Zhao, Yankai Wei, Vicki L. Ea, Hong Nian and Ruihua Wei *

Encapsulated in a bilayer membrane, exosomes are
Abstract
enriched in various bioactive molecules, including pro-
Exosomes, nanosized extracellular vesicles of 30–150 teins, lipids, RNAs (mRNA, circular RNA, microRNA,
nm, are shed by almost all cell types. Bearing proteins, long noncoding RNA), and DNAs (genomic DNA, cDNA,
lipids, RNAs, and DNAs, exosomes have emerged as and mitochondrial DNA) [7–9]. These molecular compo-
vital biological mediators in cell-to-cell nents are capable of inducing functional responses in re-
communication, affecting a plethora of physiological cipient cells and are extraordinarily variable depending on
and pathological processes. Particularly, mounting the cellular origin and cell exposure context [10–13]. By
evidence indicates that immunologically active transferring these functional molecules between cells, exo-
exosomes can regulate both innate and adaptive somes act as potent mediators in intercellular communi-
immune responses. Herein, we review recent cation and participate in numerous physiological and
advances in the research of exosomes in several pathological processes [14]. Exosomes from both immune
immune-mediated eye diseases, including Sjögren’s cells and non-immune cells exert pivotal roles in the regu-
syndrome (SS) dry eye, corneal allograft rejection, lation of immunity [15] and have been reported to be in-
autoimmune uveitis, and age-related macular volved in the development and treatment of inflammatory
degeneration (AMD). Additionally, we discuss the and autoimmune diseases [16, 17].
potential of exosomes as novel biomarkers and drug The eye, a unique sensory organ of vision, is
delivery vesicles for the diagnosis and treatment of regarded as an immune-privileged site that prevents
eye diseases. immunogenic inflammation [18]. Still, there are sev-
eral inflammatory and immune-mediated diseases
Keywords: Exosomes, Sjögren’s syndrome, Corneal
which involve the anterior or posterior segment of
allograft rejection, Autoimmune uveitis, Age-related
the eye, even in severe cases resulting in sight-threat-
macular degeneration, Biomarkers, Drug delivery
ening conditions, such as Sjögren’s syndrome (SS) dry
eye, corneal allograft rejection, uveitis, and age-related
macular degeneration (AMD) [19–21]. Of these dis-
Introduction eases, the action of immune cells and the expression
Exosomes were first described as 50-nm diameter-sized of pro-inflammatory cytokines and chemokines induce
vesicles secreted from maturing sheep reticulocytes in local inflammatory responses which ultimately cause
the early 1980s [1, 2]. These nanovesicles sparked scien- ocular tissue damage. Although therapeutic strategies
tists’ interest, as they appeared to function from cellular have undergone substantial transformation, there are
garbage disposals to potent intercellular communication still some challenges remaining [22, 23].
mediators. Typically, exosomes are a subtype of extracel- In this review, we highlight and discuss the recent
lular vesicles (EVs) (30–150 nm) secreted by almost all research advances about exosomes in several immune-re-
cell types [3, 4]. They widely exist in numerous bio- lated eye diseases and their potential as biomarkers and
logical fluids including serum, urine, breast milk, tear drug delivery vesicles in the eye.
fluid, vitreous humor, saliva, and aqueous humor, under
both healthy and pathological conditions [5, 6].
Biogenesis and function of exosomes
* Correspondence: nianhong@126.com; rwei@tmu.edu.cn Exosome generation starts with the invagination of the
Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and
School of Optometry, Tianjin Medical University Eye Hospital, No.251 Fukang plasma membrane to form early endosomes. As the early
Road, Nankai District, Tianjin 300384, People’s Republic of China endosomes mature, intraluminal vesicles (ILV) are
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