Extracellular vesicle therapeutics from plasma and adipose tissue

Abstract

Extracellular vesicles (EVs) are cell-released lipid-bilayer nanoparticles that contain biologically active cargo involved in physiological and pathological intercellular communication. In recent years, the therapeutic potential of EVs has been explored in various disease models. In particular, mesenchymal stromal cell-derived EVs have been shown to exert anti-inflammatory, anti-oxidant, anti-apoptotic, and pro-angiogenic properties in cardiovascular, metabolic and orthopedic conditions. However, a major drawback of EV-based therapeutics is scale-up issues due to extensive cell culture requirements and inefficient isolation protocols. An emerging alternative approach to time-consuming and costly cell culture expansion is to obtain therapeutic EVs directly from the body, for example, from plasma and adipose tissue. This review discusses isolation methods and therapeutic applications of plasma and adipose tissue-derived EVs, highlighting advantages and disadvantages compared to cell culture-derived ones.

Keywords: Adipose tissue; extracellular vesicles; isolation methods; plasma; therapeutic.

Figure 1:

Schematic representation of common extracellular vesicle (EV) isolation methods. Low (+), medium (++), high (+++). CE, centrifuge; DG, density gradient; SEC, size-exclusion chromatography; TFF, tangential flow filtration; UC, ultracentrifugation.

Figure 2:

Example of a platelet-rich plasma (PRP) preparation method and comparison of growth factors in platelet-depleted PRP and PRP-derived EVs [52]. bFGF, basic fibroblast growth factor; EVs, extracellular vesicles; PDGF-BB, platelet-derived growth factor BB; TGF-β, transforming growth factor-β, VEGF, vascular endothelial growth factor.

Figure 3:

(A) Schematic of chronic cutaneous wounds in a diabetic rat model described in [52]. Diabetes was induced with intraperitoneal administration of streptozotocin (STZ), with glucose levels > 250 mg/dL considered indicative of diabetes. Skin was excised from the back and wound beds were untreated (control) or treated with sodium alginate hydrogel (SAH), activated platelet-depleted PRP in SAH, or PRP-EVs in SAH. (B) Wound repair photos at day 0 (left) and day 14 (right) after skin excision. Scale bar, 1 cm. (C) Three-dimensional reconstructed images of blood vessels in the wounds obtained by micro computed tomography 14 days after skin excision. (D) Hematoxylin and eosin-stained sections of wounds 14 days after skin excision. Adapted with permission from [52].

Figure 4:

Characteristics of adipose-derived mesenchymal sromal cell (AMSC) EVs and lipoaspirate nanoparticles (Lipo-NPs) isolated by TFF. Lipo-NPs are faster to obtain (few hours) and have higher yields (30-fold) compared to AMSCs-EVs (take one month to obtain). AMSC-EVs and Lipo-NP have similar size and shape (spherical), but the former has higher protein levels and lower glycerolipid and microRNA (miRNA) levels [21]. SEC-based processing of Lipo-NPs can remove lipoproteins (accounting for approximately 53% NPs isolated by TFF). Cryogenic transmission electron microscopy images are reproduced with permission from [21].