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Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5403_Библиотеки_им_академика_М_И_Перельмана

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Smart Drug Delivery Systems – Futuristic Window in Cancer Therapy
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secreted by cells. These methods aim to enhance the therapeutic potential of exosomes by incorporating specific drugs, proteins, nucleic acids, or other bioactive molecules.
Freeze-thaw cycling involves subjecting exosome samples to rapid freezing fol­lowed by thawing. This process helps to disrupt the integrity of the exosomes, allow­ing for enhanced cargo loading. During freezing, the exosome membrane becomes more permeable, which facilitates the uptake of therapeutic cargo molecules. Sato et al., demonstrated the utilization of freeze-thaw procedures to manufacture exo­some-mimetic liposomal particles [31]. However, when compared to other methods of drug encapsulation, freeze-thaw cycling can promote exosomal aggregation and is often less successful than sonication or extrusion [24, 29].
Chemical transfection methods have been used to load exosomes with siRNA as shown in several studies [32, 33]. This approach may not be suitable due to a decreased loading efficiency as compared to electroporation. Furthermore, the Lipofectamine 2000 reagent was shown to make micelles, which could have impaired the quality of the exosomal preparation. Altogether, chemical transfection of exosomes is inefficient for loading drugs into exosomes [23]. Transfection of cells can indeed be used as a method for loading therapeutic cargo into exosomes. In this approach, instead of directly loading the cargo into exosomes, the cargo is introduced into the donor cells, which then release the cargo-loaded exosomes [23]. This method involves transfecting the donor cells with the desired therapeutic cargo, typically using transfection reagents or techniques such as electroporation. In a recent study by Katakowski et al., bone marrow stromal cells were utilized to transfect with miR-146b and resulting exosomes from these cells were isolated to treat 9L gliosarcoma cells. The obtained exosomes from transfected cells revealed increased miR-146b expression and has been shown to inhibit glioma development in rat models [34].
. Role of exosomes in tumor microenvironment
The role of exosomes in the tumor microenvironment is a fascinating and rapidly growing field of research [35, 36]. Exosomes are small extracellular vesicles that are released by various cell types, including cancer cells, into the surrounding environ­ment [37]. They play an important role in intercellular communication between cancer cells and their tumor microenvironment, facilitating the exchange of molecu­lar signals and genetic material, and have also been linked to a variety of physiological and pathological processes, including cancer development and progression [35, 38]. The microenvironment, in the context of cancer, refers to the cellular and non-cellu­lar components surrounding the tumor, including stromal cells, immune cells, fibro­blasts, the extracellular matrix, blood vessels, basement membrane, and endothelial cells [38]. These components actively interact with cancer cells and can influence tumor growth, metastasis, and response to therapy. Considering all these factors/ components, there are four primary modes which exosomes from various sources can alter the TME: through facilitating immunological escape, drug resistance, increasing metastasis, and enhancing angiogenesis.
. Exploring the role of exosomes in immune evasion
Exosome-mediated immune evasion occurs when these vesicles are utilized by can­cer cells and pathogens to escape immune surveillance [39, 40]. These entities exploit
Exosome-Based Smart Drug Delivery for Cancer Treatment DOI: http://ITexLi.113744
exosomes to carry specific molecules that suppress the immune system, allowing them
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to evade detection and continue their malignant or infectious activities. The function of T cells can also be inhibited by these exosomes, and there are numerous ways to do this [41]. The activation of T cells’ immune systems to combat cancer cells is inhibited in one approach by the binding of programmed cell death ligand 1 (PDL1) to PD1 receptors on T cell membranes [42]. They also contribute to immune evasion through the transfer of immunosuppressive molecules. Cancer cells and pathogens package molecules such as transforming growth factor-beta (TGF-β), interleukin-10 (IL-10),
and FasL into exosomes [43]. When these exosomes interact with immune cells, they can inhibit the activation and function of T cells, natural killer cells, and dendritic cells, subsequently undermining the immune response. Exosomes also participate in the establishment of an immunosuppressive microenvironment. They can influence the behavior of surrounding cells, including immune cells, by transmitting signals that promote an environment conducive to immune evasion. For instance, tumor-derived exosomes can induce the differentiation of regulatory T cells (Tregs), which suppress immune responses and foster tumor growth [44]. Exosomes associated with tumors have been shown to alter the phenotype of macrophages in multiple malignancies from M1 (tumor resistance, pro-inflammatory) to M2 (tumor promotion, anti-inflamma­tory) [45–48]. As a result, exosomes derived from these altered M2 macrophages can promote migration and invasion further. This was shown in a recent study by Lan
al., who investigated that macrophage-derived exosomes contained high levels of
et miR-21-5p and miR-155-5p, which caused BRG1, a crucial component in colorectal cancer metastasis, to be downregulated [49]. Figure
summarizes these effects.
Furthermore, exosome-mediated immune evasion can dampen the effectiveness
of immunotherapies [43]. Immunotherapeutic strategies aim to enhance the immune system’s ability to recognize and eliminate cancer cells or pathogens [50]. However, exosomes produced by these entities can interfere with this process. They can either directly inhibit immune cells’ activity or carry molecules that counteract the effects of immunotherapy. Understanding this phenomenon is vital for the development of strategies to overcome immune evasion [51]. Researchers are exploring various approaches, including targeting specific molecules carried by exosomes, modulat­ing exosome release, or utilizing exosomes for therapeutic purposes. By unraveling the mechanisms of exosome-mediated immune evasion, scientists hope to optimize immunotherapies and improve the prognosis for patients affected by diseases
Figure 1. Exosome-mediate tumor evasion.
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involving immune evasion mechanisms [43, 52]. Further research in this area prom­ises to enhance our understanding of immune evasion mechanisms and pave the way for innovative therapeutic interventions.
. Understanding how exosomes drive cancer progression
One important role of exosomes in the cancer-associated microenvironment is their ability to promote tumor progression and metastasis. Exosomes released by cancer cells can transfer oncogenic cargo (such as growth factors, cytokines, miRNA proteins, RNA, DNA, and lipids) to recipient cells in the microenvironment, altering their behavior and promoting a pro-tumorigenic state. Exosomes have been shown to promote EMT, stimulate cell growth, and even disrupt the ECM to facilitate invasion and metastasis from the initial site to distant sites in the body [53]. Furthermore, exosomes can confer invasive properties to cancer cells, leading to enhanced metasta­sis. Exosomes released by primary tumor cells can prepare distant sites for metastatic colonization by promoting pre-metastatic niche formation. They achieve this by influencing the extracellular matrix, remodeling, and preparing it for better adher­ence and colonization of metastatic cells. Wang
et al., recently showed that miR­181-5p might be transferred by cancer-associated fibroblast exosomes to breast cancer cells, inhibiting CDX2, and accelerating EMT [25]. Previous studies by Hoshino et al., demonstrated that exosomes could establish at future metastatic locations, and the location of this could be determined in part owing to the combination of integrins situated on the exosomes [54]. Remarkably, a recent study from Yuan et al., suggested that bone metastases were more closely associated with breast cancer exosomes harboring miR-21 than non-metastatic tumors [55]. Moreover, exosomes can carry enzymes that facilitate the degradation of the extracellular matrix, allowing cancer cells to invade surrounding tissues and intravasate into blood or lymphatic vessels, ultimately spreading to distant organs [56]. By modifying the tumor microenviron­ment and enhancing the migratory and invasive abilities of cancer cells, exosomes contribute significantly to cancer progression [57].
Recent research on breast cancer exosomes containing miR-4443, which blocks tis­sue inhibitors of metalloproteinase 2 (TIMP2), suggested that the tumoral ECM may be degraded [58]. This study employed a mouse model to demonstrate that the release of these exosomes promoted metastasis and reduced metastases in vivo as a conse­quence of miR-4443 suppression [58]. Exosomes can carry different biomolecules, such as RNA, miRNA, DNA, and proteins, or which can influence different signaling pathways in other cells, according to numerous recent studies [59]. These may involve transfers between cancer cells and stromal cells or autocrine/paracrine actions on cancer cells [6]. A recent study demonstrated that lymph angiogenesis and enhanced metastasis through lymph nodes were induced by exosomes produced by bladder cells that contained the lncRNA LNMAT2 [60]. Another study revealed that EphA2, a kinase that influences ERK signaling to accelerate cancer growth, was abundant in exosomes isolated from drug-resistant breast cancer cells [60]. Exosomal SOX2 DNA was examined as a potential biomarker of glioblastoma cancer progression [61].
. Exosomes as mediators of drug resistance in cancer
Drug resistance is a critical issue in the field of medicine, affecting the effectiveness of various treatments [62]. One emerging area of research that holds great promise
Exosome-Based Smart Drug Delivery for Cancer Treatment DOI: http://ITexLi.113744
Figure 2.
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Exosome mediated chemo-resistance.
in tackling drug resistance [63]. Exosomes have recently emerged as key media­tors in the development and propagation of drug resistance in cancer and other diseases [64, 65]. Drug resistance is a complex phenomenon characterized by cells becoming less responsive or resistant to the effects of therapeutic drugs (Figure ) [66]. This can occur through various mechanisms, including reduced drug uptake, increased drug efflux, altered drug metabolism, and the activation of cell survival pathways [66]. One-way exosomes contribute to drug resistance by transporting molecules involved in the resistance phenotype. For instance, exosomes secreted by cancer cells can carry multidrug resistance proteins, such as P-glycoprotein, which actively pump chemotherapeutic drugs out of recipient cells, reducing their efficacy [67].
Additionally, exosomes may transfer genetic material, such as microRNAs and circular RNAs, that can alter cellular signaling pathways, leading to drug resistance [68]. Interestingly, exosomes themselves can be influenced by the presence of drugs, further affecting drug resistance. Studies have shown that chemotherapeutic drugs can modify the cargo composition of exosomes, making them more resistant to treatment [69]. This implies that exosomes contribute not only to drug resistance but also adapt to therapy, potentially amplifying resistance mechanisms. Examples of the second approach indicated above have been demonstrated in a variety of cancers. For example, breast cancer cells may directly sequester adriamycin in exosomes to increase resistance [70]. By using UV spectrophotometry, it was demonstrated that adriamycin was localized within the exosomes secreted by drug­resistant cells [70].
. Exosomes as key players in angiogenesis
Several mechanisms have been proposed to explain how exosomes promote angiogenesis [71]. One mechanism involves the direct transfer of pro-angiogenic molecules from exosomes to recipient cells [72]. Exosomes have emerged as critical
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Figure 3. Role of exosome in angiogenesis.
players in tumor angiogenesis [72–75]. For example, exosomal transfer of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and matrix metal­loproteinases (MMPs) can activate endothelial cells, promoting their sprouting and migration towards the site of angiogenesis [71]. Additionally, cancer cell-derived exosomes can influence the behavior of stromal cells in the tumor microenviron­ment, further enhancing angiogenesis and supporting tumor growth [76]. Moreover, exosomes can mediate angiogenesis by altering the expression of specific genes or proteins in recipient cells. Figure  illustrates these effects.
Exosomal cargo, such as microRNAs, can be transferred to endothelial cells and regulate gene expression, thereby modulating angiogenic processes [77]. The transfer of functional microRNAs, which can act as regulators of gene expression, provides an additional layer of complexity to the exosome-mediated regulation of angiogenesis. Understanding the mechanisms by which exosomes promote angiogenesis provides exciting opportunities for developing novel therapeutic strategies aimed at modu­lating angiogenesis in diverse contexts, ranging from tissue regeneration to cancer treatment. Further research in this field holds the potential to revolutionize the field of vascular biology and improve patient outcomes in a variety of diseases.
. Emerging role of exosomal lncRNAs in tumor progression and metastasis
Exosomal long non-coding RNAs (lncRNAs) are important components of the tumor microenvironment [78, 79]. They have been reported to modify a variety of characteristics of the tumor microenvironment in the setting of cancer, includ­ing immune evasion, tumor development, angiogenesis, metastasis, and drug resistance [80]. Additionally, lncRNAs have the potential to be used as diagnostic or prognostic biomarkers in several cancer types [81], and can be extracted from a variety of biofluids, including urine, blood, and saliva offering a non-invasive way to track the progression of diseases. Studies have confirmed that exosomal lncRNAs exhibit differential expression in cancer patients as compared to healthy individuals,
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Exosome-Based Smart Drug Delivery for Cancer Treatment DOI: http://ITexLi.113744
suggesting their potential as non-invasive diagnostic tools. Clinicians may be able
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to identify malignancies at an early stage by evaluating the expression of exosomal lncRNAs, enabling prompt treatment options and improving patient outcomes. One study revealed that PCAT-1, MALAT1, and SPRY4-IT1 were substantially concen­trated in urine samples [82], while pCAT-1 and UbC H19 were elevated in the serum of bladder cancer patients [83, 84].
Patients with prostate cancer had elevated levels of P21 in their urine [85].
Numerous elevated lncRNAs have been identified through plasma analysis as poten­tial biomarkers for various malignancies, including SAP30L-AS1 and SChLAP1 for prostate cancer [79], HOTAIR for breast cancer, the LNCV6 family for colon cancer, SOX2-OT for lung squamous cell carcinoma, and the LNCV6 family for colorectal cancer. Within the cervicovaginal lavage of cervical cancer patients, HOTAIR and MALAT1 were elevated while MEG3 was downregulated [86]. Upregulation of MALAT1 was seen in serum biomarker analysis for epithelial ovarian cancer [87], UEGC1 and HotTip for gastric cancer [88–90] HOTAIR for glioblastoma multiforme [90]. On the other hand, certain exosomal lncRNAs have been found to have tumor­suppressive effects, inhibiting tumor cell proliferation and metastasis. For instance, lncRNA Gas5 has been identified to be downregulated in non-small cell lung cancer patients’ serum, pointing to its potential function as a tumor suppressor [91]. In a previously described CRC animal model, carcinoma-associated fibroblasts (CAFs) were found to enhance stemness and chemoresistance by transferring exosomal H19 lncRNA, which in turn activated the beta-catenin pathway [92]. It has been dem­onstrated that the lncRNA RUNX2-AS1 contained in multiple myeloma exosomes interacts with the transcription factor RUNX2 to reduce the osteogenic potential of mesenchymal stem cells [93]. Under hypoxic conditions, the lncRNA UCA1 found in the exosomes of bladder cancer cells facilitated EMT and altered the tumor microen­vironment [94].
The pro-oncogenic CCAT2, POU3F3, and HOTAIR in glioma cells, as well as
exosomal lncRNAs, have been demonstrated to enhance angiogenic factors and hence promote invasion and metastasis [95–97]. Apoptosis suppression was indi­cated by an increase in Bcl2 expression and a decrease in Bax and caspase 3 [98]. The lncRNA MALAT1, which is derived from exosomes of epithelial ovarian cancer cells, has been identified to promote the pro-angiogenic genes VEGF-A, VEGF-D, IL-8, and angiogenin [87]. Another Study demonstrated that PCAT1 binds to miR-326 to enhance cell proliferation in esophageal squamous cell carcinoma while MALAT1 stimulates cell proliferation in breast cancer and non-small cell lung cancer [99,100]. ZFAS1 stimulates cell cycle, apoptosis, and EMT in gastric cancer [59], whereas UCA1 has the same impact in bladder cancer [94]. By altering the expres­sion of HNRNPK, 91H promotes metastasis in colorectal cancer [101]. H19 competes with miR-141 and turns on the β-catenin pathway, retaining tumor cell stemness and driving drug resistance [92]. RUNX2-AS1, LncRNA H19, FMR1-AS1, and Sox2ot have been examined for their functions in promoting tumor stem cells in various malignancies [92, 93, 102, 103].
Exosomal lncRNA has also been found to be a significant contributor to drug
resistance in several malignancies. For example, UCA1 was the cause of tamoxifen resistance in breast cancer [104], cisplatin resistance in ovarian cancer [105], and cetuximab resistance in metastatic colorectal cancer [106]. For instance, AGAP2-AS1 and SNHG14 have reported trastuzumab resistance in breast cancer [91, 107]. Gefitinib resistance in esophageal squamous cell carcinoma was caused by Part1 [108]. Increased lncRNA SBF2-AS1 activity in glioblastoma has been related to
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temozolomide resistance [68]. Erlotinib and gefitinib resistance in non-small cell lung cancer has been associated with RP11-838N2.4 and H19 [98, 109]. Sunitinib resistance was increased by ARSR in renal cancer [110]. Moreover, exosomal lncRNAs can also modulate the tumor immune response. They can influence the activity and function of various immune cells, such as T cells, natural killer cells, macrophages, and dendritic cells [111]. By regulating immune cell functions, exosomal lncRNAs can impact immune surveillance, immune evasion, and immune suppression within the tumor microenvironment. In a nutshell, exosomal lncRNAs have emerged as important regulators of the tumor microenvironment. Their expression patterns have been linked to tumor aggressiveness, metastasis, and drug resistance. Therefore, exosomal lncRNAs may serve as prognostic indicators and therapeutic targets. Modulating the expression or function of exosomal lncRNAs could potentially interfere with tumor growth, reduce metastatic potential, and sensitize cancer cells to existing therapies.
. Promising role of exosomes in enhancing drug delivery to specific
cellular targets
Exosomes are being extensively explored for targeted delivery in cancer treatment. They offer several advantages in this context. One of the key benefits is their ability to specifically target cancer cells, reducing off-target effects and enhancing the effec­tiveness of therapy. Researchers have been able to modify the surface of exosomes to ensure their uptake by cancer cells. By loading these engineered exosomes with therapeutic agents such as drugs, siRNAs, or gene-editing tools, they can deliver the cargo directly to the tumor site. This targeted delivery enables the potent anticancer agents to act specifically on cancer cells, increasing their efficacy while minimizing adverse effects on healthy tissues. This was demonstrated by employing the delivery of siRNA to bladder cancer cells using exosomes that were obtained from HEK293 human embryonic kidney cells. Electroporation was used to introduce PLK1 siRNA to the exosomes before they were co-cultured with UMUC3 metastatic bladder cancer cells. According to an in vitro study, bladder cancer cells internalized HEK293 exo- somes more than normal bladder cells, which resulted in an efficient knockdown of PLK-1 mRNA and protein [21].
Exosomes can also carry drugs that are otherwise challenging to deliver directly to tumor tissues. These vesicles have the advantage of being able to navigate through biological barriers, including the extracellular matrix and the blood-brain barrier, to reach their intended target. This ability makes them particularly useful for deliver­ing therapeutics to tumors located in difficult-to-reach sites [112, 113]. A zebrafish model was used to examine the exosomes in vivo after they had been extracted, characterized, and loaded with chemo agents via incubation. In comparison to the basic drugs, the loaded exosome systems demonstrated substantially better CNS delivery capability [114]. Moreover, exosome-mediated chemotherapeutic administration has been found to increase anti-cancer effects in a number of studies [115–118]. Doxorubicin, another of the most potent anti-cancer drug, is employed to treat leukemia, lymphoma, and a variety of solid tumors. It has been observed that exosomes can carry chemotherapeutic drugs like doxorubicin and paclitaxel. However, because of its poor biocompatibility and substantial side effects such as bone marrow suppression and cardiotoxicity, the clinical usage of doxorubicin
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Exosome-Based Smart Drug Delivery for Cancer Treatment DOI: http://ITexLi.113744
is extremely limited. Many nanoparticle technologies are being used to improve
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doxorubicin’s biocompatibility and anti-cancer properties, but they also cause immunological response and oxidative damage [118, 119]. Exosome-mediated anti­cancer therapy has extensively investigated doxorubicin because of its easy-to-track intrinsic fluorescence [118]. The optimized cholesterol endocytosis process and phospholipid composition of exosomal membranes allow exosomes to target cancer cells better than liposomes [120]. Since doxorubicin frequently causes cardiotoxic­ity, loading doxorubicin into exosomes prevents doxorubicin from reaching cardiac endothelial cells. As a result, this lowers the risk of cardiotoxicity [121]. It has been revealed more recently that the cellular absorption rate and anticancer effect of doxorubicin in osteosarcoma could be improved by exosomes produced from mesenchymal stem cells [122]. In cisplatin-resistant patients, paclitaxel is frequently used to overcome drug resistance [123]. Mesenchymal stromal cells treated with paclitaxel were able to generate paclitaxel-loaded exosomes, which exhibited power­ful anti-cancer effects in human pancreatic cancer [26]. MDR stands for multiple drug resistance, and it is one of the main challenges to effective cancer treatment. Exosomes have demonstrated efficacy in overcoming multidrug resistance in can­cers. In MDCK MDR1 cells, paclitaxel-loaded macrophage-derived exosomes dem­onstrated higher cell uptake and a lower IC50 than free paclitaxel, circumventing the P-glycoprotein drug efflux transporter [30]. Exosomes produced from U-87 MG cells have the potential to deliver paclitaxel and overcome MDR, which could lead to an enhanced therapeutic effect in glioblastoma multiforme [124]. Furthermore, the use of exosomes in cancer treatment holds promise for personalized medicine. Exosomes can be isolated from a patient’s own cells, loaded with specific therapeutic agents, and then reintroduced back into the patient. This approach takes advantage of the unique characteristics of each patient’s tumor, tailoring the treatment to their specific needs. While the use of exosomes in targeted delivery for cancer treatment shows great potential, there are still challenges that need to be addressed. These include optimizing exosome production and cargo loading techniques, ensuring the stability of exosomes during storage and transportation, and further improving their targeting efficiency. In addition, the exosomes were native to the animal and were small, so they naturally avoided phagocytosis, which lowered the immunologi­cal response [125]. Zhou et mesenchymal stem cells were loaded with siRNA and oxaliplatin and used for the treatment of pancreatic cancer in a rat model. In increased the uptake of these compounds, indicating a greater therapeutic effect than a free drug.
Exosomes have also been explored as potential diagnostic and prognostic biomark
ers in cancer. The analysis of exosomes obtained from body fluids, such as blood or urine, can provide valuable information about the presence of specific genetic altera­tions or the expression of tumor-related molecules. This non-invasive approach has the potential to revolutionize cancer diagnosis and monitoring, allowing for earlier detection and personalized treatment strategies. Qambrani et that cancer-cell-derived exosomes can function as both a drug delivery system and a potential fluorescent biomarker, as shown by HeLa-derived exosomes loaded with doxorubicin and silver nanoclusters [127]. Recently, there has been growing interest in using exosomes derived from bovine milk as a drug delivery vehicle [128, 129]. For example, Li et therapeutic impact against cancer cells in
[130] recently demonstrated that doxorubicin uptake and
al.,
[126] showed that exosomes from bone marrow
al.,
vitro
vivo
and in
were considerably improved by first
vitro
, exosomal delivery
[127] demonstrated
al.,
-
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isolating milk exosomes, coating them with hyaluronan for CD44-targeting, and then loading them with the drug. Figure  depicts the appearance of an isolated exosome and exosome-specific biomarker analysis in the experimental context [131].
In a recent study, Carobolante et al., delineated that milk-derived exosomes had a less efficient uptake when compared to exosomes produced by Caco-2 epithelial cells. Additional modifications are necessary for milk-derived exosomes to be utilized as a drug delivery system [132]. Another study confirmed that paclitaxel-loaded exosomes (milk derived) inhibited tumor growth more effectively than free paclitaxel, with fewer systemic side effects [133]. In one instance of drug delivery, exosomes contain­ing curcumin were used to treat inflammatory disease. In a clinical trial, exosomes formed a complex with curcumin that increased its effectiveness compared to free curcumin. In another study, curcumin was loaded onto exosomes derived from EL-4 murine tumor cells via incubation.
In vitro experiments revealed that exosomal curcumin substantially decreased inflammatory cytokine levels when compared to curcumin in its native form [134–136].
Exosomes have been extensively studied for their ability to deliver genetic thera­pies including small interfering RNA (siRNA) and microRNA (miRNA), because they naturally carry nucleic acids like DNA and RNA [3, 5], as previously mentioned [117]. The expression levels of target genes can be downregulated or disrupted using siRNA as a therapeutic agent. Typically, siRNA is unstable and rapidly destroys in the
Figure 4. (A) A flowchart depicting the isolation of exosomes from human peripheral blood neutrophils (N-ex). (B) Transamination electron microscopy (TEM) analysis of N-ex. (C and D). Morphological study of N-ex using atom force microscopy (AFM). N-ex nanoparticle tracking assay (NTA) for size determination particle size (E), zeta potential (F). (G) DLS was used to measure the PDI of N-ex. (H) Western blot studies of exosomal biomarkers (CD63, CD81 CD9, and Alix) and ER markers (calnexin) in N-ex. (I and J) fluorescence confocal laser microscopy and imaging flow cytometry were used to investigate DiR-labeled N-ex untacking in the gastric cancer cell (HGC27). The nuclei of the cells were stained with nuclear dye DAPI. Scale bars, 20μm. Adopted from ref. [131].
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bloodstream. Exosomes serve as a delivery vehicle for these RNA molecules, protect-
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al.,
ing them from destruction in systemic circulation [117]. Kamerkar et siRNA-loaded exosomes in pancreatic cancer mice models [137]. This study proves that compared to siRNA-loaded liposomes; the exosome group showed a higher reduction in tumor growth as well as a lower clearance from the body. Wahlgren
et
[32] reported that exogenous siRNA was inserted into exosomes delivered to
al.,
human blood cells after exosomes were isolated from lung cancer cells, suggesting the potential of utilizing exosomes for gene therapy. Nevertheless, the advancements in exosome research provide a promising avenue for improving cancer treatment out­comes and minimizing side effects associated with conventional therapies. Ongoing studies continue to explore the full potential of exosomes in targeted delivery for cancer therapy.
. Challenges and limitations in implementing exosome-based therapies
used kRAS
in clinical practices
Exosomes have gained significant attention in the field of medicine due to their
potential clinical applications. One of the most promising applications of exosomes is in regenerative medicine. Exosomes derived from stem cells have shown great potential in promoting tissue repair and regeneration. They can transfer bioactive molecules such as proteins, nucleic acids, and lipids to target cells, stimulating healing processes. As previously discussed, exosomes, could deliver drugs to target areas and cross barriers when compared to other nanoparticles. Exosomes’ drug efficacy and half-life were well maintained when they were injected into the recipient cell, accord­ing to the research findings. Because the exosomes are endogenous mediators, they possess natural cell permeability, which allows them to pass physical barriers and even avoid lysosomal breakdown and endosomal pathways [138]. Macrophage-derived genetically engineered exosomes can transport drugs without being rejected [139]. These targeting characteristics can be tailored to malignancies or other disorders with specific markers or proteins. They can also cross the BBB, allowing CNS-active drugs to be delivered [125].
Exosomes also hold promise as diagnostic markers for several cancer types and as
an early detection tool in many clinical studies. This has the potential to revolution­ize disease diagnosis and monitoring, enabling earlier detection and personalized treatment approaches. For instance, the goal of the colon cancer clinical study NCT04523389 is to create diagnostic markers. As seen on Clinicaltrials.gov, accessed on Aug 8, 2023, there are currently dozens of trials when searching for the terms “can­cer” and “exosomes.” While most focus on the use of exosomes as a diagnostic marker, some have a specific interest in using exosomes as a delivery system. However, despite the progress made in exosome research, several challenges remain. Standardization of methods for exosome isolation, characterization, and quantification is crucial for ensuring consistent and reliable results. Additionally, the large-scale production of exosomes and their scalable purification for clinical use need to be addressed [125]. Overall, the clinical use of exosomes is an exciting and rapidly evolving field. With further research and development, exosomes hold immense promise for advancing regenerative medicine, diagnostics, and drug delivery, potentially transforming the way we approach various diseases and conditions in the future. Table recent clinical trials demonstrating the various ways to exploit exosomes as a natural drug delivery system.
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highlights