Table 4 Challenges and overcoming of exosomes in the clinical setting
From: Tumorigenic and tumoricidal properties of exosomes in cancers; a forward look
Challenging | Description | Overcoming | Ref |
|---|---|---|---|
Heterogeneity | Different cell types and the microenvironment result in various cargo | - Developing standardized isolation and purification methods | |
Yield and purity | Risk of contamination with cellular debris or other unwanted components during isolation | Optimizing cell culture conditions and increasing the release of exosomes by: - Precise adjustment of the availability of nutrients, oxygen levels, and growth factors - Simultaneous suppression of the activity of genes that inhibit exosome biogenesis. For example, knocking down Rab4 - Optimization of downstream processing methods. including the use of specialized purification methods, such as immunoaffinity-based methods, ultracentrifugation, and size-exclusion chromatography - Bioreactors, 3D cultures, and microfluidic devices | |
Reproducibility | Ability to obtain consistent and reliable results due to inefficient separation methods, difficulties in characterization, and lack of specific biomarkers | - Establishing uniform approaches in exosome isolation and purification methods - Instrument calibration - Standardized and transparent reporting, and education | [264] |
Specificity | high selectivity for isolating only exosomes while preventing the inclusion of any other extracellular vesicles or impurities | Development of methods that exclusively separate and cleanse exosomes | [264] |
Large-scale manufacturing and purification | - Scalability of exosome isolation and purification methods - Complex and time-consuming process of exosome isolation - Limited production output of exosomes and high development costs - The complexity associated with scaling up the manufacturing process | - Increasing output, and standardized procedures in large-scale exosome manufacturing - To scale up the culture of anchorage-dependent cells used for exosome production, it is necessary to employ technologies that maximize available surface area - Employing well-established cell lines that release the specific exosomes alongside a rigorously defined serum-free medium allows for efficient cost utilization | |
Quality control | - Need for specific biomarkers - Difficulty characterizing the exosomes | - Establishing dependable and replicable techniques for quality assurance - Standardized operating procedures combined with a streamlined closed operating system that includes a fileable quality control testing program | |
Analysis of Complex Cargos | A significant challenge in exosome-based cancer diagnosis | - Analysis of accurate and reproducible properties of exosomes including concentration, particle size, zeta potential and exosome markers | |
Batch-to-Batch Variation | Inconsistency in the quality and quantity of exosomes produced from different batches due to several factors, including differences in cell source or culture conditions, inefficient separation methods, and difficulties in characterization | - Standardizing the exosome production process, - Enhancing the reproducibility and reliability of clinical-grade exosomes | Â |
Dosing | The determination of the most suitable dosage of SC-EXOs for effective cancer treatment is still being investigated. The dosing requirement could differ depending on the type of cancer, how it is infused, and the therapeutic payload contained within the exosomes | During preclinical investigations, injections containing particles ranging from 107 to 1011 have been administrated | [276] |
Route of administration | The most effective routes of administration for SC-EXOs in cancer treatment include intravenous, intraperitoneal, intra-tumoral, and subcutaneous injection | - Intravenous administration facilitates the widespread distribution of SCs-Exo throughout the body, allowing for targeted treatment of multiple tumor sites and metastases - Local injection allows for the direct delivery of SCs-Exo into precise tumor areas, optimizing their concentration at the activity site | [276] |
Short Half-Life in Vivo | Constraining exosomes' therapeutic potential due to limited duration in the body with rapid recognition by: - Diverse enzymatic breakdown mechanisms in bodily fluids like blood and lymph systems break the exosome membrane - The reticuloendothelial system (RES) clears foreign particles from the bloodstream | Employing diverse strategies to bolster the stability and endurance of exosomes: - Enhancing the resilience of the exosomal membrane by coating it with protective materials or engineering it to resist enzymatic degradation - Shielding exosomes from the reticuloendothelial system by encapsulating them in biocompatible materials or nanoparticles | |
Risk of thrombosis and hemostatic disorders | Thrombosis and homeostatic imbalance in biofluid-derived exosomes can contribute to the development of certain diseases, including cancer metastasis | Minimized the risk of thrombosis from exosome injection by: - Use of thrombolytic drugs, platelet-derived exosomes, immunoglobulin-M (IgM) antibodies, and nanomedicine | Â |
Long-term preservation | storage conditions can impact the size distribution, quantity, contents, and cellular uptake of exosomes Ensuring the stability and functionality of exosomes over extended periods | - Lyophilizing - Employing stabilizing agents like sugars or polyethylene glycol for preservation purposes - Minimizing the freeze–thaw cycles, as repeated cycles may affect the morphology and functionality of exosomes |