Exosomes — membrane-bound vesicles, roughly 100 nm in size, shed by virtually every cell type in the body — were once dismissed as cellular waste products. That view changed when researchers began discovering that exosomes are critical mediators of intercellular communication, carrying proteins, lipids, and nucleic acids that provide detailed molecular information about their cell of origin. A cancer cell’s exosomes look different from a healthy cell’s. A neuron under stress releases different vesicular cargo than a resting one. This molecular specificity has opened two parallel lines of investigation: using exosomes as diagnostic biomarkers detectable in blood, urine or saliva without tissue biopsy; and engineering or harnessing them as delivery vehicles for therapeutic cargo [1]. 

This article discusses extracellular vesicle (EV) biology, including how exosomes are formed and what cargo they carry. It highlights emerging diagnostic applications, particularly in oncology and liquid biopsy. It examines the rise of exosome-based therapeutics, from drug delivery to immunotherapy. It also outlines the automation of EV isolation and key characterisation technologies—such as particle sizing, zeta potential, and molecular profiling—that enable reliable and reproducible exosome research.

Australia is playing a growing role in EV research, supported by NHMRC-funded programs and leading institutes. Monash University and the Hudson Institute have received funding (including via CUREator) to produce novel exosome therapies for ovarian cancer and to develop exosome-based diagnostic tools [2]. La Trobe University is studying exosome biomarkers for neurodegeneration [3] while the University of Queensland is developing exosome-based tools for CAR-T cell engineering [4]. These groups are contributing to advances in cancer biology, liquid biopsy development, and translational EV research, helping bridge the gap between laboratory discovery and clinical application.

Understanding Extracellular Vesicles: Biology and Classification

Extracellular vesicles (EVs) are membrane-bound particles released by cells into their surrounding environment, as defined in the International Society for Extracellular Vesicles MISEV guidelines. They encompass three main subtypes: exosomes, microvesicles, and apoptotic bodies. Exosomes are typically ~30–150 nm in diameter and are formed through the endosomal pathway, where multivesicular bodies fuse with the plasma membrane to release their contents. Microvesicles are larger (~100–1,000 nm) and are generated by direct outward budding from the plasma membrane. Apoptotic bodies, which are >1,000 nm, are released during programmed cell death.

The International Society for Extracellular Vesicles introduced the MISEV guidelines, “Minimal Information for Studies of Extracellular Vesicles” in 2014, with the latest update (MISEV2023) providing best practices for EV production, isolation, and characterisation across cell culture, biofluids, and tissues. The guidelines emphasize classifying EVs based on measurable properties—such as size, density, and molecular markers—rather than origin, as current methods cannot reliably distinguish exosomes from microvesicles.

EVs carry a range of molecules, including proteins, lipids, RNA, and DNA. This cargo reflects the condition of the cell they come from. Because of this, EVs can be used as non-invasive disease biomarkers and as targeted delivery systems for therapies [5]. 

Why Size and Concentration Matter

EV size strongly affects how they behave in the body. Small EVs, like exosomes (~30–150 nm), can cross barriers such as the blood-brain barrier, allowing detection of brain biomarkers and delivery of drugs to the central nervous system. Size also determines how EVs enter cells. Different uptake pathways—like endocytosis or membrane fusion—impact how effectively EVs can deliver therapies, making accurate size control important.

Therefore measuring EV size and concentration accurately is essential for any study, as required by the MISEV guidelines. Proper characterisation ensures reproducibility, helps predict EV behaviour in the body, and supports their use in diagnostics and therapeutics.

Exosomes as Diagnostic Biomarkers

Extracellular vesicles (EVs) have strong diagnostic potential. Found in blood, urine, saliva, and cerebrospinal fluid, they carry molecules that reflect their cell of origin. This allows non-invasive disease detection, or liquid biopsy, without tissue sampling. Liquid biopsy is rapidly growing in cancer and neurological research, enabling early detection, disease monitoring, and treatment tracking using EV-associated proteins, RNA, and DNA.

Liquid Biopsy: Early Cancer Detection from Accessible Biofluids

Liquid biopsy is a non‑invasive test that analyses circulating biomarkers—such as circulating tumour cells (CTCs), cell‑free DNA (cfDNA), and extracellular vesicles (EVs)—from body fluids like blood, instead of relying on tissue sampling.

A landmark example of this approach was the 2015 Nature study by Melo and colleagues [6], which showed that GPC1‑positive exosomes isolated from patient blood could distinguish early‑stage pancreatic cancer from healthy controls with high reported accuracy, demonstrating for the first time that tumour‑associated EV surface proteins could act as circulating cancer biomarkers. Since then, researchers worldwide have been working to identify EV markers that are robust, reproducible, and clinically useful across larger patient populations, an active area of translational research. EV liquid biopsy work has advanced most in pancreatic, prostate, lung, ovarian, and colorectal cancer studies, though a key challenge remains distinguishing tumour‑derived EVs from the large background of non‑tumour EVs in circulation, as their concentrations and cargo vary widely [7]. In Australia, groups such as those at the Walter and Eliza Hall Institute are exploring EV roles in cancer and blood disease diagnostics, including EV links to tissue damage and potential blood tests for disease monitoring [8]. 

Neurological Disease Biomarkers: EVs in Blood and CSF

Extracellular vesicles (EVs), including exosomes, can cross the blood–brain barrier in both directions, meaning brain‑derived EVs can be detected in peripheral blood and blood‑borne EVs can access the central nervous system. This bidirectional crossing supports their use as minimally invasive biomarkers for neurological disease, as EVs carrying neuronal cargo appear in blood and other fluids. For example, neuronal EVs with tau, amyloid‑β, or synaptic proteins are being explored as early Alzheimer’s disease biomarkers, detectable without cerebrospinal fluid sampling. EVs also rise rapidly in blood after traumatic brain injury, offering potential for fast diagnosis. In Parkinson’s disease research, EV fractions containing neuronal protein, alpha‑synuclein have been investigated as markers of disease state. A major methodological challenge remains identifying truly CNS‑origin EVs using surface markers like L1CAM, which requires careful validation and technical refinement [9].

The Standardisation Problem: Why MISEV Guidelines Matter

Clinical use of extracellular vesicles (EVs) is limited by inconsistent isolation, characterisation, and reporting methods across laboratories. To address this, MISEV2023 provides consensus guidelines on isolation, minimum characterisation, and reporting standards. According to MISEV, studies should include at least one method for size measurement, one for particle concentration, and one EV marker protein. Despite progress, no EV-based diagnostic test has yet been approved for clinical use, with standardisation remaining a key barrier to translation [10].

Therapeutic Applications of Exosomes

EVs are not only diagnostic tools — their ability to carry functional molecular cargo across biological barriers, combined with natural surface proteins that facilitate cellular uptake, makes them compelling candidates as therapeutic delivery vehicles. Research ranges from loading EVs with RNA therapeutics, to generating MSC-derived EVs for tissue repair, to engineering dendritic cell EVs for cancer vaccination. Each approach draws on a different aspect of EV biology [11,12].

Loading Therapeutic Cargo into Extracellular Vesicles

EVs can be loaded with therapeutic molecules in several ways, including passive incubation, electroporation, sonication, extrusion, or genetically engineering the parent cells to produce EVs with built-in cargo. Each method has limitations—for example, electroporation can damage EVs, passive loading is often inefficient, and genetic engineering is more effective but harder to establish. EVs are being studied to deliver treatments such as siRNA, miRNA, antisense oligonucleotides, proteins, and CRISPR-Cas9 tools. Compared to synthetic nanoparticles, EVs offer lower immunogenicity, have natural surface proteins that help cellular uptake, and can cross biological barriers. However, producing enough EVs at clinical scale remains a major challenge [13].

MSC-Derived EVs and Regenerative Medicine

Mesenchymal stem cell–derived extracellular vesicles (MSC-EVs) have shown strong anti-inflammatory and tissue repair effects in preclinical studies, including heart, brain, and bone injuries. They are thought to work by delivering bioactive molecules like growth factors and microRNAs that reduce inflammation and support tissue healing. Based on these results, early clinical studies are now testing MSC-EVs for conditions such as graft-versus-host disease, COVID-19 lung injury, and osteoarthritis, showing strong potential for future therapies. However, producing them at large scale and maintaining consistent quality remains a major challenge [11]. In Australia, MSC-EV research is supported by universities and institutes such as the University of Queensland, La Trobe University, and the Walter and Eliza Hall Institute, along with industry collaborations focused on developing EV-based regenerative treatments.

EV-Based Cancer Immunotherapy

Dendritic cell–derived extracellular vesicles (Dex) can carry tumour antigens and activate T cells, triggering an immune response without using live cells. This is why they are being studied as cell-free cancer vaccines. Early research first showed that these vesicles could stimulate tumour-specific immune responses and slow tumour growth in preclinical models. Phase I clinical trials in melanoma and non-small cell lung cancer later showed that these exosome-based vaccines are safe and can trigger immune activity, although their full clinical benefit is still being studied. In contrast, tumour-derived EVs (TEXs) can suppress the immune system, helping cancer cells evade attack, which is important when designing combination therapies such as checkpoint inhibitors [14]. In Australia, this area is supported by NHMRC-funded research programs and major institutes focused on cancer immunology and EV-based therapies. 

Engineered Nanoparticles as Therapeutic Delivery Systems

The success of synthetic nanoparticles in medicine helps explain why EV research is growing. Lipid nanoparticles (LNPs), in particular, have become a major medical technology and were proven at global scale through COVID-19 vaccines. Learning how these particles work—and their limitations—helps highlight why researchers are exploring EVs and hybrid delivery systems as potential alternatives.

Lipid Nanoparticles: Clinical Validation at Global Scale

Lipid nanoparticles (LNPs) are typically made from four key components—an ionisable lipid, PEG-lipid, cholesterol, and a phospholipid—which self-assemble into ~100 nm particles that protect mRNA and enable delivery into cells. The ionisable lipid plays a critical role: it remains neutral in the bloodstream to reduce immune reactions, but becomes positively charged in the acidic endosome, helping release the mRNA into the cell. This technology underpins approved products such as Onpattro (patisiran), as well as the COVID-19 vaccines Comirnaty and Spikevax. LNPs are also being explored in clinical trials for cancer vaccines, cystic fibrosis treatments, and in vivo gene editing. However, scaling up LNP production using traditional methods remains challenging, as maintaining consistent particle size, uniformity, and encapsulation efficiency from lab to GMP scale requires precise control. A formulation that works at 200 µL bench scale may not reproduce identically at 250 mL clinical scale without careful process design.

Formulation platforms such as the Micropore AXF Pathfinder and HORIZON [15] systems overcome scale-up challenges by maintaining identical mixing geometry across all volumes. Its crossflow mixing design is consistent from sub-millilitre discovery runs through to GMP-scale production, enabling direct process transfer without the need for reformulation [16]. 

Polymer Nanoparticles and Targeted Delivery

Polymer nanoparticles, such as PLGA and chitosan, can be designed to break down at controlled rates and easily modified for targeted delivery. By adding molecules like antibodies or peptides, they can be directed to specific cells. Many approaches rely on the enhanced permeability and retention (EPR) effect, where nanoparticles build up in tumours, but this design rationale does not always work reliably in humans. Like lipid nanoparticles, polymer nanoparticles are characterised by key properties including size, polydispersity (PDI), zeta potential, and encapsulation efficiency [17]. 

The Isolation of Exosomes

Efficient exosome isolation remains a major challenge in advancing extracellular vesicle research and clinical translation. Traditional methods such as ultracentrifugation and polymer-based precipitation have been widely used but are often time-consuming, low throughput, and can compromise purity or yield. More recent approaches, including microfluidic technologies, have improved specificity and throughput by targeting exosome surface markers, but challenges remain in balancing purity with recovery and achieving consistent results across laboratories [22].

Automated systems such as the Exodus H600 are designed to address these limitations by providing a standardised, high-throughput isolation workflow. Based on ultrasonic nano-filtration technology, the system enables efficient enrichment of exosomes from biofluids such as blood, urine, and cerebrospinal fluid, while reducing co-isolation of contaminants. Its automation minimises operator variability and improves reproducibility, while supporting scalable processing from research to translational workflows. As exosome research continues to advance in diagnostics, therapeutics, and biomarker discovery, platforms like the Exodus H600 are critical for improving consistency, throughput, and reproducibility—helping to accelerate the translation of exosome-based technologies into clinical practice [23].

Characterising EVs and Nanoparticles: The Analytical Toolkit

Exosome heterogeneity is one of the biggest challenges in EV research. Exosomes vary widely in size, composition, and biological function, even when released from the same cell type. Their cargo—proteins, lipids, and nucleic acids—can differ depending on the cell’s state, environment, and disease condition. In complex biofluids like blood, exosomes are mixed with other vesicles and particles, making it difficult to isolate specific subpopulations with confidence. This heterogeneity can impact data interpretation, reproducibility, and biomarker discovery, highlighting the need for more selective isolation approaches and advanced analytical tools. Automated platforms such as the EXODUS system are helping address this by improving standardisation and reducing operator-dependent variability in exosome isolation workflows.

Once exosomes are isolated, robust characterisation is essential. MISEV2023 sets minimum requirements for EV studies, while regulatory agencies require defined critical quality attributes for nanoparticle-based medicines. Without thorough characterisation, researchers cannot be confident that the material they are using is what they intended, or that observed biological effects truly reflect the particles themselves rather than artefacts of preparation.

Particle Size and Concentration: DLS and NTA

Particle size analysis is a critical step in both extracellular vesicle (EV) research and nanoparticle formulation, as size directly influences biological behaviour, stability, and therapeutic performance. Dynamic Light Scattering (DLS) measures fluctuations in scattered laser light caused by Brownian motion of particles in suspension. From this, the diffusion coefficient is calculated and converted into hydrodynamic diameter using the Stokes–Einstein equation. This technique provides rapid measurements of average particle size and polydispersity index (PDI) using minimal sample volumes, making it widely used for routine quality control of both EVs and lipid or polymer nanoparticles. Instruments such as the Zetasizer Ultra extend this capability through multi-angle dynamic light scattering (MADLS), improving size resolution and enabling more robust size distribution and concentration estimates from the same sample.

In contrast, Nanoparticle Tracking Analysis (NTA) used by the NanoSight Pro, visualises and tracks individual particles in real time using light scattering microscopy and Brownian motion analysis. This produces a number-based size distribution and absolute particle concentration, which is particularly valuable for heterogeneous EV samples where intensity-based methods can be biased by larger particles. NTA also offers fluorescence detection, allowing specific EV subpopulations—such as CD63-positive exosomes—to be selectively identified within complex biological mixtures.

MISEV2023 guidelines recommend that EV studies report at least one method for size and one for concentration measurement, a requirement that is fulfilled by combining DLS and NTA. Together, these complementary techniques provide a more complete and reliable characterisation of EV and nanoparticle systems, supporting both research reproducibility and regulatory expectations for critical quality attributes in therapeutic development.

Surface Charge: Zeta Potential

Zeta potential describes the surface charge of particles and is a key indicator of colloidal stability, helping predict whether particles will remain dispersed or tend to aggregate over time. For extracellular vesicles (EVs), zeta potential is typically in the range of approximately −20 to −30 mV in physiological buffers, reflecting the overall negative charge of the phospholipid membrane. In contrast, ionisable lipid nanoparticles (LNPs) are specifically engineered to have near-neutral charge at physiological pH to reduce immune recognition, while becoming positively charged in the acidic endosomal environment to enable cargo release. Zeta potential is measured using Electrophoretic Light Scattering (ELS), which is commonly integrated into dynamic light scattering (DLS) instruments such as the Zetasizer Ultra, enabling charge and size characterisation from the same sample.

Binding Affinity and Drug-Cargo Interactions

Understanding how therapeutic cargo interacts with an EV membrane or nanoparticle surface requires thermodynamic insight that biological activity assays alone cannot provide. Isothermal Titration Calorimetry (ITC) directly measures the heat released or absorbed during binding events, enabling a full thermodynamic profile in a single label-free experiment, including binding affinity (KD), enthalpy (ΔH), entropy (ΔS), and stoichiometry (n). In EV and nanoparticle research, ITC is used to study drug–membrane interactions, surface protein binding, antibody–antigen interactions for targeted delivery systems, and compatibility between cargo and formulation components.

While fluorescence or functional assays may confirm that binding or uptake occurs, they cannot explain the underlying thermodynamic forces driving these interactions. Instruments such as the Malvern MicroCal PEAQ-ITC provide this deeper level of understanding by quantifying binding events directly, supporting optimisation of drug loading and surface modification across both EVs and nanoparticle platforms.

Australian Research Spotlight

Australian research plays a significant role in advancing extracellular vesicle (EV) and nanoparticle science, with strong activity across both fundamental biology and translational applications. At the Peter MacCallum Cancer Centre, researchers are actively investigating EVs as cancer biomarkers and in liquid biopsy approaches, with recent studies exploring EV-associated molecular signatures for improved cancer detection and monitoring. At the Walter and Eliza Hall Institute (WEHI), EV biology is being studied within broader cancer and immune regulation research, particularly in how intercellular communication influences tumour progression and immune responses.

At the Australian Institute for Bioengineering and Nanotechnology (AIBN), University of Queensland, research focuses on mRNA technologies, EV and lipid nanoparticle (LNP) delivery systems, directly supporting advances in vaccine development and gene therapy platforms [18]. The UQ Centre for Extracellular Vesicle Nanomedicine, is driving translational EV research into diagnostics and therapeutics [19].

Monash University has also contributed significantly to EV biology and cancer nanomedicine, with research highlighting EV roles in intercellular signaling, immune modulation, and therapeutic delivery strategies [20]. At La Trobe University, the Research Centre for Extracellular Vesicles provides a dedicated national hub for EV science, focusing on how EVs regulate cell and tissue communication in health and disease [21].

Together, these programs highlight Australia’s growing contribution to global EV and nanoparticle research, spanning discovery science through to clinical translation in cancer, infectious disease, and regenerative medicine.

Challenges and Future Directions

Several key challenges remain in extracellular vesicle (EV) and nanoparticle translation. EV production from cell culture is still low yield, and although bioreactor-based scale-up is improving, it is not yet a routine manufacturing solution. EV populations are also highly heterogeneous, and current isolation methods such as density gradients and size-exclusion often co-purify non-EV contaminants, making it difficult to obtain pure subpopulations. While MISEV2023 has improved reporting standards, reproducibility between laboratories remains a limitation. In parallel, no EV-based therapeutic has yet been approved, and regulatory frameworks for EV biologics are still evolving through agencies such as the FDA and EMA. Translating EV biomarkers into clinical diagnostics also requires large, prospective validation studies. For lipid nanoparticles (LNPs), a major limitation is their tendency to accumulate in the liver, with expanding delivery to other tissues remaining an active research focus.

Despite these challenges, several promising directions are emerging. Engineered EVs with modified surface proteins are being developed to improve tissue targeting and specificity. Hybrid EV–LNP systems are also being explored to combine the biological advantages of EVs with the scalability of LNP manufacturing. In LNP platforms, self-amplifying RNA (saRNA) offers the potential for lower dosing while maintaining efficacy. Artificial intelligence is increasingly being used to analyse EV cargo and identify biomarker signatures at scale. Overall, while no EV-based diagnostic or therapeutic has yet reached approval, active regulatory engagement and rapid technological progress suggest a strong pipeline toward future clinical translation [13].

ATA Scientific’s Commitment to EV and Nanoparticle Research

ATA Scientific supports Australian EV and nanoparticle researchers with access to analytical instrumentation that meets MISEV2023 characterisation requirements and pharmaceutical CQA frameworks. From nanoparticle engineering, EV isolation and particle size and concentration measurement through to zeta potential, binding affinity and biomolecular interaction analysis, our team provides instruments and application expertise for each stage of EV biology and nanoparticle drug development research.

For those interested in exploring EV isolation or nanoparticle engineering and characterisation, our team of specialists at ATA Scientific are available to assist.

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