In a groundbreaking advancement poised to revolutionize the field of therapeutic delivery, researchers at Sweden’s Karolinska Institutet have unveiled a sophisticated technique that leverages engineered extracellular vesicles (EVs) to efficiently transport therapeutic proteins and RNA into living cells. This promising new method, detailed in a recent article published in Nature Communications, demonstrates significant potential for delivering gene editors and protein therapeutics with unprecedented precision and efficacy in vivo, marking a major stride toward innovative treatments for a host of severe diseases.
Extracellular vesicles, naturally secreted by living cells, act as microscopic carriers facilitating intercellular communication by transporting biological molecules such as proteins, RNA, and lipids. While EVs have long been recognized for their potential in targeted drug delivery, their clinical translation has been hindered by major technical challenges, including inefficient release of therapeutic cargo inside recipient cells. The team at Karolinska Institutet has addressed these bottlenecks by embedding two critical molecular components into EVs: a segment derived from a bacterial protein known as intein, and a fusogenic protein obtained from a virus. This ingenious bioengineering feat enhances the vesicles’ ability to escape endosomal entrapment and release their therapeutic payload directly into the cytoplasm of target cells.
The viral fusogenic protein plays a pivotal role in the fusion of EVs with the endosomal membrane once internalized by the recipient cells. This fusion facilitates the transit of encapsulated therapeutic agents from the endosome into the cell’s cytosol, circumventing the typical degradation pathways. Concurrently, the intein operates as a molecular switch, capable of self-excision and protein splicing, which permits the precise intracellular liberation of protein-based therapeutics. This dual approach significantly optimizes the delivery mechanism, overcoming the historical hurdles associated with poor endosomal escape and insufficient intracellular bioavailability.
Professor Samir EL Andaloussi, a leading expert in the domain and the study’s corresponding author, emphasizes the transformative nature of this work. He describes the engineered EV platform as a versatile vehicle capable of addressing diverse medical challenges ranging from systemic inflammation to inherited genetic disorders and complex neurological diseases. The ability to reliably deliver cargo into cells broadens the therapeutic horizon to include not only traditional protein pharmaceuticals but also cutting-edge gene editing technologies such as CRISPR/Cas9, which hold immense promise for curing debilitating diseases at their genetic roots.
The research team conducted extensive experimental validation in both cultured cells and animal models to ascertain the functional advantages of their engineered EVs. They successfully delivered Cre recombinase, an enzyme instrumental in site-specific DNA recombination, and CRISPR/Cas9 components, which enable precise genomic editing. Remarkably, injections of EVs carrying Cre recombinase into murine brain regions, specifically the hippocampus and cortex, elicited significant cellular modifications, demonstrating effective targeting and intracellular delivery in the central nervous system. These findings highlight the technology’s capacity to overcome the formidable barriers presented by the blood-brain barrier and complex neural tissue architecture.
Dr. Xiuming Liang, the study’s first author, underscores the clinical implications: “The efficiency with which these extracellular vesicles can deliver gene editing tools such as CRISPR/Cas9 opens new avenues for intervening in severe central nervous system genetic disorders, including Huntington’s disease and spinal muscular atrophy. This technology could fundamentally alter the landscape of precision medicine for neurological conditions, enabling therapies that were previously impossible due to delivery constraints.”
Beyond neurological applications, the researchers demonstrated that their EV engineering approach could mitigate systemic inflammation in animal models, pointing to its broad therapeutic applicability. Systemic inflammation underpins numerous chronic diseases, including autoimmune disorders and sepsis; thus, innovative delivery systems that can target relevant cells and tissues with anti-inflammatory proteins or RNA molecules are critical. These engineered EVs, by virtue of their natural origin and enhanced payload release mechanisms, offer an elegant solution that combines biocompatibility with therapeutic potency.
The crux of the study lies in an elegant fusion of biology and bioengineering. The scientists exploited the modular nature of inteins—a class of protein domains capable of catalyzing their own excision and ligation of surrounding protein fragments—to regulate the release of therapeutic proteins once inside the cell. By integrating these inteins into the EV cargo, therapeutic proteins remain inactive during transit, thereby maintaining stability and reducing off-target effects. When the EV merges with the recipient cell’s cytoplasm, the intein-mediated splicing event triggers instant activation of the therapeutic proteins at the desired intracellular location.
Complementing this intricate molecular design, the fusogenic viral protein, borrowed from viruses known for their exceptional cell-fusion capabilities, enhances the EV’s membrane fusion potential. This viral component mimics a natural biological process by facilitating the EV’s escape from the endosome, a cellular compartment that often acts as a bottleneck preventing therapeutic molecules from reaching their intracellular targets. The incorporation of this fusogenic protein effectively bypasses endosomal degradation pathways, a notorious obstacle in nucleic acid and protein delivery systems.
Crucially, this research was carried out within the supportive infrastructure of the Karolinska Advanced Therapy Medicinal Products (ATMP) Center, ensuring stringent validation and adherence to translational research standards. The multi-disciplinary team, including experts in molecular biology, bioengineering, and therapeutic development, meticulously characterized the engineered EVs, verifying their safety, delivery efficiency, and therapeutic outcomes in animal models. Such concerted efforts exemplify the collaborative nature of contemporary biomedical research aimed at tackling some of humanity’s most intractable medical challenges.
Collectively, the findings illuminate a new realm of possibilities for EV-based drug delivery systems. By overcoming key biological barriers, such as endosomal entrapment and cargo release, these engineered vesicles effectively bridge the gap between promising molecular therapeutics and their clinical applicability. Given their natural origin, engineered EVs also harbor advantages over synthetic nanoparticles and viral vectors regarding immunogenicity and biocompatibility, potentially reducing adverse effects during repeated administrations.
The potential clinical implications are vast. From genetic disorders that currently lack effective treatments to complex diseases with multifactorial pathologies, the ability to deliver multiple therapeutic modalities—including genome editors, RNA interference molecules, and functional proteins—inside target cells with high precision could shift the paradigm of modern medicine. Moreover, the platform’s modularity means it could be tailored to various disease targets by swapping specific cargoes or modifying surface proteins for targeted delivery.
Looking ahead, while the preclinical results are highly encouraging, further investigations in larger animal models and eventually clinical trials will be essential to determine safety profiles, dosage parameters, and therapeutic indices in humans. Nonetheless, this innovative approach to EV engineering represents a vital step toward the practical realization of precision gene and protein therapies. It exemplifies how deep molecular insights combined with creative bioengineering can lead to therapies that were previously relegated to the realm of science fiction.
In summary, the Karolinska Institutet team’s novel strategy for engineering extracellular vesicles heralds a new era in therapeutic delivery technology. By harnessing the synergistic effects of intein-mediated protein release and viral fusogenic capabilities, they have designed a delivery system capable of crossing biological barriers and releasing therapeutics efficiently inside cells. This breakthrough holds tremendous promise for treating a broad spectrum of diseases, including those of the nervous system, genetic origin, and inflammatory conditions, bringing the vision of targeted, effective gene and protein therapies closer to reality than ever before.
Subject of Research: Animals
Article Title: Engineering of extracellular vesicles for efficient intracellular delivery of multimodal therapeutics including genome editors
News Publication Date: 29-Apr-2025
Web References:
https://www.nature.com/articles/s41467-025-59377-y
http://dx.doi.org/10.1038/s41467-025-59377-y
References:
Liang, X., Gupta, D., Xie, J., et al. (2025). Engineering of extracellular vesicles for efficient intracellular delivery of multimodal therapeutics including genome editors. Nature Communications. doi:10.1038/s41467-025-59377-y
Keywords: Drug delivery, Biotechnology, Gene therapy, Genome editing, CRISPRs, Cell biology
