The study, published in Nature Biomedical Engineering, describes an engineered lipid nanoparticle known as CD34/LNP^DP. The platform is designed to deliver messenger RNA and CRISPR/Cas gene-editing components specifically to cells carrying CD34, a surface marker commonly associated with human HSPCs. By coupling the nanoparticle to an anti-CD34 antibody, the researchers aimed to improve cellular targeting while avoiding the need to remove stem cells from the body for laboratory manipulation.

HSPCs reside primarily in the bone marrow and are responsible for replenishing the entire blood and immune system throughout life. Their biology makes them attractive targets for treating inherited blood disorders, but also makes them unusually difficult to engineer. Many long-term haematopoietic stem cells remain in a dormant, or quiescent, state. This limits the efficiency of approaches that depend on active cell division or high rates of cellular uptake. In addition, excessive manipulation can damage stem-cell function, reducing the ability of edited cells to repopulate the blood system.

To identify a suitable delivery vehicle, the investigators screened 15 different lipid nanoparticles for their capacity to transport reporter messenger RNA into human HSPCs. Lipid nanoparticles are microscopic assemblies of fats and related molecules that can protect nucleic acids in the bloodstream and facilitate their entry into cells. The selected formulation, LNP^DP, showed effective delivery in human HSPCs under ex vivo conditions, where cells are treated outside the body, and also demonstrated activity in vivo when directed toward CD34-positive cells.

The antibody-conjugated system was then tested with CRISPR/Cas editing cargos. In this approach, messenger RNA can encode the Cas nuclease, while a guide RNA directs the nuclease to a chosen DNA sequence. Once inside the target cell, the Cas protein creates a precise break in the genome. The cell’s own repair machinery then introduces a mutation or uses a supplied template to modify the target sequence. The researchers reported high editing efficiency in human HSPCs treated ex vivo with CD34/LNP^DP, suggesting that the formulation could support gene editing without relying on viral vectors.

The next experiments examined whether the nanoparticles could work inside living organisms. Humanized mice, which carry human blood-forming cells, received the CD34/LNP^DP system through intrafemoral administration, an approach that delivers the material directly into the marrow cavity of the thigh bone. This route places the nanoparticles close to the HSPC population and may reduce the barriers associated with systemic delivery. The treatment produced efficient editing in human HSPCs and did not cause detectable disruption of overall haematopoiesis, according to the study.

One of the first genetic targets was the erythroid-specific enhancer of BCL11A. This regulatory DNA element controls the activity of BCL11A in red blood cell precursors. BCL11A normally suppresses the production of fetal haemoglobin after birth. Disrupting its erythroid enhancer can therefore reactivate fetal haemoglobin, or HbF, a form of haemoglobin that is normally abundant before birth and can compensate for defective adult haemoglobin in disorders such as sickle cell disease and some forms of beta-thalassaemia.

In the humanized mice, editing the BCL11A enhancer within HSPCs was followed by sustained HbF reactivation in erythroid cells during long-term observation. The result is important because a durable therapeutic effect requires editing of stem cells that continue to generate blood-cell descendants over time, rather than only modifying short-lived progenitor cells. The findings indicate that CD34/LNP^DP can reach a biologically meaningful HSPC compartment and preserve the transmission of the edit through blood production.

The researchers also explored a second disease model involving a mutation in ELANE, a gene associated with severe congenital neutropaenia. Variants in ELANE can impair the development and maturation of neutrophils, leaving patients vulnerable to recurrent and potentially life-threatening infections. In humanized mice carrying an ELANE mutation, intrafemoral administration of CD34/LNP^DP directed CRISPR editing toward exon 2 of the gene. The treatment achieved robust editing in human HSPCs and partially improved the defect in neutrophil development during long-term follow-up.

Although the results do not yet establish a clinical treatment, they demonstrate a potential alternative to conventional ex vivo HSPC gene therapy. Current strategies often require patients’ stem cells to be collected, purified, edited in a specialized laboratory and reinfused after conditioning treatment. An in vivo approach could eventually simplify this process, but it must overcome major challenges, including precise tissue distribution, immune reactions, dose control, off-target editing and the need to reach enough long-term stem cells to produce a durable benefit. The study’s use of an anti-CD34 antibody provides a targeting mechanism, while the nanoparticle protects and transports the gene-editing cargo.

The work also highlights the importance of delivery technology in the development of genetic medicines. CRISPR systems are capable of rewriting disease-associated DNA, but their therapeutic value depends heavily on whether they can reach the correct cells at an effective dose while minimizing unintended exposure. By combining a selected lipid formulation with antibody-mediated recognition of CD34, the researchers created a platform that targets a clinically relevant human cell population in its native bone-marrow environment. Further studies will be needed to evaluate safety, editing precision, manufacturing requirements and performance in larger and more physiologically representative models. Even so, the findings position CD34-targeted lipid nanoparticles as a promising route toward durable in vivo engineering of the human blood-forming system.

Subject of Research: In vivo genetic engineering of human haematopoietic stem and progenitor cells using CD34-targeted lipid nanoparticles.

Article Title: Engineered lipid nanoparticles for in vivo and durable editing of haematopoietic stem cells within humanized mice

Article References: Du, J., Luo, Z., Xie, D. et al. “Engineered lipid nanoparticles for in vivo and durable editing of haematopoietic stem cells within humanized mice.” Nature Biomedical Engineering (2026). https://doi.org/10.1038/s41551-026-01765-w

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41551-026-01765-w

Keywords: lipid nanoparticles, haematopoietic stem cells, HSPCs, CRISPR/Cas gene editing, CD34 targeting, in vivo gene therapy, BCL11A, fetal haemoglobin, ELANE, neutropaenia, humanized mice

Adeno-associated viruses have long represented the viral vector of choice for gene therapy, thanks to their relatively benign immunogenic profile and efficient transduction capabilities. Engineering efforts have focused intensively on refining their tropism—the natural preferences that dictate which tissues or cell types they infect. By modifying capsid proteins and deploying directed evolution tactics, researchers have been able to customize AAV vectors for enhanced permeability across biological barriers, including the formidable blood-brain barrier. However, hurdles remain, chiefly the host immune response that can limit repeat dosing and the constrained packaging capacity that restricts delivery of larger genetic constructs.

In contrast, lipid nanoparticles have emerged from the successes of mRNA vaccine technology, offering a synthetic, non-viral vehicle with impressive payload versatility. Their modular lipid compositions can be selectively engineered to favor accumulation in specific tissues, and advances in ionizable lipid chemistry have greatly improved endosomal escape, enhancing cytosolic delivery. LNPs sidestep many immunogenicity issues associated with viral vectors, though they must contend with rapid clearance by the mononuclear phagocyte system and occasional dose-limiting toxicities. The capacity to encapsulate diverse nucleic acid payloads—from mRNA to CRISPR components—positions LNPs as flexible delivery powerhouses with significant therapeutic promise.

Meanwhile, extracellular vesicles, nature’s own delivery couriers, have captured the imagination of the gene therapy community as biomimetic vehicles that inherently communicate between cells. These nanoscale vesicles, secreted by virtually all cell types, carry proteins and nucleic acids that can modulate recipient cell function. Capitalizing on EVs’ intrinsic targeting abilities and biocompatibility, scientists have begun bioengineering strategies to load therapeutic gene cargo selectively and enhance tissue tropism. Despite the allure of minimal immunogenicity, EV research faces substantial challenges in scalable manufacturing, cargo loading efficiency, and comprehensive characterization, which currently limit their translational pace.

Delving into the engineering principles behind these platforms reveals contrasting philosophies. Viral vectors like AAVs leverage natural evolutionary design, which is then refined through molecular engineering to optimize tropism and immune evasion. LNPs are purely synthetic, crafted from tailored components that assemble into nanoparticles capable of fusing with cellular membranes and releasing their payload intracellularly. EVs occupy a hybrid position, being biological entities that can be modified either by manipulating donor cells or via post-isolation techniques to augment their functional capabilities. Understanding these fundamental design aspects provides crucial insight into how each platform can be adapted for specific therapeutic contexts.

Targeting capabilities remain paramount when considering therapeutic efficacy. For AAVs, capsid engineering and peptide display techniques can redirect the virus toward desired tissues, with varying degrees of success depending on the organ system. LNPs have been famously tailored to preferentially accumulate in the liver—a prime site for metabolic gene therapies—though innovations in lipid composition and surface functionalization are extending their reach to spleen, lungs, and even the central nervous system. EVs offer a unique advantage due to their endogenous targeting motifs, though predictable redirection requires further elucidation of vesicle surface markers and receptor-ligand interactions.

Immunogenicity is a critical factor that governs both patient safety and therapeutic durability. AAVs, despite their generally mild immune profile, can elicit neutralizing antibodies that diminish vector efficacy and preclude repeated administration. LNPs have shown a comparatively low immunogenic footprint but are not without risks; certain lipid components can trigger inflammatory cascades or hypersensitivity reactions, necessitating careful lipid selection and dosing strategies. EVs are inherently less immunogenic due to their native origin, potentially enabling stealthy delivery, though their heterogeneity and source variability could influence immune recognition profiles.

Clinical progress with these platforms highlights their translational landscapes. Multiple AAV-based therapies have secured regulatory approvals, particularly for inherited retinal diseases, spinal muscular atrophy, and hemophilia, demonstrating the vector’s potent capabilities. LNPs vaulted into the limelight with the COVID-19 mRNA vaccines, proving their clinical viability on a global scale. Meanwhile, EV-based gene delivery is predominantly in preclinical or early-phase clinical stages, with ongoing trials and studies striving to overcome manufacturing and standardization barriers. The convergence of these trajectories suggests a future where hybrid systems or combinatorial approaches might harness the complementary strengths of each platform.

What stands out across all platforms is the necessity for personalized delivery strategies that tailor vector design to the disease and patient characteristics. For monogenic diseases with well-delineated target tissues, viral vectors remain a robust choice. In contrast, genetically complex diseases or those requiring transient gene expression might benefit from the versatility of LNPs. EVs could carve a niche in immunomodulation or applications demanding minimal immune perturbation. The clinical decision-making process is poised to become increasingly nuanced as molecular understanding deepens.

Emerging innovations are pushing the envelope further, with engineered AAVs incorporating microRNA response elements to avoid off-target effects, and LNP formulations integrating targeting ligands that enhance cellular uptake at desired sites. EVs are being biofunctionalized with synthetic peptides or antibodies, augmenting their intrinsic homing capabilities. Additionally, hybrid platforms combining viral and synthetic components are under exploration, aiming to overcome payload size limitations or immunogenicity bottlenecks inherent to single vectors.

Manufacturing scalability also presents a formidable challenge. AAV production demands sophisticated cell culture and purification technologies to yield vectors at clinical grades and volumes. LNP synthesis benefits from established scalable chemistry processes but requires stringent quality control to ensure particle uniformity and encapsulation efficiency. EV isolation, currently reliant on labor-intensive ultracentrifugation or chromatography methods, must evolve toward robust, GMP-compliant processes to facilitate widespread clinical use.

The future of gene delivery platforms is integrally linked to technological advances in genomics, proteomics, and nanotechnology. High-throughput screening platforms allow rapid identification of vector variants with improved tropism or lower immunogenicity. Computational modeling is increasingly leveraged to predict vector interactions and optimize design parameters. Furthermore, single-cell analysis is unraveling cell-type specific delivery patterns, enabling precision therapeutics that were previously unattainable.

Ethical and regulatory frameworks play a pivotal role as well. Ensuring safety and efficacy while accelerating translation demands transparent reporting and harmonized approval pathways. Post-treatment monitoring will be crucial, particularly for vectors with long-lasting or permanent gene modifications, to detect adverse events and long-term outcomes. Patient stratification and informed consent are equally important, underpinning responsible clinical innovation.

Interdisciplinary collaboration emerges as a foundational pillar in this endeavor. Contributions from virology, materials science, immunology, and clinical medicine coalesce to tackle the multifaceted engineering challenges intrinsic to gene delivery. Training the next generation of researchers equipped with this diverse expertise will sustain momentum toward transformative therapies. Equally, partnership with industry and regulatory bodies accelerates translation from bench to bedside, ensuring innovations reach patients swiftly and safely.

In essence, the landscape of gene delivery is at an inflection point, marked by advances that promise to revolutionize treatment paradigms across a multitude of genetic and acquired diseases. The intricate engineering efforts underlying AAVs, LNPs, and EVs delineate a spectrum of options tailored to diverse therapeutic demands. While challenges remain—from payload constraints and immunogenicity to manufacturing hurdles—the collective momentum, built on robust scientific inquiry and translational foresight, heralds an era where safe, scalable, and precise gene therapies become a clinical reality.

As these platforms mature, synergy rather than competition may define their evolution, leveraging complementary strengths to achieve therapeutic outcomes unattainable by any single vector. Ultimately, the rational design and integration of next-generation gene delivery vehicles stand poised to unlock the full potential of genetic medicine, transforming lives across the globe.

Subject of Research: Emerging gene delivery platforms encompassing adeno-associated viruses, lipid nanoparticles, and extracellular vesicles for precision and efficient gene therapy.

Article Title: Engineering challenges and translational opportunities in emerging gene delivery platforms.

Article References:
Ma, Y., Dong, S., Wu, A. et al. Engineering challenges and translational opportunities in emerging gene delivery platforms. Nat. Biomed. Eng (2026). https://doi.org/10.1038/s41551-026-01643-5

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41551-026-01643-5