From a natural gene-regulatory mechanism to a fundament of modern biotechnology, RNA interference is reforming how science approaches disease, ageing, and biological resilience.
By Somi Rishabh
Before scientists learned to edit the genome, cells had already mastered the art of silence with tiny strands of RNA that can suppress up to 90% of a target gene without ever touching DNA. This once obscure biological process is now leading to a revolution in medicine, ageing research, and applied biotechnology. Initially defined as a natural defence mechanism, RNA Interference (RNAi) safeguards cells against viral genetic information and aberrant gene expression. At its core lies a simple but powerful principle: small RNA molecules, such as small interfering RNA (siRNA) and microRNA (miRNA), bind to complementary messenger RNA (mRNA) and prevent it from being translated into protein. This ability to control the expression of genes without modifying the underlying DNA has made RNAi a singularly powerful biological resource (Moffat et al., 2006). As of 2026, advances in RNAi research have gained momentum toward clinical reality. Today, researchers focus on two tightly interconnected objectives: reliable, long-lasting knockdown of target mRNAs in patients and safe, tissue-specific delivery of siRNAs.
Silencing Disease at its Source
An example of a clinical RNAi application is inclisiran (Leqvio®). It is a GalNAc-conjugated siRNA designed to reduce low-density lipoprotein (LDL) cholesterol levels. Approved by the EU in 2020 and the U.S. FDA in 2021, inclisiran demonstrated sustained efficacy in large, randomised controlled trials, resulting in approximately 59% in LDL-C reduction (Novartis, 2025). These findings provided strong practical evidence that siRNA systems, when administered systemically, can result in persistent, clinically significant inhibition of target proteins in humans (U.S. Food and Drug Administration, 2021; 2022).
Similarly, the ongoing EPHARNA program uses an EphA2-targeting siRNA in nanoliposomes, showing a strong inhibitory effect on tumour growth and advancing Phase I first-in-human trials (Reddy et al., 2025). Together, inclisiran and EPHARNA confirm RNAi as a versatile platform for long-term effects across diseases.
Clinical trials led by UCL’s National Amyloidosis Centre have applied RNAi therapy to real patients. In particular, the APOLLO-B study revealed that patisiran, a medication used to treat polyneuropathy, resulted in preserved functional outcome in patients with transthyretin cardiac amyloidosis (Maurer et al., 2023). Similarly, the HELIOS-B study found that vutrisiran significantly reduced mortality and major cardiovascular events (Fontana et al., 2025).
RNAi and Ageing
Beyond treating diseases, RNA interference has opened up a path to the study of ageing. Ageing arises from dysregulation of gene expression, cellular response to stress, and accumulation of molecular damage. Recent studies show that RNAi pathways are involved in cellular homeostasis during stress, affecting other processes, including inflammation, mitochondrial activity, and protein degradation (Ebenezer et al., 2025).
Recent dermatological findings suggest that RNAi-based approaches can selectively silence inflammatory and ageing-related molecular pathways of skin tissues upon appropriate delivery systems. A microRNA-targeted approach has shown particular potential. By modulating networks in fibroblasts (skin-building cells) and keratinocytes (epidermal cells), it reduces markers of senescence. This also lowers levels of inflammatory factors released by the senescence-associated secretory phenotype (SASP) and restores extracellular matrix gene expression. This indicates the role of RNAi in reprogramming ageing-related transcriptional networks (Kim et al., 2023).
Delivery-centred research also shows that using advanced nanocarriers and transdermal delivery methods enhances intracellular siRNA uptake and activation of the RNA-induced silencing complex (RISC) in skin cells, thereby improving RNAi efficacy in cutaneous models (Sufianov et al., 2023; Moazzam et al., 2024).
Challenges and Future Endeavours
RNA interference, though promising, faces substantial obstacles. One major issue is durability. Some experiments suggest that the effects of RNAi could decrease over time, even in non-dividing cells, due to inherent mechanisms of resistance in cells (Jose et al., 2024). Despite these challenges, RNA interference represents a paradigm shift in the approach to molecular control based on biotechnology. Unlike genome-editing technologies that make permanent changes to the DNA, RNAi provides a very specific and reversible method of regulating the expression of genes. Such a degree of flexibility is useful, especially in highly complex biology, where irreversible genetic modifications can have unknown side effects. What began as a quiet cellular defence mechanism is rapidly transforming into a programmable biological platform. As mechanistic precision converges with smarter delivery technologies, RNA interference is moving beyond single-gene therapies toward multi-target systems capable of reshaping entire disease pathways. If the last decade proved that genes can be silenced, the next may prove that regulation itself can be designed: precise, reversible, and intentionally engineered.
References:
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Ravali Annam Reddy et al. EphA2 siRNA in DOPC nanoliposomes (EPHARNA): A phase I clinical trial in patients with solid tumors. J Clin Oncol 43, 3086-3086(2025). DOI:10.1200/JCO.2025.43.16_suppl.3086.
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