1. Introduction
Regenerative medicine and in situ tissue engineering have emerged as transformative strategies for treating complex tissue injuries and degenerative diseases. Central to their success is the ability to deliver nucleic acids, including plasmid DNA (pDNA), small interfering RNA (siRNA), microRNA (miRNA), and messenger RNA (mRNA), efficiently to targeted cells to modulate gene expression and promote tissue regeneration (Motamedi et al., 2024; Wu et al., 2025; Yuan et al., 2025). Despite the promise of gene-based therapeutics, their clinical translation is hindered by several challenges, including enzymatic degradation, off-target effects, limited cellular uptake, immunogenicity, and toxicity (Motamedi et al., 2024; Zhu et al., 2022, as cited in Motamedi et al., 2024).
Delivery systems for nucleic acids can be broadly categorized into viral and non-viral vectors. Viral vectors, including adenoviruses, adeno-associated viruses (AAVs), and lentiviruses, exploit the natural gene transfer mechanisms of viruses, providing high transduction efficiency and stable expression (Motamedi et al., 2024; Wu et al., 2025; Yan et al., 2022, as cited in Motamedi et al., 2024). AAV vectors are particularly well-studied, with applications in neurogenesis, skeletal muscle gene editing, and spinal cord repair (Finkel et al., 2024, as cited in Wu et al., 2025; He et al., 2021, as cited in Wu et al., 2025; Wang et al., 2019, as cited in Motamedi et al., 2024). Lentiviral vectors have demonstrated utility in nerve regeneration and targeted gene silencing but are constrained by risks of insertional mutagenesis and immunogenicity (Wu et al., 2013, as cited in Wu et al., 2025; Castanotto & Rossi, 2009, as cited in Motamedi et al., 2024). Although viral vectors achieve high efficiency, their safety profile limits broader clinical adoption, prompting the development of safer alternatives.
Non-viral vectors, particularly engineered nanoparticles, have gained prominence due to their lower toxicity, tunable properties, and favorable safety profiles. These carriers include lipid-based nanoparticles (LNPs), polymeric nanoparticles (PNPs), inorganic nanoparticles (INPs), and biomimetic vectors such as exosomes and peptide-based systems (Motamedi et al., 2024; Wu et al., 2025; Yuan et al., 2025). LNPs, composed of ionizable cationic lipids, phospholipids, cholesterol, and polyethylene glycol (PEG) lipids, provide protection against nucleic acid degradation and enable cell-specific targeting through ligand conjugation, exemplified by GalNAc-siRNA conjugates for liver therapy (Kulkarni et al., 2018, as cited in Wu et al., 2025; Lamb, 2021, as cited in Motamedi et al., 2024). Polymeric carriers, including polyethyleneimine (PEI), poly(amidoamine) dendrimers (PAMAM), chitosan nanoparticles, and poly(L-lysine) derivatives, offer flexibility in engineering charge, surface functionality, and endosomal escape mechanisms (Wu et al., 2025; Walsh et al., 2021, as cited in Wu et al., 2025). Inorganic nanoparticles, such as gold, mesoporous silica, and cerium oxide, provide structural stability and high surface area for functionalization, though concerns over long-term bioaccumulation persist (Wu et al., 2025; Yuan et al., 2025). Biomimetic vectors, including exosomes and engineered bacteria, further enhance biocompatibility, immune evasion, and cell-specific delivery (Zhang et al., 2020, as cited in Wu et al., 2025; Xu et al., 2009, as cited in Motamedi et al., 2024).
Integration of these delivery systems into biomaterial scaffolds is crucial for achieving localized, controlled, and sustained release. Scaffold platforms include injectable hydrogels, three-dimensional (3D) porous scaffolds, and sheet-like systems (Wu et al., 2025). Hydrogels, particularly temperature-sensitive, self-assembling, and stimuli-responsive systems, facilitate minimally invasive delivery and protect nucleic acids from degradation while providing controlled release kinetics (Wu et al., 2025; Ding et al., 2019; Ka & Ce, 2017, as cited in Wu et al., 2025). Three-dimensional scaffolds mimic the extracellular matrix, enabling structural support alongside gene delivery. These scaffolds have demonstrated enhanced outcomes in bone regeneration, nerve repair, and vascularized tissue engineering when combined with non-viral nanocarriers (Walsh et al., 2021, as cited in Wu et al., 2025; Zhang et al., 2021, as cited in Wu et al., 2025). Sheet-like delivery systems, including layer-by-layer (LbL) films, polymer fiber films, and microneedle patches, provide sustained, superficial release for skin, wound, and ulcer repair (Castleberry et al., 2016a, as cited in Wu et al., 2025; Qu et al., 2020, as cited in Wu et al., 2025).Clinical translation of these systems, however, faces multiple challenges. Mechanical limitations, particularly in self-assembling hydrogels, limit load-bearing applications. Long-term biocompatibility and bioaccumulation of inorganic nanoparticles raise safety concerns (Wu et al., 2025). Furthermore, manufacturing complexity, sterilization, and regulatory compliance present substantial hurdles for widespread clinical adoption. Light-responsive systems are constrained by limited tissue penetration, precluding use in deeper tissue sites (Wu et al., 2025). Despite these challenges, meta-analysis across preclinical studies consistently demonstrates that non-viral vectors combined with biomaterial scaffolds significantly improve gene delivery efficiency, tissue repair, and regeneration outcomes, highlighting their potential as clinically translatable platforms (Motamedi et al., 2024; Wu et al., 2025; Yuan et al., 2025).
