Gene therapy is a technique that aims to treat or cure disease through the modification of gene expression. Mutation and deletion in the genome may cause diseases by interfering with metabolic pathways, cell cycle regulation, cytoskeleton, and ligand/receptor function. Gene therapy is an emerging treatment that rewrites or fixes errors at the genetic level and overcomes the limitations associated with the direct administration of therapeutic proteins, including low bioavailability, systemic toxicity, in vivo instability, high hepatic and renal clearance, and high manufacturing cost. Many gene therapeutic drugs are being developed to treat diseases including cancer, genetic diseases, and infectious diseases.
Gene therapy can work by replacing a disease-causing gene with a healthy copy of the gene, suppressing a disease-causing gene that does not function properly, or introducing a new or modified gene into the body. Antisense oligonucleotides (ASOs), micro ribonucleic acids (miRNAs), small interfering RNAs (siRNAs), and short hair-pin ribonucleic acid (shRNA) can be developed as gene therapeutic drugs to inhibit the expression of specific proteins by silencing mRNAs in cells. Corrective gene therapy involves targeted modification of genome sequences in eukaryotes using engineered or bacterial nucleases such as zinc finger nucleases (ZFNs), clustered regulatory interspaced short tandem repeats (CRISPR)/CRISPR-associated (Cas) proteins, and transcription activator-like effector nucleases (TALEN). The goals of gene editing are to disrupt harmful genes or to repair mutated genes.
Amerigo Scientific provides building blocks, modified nucleoside derivatives, and intermediates for the chemical synthesis of nucleic acids, high-quality synthetic mRNAs and GMP-grade enzymes for mRNA synthesis, as well as CRISPR/Cas proteins for gene editing.
Building blocks, modified nucleoside derivatives, intermediates, and other reagents for nucleic acid synthesis
High-quality synthetic mRNA products with great stability that can be efficiently translated into factors or receptors
Class 2 CRISPR/Cas enzymes including Cas9, Cas12a, Cas12b, Cas12f, and Cas13 nucleases for gene editing
GMP-grade mRNA synthesis enzymes for the development and manufacture of mRNA therapeutic drugs
In gene therapy, the desired genes can be transferred into cells either directly or via a vector. Because naked nucleic acid molecules can be simply fragmented by enzymes, vectors are useful for delivering genes into target cells. Gene vectors are generally classified into viral and non-viral types. Non-viral vectors such as liposomes, lipid nanoparticles, polymers, dendrimers, and inorganic scaffolds are being developed for gene delivery. Nevertheless, viruses are naturally evolved gene delivery systems that inherently provide high levels of transduction efficiency. Common viral vectors are adenovirus, adeno-associated virus (AAV), retrovirus, lentivirus, and herpes simplex virus (HSV).
Each viral vector has its own unique advantages and limitations for gene therapy applications, and may require further refinement for therapeutic purposes. Adenoviruses are non-integrated, non-enveloped, linear dsDNA viruses that can deliver genes to both dividing and non-dividing cells with very high transduction efficiency, but often stimulate an immune response to infected cells, causing a loss of therapeutic gene expression after injection. Similar to adenoviruses, AAVs can infect both dividing and non-dividing cells, but they have limited packaging capacity (<5 kb). In addition, AAVs are highly stable, non-pathogenic and do not initiate an immunological response and pathological effects in humans. Retroviruses are generally single-stranded, diploid, circular enveloped RNA viruses, and they can be permanently integrated into the genome of infected cells and require cell division for transduction. Lentiviruses can transduce both dividing as well as non-dividing cells, resulting in prolonged gene expression. HSV vectors have the advantage of being able to infect non-dividing cells and the ability to carry large exogenous DNA, but cytotoxicity and maintenance of transgene expression limit their applications.
Viral Vector Comparison for Gene Therapy
Vector | Adenovirus | AAV | Retrovirus | Lentivirus | HSV |
---|---|---|---|---|---|
Genome | dsDNA | ssDNA | ssRNA | ssRNA | dsDNA |
Tropism | Dividing and non-dividing cells | Dividing and non-dividing cells | Dividing cells | Dividing and non-dividing cells | Dividing and non-dividing cells |
Packaging Capacity | ~8-36kb | ~5kb | 8kb | 8-10kb | >30kb |
Integration | Non-integrating | Non-integrating | Integrating | Integrating | Non-integrating |
Expression | Transient | Stable | Stable | Transient or stable | Stable |
Immunogenicity | High | Low | Moderate | Moderate | High |
Amerigo Scientific provides viral packaging systems, as well as AAV-related products including empty capsids, antibodies, ELISA kits, and serotype testing panels for viral vector preparation.
Systems for packaging of expression cassette into retroviral or lentiviral particles
Well-characterized AAV empty capsids that can be used as reference materials in assays
Antibodies for monitoring and optimizing entire AAV production processes
ELISA kits for the determination of full and empty capsids of AAV serotypes
Testing panels for the selection of the optimal AAV serotype for specific applications
Compared with viral vectors, non-viral vectors have lower cytotoxicity, immunogenicity and mutagenicity, which are promising delivery systems to promote the development of gene therapy. Cationic polymers are an important non-viral gene therapy vector due to their versatile chemical structure and potential high loading capacity. They neutralize negatively charged genetic material to form a complex and deliver the payload to target cells. Lipids are a common type of gene delivery vectors. Most lipids consist of positively charged headgroups that bind to the anionic phosphate groups of nucleic acids through electrostatic interactions to form lipid complexes. Lipid complexes are often present as liposomes, solid lipid nanoparticles, or lipid emulsions due to the self-assembled lipid tail structure. Compared with other vector materials, lipids are biodegradable, less toxic, and can incorporate both hydrophilic and hydrophobic substances. Inorganic gene vectors are more stable than organic materials. Common inorganic vectors include mesoporous silica nanoparticles, gold nanoparticles, magnetic nanoparticles, carbon nanotubes, graphene, upconversion nanoparticles, and quantum dots.
Amerigo Scientific provides a variety of non-viral vector materials and research tools for gene delivery.
Lipid materials and PEGylated derivatives that can be used to form lipid nanoparticles for mRNA delivery
Liposomes, modified liposomes, and other research tools for drug delivery
N-acetylgalactosamine (GalNAc) CPG for the synthesis of siRNA-GalNAc conjugates
ZnO QDs and ZnO2 NPs with consistency and stability for drug delivery
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