What are the commonly used transfection methods?

Transfection is a technique used to introduce exogenous nucleic acids (e.g., plasmid DNA, mRNA, siRNA, and oligonucleotides) into eukaryotic primary cells or cell lines in vitro or into carefully selected animal models in vivo. The commonly used transfection methods broadly fall into three categories - physical, viral, and chemical methods. Of the three main types of transfection, chemical-mediated transfection is the most widely used in contemporary research for its ease and cost-effectiveness.

• Physical-Mediated Transfection

Physical transfection methods, such as electroporation, microinjection, and biolistic particle delivery, rely on a diverse set of physical tools that use mechanical or electrical forces to deliver exogenous nucleic acids. Of the various types of physical transfection, electroporation is the most widely used.

• Chemical-Mediated Transfection

Chemical-mediated transfection relies on electrostatic interactions to deliver exogenous nucleic acids into cells. In this method, electrostatic forces between the cationic charges on the lipid or polymer groups of transfection reagents and the negatively charged phosphates of nucleic acids cause the two substances to associate, resulting in positively charged transfection complexes. These cationic transfection complexes, in turn, interact with negatively-charged glycoproteins, such as heparan sulfate proteoglycans, expressed on the cell surface triggering the cellular uptake of exogenous nucleic acid via endocytosis or phagocytosis.

• Viral-Mediated Transfection

Viral-mediated transfection, also known as transduction, is widely used in clinical research for its high in vivo transfection efficiency and sustained gene expression without severely affecting cell viability. In contrast to chemical transfection methods, no transfection reagent is required. Instead, the viral vector infects the cells and delivers the genetic material directly to the nucleus. Common viral delivery systems include adenoviral, oncoretroviral, lentiviral, baculovirus, and vaccinia virus-based vectors.