Fig. 4.

Inscribing light sensitivity in cardiac tissue. A: the most common approaches to optogenetic transduction include the generation of a transgenic animal or different ways of gene delivery: direct plasmid transfection, virally mediated, or cell mediated; the relative efficacy and safety of these approaches is depicted. B: the cell delivery approach works for well-coupled cells like in the myocardium where a tandem cell unit can be formed between a nontransduced myocyte and a nonexcitable donor cell; shown are a canine adult ventricular cell and a donor ChR2 HEK cell where optical stimuli (at 0.2 Hz) drive action potentials in the myocyte [modified with permission from Jia et al. (64)].