Table 3.

Delivery of DNA and RNA With VEGF as an Example

	Purpose	Transduced/ Delivered NA	Route	Features	Examples of Use
Plasmid-mediated delivery	Intended CA and PA therapies	VEGF-encoding plasmids	IM, IMC, TREC	Advantage: Safety, ease Disadvantage: transiency	Clinical trials for CAD and PAD
Modified RNA delivery	Improve heart function	VEGF modified RNA	IMC	Advantage: Sustained effect	Mouse MI model
Adenovirus	Robust VEGF secretion	Different VEGF isoforms	IV, IM, IMC, TREC	Inflammation, hepatotropism	Clinical trials for CAD and PAD
AAV	Sustained VEGF secretion/VEGF inhibition	VEGF/shRNA	IM, IMC, IC, IO	Nonimmunogenic or inflammatory, sustained, postmitotic cell tropism, ease of combinatorial delivery; inducible vectors	VEGF production in preclinical models of myocardial, ocular, and brain angiogenesis, limb ischemia, neurogenesis
Lentivirus	Sustained VEGF secretion/VEGF inhibition	VEGF/shRNA	IM, IMC, IC, IO	Efficient, stable transduction; transduce both dividing and postmitotic cells, inducible constructs	VEGF production in preclinical models of myocardial, peripheral, ocular, and cerebral angiogenesis; VEGF silencing in tumors
VEGF ectopic/overexpression, conditional	Ectopic/overexpression of VEGF in selected organs or cell types	Different VEGF isoforms	Transgenesis	Organ/cell-type specificity dictated by the choice of driving. promoter; temporal controls by tamoxifen inducibility	Conditional VEGF induction in many different organs and by specific cell types therein
VEGF ectopic/overexpression, conditional and reversible	Ectopic/overexpression of VEGF in selected organs or cell types in a reversible manner	Different VEGF isoforms	Transgenesis	VEGF on and off switching regulated by doxycycline	Distinguishing phenotypes requiring continuous VEGF from “hit-and-run” actions
Transgenic modifications of endogenous VEGF	Replacing endogenous VEGF gene (or its regulatory sequences) with a modified version	A construct targeting the VEGF locus	Gene replacement	Enables precise mutations in both coding and noncoding regions affecting any facet of VEGF biology	Transgenic reporter for endogenous VEGF expression; VEGF hypomorphic alleles; VEGF with altered splicing pattern; hypoxia nonresponsive VEGF (an ALS model)
Conditional VEGF LOF	Precluding endogenous VEGF production	VEGF deletion using the Cre/lox system	Option of delivering Cre via viral infection	Enables VEGF deletion in organ/cell type of choice using floxed VEGF and a tissue-specific Cre recombinase	VEGF deletion in almost every adult organ; uncovers the whole spectrum of nonvascular VEGF functions
Conditional and reversible VEGF LOF	Reversible inhibition of endogenous VEGF signaling	Conditional induction of a transgene encoding a VEGF trap	Inducer added in drinking water	On and off switching of a doxycycline-regulated VEGF decoy receptor	Produce hypoperfused myocardium for modeling ischemic heart disease; study reversibility of phenotypes caused by VEGF blockade or insufficient perfusion

AAV indicates adeno-associated virus: ALS, amyotrophic lateral sclerosis; CA, cardiac angiogenesis; CAD, coronary artery disease; IC, intracerebral; IM, intramuscular; IMC, intramyocardial; IO, intraocular; IV, intravascular; LOF, loss of function; MI, myocardial infarction; PA, peripheral angiogenesis; PAD, peripheral artery disease; shRNA, short hairpin RNA; TREC, transendocardial (catheter-aided); and VEGF, vascular endothelial growth factor.