Biologic brachytherapy: ex vivo transduction of microvascular beds for efficient, targeted gene therapy.
BACKGROUND
Gene therapy for cancer holds enormous therapeutic promise, but its clinical application has been limited by the inability to achieve targeted, high-level transgene expression with limited systemic toxicity. The authors have developed a novel method for delivering genes to microvascular free flaps (commonly used during reconstructive surgery) to avoid these problems.


METHODS
During the finite period in which a free flap is separated from the host (ex vivo), it can be perfused with extremely high titers of genetic material through the afferent artery, resulting in efficient transduction of the tissue. Before reanastomosis, unincorporated genetic material is flushed from the flap, minimizing systemic toxicity.


RESULTS
In a rodent model using an adenoviral vector containing the lacZ reporter gene, high regional expression of beta-galactosidase was achieved in all the different cells in a microvascular free flap. Moreover, no beta-galactosidase staining was observed outside of the transduced flap, and viral sequence was undetectable by polymerase chain reaction analysis in other tissues. Further analysis confirmed that high-level transgene expression was precisely localized to the explanted tissue, with no collateral transduction.


CONCLUSIONS
Targeting gene delivery with minimal systemic toxicity is essential for successful gene therapy. This form of "biological brachytherapy" provides a new opportunity to deliver targeted therapeutic transgenes to patients undergoing reconstructive surgery and allows microvascular free flaps to perform therapeutic and reconstructive functions.
Michaels
Joseph
J
Laboratory of Microvascular Research and Vascular Tissue Engineering, Institute of Reconstructive Plastic Surgery, New York University Medical Center, New York 10016, USA.
Levine
Jamie P
JP
Hazen
Alexes
A
Ceradini
Daniel J
DJ
Galiano
Robert D
RD
Soltanian
Hooman
H
Gurtner
Geoffrey C
GC
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001918:Brachytherapy; D004797:Enzyme-Linked Immunosorbent Assay; D015316:Genetic Therapy / Q000379:methods*; D007763:Lac Operon; D008297:Male; D023421:Models, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D013524:Surgical Flaps / Q000098:blood supply; D001616:beta-Galactosidase / Q000378:metabolism
D001616:beta-Galactosidase