Potent Intradermal Gene Expression of Naked Plasmid DNA in Pig Skin Following Pyro-drive Jet Injection

Abstract

Intradermal administration of naked DNA with a conventional needle syringe is a simple and inexpensive method to expose an encoded antigen to the dermal immune system. We aimed to enhance intradermal gene expression with a pyro-drive jet injector using pig skin, which is similar in structure and biomechanical properties to human skin. When Cy3-labeled plasmid (pCy3) was applied to pig skin with the jet injector, pCy3 was distributed preferentially in the intradermal tissue. Precise localization analysis revealed that pCy3 was also detected in the intracellular nucleus, and the frequency was substantially higher with the jet injector than with a needle syringe. When a luciferase expression plasmid (pLuc) was injected transdermally, the luciferase activity was 380-fold higher with the jet injector than with a needle syringe. Furthermore, immunohistochemistry analysis showed that the epidermis was positive for luciferase protein expression. These data indicate that the jet injector facilitates stable intradermal administration, resulting in more efficient gene expression compared to that with conventional syringe methods. Thus, intradermal administration of an antigen-expression plasmid with the pyro-drive jet injector may provide a clinically viable method for future gene therapy.

Induction of potent antitumor immunity by intradermal DNA injection using a novel needle‐free pyro‐drive jet injector

“… 10 Although this explanation accounts for the efficient induction of OVA‐specific CTLs with the use of the PJI, whether resident DCs in the epidermis such as Langerhans cells and dermal DCs are indeed preferentially induced after injection of plasmid DNA using the PJI rather than a needle syringe remains to be clarified. Because the injection power of the PJI is primed by gunpowder, the injection occurs at very high flow rate (approximately 1 ml s −1 ), 12 and the flow rate for injection with a needle syringe is less than 0.025 ml s −1 . 24 Because the injection flow rate affects subsequent protein expression, 24 the much higher injection flow rate with the PJI than with a needle syringe is likely to account for the augmented protein expression.…”

“…The PJI (called Actranza) was provided by the Daicel Corporation, and 25 mg ignition powder and 40 mg smokeless powder were used for mice (Figure S1 ). 9 , 10 , 11 , 12 After the mouse abdominal skin was shaved, 20 μl OVA‐expression plasmid DNA (pOVA, 2 mg/ml; Addgene) or GFP‐expression plasmid DNA (pGFP, GFP cDNA subcloned in the pCAGGS vector, 13 provided from Dr. Miyazaki, 2 mg/ml) was intradermally injected into both the right and left flank areas (two sites each, total four sites/mouse) using the PJI or a needle syringe (Micro‐Fine Insulin Syringe 30G × 8 mm needle; BD Biosciences). OVA protein in PBS (1 or 10 mg/ml; Sigma‐Aldrich) was emulsified in an equal volume of CFA (BD Difco), and 100 μl of the emulsified mixture (CFA/OVA, 500 μg as a positive control or 50 μg for comparison with AlumVax) was subcutaneously injected into two sites in both flanks.…”

“…8 Very recently, we developed a novel needle‐free PJI that has the advantage of adjustability in the dose delivered and depth of delivery through a choice between two types of explosive. 9 , 10 , 11 , 12 Luciferase‐ and OVA‐expression DNA were efficiently delivered to dermal tissue by intradermal injection with the PJI, and protein expression was found to be far higher than with a typical needle syringe. 9 , 10 In addition, OVA‐specific antibody production was greatly enhanced.…”

“…In contrast with the typical needle injection, needle‐free injection offers several advantages that are useful in situations of large‐scale vaccination or limited vaccine supply: dose‐sparing because of intradermal efficiency, elimination of needle‐stick injuries and cross‐contamination by re‐use, and lower healthcare costs 8 . Very recently, we developed a novel needle‐free PJI that has the advantage of adjustability in the dose delivered and depth of delivery through a choice between two types of explosive 9–12 . Luciferase‐ and OVA‐expression DNA were efficiently delivered to dermal tissue by intradermal injection with the PJI, and protein expression was found to be far higher than with a typical needle syringe 9,10 .…”

A Review of Genes Involved in Wound Healing

“…Based on the studies carried out recently, injected plasmid-DNA could be transferred to distant organs by CD11b+ cells beyond regional lymph nodes. Additionally, the transgene transport and cellular uptake could be amplified using inflammation in this model ( 43 ).…”