This protocol describes a method to inject plasmid DNA into the mouse kidney via the renal pelvis to produce transgene expression specifically in the kidney.
Hydrodynamic injection creates a local, high-pressure environment to transfect various tissues with plasmid DNA and other substances. Hydrodynamic tail vein injection, for example, is a well-established method by which the liver can be transfected. This manuscript describes an application of hydrodynamic principles by injection of the mouse kidney directly with plasmid DNA for kidney-specific gene expression. Mice are anesthetized and the kidney is exposed by a flank incision followed by a fast injection of a plasmid DNA-containing solution directly into the renal pelvis. The needle is kept in place for ten seconds and the incision site is sutured. The following day, live animal imaging, Western blot, or immunohistochemistry may be used to assay gene expression, or other assays suited to the transgene of choice are used for detection of the protein of interest. Published methods to prolong gene expression include transposon-mediated transgene integration and cyclophosphamide treatment to inhibit the immune response to the transgene.
The hydrodynamic tail vein injection technique has become a commonly used way to achieve high levels of gene expression in mouse liver1,2. The kidneys are also transfected by this technique at a much lower level, approximately 100-fold less3. The hydrodynamic renal pelvis injection described here provides a simple way to control the specificity of organ expression through physical means using the same hydrodynamic principles that have been established previously in liver4,5, muscle6, and other organs7,8. This method transfects cells in live animals in vivo by using pressure and speed to force fluid containing DNA into the cells, simultaneously inducing damage to the organ that is quickly resolved9. Using well-established surgical techniques to visualize the kidney via a flank incision10 along with a single injection by insulin syringe, we have found successful transfection of various types of kidney cells, mainly interstitial fibroblasts, tubules, and collecting duct11. Dissection of these mice has shown that other organs are not transfected at levels high enough to visualize by luciferase imaging techniques11. Since the technique is non-viral, use of plasmid DNA for transfection permits fast and easy preparation of the reagents required for injection.
We have used localized hydrodynamic injections to express the antioxidant glutathione S-transferase A4, the insulin-like growth factor-1 receptor, and the hormone erythropoietin in the kidney, all with the expected biological effects11,12,13. Detailed evaluation of route of administration, injection volume, DNA dosage, and promoter choice has been performed11. Additionally, both the piggyBac transposon system and/or cyclophosphamide treatment to suppress the immune reaction to the transgene have been shown to improve long-term gene expression outcomes11. Other investigators have used a renal vein approach in rat with success, achieving high transfection efficiency for time periods of greater than one month14. However, genetic correction of phenotypes mimicking human disease are usually performed in mice first as a proof-of-concept since most mammalian genetic models are mouse models. We compared renal vein injection to renal pelvis injection and found that injection into the renal pelvis was superior to the renal vein for gene expression (approximately ten-fold higher) and survival11. The renal pelvis is an ideal route of entry into the kidney because it is flexible enough to tolerate fluctuations in urine production and is often able to maintain its structural integrity even when dilated during hydronephrosis. Additionally, injection into the renal pelvis allowed access to the kidney without piercing the kidney capsule, allowing the injected fluid to be visibly retained by the kidney better than intraparenchymal injection. Other mouse organs do not have a route of entry other than the vasculature, but the urinary space of the kidney is an ideal injection site. Additionally, injection into the renal vein resulted in leakage of blood into the abdominal cavity. The total kidney volume of wild-type mouse kidneys has been estimated by magnetic resonance imaging to be approximately 0.2 cm3, so the volume of a single kidney is approximately equal to the amount of fluid injected by renal pelvis hydrodynamic injection (100 µL)15. Herein, we have made available all of the detailed nuances of the hydrodynamic renal pelvis injection protocol to achieve reproducible transfection of the kidney.
In this protocol a robust method for achieving reproducible gene expression specifically in the kidney is described. In the hands of a moderately experienced surgeon we have found the percentage of mice transfected by this technique to be in the range of 50-100%, depending on mouse age and the sensitivity of the readout of the transgene. The level of luciferase gene expression was above background for several months in mice receiving piggyBac transposons and completely maintained for several weeks in immunocompr…
The authors have nothing to disclose.
A Career Development Award from the Department of Veterans Affairs [BX002797] supported L.E.W. and the National Institutes of Health [R01-DK095867] and American Heart Association [15GRNT25700209] supported J.C. The National Institutes of Health [DK093660], Department of Veterans Affairs [BX002190], and the Vanderbilt Center for Kidney Disease supported M.H.W. This material is the result of work supported with resources and use of facilities at the VA Tennessee Valley Healthcare System.
AnaSed Xylazine | Patterson Veterinary | 07-808-1947 | Anesthetic – Not controlled substance |
BD Insulin Syringe 0.5 mL 29G 1/2 Inch | Cardinal Health | 309306 | Required syringes |
Buprenex | Pharmacist/Veterinarian | Analgesia – Controlled Substance | |
Dynarex Disposable Towel Drape | Thermo Fisher Scientific | 19-310-671 | Place over heat pad |
EndoFree Plasmid Maxi Kit | Qiagen | 12362 | Use only endotoxin-free plasmid DNA |
Endosafe Gel-Clot LAL Rapid Positive Control | Charles River | PC200 | Positive control for endotoxin test |
Endosafe Gel-Clot LAL Rapid Single Test Vial | Charles River | R13500 | Endotoxin test |
Extra Fine Micro Dissecting Scissors | Roboz Surgical Instrument | RS-5882 | Surgical tool |
Fisherbrand Instant Sealing Sterilization Pouch – 9" | Thermo Fisher Scientific | 01-812-51 | For autoclaving surgical tools |
Gaymar Heat Pump | Paragon Medical | TP-700 | Water-circulating heat pump |
Germinator 500 | Roboz Surgical Instrument | DS-401 | To reuse surgical tools during surgery |
Graefe Forceps | Roboz Surgical Instrument | RS-5136 | Surgical tool |
Graefe Tissue Forceps | Roboz Surgical Instrument | RS-5153 | Surgical tool |
Halsey Needle Holder, 5" Length | Roboz Surgical Instrument | RS-7841 | Surgical tool |
Heat pads – 15" x 21" – need at least 3 | Paragon Medical | TP22G | For use with Gaymar Heat Pump |
IsoFlo (Isoflurane, USP) | Abbott Animal Health | 5260-04-05 | For imaging and euthanasia |
Isotec Isoflurane Delivery System Vaporizor | Smiths Medical | VCT3K2 | For imaging and euthanasia |
Ketamine | Pharmacist/Veterinarian | Anesthetic – Controlled Substance | |
Kimwipes | Kimberly-Clark Professional | 34120 | Laboratory tissues |
Living Image software | Caliper Life Sciences | For live animal imaging | |
Luciferin | Perkin Elmer | 122796 | For live animal imaging |
Nanodrop 2000 | Thermo Scientific | ND-2000-US-CAN | Spectrophotometer for DNA measurement |
Prevantics Swabs | Thermo Fisher Scientific | 23-100-110 | For skin surgery prep |
Prolene 5-0 sutures Taper 30" | Thermo Fisher Scientific | NC0256891 | Non-absorbable sutures for skin |
Puralube Brand Opthalmic Ointment | Patterson Veterinary | 07-888-2572 | To keep eyes moist during surgery |
Trans IT – QR Hydrodynamic Delivery Solution | Mirus Bio | MIR-5240 | Hydrodynamic delivery buffer for diluting DNA |
Vicryl 5-0 Sutures J303H | Thermo Fisher Scientific | NC9816710 | Absorbable sutures for muscle layer |
Wahl Mini Arco Clipper | Med-Vet International | 8787-1550 | Shaver for skin prep |
Xenogen IVIS 200 | Caliper Life Sciences | For live animal imaging |