Kidney Week

Abstract: SA-PO642

Adeno-Associated Virus (AAV)-Mediated Gene Therapy in Nphs1 Knockout Mice: A Strategy for Treating Congenital Nephrotic Syndrome

Session Information

• Genetic Kidney Diseases: Models, Mechanisms, and Therapies
  October 26, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Genetic Diseases of the Kidneys

• 1202 Genetic Diseases of the Kidneys: Non-Cystic

Authors

• Saida, Ken, Boston Children's Hospital, Boston, Massachusetts, United States

Ken Saida, MD, PhD

• Yu, Seyoung, Boston Children's Hospital, Boston, Massachusetts, United States

Seyoung Yu, MS

• Braun, Alina, Boston Children's Hospital, Boston, Massachusetts, United States

Alina Braun, MD

• Franken, Gijs AC, Boston Children's Hospital, Boston, Massachusetts, United States

Gijs AC Franken, MS, MSc, PhD

• Lomjansook, Kraisoon, Boston Children's Hospital, Boston, Massachusetts, United States

Kraisoon Lomjansook, MD

• Lemberg, Katharina, Boston Children's Hospital, Boston, Massachusetts, United States

Katharina Lemberg, MD

• Kolvenbach, Caroline Maria, Boston Children's Hospital, Boston, Massachusetts, United States

Caroline Maria Kolvenbach, MD, DrMed

• Mansour, Bshara, Boston Children's Hospital, Boston, Massachusetts, United States

Bshara Mansour, MD

• Yousef, Kirollos, Boston Children's Hospital, Boston, Massachusetts, United States

Kirollos Yousef, MBChB, MS

• Riedhammer, Korbinian M., Boston Children's Hospital, Boston, Massachusetts, United States

Korbinian M. Riedhammer, MD

• Mertens, Nils David, Boston Children's Hospital, Boston, Massachusetts, United States

Nils David Mertens, MD

• Elmubarak, Izzeldin, Boston Children's Hospital, Boston, Massachusetts, United States

Izzeldin Elmubarak, MD

• Schneider, Ronen, Boston Children's Hospital, Boston, Massachusetts, United States

Ronen Schneider, MD

• Shril, Shirlee, Boston Children's Hospital, Boston, Massachusetts, United States

Shirlee Shril

• Buerger, Florian, Boston Children's Hospital, Boston, United States

Florian Buerger, MD, PhD

• Hildebrandt, Friedhelm, Boston Children's Hospital, Boston, Massachusetts, United States

Friedhelm Hildebrandt, MD

Background

Finnish-type congenital nephrotic syndrome (CNS) causes nephrin dysfunction and disrupts glomerular filtration barrier. Podocyte-specific Nphs1 knockout mouse models recapitulate the human CNS phenotype and have a median survival of 18 days (Buerger F. Am J Physiol Renal Physiol 2024). Establishing AAV-based gene therapy in neonatal mice is crucial for treating CNS. Although AAV serotypes exhibit broad organ tropism, efficient kidney targeting, particularly in podocytes, remains challenging. In addition, the efficiency of AAV-mediated gene expression in neonatal mouse kidneys remains unclear.

Methods

Retro-orbital (RO) and intrarenal injections of AAV capsids (AAV9, AAV-PHP.S, AAV-DJ, and AAV-KP1) carrying the CAG promoter and tdTomato were administered to P1 mice (Nphs1^tm1.1Pgarg/J Nphs2-Cre⁺ vs. control). The injected AAV dose was >1E+14 vg/kg. For RO injections, 10 µL of AAV was injected into each eye using a 31-gauge insulin syringe under cryo-anesthesia. For intrarenal injections, 10 µL AAV was percutaneously delivered into the left kidney over a minute using a syringe pump. The mice were dissected three weeks post-injection, and transduction efficiency was assessed by immunofluorescence (IF) and flow cytometry (FC).

Results

RO injection in P1 mice resulted in transduction of the proximal tubules and glomeruli. In glomeruli, distinct podocyte transduction was confirmed by super-resolution microscopy. FC analysis of AAV9 and AAV-PHP.S injected mice shows transduced podocytes accounting for >13%, as indicated by the presence of podocalyxin-positive cells expressing tdTomato. Intrarenal injection of AAV-KP1 into the left kidney of P1 mouse resulted in significant tdTomato expression in both tubular and glomerular cells, whereas the uninjected right kidney showed only glomerular transduction. We achieved a podocyte transduction rate of >50% in most of the mature glomeruli via intrarenal injection.

Conclusion

This study demonstrated the feasibility of podocyte transduction, providing a proof-of-principle for AAV gene therapy in a CNS mouse model. Further optimization is required to enhance the efficiency of AAV delivery to podocytes.