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Biodistribution and Shedding Studies for Lentiviral Vectors in Immunocompromised Mouse Models

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Biodistribution and Shedding Studies for Lentiviral Vectors in Immunocompromised Mouse Models

Biodistribution and Shedding Studies for Lentiviral Vectors

CELL & GENE | RNA | BIOLOGICS

    What is the primary analytical method for LVV biodistribution studies?

    A: Quantitative PCR (qPCR) or droplet digital PCR (ddPCR) are the standard assays used to detect and quantify vector DNA sequences in collected tissues and fluids, providing high sensitivity and specificity.

    Why are immunocompromised models required for lentiviral vector studies?

    A: These models are necessary to prevent host immune clearance of the vector and the human cells it transduces. This allows for the accurate assessment of long-term vector persistence, integration, and expression, which mirrors the intended human therapeutic context.

    What sample types are collected for shedding analysis?

    A: A comprehensive shedding study analyzes excreta (urine, feces), saliva, blood, and environmental samples such as cage swabs to evaluate the potential for vector transmission.

    How long are biodistribution studies typically run?

    A: Study duration is program-dependent and guided by regulatory feedback. Timelines can range from several weeks to more than six months post-administration to capture both initial distribution kinetics and long-term vector persistence.

This page outlines the regulatory-driven requirements and technical execution of biodistribution and shedding studies for lentiviral vectors (LVVs) within immunocompromised animal models. We detail the quantitative PCR (qPCR) and droplet digital PCR (ddPCR) methodologies for assessing vector presence in target and non-target tissues, as well as the comprehensive sample collection required for a robust shedding analysis. These studies are required components of the Investigational New Drug (IND) application, providing safety data to support an 18-24 month timeline to get candidates to IND.

A stylized 3D rendering of a DNA double helix, composed of light-colored spheres on a translucent blue backbone, set against a soft-focus, light blue background.

Designing Robust LVV Biodistribution Studies

A well-designed biodistribution study is a required component of any preclinical program for an integrating vector like a lentivirus. The objective is to precisely quantify the vector’s location, concentration, and persistence across a comprehensive panel of tissues over time. For LVV programs, particularly those involving ex vivo modification of human cells, the use of immunocompromised models is standard to ensure the survival of the therapeutic cell product and enable meaningful long-term analysis.

Our approach focuses on:

  • Tissue Collection: A full panel of tissues is collected at multiple time points post-administration, based on FDA and EMA guidance.

  • Quantitative Analysis: We employ validated qPCR and ddPCR assays to detect vector sequences with high sensitivity, providing absolute quantification of vector copy numbers per cell.

  • Data Interpretation: The resulting data set informs the safety profile by confirming delivery to the target organ system and quantifying any presence in non-target tissue biodistribution.

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Quantifying Vector Shedding for Environmental Risk Assessment

Shedding studies evaluate the potential for a vector to be released from the subject through excreta and secreta. This analysis is a key part of the environmental risk assessment required by regulatory bodies. The study design must be rigorous, accounting for all potential routes of excretion.

We systematically collect and process samples including:

  • Urine and Feces

  • Saliva

  • Blood

  • Cage Swabs

Each sample type is analyzed using the same sensitive qPCR or ddPCR methods as the biodistribution component to determine if, and for how long, vector sequences are detectable. This provides a clear picture of any potential for horizontal transmission.

“We started collaborating with UPenn Vector core in 2023 and the AAV vector which they manufactured laid a foundation for development of a gene therapy candidate which will enter soon preclinical studies. The key people from UPenn Vector Core joined Franklin Biolabs and our partnership transitioned without interruption from UPenn Vecor Core to Franklin Biolabs Research Vector Division. Franklin Biolabs is our trusted partner in our AAV-vector based gene therapy candidate development and we hope to continue the partnership for years to come.”
— Biotech Partner

A close-up of a scientist in blue gloves gently holding a small, white laboratory mouse, likely in a research setting.

Integrating Biodistribution Data with Histology

Quantitative PCR data provides information on vector location and concentration, while integrating this with histology clarifies the biological effect. By correlating vector copy number with microscopic tissue analysis, we can assess any potential local inflammation, cellular changes, or other findings associated with vector presence. This dual-pronged approach strengthens the overall safety assessment. The strategic value of confirming predominant target organ sequestration to build a favorable safety profile is a widely accepted principle for advancing vector-based programs.

Our GxP-compliant studies are conducted within our >100,000 sq ft facility, which includes extensive animal housing and specialized laboratory space. While the Franklin Biolabs brand was established in 2024, our core scientific team brings a long history of success: since 2019, programs leveraging their preclinical data packages have achieved a 100% IND success rate.

All in vivo studies are conducted in strict accordance with the 3Rs principles (Replacement, Reduction, and Refinement). Through our strategic partners, such as the AAALAC-accredited Bioculture Group, we ensure all research adheres to the highest ethical standards and USDA regulations.

Scientific Process Diagram

This content is for informational purposes. For guidance specific to your therapeutic program, please contact our team for a consultation.

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