A Transgenic tdTomato Rat for Cell Migration and Tissue Engineering Applications

Area of Science:

• Regenerative Medicine
• Biomaterials Science
• Transgenic Animal Models

Background:

• Engineered tissues are crucial for organ transplantation due to donor shortages.
• Tracking implanted cells is vital for safety and efficacy, but green fluorescent protein (GFP) faces autofluorescence challenges in musculoskeletal tissues.
• Tandem-dimer tomato (tdTomato) offers superior brightness and reduced autofluorescence compared to GFP.

Purpose of the Study:

• To create a transgenic rat line ubiquitously expressing tdTomato for improved cell tracking in tissue engineering.
• To assess the utility of tdTomato rats in fabricating and implanting engineered skeletal muscle units (SMUs).
• To evaluate a modular approach for combining SMUs to address larger tissue defects and validate cell migration in a volumetric muscle loss (VML) model.

Main Methods:

• Generation of a transgenic rat line expressing tdTomato under the human ubiquitin C promoter.
• Fabrication of tdTomato-expressing SMUs from isolated muscle cells.
• Implantation of modular tdTomato SMUs into a VML defect in GFP-expressing rats.
• Histological analysis to assess cell integration, migration, and tissue regeneration.

Main Results:

• Successful generation of tdTomato transgenic rats enabling robust cell tracking.
• Implantation of modular SMUs significantly reduced VML defect size after 28 days.
• Histology confirmed tdTomato (implanted) and GFP (host) cell co-localization at the repair site, indicating successful regeneration and cell integration.
• Validation of a modular SMU assembly method for creating larger engineered tissues.

Conclusions:

• Transgenic tdTomato rats provide a superior tool for tracking cells in tissue engineering applications, overcoming GFP limitations.
• The study successfully demonstrated the efficacy of engineered skeletal muscle units in repairing VML injuries.
• A novel modular approach for scaling engineered tissues was validated, paving the way for clinical applications in volumetric tissue repair.