Characterization of age-dependent changes to hemodynamics and thymocyte motility in the native thymus after SL-TBI using two-photon intravital microendoscopy 4457

Abstract Description The thymus, as the primary site of T cell maturation, plays a critical role in the functionality of the adaptive immune system, and as such, the recovery of the thymus after injury and the role that the thymus vasculature system plays in the thymus regeneration process is of significant medical interest. Previously, our lab developed an intravital thymus imaging method and found significant increases in thymus blood vessel diameter, leakage, frequency, and area after sublethal total body irradiation (SL-TBI). To further study hemodynamics and thymocyte motility, we developed a vacuum-stabilized two-photon microendoscope. The stabilization of the vacuum system was found to sufficiently minimize tissue movement (±5 μm displacement) and enable optical sectioning of the thymus. To study thymus recovery, wild-type (C57BL/6J) and UBC-GFP (C57BL/6-Tg (UBC-GFP)30Scha/J) mice ranging in age from 8-52 weeks received SL-TBI (4.5 Gy). Wild-type mice received 106 whole BM cells from UBC-GFP mice 1-day after SL-TBI and were imaged 7/14-days post transplantation to study thymocyte motility. In contrast to previous measurements, blood vessel diameters were found to significantly decrease from 7 to 14 days and significant thymocyte motility was observed, with a max average velocity of ∼15 μm/min. These results provide insight into the thymus recovery process and demonstrate intravital microendoscopy as a powerful tool to study the native thymus. Funding Sources NIH 1R01HL171971-01A1 Topic Categories Technological Innovations in Immunology (TECH)