Improving Thymus Implantation for Congenital Athymia with Interleukin-7

Patients receiving thymus implantation develop a functional but incomplete T cell compartment. Our objective was to develop a mouse model to study clinical thymus implantation in congenital athymia and to optimize implantation procedures to maximize T cell education and expansion of naïve T cells. Treating implanted mice with recombinant interleukin (IL-7) promoted homeostatic expansion that improved T cell development, expanded the T cell receptor repertoire, and normalized the naïve T cell compartment. After culturing, slices of thymus were transplanted intrarenally, under the kidney capsule, into 4-week old male Foxn1nu mice. After 12 weeks, cells were collected and pooled from spleens, lymph nodes, and blood. After RBC lysis using ACK Lysing Buffer, T cells were isolated using a MojoSort Mouse T Cell Isolation Kit. RNA samples were collected from T cells using NucleoSpin RNA purification kit. Before implant, osmotic pumps were primed in 0.9% NaCl saline at 37°C for 2 days. On the day of thymus implantation, the pump was filled with 10 mg IL-7 in 180 μL PBS (or vehicle) and implanted in mouse subcutaneously after thymus implantation. Naive treatment group received no surgical procedures or treatment.