IF a bioengineered thymus construct—composed of a young decellularized murine thymus scaffold recellularized with autologous aged thymic epithelial cells (TECs) transduced with AAV-FOXN1 at a multiplicity of infection (MOI) of 100—is implanted subcutaneously into 18-month-old C57BL/6 mice,

THEN functional thymopoiesis will be restored, evidenced by a ≥40% increase in peripheral naive T-cells (CD62L+CD44-) relative to age-matched controls and T-cell receptor excision circle (TREC) levels rising to ≥60% of young mouse baselines by week 8, alongside the histological restoration of organized K8+ cortical and K5+ medullary domains,

BECAUSE

1. Age-related thymic involution involves both the loss of intrinsic TEC functionality (driven by down-regulation of the master regulator FOXN1) and the deterioration of the thymic extracellular matrix microenvironment.
2. Transduction with AAV-FOXN1 forces the transcriptional rejuvenation of aged TECs, upregulating downstream targets required for T-cell lineage commitment and selection.
3. Seeding these rejuvenated TECs onto a decellularized scaffold derived from a young donor provides the optimal structural and signaling cues (preserved via SDS/Triton X-100 decellularization) required for spatial cortico-medullary organization.
4. [SPECULATIVE] The restored 3D physical niche combined with high Foxn1 expression synergistically supports the recruitment of circulating lymphoid progenitors and their subsequent maturation into fully functional naive T-cells, circumventing the age-related fibrotic restrictions of the endogenous thymus.

One-liner: Combining AAV-FOXN1 genetic rejuvenation of aged TECs with the structural youth of young decellularized scaffolds restores robust naive T-cell output and reverses immunosenescence.

SENS category: RepleniSENS

Key references: • doi.org/10.1172/jci.insight.140313] • doi.org/10.1172/jci.insight.140313],