Static Magnetic Field-Mediated Parathyroid Xenotransplantation Modulates Lymphocyte Migration: A Potential Immunosuppression-Free Long-Term Treatment for Hypoparathyroidism

Static magnetic fields (SMFs) are underexplored as biophysical tools for transplant immunomodulation. This study investigated a 300 mT SMF as a non-pharmacological adjuvant to enhance graft survival in parathyroid xenotransplantation. Human parathyroid tissues were transplanted into Sprague-Dawley rats (n = 20) across four groups: control (G1), SMF-only (G2), transplantation-only (G3), and SMF-assisted transplantation (G4). Following 30-day continuous SMF exposure, functional and immunological assessments were performed. G4 achieved the highest systemic PTH recovery (p = 0.009) without altering intrinsic secretory capacity. Systemic cytokine profiling revealed significant IFN-gamma suppression in G4 (p = 0.0024), suggesting downregulation of Th1-mediated rejection pathways. While G2 showed pro-inflammatory increases (TNF-alpha, GM-CSF), G4 maintained baseline levels, confirming biocompatibility. IHC confirmed that SMF exposure sequestered lymphocytes to the graft periphery, preventing the diffuse infiltration observed in G3. In conclusion, continuous SMF exposure modulates the immune microenvironment by altering lymphocyte migration and IFN-gamma signaling. This biophysical strategy provides localized immunoprotection, potentially offering a drug-free alternative to systemic immunosuppression in endocrine tissue transplantation.