Allogeneic processed thymus tissue

The thymus is a critical organ of the immune system as it is responsible for the maturation and selection of thymocytes so that they ultimately become naïve T cells. Normally, T cell precursors from the bone marrow migrate to the thymus for maturation and differentiation. Congenital athymia is characterized by the absence of a thymus at birth, leading to the lack of functional T cells and profound immune deficiency; therefore, patients with congenital athymia are at high risk for developing life-threatening or fatal infections as well as autologous graft-versus-host disease.

Allogeneic processed thymus tissue aims to restore thymic function in patients with congenital athymia. Thymus tissue is obtained from unrelated infant donors to be processed and cultured, so that the thymus tissue preserves thymic epithelial cells but lacks most of the donor thymocytes. The resulting allogeneic processed thymus tissue is then surgically implanted into the muscles of recipients with congenital athymia. T cell progenitors from the bone marrow of the recipient are migrated to the implanted allogeneic processed thymus tissue, which provides an environment for progenitor cells to undergo positive and negative selection to develop into naïve immunocompetent recipient T cells.