Reconstitution of the immune system after hematopoietic stem cell transplantation

T cell reconstitution after allogeneic hematopoietic cell transplantation (alloHCT) is indispensable for the success of this procedure. Thymus plays a key role after alloHCT in the generation of a broad T cell repertoire. However, the thymus is very sensitive to a wide range of insults during the alloHCT period such as conditioning regimen, corticosteroids, infections or graft-versus-host disease. While thymus as the potential for endogenous regeneration, this regeneration is often suboptimal and delayed. Therefore development of new therapeutic strategies to enhance thymic regeneration after alloHCT is expected. Murine models allow identification of numerous promising therapeutic strategies and some of them, such as interleukin 7, sex steroids ablation, keratinocyte growth factor or growth hormone are already evaluated in the clinical setting.