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Acute graft-versus-host disease (aGvHD) continues to be a major obstacle to allogeneic haematopoietic stem cell transplantation. Thymic damage secondary to aGvHD along with corticosteroids and other non-selective T lymphocyte-suppressive agents used in the treatment of aGvHD concurrently impair thymopoiesis and negatively impact on immunoreconstitution of the adaptive immune compartment and ultimately adversely affect clinical outcome. Extracorporeal photopheresis (ECP) is an alternative therapeutic strategy that appears to act in an immunomodulatory fashion, potentially involving regulatory T lymphocytes and dendritic cells. By promoting immune tolerance and simultaneously avoiding systemic immunosuppression, ECP could reduce aGvHD and enable a reduction in other immunosuppression, allowing thymic recovery, restoration of normal T lymphopoiesis, and complete immunoreconstitution with improved clinical outcome. Although the safety and efficacy of ECP has been demonstrated, further randomised controlled studies are needed as well as elucidation of the underlying mechanisms responsible and the effect of ECP on thymic recovery.

In the recent past, the gene therapy field has witnessed a remarkable series of successes, many of which have involved primary immunodeficiency diseases, such as X-linked severe combined immunodeficiency, adenosine deaminase deficiency, chronic granulomatous disease, and Wiskott-Aldrich syndrome. While such progress has widened the choice of therapeutic options in some specific cases of primary immunodeficiency, much remains to be done to extend the geographical availability of such an advanced approach and to increase the number of diseases that can be targeted. At the same time, emerging technologies are stimulating intensive investigations that may lead to the application of precise genetic editing as the next form of gene therapy for these and other human genetic diseases.

Abstract: One concern in the use of transplantation of non-hematopoietic stem cells from human umbilical cord blood (CB-nHSCs) is the possibility of rejection by the host''s immune system. This study shows that both CB-nHSCs and their progenies after passaging, neuronal differentiation or IFN-γ treatment have no significant effects on proliferation of xenogenic T lymphocytes. CB-nHSCs transplanted into the striatum of SD rat are shown to induce a lower level of CD4 and CD8 expression in the brain and in the peripheral blood and to survive better in the brain than SH-SY5Y cells. The results indicate that both undifferentiated and differentiated CB-nHSCs all have weak immunogenicity. [Copyright &y& Elsevier]