Bone marrow transplantation in the treatment of systemic sclerosis

Systemic sclerosis (SSc) is an uncommon, progressive, sometimes lethal fibrotic disease whose pathogenesis probably includes immunologic elements, especially early in its course. There is no proven therapy for this disease, although some promising results have been obtained with the use of immunosuppressive drugs such as cyclophosphamide. There exists a subgroup of patients who have rapidly progressive disease or who are not responsive to conventional treatment, and who may benefit from intensive immunosuppression with stem cell rescue (stem cell transplantation). The rationale for bone marrow transplantation (BMT), and, more recently, peripheral blood stem cell transplantation (SCT), has been validated by studies on animal models of autoimmunity. Autologous transplantation has shown encouraging anecdotal results, and it is now being evaluated in phase I/II studies in patients with predictably poor outcome. In this light, reliably identifying patients early in the course of SSc is extremely important in order to establish correct eligibility criteria. For patients unable to tolerate transplant regimens, other approaches may be feasible. In this regard, nonmyeloablative approaches, such as immunosuppression without rescue and mixed chimerism, are also discussed.