Hematopoietic Stem Cell Transplantation in Rheumatic Diseases

Hematopoietic stem cell transplantation (HSCT) is an emerging therapeutic strategy for severe autoimmune rheumatic diseases (AIRD) where conventional therapies often fail to achieve long-term remission. This review focuses on the role of HSCT in specific AIRD, including systemic sclerosis (SSc), systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), deficiency of adenosine deaminase 2 (DADA2), antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, Takayasu arteritis (TA), and juvenile idiopathic arthritis (JIA).

The objective was to evaluate the efficacy, immunological mechanisms, patient selection criteria, conditioning regimens, and outcomes of HSCT in the management of these specific AIRD, with a focus on systemic sclerosis-associated interstitial lung disease (SSc-ILD).

A comprehensive literature review was conducted, analyzing clinical trials, observational studies, and preclinical research on HSCT in the following AIRD: SSc, SLE, RA, DADA2, ANCA-associated vasculitis, TA, and JIA. The review examined pulmonary outcomes, immune reconstitution, CD34+ cell selection, and post-transplant immunosuppression. Keywords used in the search included SSc, SLE, RA, DADA2, ANCA-associated vasculitis, Takayasu arteritis, and JIA.

HSCT has demonstrated promising outcomes, particularly in diffuse cutaneous SSc with ILD improvement and in refractory cases of SLE, RA, and JIA. In DADA2, HSCT can reverse hematological, immunological, and vascular phenotypes. While effective in some cases of ANCA-associated vasculitis and TA, relapses and complications remain a concern. Immunological benefits include the regeneration of a self-tolerant immune system. However, early transplant-related mortality (TRM) necessitates careful patient selection and reduced toxicity conditioning.

HSCT offers a transformative approach for select patients with refractory SSc, SLE, RA, DADA2, ANCA-associated vasculitis, TA, and JIA, achieving long-term, drug-free remission in some. Future research should optimize conditioning protocols, refine patient selection, and assess long-term outcomes to maximize HSCT benefits and minimize risks.