Autologous hematopoietic stem cell transplantation reverses skin fibrosis but does not change skin vessel density in patients with systemic sclerosis

Hematopoetic stem cell transplantation (HSCT) improves survival in patients with severe systemic sclerosis (SSc) by resetting the immune system. We studied how HSCT acts on the key SSc skin pathology findings (fibrosis and vascularization). In mean, 3 skin punch biopsies per patient (range 2–6) were analyzed from 13 patients (5 females) with severe diffuse SSc before and up to 96 months after HSCT. Fibrosis of the four skin layers was graded semi-quantitatively and an overall fibrosis score was then calculated. Vessel numbers and calibers were assessed in the superficial and deeper dermis after immune-staining for endothelial antigens (CD31, VE-cadherin and vWF). The median age of patients at HSCT was 47 (24–64) years. The overall median modified Rodnan skin score decreased from 24 to 10 (P = 0.003) at first follow-up within a median of 9 (6–36) months after HSCT as did the histological skin score (P = 0.03). The modified Rodnan skin score and the fibrosis score correlated positively (r = 0.589, P < 0.001). The vessels density did not significantly change after HSCT nor did the expression of the tested endothelial markers. Although improving skin fibrosis in patients with SSc, HSCT does not alter vessel density within skin biopsies.