Non-invasive Estimation of Microvasculopathy & Endothelial Dysfunction in Stem Cell Transplant Recipients and its Relationship with GVHD

Introduction: Microvasculopathy and endothelial dysfunction play important roles in the development of post-transplant complications, including graft-versus-host disease (GVHD). We assessed structural microvasculopathy by employing nailfold video capillaroscopy (NFVC) and endothelial dysfunction via flow-mediated dilatation (FMD) of the brachial artery in recipients of hematopoietic stem cell transplantation.

Patients and methods: Recipients of stem cell transplantation were included in this study post day+100 and divided into two cohorts. The first cohort consisted of 35 recipients of allogeneic hematopoietic stem cell transplantation (HCT) and the second cohort was comprised of 31 recipients of autologous HCT. A third cohort included 35 healthy individuals. NFVC was conducted on the second to fifth fingers of both hands using an Optilia video capillaroscope at 200× magnification, and the images were analyzed according to the European Alliance of Associations for Rheumatology (EULAR) criteria. The following parameters were used to measure vasculopathy: (a) median capillary density, derived from the capillary density of eight fingers, (b) median capillary diameter, derived from maximum capillary apical diameters of eight fingers, and (c) significant neoangiogenesis (neoangiogenesis present in ≥2 fingers). FMD of the right brachial artery was observed by high-resolution ultrasonography using the principle of post-occlusive reactive hyperemia, and video images were analyzed using edge-detecting software.

Results: The median capillary diameter was significantly higher in the allo-HCT cohort (20.56±5.17 micrometer) compared to the auto-HCT cohort (16.19±3.31 micrometer; p<0.001) and healthy controls (14.66±2.61 micrometer; p<0.001). The median capillary density was significantly lower in the allo-HCT cohort (median: 6 capillaries/mm, range: 5-9 capillaries/mm) compared to the auto-HCT cohort (median: 8.5 capillaries, range: 5-12 capillaries/mm; p<0.001) and healthy controls (median: 8 capillaries/mm, range: 7-10.5 capillaries/mm; p<0.001). The allo-HCT cohort had a higher proportion of patients with significant neoangiogenesis (86%) than the auto-HCT cohort (10%) and healthy controls (9%). The presence of significant neoangiogenesis was more frequent in the subgroup of patients with a history of GVHD (93%) compared to the subgroup of patients without any history of GVHD (57%; p=0.044). No significant differences in NFVC parameters or FMD were observed between recipients of myeloablative and reduced-intensity conditioning regimens. There was no significant difference in NFVC parameters between the auto-HCT cohort and healthy controls. There was no significant difference in FMD among the three cohorts; however, a higher proportion of patients in the allo-HCT cohort (28%) had lower FMD than those in the auto-HCT cohort (3%) and healthy controls (6%), suggesting endothelial dysfunction.

Conclusions: Our findings demonstrate the presence of structural microvasculopathy in allo-HCT recipients and suggest a possible role of alloreactivity in the pathogenesis of post-HCT microvasculopathy.