Cerebral hemodynamic changes after haploidentical hematopoietic stem cell transplant in adults with sickle cell disease

Preliminary evidence from a series of 4 adults with sickle cell disease (SCD) suggests that hematopoietic stem cell transplant (HSCT) improves cerebral hemodynamics. HSCT largely normalizes cerebral hemodynamics in children with SCD. We tested the hypothesis in adults with SCD that cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2) measured using magnetic resonance imaging, normalized to healthy values, comparing measurements from ∼1 month before to 12 to 24 months after HSCT (n = 11; age, 33.3 ± 8.9 years; 389 ± 150 days after HSCT) with age-, race- and sex-matched values from healthy adults without sickle trait (n = 28; age, 30.2 ± 5.6 years). Before transplant, 7 patients had neurological indications for transplant (eg, overt stroke) and 4 had nonneurological reasons for haploidentical bone marrow transplant (haplo-BMT). All received haplo-BMT from first-degree relatives (parent, sibling, or child donor) with reduced-intensity preparation and maintained engraftment. Before transplant, CBF was elevated (CBF, 69.11 ± 24.7 mL/100 g/min) compared with that of controls (P = .004). Mean CBF declined significantly after haplo-BMT (posttransplant CBF, 48.2 ± 13.9 mL/100 g/min; P = .003). OEF was not different from that of controls at baseline and did not change significantly after haplo-BMT (pretransplant, 43.1 ± 6.7%; posttransplant, 39.6 ± 7.0%; P = .34). After transplant, CBF and OEF were not significantly different from controls (CBF, 48.2 ± 13.4 mL/100 g/min; P = .78; and OEF, 39.6 ± 7.0%; P > .99). CMRO2 did not change significantly after haplo-BMT (pretransplant, 3.18 ± 0.87 mL O2/100 g/min; posttransplant, 2.95 ± 0.83; P = .56). Major complications of haplo-BMT included 1 infection-related death and 1 severe chronic graft-versus-host disease. Haplo-BMT in adults with SCD reduces CBF to that of control values and maintains OEF and CMRO2 on average at levels observed in healthy adult controls. The trial was registered at www.clinicaltrials.gov as #NCT01850108.