This study is a prospective, randomized, controlled, double-blinded clinical trial in patients with sickle cell diseases, ages 10-21 years, with acute, severe vaso-occlusive pain crisis. The goal of this project is to evaluate the clinical effectiveness and safety of inhaled nitric oxide (NO) in the treatment of vaso-occlusive pain crisis in pediatric patients with sickle cell disease. This is the first study to access the effectiveness and safety of inhaled NO to treat vaso-occlusive sickle cell pain crisis. Prevention and treatment of pain crisis is one of the greatest challenges in sickle cell disease. Vaso-occlusion results from polymerization of hemoglobin S (HbS) at low oxygen saturation and susequent sickling of red blood cells within the microcirculation. At present, there is no specific approved therapy to attenuate or reverse pain crisis in pediatric patients. Recently, inhaled nitric oxide has been shown to increase oxygen afinity of sickle erythrocytes in stable adult sickle cell patients indicating that NO may inhibit HbS polymerization. If NO increases oxygen affinity of HbS during pain crisis, it may attenuate and possibly reverse the crisis. This may reduce the requirement for narcotic therapy and transfusions, the frequency and duration of hospital admissions, and the severity of long-term sequelae. To evaluate clinical effectiveness, the primary outcome measure will be change in pain assessment score pre- and post-inhalation therapy. Secondary measures will be requirement for pain medication, transfusions, and hospitalization, and concentration of acute phase reactants. Outcome measures to evaluate safety will be concentrations of methemoglobin, methemoglobin reductase and nitrogen dioxide (NO2), oxygen saturation, vital signs, oxygen transport and cell sickling. M01RR02172-18-0196 Open-label study of C1 INH-IMMUNO in the treatment of Hereditary Angioedema (HAE). HAE is a condition in which acute, recurrent episodes of well circumscribed, nonpitting, subepithelial edema primarily involving the extremities, face, abdomen, and larynx. HAE is characterized by a marked decrease in functional C1 inhibitor. This study attempts to control the symptoms of HAE by administering C1 inhibitor. The C1 inhibitor is effective therapy for the treatment of attacks of HAE with no adverse reactions.