GMI-1070 is a new drug that may reduce the stickiness of cells in the blood. The purpose of this study is to evaluate whether GMI-1070 can reduce the time it takes for pain to go away in patients with vaso-occlusive crisis (also known as a sickle cell pain crisis). The study will also collect information on the safety of GMI-1070, how much of the drug is in the blood and urine, and if there are any other effects when used in patients who are in the hospital for a sickle cell pain crisis.