The question that is posed in the research is what effect does differing hemoglobin from patients with sickle cell anemia on lung epithelial tissue.
The experiments concluded in the discussion that while all of the hemoglobin variants caused damage to the cells, the Hbs and HbE were less stable than HbA, and as a result, were more likely to lead to heme loss in the proteins. In addition, Hbs and HbE both allowed higher permeability of epithelial cells, but not in HbA. The conclusion of the data assumes that while free Hb in the blood by itself is damaging. However, if the Hb was of the variant where the Hb is less structurally sound, as in dysfunctional Hb, there was more damage to the function of other cells.
The impact on SCD is that while it was thought that just the presence of free Hb in the blood is damaging, because of the protein instability of Hb in patients with sickle cell anemia, their Hb are more likely to be damaging to the lung epithelial cells compared to Hb protein from someone who is not ill. The fact that it is more damaging indicates that when researching the treatment of SCD symptoms, a model that uses a normal Hb would not be an accurate representation of the symptom of people with SCD. Knowing this would create a better model for a scientist to use to research treatments.