[Hydroxyurea treatment in patients affected with sickle cell anemia: efficacy and safety]

Improvement of SCD morbimortality in children: experience in a remote area of an African country

BACKGROUND

Sickle cell disease (SCD) is a public health problem in the Democratic Republic of Congo. While reference sickle cell centers have been implemented in capital cities of African countries and have proven to be beneficial for SCD patients. In the Democratic Republic of Congo, they have never been set up in remote areas for families with low or very low sources of income.

METHOD

A cohort of 143 children with SCD aged 10 years old (IQR (interquartile range): 6-15 years) (sex ratio male/female = 1.3) were clinically followed for 12 months without any specific intervention aside from the management of acute events, and then for 12 months with a monthly medical visit, biological follow-up, and chemoprophylaxis (folic acid/penicillin), adequate fluids and malaria prevention.

RESULTS

The median age of patients at the diagnosis of SCD was 2 years (IQR: 1-5). The implementation of standardized and regular follow-ups in a new sickle cell reference center in a remote city showed an increase in the annual mean hemoglobin level from 50 to 70 g/L (p = 0.001), and a decrease in the lymphocyte count and spleen size (p < 0.001). A significant decrease (p < 0.001) in the average annual number of hospitalizations and episodes of vaso-occlusive crises, blood transfusions, infections, and acute chest syndromes were also observed.

CONCLUSIONS

The creation of a sickle cell reference center and the regular follow-up of children with sickle cell disease are possible and applicable in the context of a remote city of an African country and represent simple and accessible measures that can reduce the morbimortality of children with sickle cell disease.

Two assays to evaluate potential genotoxic effects of hydroxyurea in sickle cell disease patients

Hydroxycarbamide, well known in clinical settings as hydroxyurea (HU), is an antineoplastic agent inhibiting the ribonucleotide reductase enzyme, and thus, the conversion of ribonucleotides into deoxyribonucleotides. A concern about long term side effects of HU treatment in sickle cell disease patients, particularly genotoxicity, has often been evoked. The present study assessed two suitable methods to evaluate oxidative DNA damage associated with HU: the comet assay on blood lymphocytes and the quantification of urinary excretion of 8-oxodeoxyguanosine (8-oxodG). Both methods were applied in a preliminary study including seven sickle cell disease patients treated with HU, seven untreated sickle cell disease patients and five healthy volunteers. Concerning DNA damage, the comet assay and the 8-oxodG assay did not reveal any significant differences among the three groups. Methodologies used in this pilot study could be suitable to carry out further research in this area including a larger size sample setting.

A biophysical indicator of vaso-occlusive risk in sickle cell disease

The search for predictive indicators of disease has largely focused on molecular markers. However, biophysical markers, which can integrate multiple pathways, may provide a more global picture of pathophysiology. Sickle cell disease affects millions of people worldwide and has been studied intensely at the molecular, cellular, tissue, and organismal level for a century, but there are still few, if any, markers quantifying the severity of this disease. Because the complications of sickle cell disease are largely due to vaso-occlusive events, we hypothesized that a physical metric characterizing the vaso-occlusive process could serve as an indicator of disease severity. Here, we use a microfluidic device to characterize the dynamics of "jamming," or vaso-occlusion, in physiologically relevant conditions, by measuring a biophysical parameter that quantifies the rate of change of the resistance to flow after a sudden deoxygenation event. Our studies show that this single biophysical parameter could be used to distinguish patients with poor outcomes from those with good outcomes, unlike existing laboratory tests. This biophysical indicator could therefore be used to guide the timing of clinical interventions, to monitor the progression of the disease, and to measure the efficacy of drugs, transfusion, and novel small molecules in an ex vivo setting.