Improved oxygen delivery to tissues and iron chelator transport through the use of lysed and resealed red blood cells: a new perspective on Cooley's anemia therapy

Molecular characterization of hepatitis B virus (HBV) isolated from a pediatric case of acute lymphoid leukemia, with a delayed response to antiviral treatment: a case report

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is effectively used as the first-line antiviral for chronic hepatitis B virus (HBV) infection in adults and children older than 12 years. To date, no confirmed case of virologic breakthrough (VBT) in a pediatric case has been reported.

CASE PRESENTATION

Here we describe a case of a 5-year old, asymptomatically infected with HBV infection two months after chemotherapy for precursor B acute lymphoblastic leukemia (ALL). Although the 5-year old male is South African, his family originated from Guinea. At the end of the one-year follow-up, the infection progressed to chronic HBV infection, with a high viral load. At 36 weeks (8 months) post-treatment with lamivudine (LAM), there was a partial virologic response (PVR) and after 61 weeks (14 months), he was switched to TDF rescue monotherapy. Even with TDF treatment, he still experienced VBT and subsequent PVR. The full-length genome of HBV isolated 78 weeks after the switch to rescue TDF monotherapy was sequenced and belonged to genotype E. In addition to the LAM mutations (rtS256G and rtM267L), missense mutations in B-cell, T-cell, HLA class I and II-restricted epitopes emerged, which were to evade and escape host surveillance, leading to delayed viral clearance, persistence and disease progression. Two further events of VBT occurred between weeks 113 and 141 of TDF rescue-therapy. Viral loads and liver enzymes are normalizing progressively with long-term therapy.

CONCLUSION

Although the host immune reconstitution may be delayed, prolonged TDF treatment was effective in treating this pediatric case of HBV infection with VBT and PVR.

Enhanced O2 Transportation During Cardiopulmonary Bypass in Piglets by the use of Inositol Hexaphosphate Loaded Red Blood Cells

A continuous lysing and resealing of erythrocytes permitted internalization of inositol hexaphosphate (IHP), a strong allosteric effector of Hb, leading to significant rightward shifts of the HbO2 dissociation curve. Twelve piglets were put on cardiopulmonary bypass (CPB) with the heart beating, cooled to 25° C then rewarmed to 37° C before weaning off CPB. AoP, LV pressure, PAP, and cardiac output (CO) were monitored. Blood samples were taken before CPB, at 25° C, at 30° C, at 37° C and after CPB for assessment of blood gases, arterio-venous difference in O2 content, lactates, P50 (partial pressure of O2 at 50% Hb saturation), and ionogram. Control group I included five pigs where the CPB circuit was primed with Ringer's lactate solution and porcine blood. In group II (n=5), priming was done with Ringer's lactate solution and IHP loaded erythrocytes. P50 was significantly higher during CPB than before surgery in group II (20%), but not in group I (1%). There was a significant increase in VO2 in group II (6.02 ml/min) compared to group I (4.03 ml/min) (p < 0.05) after CPB. Hemodynamics improved after CPB in group II (mean AoP 42 mmHg and syst LVP 70 mmHg) compared to group I (AoP 25 mmHg and syst LVP 22.5 mmHg). These preliminary results show that O2 transportation at the end of CPB is enhanced and myocardial function is improved in piglets with the use of IHP erythrocytes.

Ex vivo production of human red blood cells from hematopoietic stem cells: what is the future in transfusion?

There is difficulty in obtaining adequate supplies of blood components, as well as disappointing performance of stabilized or recombinant hemoglobins, limited indications of oxygen transporters (perfluorocarbons), and slow development of "universal" red blood cells (RBCs). There is, therefore, a need for complementary sources of RBCs for transfusion. Thus, an attempt to generate erythroid cells in vitro makes good sense. We describe in this article a methodology permitting the massive ex vivo production of mature human RBCs having all the characteristics of native adult RBCs from hematopoietic stem cells of diverse origins: blood, bone marrow, or cord blood. This protocol allows both the massive expansion of hematopoietic stem cells/progenitors and their complete differentiation to the stage of perfectly functional mature RBCs. The levels of amplification obtained (10(5) to 2 x 10(6)) are compatible with an eventual transfusion application. We discuss in this article the state of the art of this new concept and evoke possible obstacles that need to be overcome to pass from a laboratory model to clinical practice. We analyze its possible indications in the medium and long term, discuss the economic aspects, and raise the question: Can we afford the luxury of developing this approach, one that could represent a considerable advance in blood transfusion?

High throughput HPLC-ESI-MS method for the quantitation of dexamethasone in blood plasma

Dexamethasone is a synthetic glucocorticoid with potent anti-inflammatory properties. However, its administration causes significant side effects, specially in long-term therapy. A new approach for limiting adverse effects consists in the slow and constant deliver of this drug, using dexamethasone-21-phosphate-loaded erythrocytes (RBC) as circulating bioreactors converting the non-diffusible dexamethasone-21-phosphate into the diffusible dexamethasone. In order to evaluate the real possibility to use this new method of administration, a simple, cheap and rapid assay was set to manage a large number of samples originating from clinical studies. Due to the sample complexity and analite polarity, electrospray mass spectrometry (MS) is the most powerful technique to achieve qualitative and quantitative data. In order to overcome the complex, time-consuming and expensive LC-MS/MS methods reported in the literature in the present work a standard fluxes HPLC-ESI-MS method was set up for quantitative evaluation of dexamethasone. Thanks to the extraction ion chromatogram (XIC) feature of the software, it was possible to obtain sharp profiles for dexamethasone (DXM) and for the employed internal standard (IS) flumethasone (FM), in spite of the extremely complicated chromatogram obtained after HPLC separation of acetonitrile extracted plasma sample, thus avoiding the use of the expensive deuterated internal standard. This enabled us to obtain a linear response curve, allowing the quantification of DXM from blood samples at the picomoles level.

Low doses of dexamethasone constantly delivered by autologous erythrocytes slow the progression of lung disease in cystic fibrosis patients

OBJECTIVE

To evaluate the safety and efficacy of the administration of low doses of glucocorticoids in patients with cystic fibrosis (CF) by using autologous erythrocytes loaded with dexamethasone 21-phosphate.

STUDY DESIGN

Nine consecutive CF patients (patients nos. 1-9) received autologous erythrocytes loaded with increasing amounts of dexamethasone 21-phosphate to obtain a slow delivery of dexamethasone in circulation. The appearance of possible adverse effects, the reproducibility of the procedure, and the dexamethasone pharmacokinetics were evaluated. Subsequently, patient no. 9 and eight additional patients (patient nos. 10-17) received dexamethasone 21-phosphate-loaded erythrocytes at 1-month intervals to evaluate the efficacy of continuous release in circulation of low doses of dexamethasone.

RESULTS

Erythrocytes from CF patients can be processed to be loaded with increasing dexamethasone 21-P concentrations. Once reinfused in respective donors, a slow and prolonged delivery of dexamethasone in the blood stream was measured up to 28 days. Repeated administrations of drug-loaded erythrocytes at 4-week intervals for 15 months showed that very low doses of glucocorticoids provide significant improvement in FEV1 values and significant reduction of infective relapses due to Pseudomonas aeruginosa without adverse effects.

CONCLUSIONS

The administration of very low doses of glucocorticoids using autologous erythrocytes is possible, with benefits for patients and without side effects. This method is likely to be extended to other chronic diseases.

Stable rightward shifts of the oxyhemoglobin dissociation curve induced by encapsulation of inositol hexaphosphate in red blood cells using electroporation

Rightward shifts of 50-100% of the P50 values in the oxygen dissociation curve of intracellular hemoglobin are obtained after encapsulation of inositol hexaphosphate in mouse and dog red blood cells (RBC) by electroporation. Life spans of mouse RBC-myo-inositol hexaphosphate in circulation are unchanged from the normal RBC values.

Plasma separator for encapsulating fluorescent probe in erythrocytes

Using a plasma separator, it is possible to wash large volumes of whole blood free of plasma proteins in short periods. The novelty, however, is that the same apparatus can be used to reversibly hemolyze and reseal the red blood cells (RBCs) using hypotonic and hypertonic dialysates, respectively. This technique was assessed using the fluorescent exogenous agent uranin (fluorescein sodium). Results indicate that the encapsulation of the RBCs can be completed in under 2 h. The encapsulation efficiency of the RBCs was approximately 80% with a RBC recovery rate of 75%.