Luigia Rossi

Erythrocyte-mediated delivery of drugs, peptides and modified oligonucleotides

An important determinant for the success of every new therapy is the ability to deliver the molecules of interest to the target cells or organ. This selective delivery is even more complex when the therapeutic agents are peptides, modified oligonucleotides or genes. In this paper we summarize the possibility of using autologous erythrocytes for the delivery and targeting of new and conventional therapeutics. In fact, a number of macromolecules can be encapsulated by different procedures into human erythrocytes. These modified cells can then be re-infused into the same or a compatible recipient where they can circulate for several weeks. However, drug-loaded erythrocytes can also be modified to be selectively recognized by tissue macrophages. These phagocyte cells recognize the modified drug-loaded erythrocytes which are able to release their content into the macrophage. The feasibility and safety of the use of erythrocytes as drug delivery systems was evaluated in 10 cystic fibrosis patients, where a sustained release of corticosteroids from dexamethasone 21-phosphate-loaded erythrocytes was obtained. In vitro human erythrocytes were found to be able to deliver ubiquitin analogues and modified oligonucleotides to macrophages. Thus, drug-loaded erythrocytes are safe and useful carriers of new and conventional therapeutics and can be advantageous delivery systems for new clinical applications where proteins and oligonucleotides are therapeutic agents.

Erythrocyte engineering for drug delivery and targeting.

A new procedure for the encapsulation of non‐diffusible drugs into human erythrocytes was developed. With as little as 50 ml of blood and by using a new apparatus, it was possible to encapsulate a variety of biologically active compounds into erythrocytes in 2 h at room temperature and under blood‐banking conditions. The process, which is based on two sequential hypotonic dilutions of washed red cells followed by concentration with a haemofilter and resealing of red cells, allows a 35–50% cell recovery and approx. 30% encapsulation of added drugs. The resulting processed erythrocytes have a normal survival in vivo and can be modified further, with the same apparatus, to increase their recognition by tissue macrophages to perform as a drug‐targeting system. The new equipment designed and built for this procedure was named ‘Red Cell Loader’.

Erythrocyte‐mediated delivery of dexamethasone in patients with chronic obstructive pulmonary disease

Human erythrocytes from ten patients with chronic obstructive pulmonary disease (COPD) were loaded with increasing amounts of dexamethasone 21‐phosphate and were re‐infused into the original donors. Drug‐loaded erythrocytes acted as circulating bioreactors, converting the non‐diffusible dexamethasone 21‐phosphate into the diffusible dexamethasone. Pharmacokinetic analyses on these patients showed that a single administration of drug‐loaded erythrocytes was able to maintain detectable dexamethasone concentrations in blood for up to seven days. This continuous release of dexamethasone was paralleled by the suspension of β2‐agonist and oral corticosteroid treatments by all of the patients. Thus dexamethasone 21‐phosphate‐loaded erythrocytes are safe carriers for corticosteroid analogues and are a useful alternative to frequent oral or inhaled drugs in elderly patients with COPD.

Ultrastructural analysis of pancreatic acinar cells from mice fed on genetically modified soybean

No direct evidence that genetically modified (GM) food may represent a possible danger for health has been reported so far; however, the scientific literature in this field is quite poor. Therefore, we investigated the possible effects of a diet containing GM soybean on mouse exocrine pancreas by means of ultrastructural, morphometrical and immunocytochemical analyses. Our observations demonstrate that, although no structural modification occurs in pancreatic acinar cells of mice fed on GM soybean, quantitative changes of some cellular constituents take place in comparison to control animals. In particular, a diet containing significant amount of GM food seems to influence the zymogen synthesis and processing.

Erythrocyte-Mediated Delivery of Dexamethasone in Patients With Mild-to-Moderate Ulcerative Colitis, Refractory to Mesalamine: A Randomized, Controlled Study

BACKGROUND AND AIM:Nearly 25% of patients with ulcerative colitis (UC) requiring steroids therapy become steroid-dependent after 1 yr, and virtually all develop steroid-related adverse events. We planned a controlled study to investigate the efficacy and safety of dexamethasone 21-P (Dex 21-P) encapsulated into erythrocytes (DEE).MATERIALS AND METHODS: Forty patients with mild-to-moderate UC, refractory to mesalamine, were randomly assigned to one of the following three treatments: two DEE infusions 14 days apart (group A, N = 20), oral prednisolone (0.5 mg/kg for 14 days followed by a 6 mg/weekly tapering (group B, N = 10), and sham infusions (group C, N = 10). The clinical, biochemical, and endoscopic parameters were monitored at inclusion and after 8 wk.RESULTS:In group A, a mean dose of 9.9 ± 4.1 mg Dex 21-P was loaded into autologous erythrocytes at each infusion. At 8 wk, 15 patients in group A (75%), 8 in group B (80%), and 1 in group C (10%, P < 0.001 vs A and B) were in clinical and endoscopic remission. When compared with the baseline values, C-reactive protein (CRP) dropped in groups A (1.6 mg/dL vs 0.4 mg/dL, P= 0.006) and B (1.0 vs 0.5, P= 0.02), but not in group C. No steroid-related adverse events were apparent in the patient treated with DEE, compared with 8 out of 10 patients on oral steroids (P≤ 0.01).CONCLUSION:Low doses of Dex (mean total dose ± 20 mg) loaded into autologous erythrocytes were significantly more effective than sham infusions in terms of symptoms relief, endoscopic, and biochemical improvements in UC patients refractory to mesalamine. In addition, in contrast to oral prednisolone (mean total dose ± 1 g), no steroid-related adverse events were induced.

Drug delivery by red blood cells

Drug delivery is a growing field of interdisciplinary activities that combine the use of new materials with the biochemical properties of selected drugs, with the aim of improving their therapeutic action and reducing their toxicity. In few cases, proper medical devices have been also realized to implement new drug delivery modalities. In this article, we have summarized available information and our experience on the use of autologous Red Blood Cells as carriers for drugs to be released within the vascular system. This is not a comprehensive review, but it focusses on the mechanisms that are available to distribute drugs in circulation by carrier red blood cells and provide illustrative examples on how this is currently obtained. We have not included a summary of clinical data collected in recent years using this technology but simply provided proper references for the interested readers. Finally, a special attention is devoted to the possibility of entrapping, into autologous red blood cells, recombinant drug‐binding proteins. This new strategy is opening the way at a new modality to influence the vascular distribution of drugs by realizing a dynamic circulating container (the engineered red cell) capable of reversible binding and transportation of one or more drugs of interest selected on the bases of the red cell entrapped target proteins. This new modality is not yet fully developed and explored but will certainly provide a technical solution to the problem of stabilizing drug concentration in circulation improving drug efficacy and reducing drug toxicity.

MODULATED RED BLOOD CELL SURVIVAL BY MEMBRANE PROTEIN CLUSTERING

Human and murine blood cells treated with ZnCl2 and bis(sulfosuccinimidyl)suberate (BS3) (a cross linking agent) undergo band 3 clustering and binding of hemoglobin to red blood cell membrane proteins. These clusters induce autologous IgG binding and complement fixation, thus favouring the phagocytosis of ZnCl2/BS3 treated cells by macrophages. The extension of red blood cell opsonization can be easily modulated by changing the ZnCl2 concentration in the 0.1–1.0 mM range thus providing an effective way to affect blood cell recognition by macrophages. In fact, murine erythrocytes treated with increasing ZnCl2 concentrations have proportionally reduced survivals when reinjected into the animal. Furthermore, the organ sequestration of ZnCl2/BS3 treated cells strongly resembles the typical distribution of the senescent cells. Since the ZnCl2/BS3 treatment can also be performed on red blood cells loaded with drugs or other substances, this procedure is an effective drug-targeting system to be used for the delivery of molecules to peritoneal, liver and spleen macrophages.

Long-term treatment with autologous red blood cells loaded with dexamethasone 21-phosphate in pediatric patients affected by steroid-dependent Crohn disease.

Background: Inflammatory bowel disease (IBD) present in childhood in 15% to 25% of cases. The aim of therapy in children is not only to guarantee normal growth but also to prevent relapse and to maintain remission. Steroids are effective to induce remission; however, resistance, dependency, and irreversible side effects can develop. The aim of this study was to determine whether treatment with repeated infusions of autologous red blood cells (RBCs) loaded with dexamethasone 21-phosphate (Dex 21-P) is safe and allows maintenance of long-term remission in children with steroid-dependent Crohn disease (CD). Patients and Methods: Eighteen consecutive pediatric patients who met the inclusion criteria were admitted to the study. Infusions of autologous RBCs loaded with Dex 21-P were performed every 4 weeks; the mean duration of treatment was 24 months. At the beginning of treatment and after 6, 12, and 24 months, we performed clinical evaluation according to the Pediatric Crohn Disease Activity Index (pCDAI). Assessment of body mass indexamethasone and bone mineral density by means of computerized bone mineralometry-dual energy x-ray absorptiometry, endoscopic evaluation, and hematic morning cortisol determination were also performed. Results: During treatment, the mean pCDAI significantly decreased (P < 0.05); 78% of patients discontinued steroids. Determination of morning cortisol showed suppression only on the first day after infusion, followed by normalization of values. Endoscopic findings showed remission in 44% of patients. None of the patients experienced serious side effects. Conclusions: These data suggest that repeated infusions of RBCs loaded with Dex 21-P can be safe and useful to maintain long-term remission in pediatric patients with moderately active CD.

Heterodimer-Loaded Erythrocytes as Bioreactors for Slow Delivery of the Antiviral Drug Azidothymidine and the Antimycobacterial Drug Ethambutol

Disseminated infection with Mycobacterium avium complex (MAC) remains the most common serious bacterial infection in patients with advanced AIDS. The organisms that make up this complex are found ubiquitously in the environment, yet rarely cause disseminated disease in nonimmunocompromised human patients; on the contrary, up to 50% of patients with AIDS may ultimately develop the pathology. Hence, therapeutic strategies able to inhibit HIV and Mycobacterium replication are needed. Because of the rapid plasma elimination and toxicity of the most commonly used drugs, daily multiple-drug therapies must often be continued throughout life, frequently causing major side effects and, as a consequence, poor patient compliance. Therefore, alternative strategies that reduce the toxicity of the drugs and allow prolonged application intervals are sorely needed. Since erythrocytes (RBCs) can behave as bioreactors able to convert impermeant prodrugs to membrane-releasable active drugs, new compounds (AZTpEMB, AZTpEMBpAZT, and AZTp2EMB) consisting of both an antiretroviral and an antimicrobial drug were designed and synthesized. Among these, only AZTp2EMB was hydrolyzed by erythrocyte enzymes and could be encapsulated inside RBCs. AZTp2EMB-loaded RBCs slowly released AZT and EMB in culture medium, reducing its concentration by one-half about every 48 hr of incubation at 37 degrees C. Moreover, when AZTp2EMB-loaded erythrocytes were incubated for 6 days in the presence of human macrophages infected with Mycobacterium avium (M. avium) a marked bactericidal effect (>1 log) was observed. Thus, AZTp2EMB-loaded erythrocytes could be used as endogenous bioreactors for AZT and EMB delivery in the treatment of HIV and M. avium infection.

New synthetic glutathione derivatives with increased antiviral activities

A series of glutathione (GSH) derivatives with aliphatic chains of different lengths, coupled by peptides bound to the α-NH2 group of Glu, were synthesized. When added to several cell lines, the C6 (n-hexanoyl), C8 (n-octanoyl) and C12 (n-dodecanoyl) derivatives were toxic while the C2 (n-ethanoyl) and C4 (n-butanoyl) derivatives were not. Preliminary experiments were performed to investigate the potential antiviral activity of the C2 and C4 derivatives compared to GSH. The C4 derivative was the most potent and fully characterized. GSH-C4 is a poor substrate of GSH metabolizing enzymes; once oxidized by disulphide-bound formation, C4 is slowly reduced by GSH-reductase. GSH-C4 completely abrogated Sendai virus replication at 7.5 mM with an EC50 of 3.6 mM, compared to 7.5 mM for GSH. GSH-C4 completely inhibited herpes simplex virus (HSV-1) virus production in Vero cells at 10 mM, while the same dose of GSH caused only a 2.5 log10 reduction. Furthermore, the GSH-C4 treatment (7.5 mM) was able to markedly reduce the cytopathic effect of HSV-1 in Vero cells. Thus, GSH derivatives with increased hydrophobic properties are more effective antiviral agents against Sendai and HSV-1 viruses than GSH, suggesting their usefulness in antiviral therapy.