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Erythrocyte-based drug delivery systems are emerging as potential new solutions for the release of drugs into the bloodstream. The aim of the present work was to assess the performance of a fully automated process (EDS) for the ex-vivo encapsulation of the pro-drug dexamethasone sodium phosphate (DSP) into autologous erythrocytes in compliance with regulatory requirements. The loading method was based on reversible hypotonic hemolysis, which allows the opening of transient pores in the cell membrane to be crossed by DSP. The efficiency of encapsulation and the biochemical and physiological characteristics of the processed erythrocytes were investigated in blood samples from 34 healthy donors. It was found that the processed erythrocytes maintained their fundamental properties and the encapsulation process was reproducible. The EDS under study showed greater loading efficiency and reduced variability compared to previous EDS versions. Notably, these results were confirmed using blood samples from Ataxia Telangiectasia (AT) patients, 9.33±1.40 and 19.41±2.10mg of DSP (mean±SD, n=134) by using 62.5 and 125mg DSP loading quantities, respectively. These results support the use of the new EDS version 3.2.0 to investigate the effect of erythrocyte-delivered dexamethasone in regulatory trials in patients with AT., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Efficacy of erythrocyte-mediated delivery of dexamethasone 21-phosphate in patients with steroid-dependent ulcerative colitis., Methods: Thirty-seven patients with steroid-dependent ulcerative colitis were randomized to infusions of dexamethasone 21-phosphate encapsulated into autologous erythrocytes (n = 19) or to sham infusions (n = 18). Each infusion was given monthly for 6 months. The primary endpoint was the proportion of patients able to discontinue oral corticosteroids during treatment while maintaining clinical remission or stable disease. Secondary endpoint was the proportion of patients with disappearance of steroid-related adverse events., Results: At each infusion, a mean of 9.8 ± 4.6 mg dexamethasone 21-phosphate was administered at each infusion, which allowed steady-state plasma levels of 8 ng/mL for the following 28 days. Thirteen patients in the dexamethasone 21-phosphate group and 4 sham-treated patients attained the primary outcome of the study, i.e., maintaining a stable condition despite oral steroids withdrawal (P = 0.008). In the remaining patients (6 and 15 in the 2 experimental groups, respectively), the treatment was prematurely withdrawn because of clinical deterioration while tapering oral steroids. At endoscopy, mucosal healing was ascertained in 4 patients and 1 patient of the 2 experimental groups, respectively (P = 0.339). At inclusion, 14 and 13 patients in the 2 experimental groups complained of steroid-related adverse events; at end of the treatment, events were still present in 5 and 13 patients, respectively (P = 0.008)., Conclusions: In patients with steroid-dependent ulcerative colitis, 6-month therapy with low dose of dexamethasone 21-phosphate allowed the withdrawal of oral steroids and the reversal of steroid-related adverse events in most patients while maintaining clinical remission (ClinicalTrials.gov number, NCT01171807).

Fludarabine phosphate (2-Fluoro-ara-AMP) is a purine analogue approved for the clinical treatment of haematological malignancies. This antimetabolite has also shown 'in vitro' antiproliferative activity against experimental models of solid mammary tumor. In this perspective, we have determined the cytotoxic effects of 2-Fluoro-ara-AMP against two human breast cancer cell lines (the ER-positive MCF-7 and the ER-negative MDA-MB-435), by adding the drug both in its free form and encapsulated into erythrocytes, as a strategy to modify the pharmacokinetic profile of the compound in order to increase its efficacy and decrease its toxicity. Similar antiproliferative activity of 2-Fluoro-ara-AMP in the two cell lines was obtained, reaching an almost complete abrogation of growth already after just 24 h of free drug exposure at all the tested doses. Meanwhile, encapsulated 2-Fluoro-ara-AMP was successfully released from erythrocytes into the culture media in a time-dependent manner with an efficacy comparable to that of the free drug treatment. This result suggests the possibility of administering 2-Fluoro-ara-AMP in patients with breast cancer using autologous erythrocytes as a system to slowly and constantly deliver 2-Fluoro-ara-A into circulation. In addition, possible mechanisms involved in the antiproliferative activity of 2-Fluoro-ara-AMP, such as the effects on cell cycle progression, p53 expression and STAT1 pathway activation in ER+ and ER- cancer cell lines, are proposed.

Purpose: To find evidence of retinal vasomotion and to examine the relationship between erythrocyte dynamics and previously observed high-frequency pulsatile blood flow through the choriocapillaris., Methods: An osmotic shock technique was used to encapsulate indocyanine green (ICG) dye in erythrocyte ghost cells at a concentration that produced maximum cell fluorescence. By obviating the plasma staining that results from aqueous ICG's high affinity for plasma proteins, high contrast was maintained between reinjected ICG-loaded erythrocytes and their plasma background. High-speed, high-magnification ICG angiograms showing individual cell movement were recorded from the intact eyes of four monkeys and three rabbits for periods up to 30 seconds., Results: In monkey retinal perifoveal capillaries, numerous erythrocytes were seen to pause for as long as 20 seconds and then resume transit. Similar pausing behavior was observed in the subfoveal choriocapillaris. Individual erythrocytes also were seen to pause in the rabbits' choriocapillaries below the medullary rays, where visualization of the cells was uninhibited by overlying retinal vasculature or dense pigment., Conclusions: Reinjected ICG-loaded erythrocytes permit routine visualization of retinal capillary and choriocapillaris hemodynamics of the intact eye. It is speculated that erythrocyte-pausing in both microcirculations facilitates metabolic exchange across capillary walls. In retinal capillaries, pausing is presumed to result from vasomotion-which has been postulated as necessary for the inhibition of retinal edema-and in choriocapillaries, to result from the shifting distributions of local perfusion pressures within the network of capillary vessel segments that comprise each lobular area of the choriocapillaris vascular plexus.

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< or = 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 has been greatly improved over the years by means of chemical and physical agents that increase bioavailability, improve pharmacokinetic and reduce toxicities. At the same time, cell based delivery systems have also been developed. These possesses a number of advantages including prolonged delivery times, targeting of drugs to specialized cell compartments and biocompatibility. Here we'll focus on erythrocyte-based drug delivery. These systems are especially efficient in releasing drugs in circulations for weeks, have a large capacity, can be easily processed and could accommodate traditional and biologic drugs. These carriers have also been used for delivering antigens and/or contrasting agents. Carrier erythrocytes have been evaluated in thousands of drug administration in humans proving safety and efficacy of the treatments. Erythrocyte-based delivery of new and conventional drugs is thus experiencing increasing interests in drug delivery and in managing complex pathologies especially when side effects could become serious issues.

Background and Aim: Autologous erythrocytes can be used as carriers of drugs, owing to the ability of their membrane to be opened and resealed under appropriate conditions. In this pilot uncontrolled study, we investigated efficacy and safety of dexamethasone-encapsulated erythrocytes in steroid-dependent IBD patients., Materials and Methods: Ten patients (5 with ulcerative colitis and 5 with Crohn's disease) with steroid dependency ranging from 8 to 60 months were studied. Seven of them were in clinical remission, and the remaining three had mild activity. Eight patients were also under azathioprine or 6-MP for at least 6 months (range 6-24 months), while another two patients were intolerant to both drugs. Fifty milliliters of blood were drawn from each subject; dexamethasone 21-Phosphate (Dex 21-P) was encapsulated into erythrocytes by means of specially designed equipment, and drug-loaded erythrocytes were infused into original donors. The procedure was repeated after 4 and 8 wk, and patients were instructed to withdraw corticosteroids., Results: A mean dose of 5.5+/-2.4 mg Dex 21-P was loaded in the erythrocytes at each treatment. Following re-infusion of loaded erythrocytes, plasma Dexamethasone (Dex) concentrations were detected after as long as 28 days. Steroids were completely withdrawn by the second month. After the third infusion, all patients, including the three with mild active disease, were in clinical remission. ESR levels dropped from 47+/-27 at baseline to 27+/-16 mm/h (p<0.02), and CRP levels from 1.6+/-1.3 to 0.6+/-0.5 mg/dl (p<0.02). After a mean follow-up of 12+/-3 months, six patients relapsed, and the remaining four patients remained in remission. Pre-existing steroid-related adverse effects disappeared during the follow-up., Conclusions: Loading of Dex 21-P in autologous erythrocytes is feasible and safe. The very low dose of Dex released in blood stream was able to maintain patients in clinical remission and allowed steroids withdrawal.

The use of a physiological carrier to deliver therapeutics throughout the body to both improve their efficacy while minimising inevitable adverse side effects, is an extremely fascinating perspective. The behaviour of erythrocytes as a delivery system for several classes of molecules (i.e., proteins, including enzymes and peptides, therapeutic agents in the form of nucleotide analogues, glucocorticoid analogues) has been studied extensively as they possess several properties, which make them unique and useful carriers. Furthermore, the possibility of using carrier erythrocytes for selective drug targeting to differentiated macrophages increases the opportunities to treat intracellular pathogens and to develop new drugs. Finally, the availability of an apparatus that permits the encapsulation of drugs into autologous erythrocytes has made this technology available in many clinical settings and competitive with other drug delivery systems.

Given the important role of macrophages in various disorders, the transient and organ specific suppression of their functions may benefit some patients. Until now, liposome-encapsulated bisphosphonate clodronate has been extensively proposed to this end. In this paper, we demonstrate that erythrocytes loaded with clodronate can also be effective in macrophage depletion. Here, clodronate was encapsulated in erythrocytes through hypotonic dialysis, isotonic resealing and reannealing to final concentrations of 4.1 +/- 0.4 and 10.1 +/- 0.8 micromol/ml of human and murine erythrocytes, respectively. The ability of clodronate-loaded erythrocytes to deplete macrophages was evaluated both in vitro and in vivo. In vitro studies on human macrophages showed that a single administration of engineered erythrocytes was able to reduce cell adherence capacity in a time-dependent manner, reaching 50 +/- 4% reduction, 13 days post treatment. The administration of loaded erythrocytes to cultures of murine peritoneal macrophages was able to reduce macrophage adhesion 67 +/- 3%, 48 h post treatment. In vivo, the ability of clodronate-loaded erythrocytes to deplete macrophages was evaluated both in Swiss and C57BL/6 mice. Swiss mice received 125 microg of clodronate through erythrocytes and 6 days post treatment 69 +/- 7% reduction in the number of adherent peritoneal macrophages and 75 +/- 5% reduction in number of spleen macrophages were observed. C57BL/6 mice received 220 microg clodronate by RBC and 3 and 8 days post treatment 65 +/- 7% reduction in the number of spleen macrophages and the complete depletion of liver macrophages were obtained. In summary, our results indicate that clodronate selectively targeted to the phagocytic cells by a single administration of engineered erythrocytes is able to deplete macrophages, even if not completely. The transient suppression of macrophage functions through clodronate-loaded erythrocytes can be used in many biomedical phenomena and research applications.

Objective: To evaluate the efficacy of erythrocytes loaded with the haemolytic toxin listeriolysin O against Mycobacterium avium replication within human macrophages., Methods: Recombinant listeriolysin O was loaded in human erythrocytes by a procedure of hypotonic dialysis and isotonic resealing. Loaded erythrocytes were modified to allow them to be recognized and taken up by human macrophages infected with M. avium. The antimycobacterial activity of the erythrocytes loaded with listeriolysin O was evaluated by supernatant and intracellular cfu counts on days 4 and 7 post-erythrocyte administration., Results: Recombinant listeriolysin O was encapsulated in human erythrocytes to reach final concentrations ranging from 1 to 4 ng/mL of erythrocytes. Erythrocytes loaded with increasing quantities of recombinant protein were able to reduce (at most by 50%) M. avium replication in a dose-dependent fashion when administered to infected macrophages., Conclusions: Erythrocytes loaded with listeriolysin O are effective against M. avium replication within macrophages. We are confident that the strategy presented could be useful against mycobacteria other than M. avium (such as Mycobacterium tuberculosis and Mycobacterium leprae) by itself or as part of an antimycobacterial treatment.

Monocyte-derived macrophages (MDMs) play a central role in the pathogenesis of infection by human immunodeficiency virus (HIV-1) and represent one of the main reservoirs of the virus in the body. In addition, MDMs can easily be infected by various herpes viruses, including herpes simplex virus type 1 (HSV-1). We have synthesized a new antiviral agent (Bis-PMEA) that consists of two 9-(2-phosphonylmethoxyethyl)adenine (PMEA) molecules bound by a phosphate bridge. This nucleotide analogue, like the parent compound PMEA, has strong and selective activity against HIV-1 and HSV-1. A drug-targeting system previously developed in our laboratory was used for the selective delivery of these drugs to macrophages. Bis-PMEA and PMEA were encapsulated into autologous erythrocytes by a procedure of hypotonic dialysis and isotonic resealing. Loaded erythrocytes were modified to increase their recognition and phagocytosis by human macrophages. By administering Bis-PMEA-loaded erythrocytes to macrophages, 47% of Bis-PMEA and 28% of PMEA was still present 10 days after phagocytosis; in contrast, only 12% of PMEA was found in macrophages receiving PMEA-loaded erythrocytes. Bis-PMEA-loaded erythrocytes were then added to macrophages infected with HIV-1 and HSV-1 and their antiviral activity evaluated. Remarkable protection was obtained against HIV-1 and HSV-1 infection (95 and 85%, respectively). Therefore, Bis-PMEA acts as an efficient antiviral prodrug that, following selective targeting to macrophages by means of loaded erythrocytes, can protect a refractory cell compartment.

Monocyte-derived macrophages (M/M) are considered important in vivo reservoirs for different kinds of viruses, including HIV. Hence, therapeutic strategies are urgently needed to protect these cells from virus infection or to control viral replication. In this paper, we report the synthesis, target delivery and in vitro efficacy of a new heterodinucleotide (AZTpPMPA), able to inhibit HIV-1 production in human macrophages. AZTpPMPA consists of two established anti-HIV drugs [zidovudine (AZT) and tenofovir (PMPA)] chemically coupled together by a phosphate bridge. This drug is not able to prevent p24 production when administered for 18 h to M/M experimentally infected with HIV-1 Bal (inhibition 27%), but can almost completely suppress virus production when given encapsulated into autologous erythrocytes (inhibition of p24 production 97%). AZTpPMPA is slowly converted to PMPA, AZT monophosphate and AZT (36 h half-life at 37 degrees C) by cell-resident enzymes. Thus AZTpPMPA should be considered a new prodrug of AZT and PMPA that is able to provide stechiometric amounts of both nucleoside analogues to macrophage cells and to overcome the low phosphorylating activity of M/M for AZT and the modest permeability of PMPA.

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 beta2-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.

Abstract: In the attempt to eradicate HIV-1 infection, a strategy to eliminate macrophages, one of the most important cellular reservoirs in sustaining virus replication during HAART, could be of great benefit in the suppression of viral rebound. Aware of the ability of clodronate to cause macrophage depletion, the effect of the administration of clodronate encapsulated in erythrocytes on disease progression and on viral rebound was evaluated in a murine model of AIDS (MAIDS). One group of LP-BM5 retroviral complex-infected C57BL/6 mice received oral administrations of azidothymidine and dideoxyinosine daily for 12 weeks; two other groups received in addition, either clodronate-loaded erythrocytes or free clodronate at 7–10 day intervals. At the end of the treatment, the three groups maintained parameters characterizing disease progression similar to those of uninfected mice and showed a significantly lower level of BM5d DNA than infected mice in all organs and cells tested. To assess the viral rebound, some animals were left for an additional 4 month period without any treatment. After this time, the BM5d DNA content in blood leukocytes increased in all groups, but the group having received clodronate-loaded erythrocytes, in addition to transcriptase inhibitors, showed a significant delay in viral rebound. [Copyright &y& Elsevier]