In vivo behaviour of rat band 3 cross-linked carrier erythrocytes

Cell or cell membrane-based drug delivery systems

Natural cells have been explored as drug carriers for a long period. They have received growing interest as a promising drug delivery system (DDS) until recently along with the development of biology and medical science. The synthetic materials, either organic or inorganic, are found to be with more or less immunogenicity and/or toxicity. The cells and extracellular vesicles (EVs), are endogenous and thought to be much safer and friendlier. Furthermore, in view of their host attributes, they may achieve different biological effects and/or targeting specificity, which can meet the needs of personalized medicine as the next generation of DDS. In this review, we summarized the recent progress in cell or cell membrane-based DDS and their fabrication processes, unique properties and applications, including the whole cells, EVs and cell membrane coated nanoparticles. We expect the continuing development of this cell or cell membrane-based DDS will promote their clinic applications.

Effects of autologous, cross-linked erythrocytes on isolated hypoperfused rabbit heart dynamics

The present study was aimed at assessing the effects of either red blood cells (RBC) or RBC cross-linked with the bifunctional dimethyl suberimidate reagent (C-RBC) on contractile force (CFo), heart rate (HR) and coronary flow (CF) of the isolated rabbit heart hypoperfused with RBC suspensions under 30 mm Hg constant pressure. RBC or C-RBC caused a rapid and marked reduction of CF, CFo and HR. In RBC-treated hearts, however, reperfusion with Tyrode solution partially restored the initial myocardial parameters, while in C-RBC-treated hearts a rapid impairment of diastolic relaxation with a subsequent, steady and increasing heart contracture was observed. Histological analysis showed that in C-RBC-perfused hearts either capillaries or precapillary arterioles were occluded by C-RBC in spite of extensive washings with Tyrode solution. These findings indicate that C-RBC impair coronary circulation markedly and irreversibly.

Applications of carrier erythrocytes in delivery of biopharmaceuticals

Carrier erythrocytes, resealed erythrocytes loaded by a drug or other therapeutic agents, have been exploited extensively in recent years for both temporally and spatially controlled delivery of a wide variety of drugs and other bioactive agents owing to their remarkable degree of biocompatibility, biodegradability and a series of other potential advantages. Biopharmaceuticals, therapeutically significant peptides and proteins, nucleic acid-based biologicals, antigens and vaccines, are among the recently focused pharmaceuticals for being delivered using carrier erythrocytes. In this article, the potential applications of erythrocytes in drug delivery have been reviewed with a particular stress on the studies and laboratory experiences on successful erythrocyte loading and characterization of the different classes of biopharmaceuticals.

Factors associated with the performance of carrier erythrocytes obtained by hypotonic dialysis

Carrier erythrocytes containing drugs, enzymes or peptides can be used as a delivery system that allows changes in the kinetic behaviour and selective biodistribution of the substances encapsulated. Hypotonic dialysis is the method most commonly used in the preparation of carrier erythrocytes, but many factors affect the yield and characteristics of the ghost erythrocytes obtained using this method. This review analyses the factors that affect the performance of carrier erythrocytes prepared by hypotonic dialysis. Factors such as the composition and osmolality range of the hypotonic buffer used, the duration of the hypotonic dialysis, temperature, the volume ratio between the erythrocyte suspension and the dialysis buffer, the inclusion in the process of an annealing phase, the composition and osmolality of the resealing buffer, and the conditions under which the final washing of the erythrocytes is carried out may all affect the morphological properties and the later in vivo behaviour of the ghost erythrocytes obtained. Changes in the yield of the encapsulation process, the in vitro drug or enzyme controlled delivery, the pharmacokinetic properties or the in vivo tissue targeting may be modified depending on the conditions under which the preparation of carrier erythrocytes by hypotonic dialysis is carried out. Chemical alterations to the membrane of carrier erythrocytes obtained by hypotonic dialysis with substances such as glutaraldehyde, band 3 cross-linking reagents, trypsin or NHS-biotin, among others, may affect the release rate of the substances encapsulated and may increase the uptake of cells by macrophages both in vitro and in vivo.

Biomedical application of immobilized enzymes

Reports on chemical immobilization of proteins and enzymes first appeared in the 1960s. Since then, immobilized proteins and enzymes have been widely used in the processing of variety of products and increasingly used in the field of medicine. Here, we present a review of recent developments in immobilized enzyme use in medicine. Generally speaking, the use of immobilized enzyme in medicine can be divided into two major categories: biosensors and bioreactors. A brief overview of the evolution of the biosensor and bioreactor technology, of currently existing applications of immobilized enzymes, of problems that researchers encountered, and of possible future developments will be presented.