Role of protein contaminants in the immunogenicity of alginates

Abstract

Alginate is widely used for cell microencapsulation and transplantation. There is a lack of standardization of alginate purity and composition. In a previous study, we compared different alginate purification methods and concluded that polyphenol and endotoxin contaminants were eliminated efficiently but residual protein contaminants persisted with all of the methods under evaluation. The objective of this study was to test the hypothesis that residual proteins play a role in the immunogenicity of certain alginate preparations. Using preparative size exclusion chromatography (SEC) and a large scale purification protocol that was derived from the findings obtained with SEC, we substantially decreased the protein content of alginate preparations. When implanted into mouse peritoneum, barium alginate beads made of alginates that were purified using SEC or the derived large scale protocol induced significantly less pericapsular cell adhesion than those made with control alginates. In conclusions, these results suggest that removing residual protein contamination may decrease the immunogenicity of certain alginate preparations. The measurement of proteins could be used as a screening method for evaluating alginate preparations.

Biocompatibility and physicochemical characteristics of alginate–polycation microcapsules

“…''HiG'' alginate (Protanal Ò LF10/60, batch S13636) was provided by FMC BioPolymer (Drammen, Norway). The alginates were purified in-house before their use, as previously described [25,26]. After their purification, the alginates contained <5 mg g À1 of proteins (microBCA assay), <250 EU g À1 of endotoxins (LAL assay) and no traces of foreign elements (X-ray photoelectron spectroscopy (XPS)).…”

Effect of prolonged gelling time on the intrinsic properties of barium alginate microcapsules and its biocompatibility

“…The microcapsules used for encapsulation studies are mostly produced from polymers known as hydrogels which are derived either naturally or through synthetic routes. In islet transplantation, the naturally obtained alginate hydrogels are widely used as they can be gelled under physiological conditions without the use of toxic chemicals and without affecting islet function (Ménard et al, 2010). Alginates microcapsules cross-linked with Ca 2þ or Ba 2þ are used successfully in both allograft and xenograft settings without the need for anti-rejection drugs, at least in rodents, with recipients becoming normoglycaemic (Silva et al, 2006).…”

Preclinical testing of drug delivery systems to bone

“…Fibrin is produced from human plasma and this bears the risk of disease transmission. Alginate preparations may be immunogenic and elicit an immune response [86]. Nevertheless, innovations help to overcome these drawbacks and many of them are now used as drug delivery systems.…”