The effect of capsule composition on the biocompatibility of alginate-poly-1-lysine capsules

Abstract

The encapsulation of islets of Langerhans in alginate-poly-l-lysine has been proposed as a method for the immunoprotection of transplanted islets. Although several capsule compositions have been reported, there has been no published study concerning the effect of capsule composition on the severity of the foreign body reaction. Empty capsules were prepared from high mannuronic acid alginate and were coated with: (1) poly-l-lysine alone, (2) poly-l-lysine plus high guluronic acid alginate, or (3) poly-l-lysine plus high mannuronic acid alginate. The capsules were placed in the renal subcapsular space or the peritoneal cavity, and retrieved after three weeks of histological examination. The recipients were WAG/01a, nude (athymic), diabetic BB, and non-diabetes prone BB rats. The severity of reaction to the capsules was determined by measuring the thickness of the pericapsular cell infiltrate or by a scoring system. The severity of the reaction to the capsules was strain-dependent in both the renal and peritoneal sites, with the BB and nude rats displaying the most severe responses. The degree of response was not affected by capsule composition in the renal subcapsular space, but in the peritoneum, the high mannuronic acid alginate capsules provoked the weakest response, and this type of capsule will be used for future transplantation work. The infiltrating cells were characterised by immunohistochemistry and electron microscopy and found to be mostly fibroblasts and macrophages.

Long-term biocompatibility, chemistry, and function of microencapsulated pancreatic islets

“…Up to now the success rates of transplantation of microencapsulated islets were low [5,[24][25][26][27]. This is Table 2 Elemental surface composition of Ca-beads (n ¼ 4) and alginate-PLL capsules (n ¼ 4) before implantation and an analysis of pure PLL (representative sample is shown) mainly caused by insufficient biocompatibility of the applied capsule materials [5,[28][29][30] which induced a non-specific foreign body reaction against not only a small portion but against the whole capsule graft with fibrosis of the capsules and necrosis of the islets as a consequence.…”

Swellable Ciprofloxacin-Loaded Nano-in-Micro Hydrogel Particles for Local Lung Drug Delivery

“…One contention related to alginate immunogenicity is associated with the ratio of alginate blocks (31,32). Alginate consists of both M-block and G-block.…”

Improved biocompatibility but limited graft survival after purification of alginate for microencapsulation of pancreatic islets

“…In order to exclude that the mild reaction towards the capsules prepared from purified alginate is specific for the AO-rat strain we also implanted empty capsules in the peritoneal cavity of four prediabetic BB-rats which reportedly are high responders toward alginate-PLL capsules [4,8]. Also in the BB-rats, 1 month after implantation, we observed the majority of capsules to be freely floating in the peritoneal cavity.…”