Suitability of polyelectrolyte shells modified with fullerene derivate for immunoisolation of cells. Experimental study.

The polymeric permiselective membranes application for immunoisolation of cells separating the transplanted cells from the host immunological system may eliminate immunosuppressive therapy during transplantation. The suitability of polyelectrolyte modified nanocoatings for immunoisolation of cells was assessed. The polymeric shells modified with incorporated fullerene derivate were applied for encapsulation of human T-lymphocyte cell line Jurkat or rat pancreatic islets of Langerhans using layer-by-layer technique. Hydroxylated fullerene was incorporated to the polyelectrolyte shell for hydrophility increase as well as for layer stability improvement. Evaluation with AFM, FTIR, fluorescence microscopy confirmed the nanocoating presence on the encapsulated cells. It was observed that polylysine-polyethyleneimine membrane with incorporated fullerenol allowed for encapsulated cells functioning in vitro. Membrane conformation applied for encapsulation of pancreatic rat islets allowed for glucose level decline during xenotransplantation into mice. The elaborated nanocoating may be recommended as the possible alternative to the space consuming microencapsulation for biomedical purposes.

Histomorphometrical analysis of porcine islets of Langerhans.

Xenotransplantation of pig islets of Langerhans may be an efficient method for treatment of type I diabetic patients. Considering the shortage of human pancreas donors, pigs offer readily available islet source. Unfortunately, their morphologic characteristics makes isolation of pig islets of Langerhans extremely difficult. The selection of a suitable donor may favorably affect the success of isolation. Therefore, we examined pig breeds and weights for their influence histomorphometric features of Langerhans islets. Pancreatic tissue biopsy specimens were obtained from Polish Large White pigs (n=5), Polish Landrace pigs (n=8), Pietrain pigs (n=4), and marked-weight pigs of 100 kg (n=8) or more than 200 kg (n=10). Biopsy specimens were fixed and stored in 4% formaldehyde. Tissue sections were stained with polyclonal guinea pig anti-insulin antibody. The number of islets per 1 cm2 was counted in each section. Mean diameters and areas of the islets were measured to calculate the percentage volume density. Differences were observed among the groups of pigs weighing 200 kg and 100 kg in islet mean diameter and area. The number of islets/cm2 was higher among Pietrain than Polish Landrace pigs (425.45±111.7 versus 315.33±36.59 islet/cm2, P<.05). Furthermore, Pietrain pigs showed the largest volume density (1.44%). Histological analysis revealed that Pietrain pigs of 100 kg and market-weight pigs of 200 kg were the best donors for islets of Langerhans.

The influence of porcine pancreas digestion parameters and islet histomorphology on islet isolation outcome.

Transplantation of the pig islets of Langerhans is considered as the future treatment for patients suffering from type I diabetes mellitus. Despite the adaptation of modified Ricordi method and highly purified collagenase, the results of pancreas digestions are precarious. Selection of proper donor and optimal digestion procedure are fundamental. The aim of this study was to assess the impact of pancreas procuring parameters on pig islets yield. The pancreata were harvested from 69 market sows weighting over 150 kg. After intraductal injection of cold collagenase solution pancreata were transported in UW solution or under conditions of two layer method (TLM). In laboratory pancreata were digested at 37 degrees C according to Ricordi isolation method or stationary in the bottle. The particular parameters of isolation procedure were considered as substantial. Pig weight, volume of infused collagenase solution, TLM application and pancreas dividing before digestion positively affected islet yield. Additionally, the influence of pancreatic islet tissue histomorphology on isolation outcome was studied. Proper donor selection as well as adequate digestion parameters could improve pig islet recovery during islet isolation.

Assessment of some porcine strains as donors of islets of Langerhans.

Mass isolation of viable porcine islets is a difficult task because of their fragility, and because of donor variability with respect to strain, age, sex, feeding, and methods of slaughtering. Not all strains are equally suitable for islet separation. The aim of this study was to evaluate porcine pancreata as an alternative source of islets for clinical transplantation. Pancreata were digested from pig strains available in Poland: 248 market weight slaughterhouse pigs and 42 pigs, belonging to the Polish Large White (WBP, 14 sows and 3 males), Polish White Pendant-Ears (PBZ; 16 sows), Pietrain (8 sows), and Yorkshire (1 sow) races. Prepurification data of recoverable islets/g and islet equivalents/g were considered as representative for the number of recoverable islets. Acceptable results namely, islet and/or islet-equivalent (IE) number of at least 1000/g, were obtained from only 56 of 248 slaughterhouse pigs, namely 2073 +/- 137.4 SE (median 1767/g) islets with values of IE of 2994 +/- 303 SE (median 1874/g). Our data support Krickhahn et al suggesting that only pancreata with an average islet size exceeding 199 microm should be digested and that only from 1 of 3 to 5 porcine pancreata is an adequate amount of islets generated.