A Comparison of Cross Sectional Surface Area Densities Between Adult and Juvenile Porcine Islets of Langerhans*

Abstract

The object of this study was to evaluate differences in islet diameters, their distribution and both cross sectional surface areas and densities of insulin containing islets between adult and juvenile porcine pancreata using a computerised image analysis system (Improvision). Five adult (A) (2-3 yrs) and 5 juvenile (J) (< 12 mths) Large White pancreata were assessed. Biopsies were taken from 5 different regions (posterior lobe, duodenal lobe, along with the head, body and tail regions of the splenic lobe) of the pancreas and tissue sections stained for insulin. In both A and J pancreata islet numbers increased with decreasing islet diameter, showing a skewed distribution. There was no statistical significance between the cross sectional surface area within A (mean 5.04 x 10(3) microm2) or J (mean 5.99 x 10(3) microm2) pancreata. Assuming islets are spherical, extrapolation from pir2 showed that the mean diameter for A was 80 microm and 87 microm in J. These compared with A 77 microm and J 86 microm diameters using conventional microscopic techniques. The percentage islet volume density relative to exocrine tissue, derived from the principle of Delesse (Area density = volume density), did not significantly differ between each of the 5 areas studied, either in A or J. The percentage islet volume densities did show a significant difference between A (mean 1.83%) (P = 0.001) but not between J pancreata (mean 2.13 %). In conclusion poor islet yields can be attributed to differences in islet volume density of islets within porcine pancreata. These results also suggest that the posterior and duodenal lobes should be used along with the splenic lobe in order to improve porcine islet yields. Furthermore, the current practise of reporting porcine islet yields and the isolation index relative to 150 microm (IEQs) needs to be redefined, based on the assumption that the average size of an adult porcine islet is 80 microm.

Islet Isolation from Juvenile Porcine Pancreas after 24-h Hypothermic Machine Perfusion Preservation

“…The size distribution of islets obtained from these juvenile rounding acini that are characterized by the abundance of zymogen granules. In marked contrast, tissue stored pigs concurs with previous reports in the literature comparing adult and young porcine donors (10,20,51,52).…”

What strain of pig should be used?

“…A higher percentage of round islets are seen with increasing donor age and are believed to be better protected from the mechanical stress during islet isolation than the predominantly dumbbell-like islets in pancreases of juvenile pigs [8]. In contrast to Ulrichs et al [8] and White et al [29] who did not find a statistically significant difference in frequency distribution of islet diameter in juvenile and adult Landrace and Large White pigs, Dufrane et al observed a greater proportion of small islets (50-100 lm in diameter) in juvenile (76% of islets) compared with adult pancreases (54% of islets) in Landrace pigs [27]. The pigs studied by Dufrane [27], successful islet isolation is possible both from juvenile and adult pig pancreases and likely depends on the presence of large islets in the donor pancreas rather than on donor age.…”

Development and Characterization of a Glucagon-Like Peptide 1-Albumin Conjugate

“…Antibody binding was visualized by 3,3-diaminobenzidine, and sections were counterstained by Meyers hematoxylin. Islet histomorphometry was carried out according to the principles of Delesse (30). The sections were examined using a Leica (Leitz Labor Lux S; Leica Microsystem, Heerbrugg, Switzerland) microscope equipped with a video camera and connected to a computer with imaging software (Q500MC; Leica Microsystem).…”