Insulin

Caprine pancreatic islet xenotransplantation into diabetic immunosuppressed BALB/c mice

BACKGROUND

Type 1 diabetes mellitus is a devastating disease for which there is currently no cure, but only lifetime management. Islet xenotransplantation is a promising technique for the restoration of blood glucose control in patients with diabetes mellitus. The purpose of this study was to explore the potential use of caprine (goat) islet cells as xenogeneic grafts in the treatment for diabetes in a mouse model.

METHODS

Caprine pancreases were harvested and transported to the laboratory under conditions optimized to prevent ischemia. Islets were isolated, purified, and tested for functionality. Caprine islets (2000 islet equivalent) were transplanted beneath the kidney capsules of diabetic BALB/c mice under thalidomide-induced immunosuppression. Blood glucose and insulin levels of grafted mice were evaluated by glucometer and enzyme-linked immunosorbent assay kit, respectively. The functionality and quality of caprine pancreatic islet grafts were assessed by intraperitoneal glucose tolerance tests.

RESULTS

The viability of purified islet cells exceeded 90%. Recipient mice exhibited normoglycemia (<11 mM glucose) for 30 days. In addition, weight gain negatively correlated with blood glucose level. The findings verified diabetes reversal in caprine islet recipient mice. A significant drop in non-fasting blood glucose level (from 23.3 ± 5.4 to 8.04 ± 0.44 mM) and simultaneous increase in serum insulin level (from 0.01 ± 0.001 to 0.56 ± 0.17 μg/l) and body weights (from 23.64 ± 0.31 to 25.85 ± 0.34 g) were observed (P < 0.05). Immunohistochemical analysis verified insulin production in the transplanted islets.

CONCLUSIONS

Purified caprine islets were demonstrated to successfully sustain viability and functionality for controlling blood glucose levels in an immunosuppressed mouse model of diabetes. These results suggest the use of caprine islets as an addition to the supply of xenogeneic islets for diabetes research.

Recombinant-DNA-derived insulin analogues as potentially useful therapeutic agents

Whilst insulin is a spectacularly successful drug for the management of diabetes mellitus, it remains difficult to mimic the physiological pattern of insulin secretion, even using the various quick-acting and insoluble formulations that are available. The introduction of recombinant-DNA technology to the manufacture of therapeutic insulin has made the rational design and production of insulin analogues with altered pharmacokinetic and pharmacological properties possible. Such analogues include 'monomeric' insulins, which do not form the insulin-zinc hexamer in solution and are absorbed more rapidly from the injection site, and long-acting insulins, which are absorbed very slowly at physiological pH. Many of these analogues are being tested clinically, and it is possible that the next generation of insulin therapy will be various combinations of rationally designed insulin analogues produced by industrial biotechnology.

Cause of death of lower limb amputees

A study was carried out on the cause of death of 100 lower limb amputees who had been admitted to the Dundee Limb Fitting Centre, Tayside, Scotland for prosthetic management or wheelchair training. A comprehensive database has been established in the Centre for 25 years and the database is updated regularly. The date of death was collected and recorded. One hundred sequential deaths were investigated to review the cause of their death and compare this with the recorded causes of death for the Tayside population for the year of study. Ninety three per cent had an amputation for vascular related causes, with 73% having a below-knee amputation and 17% above-knee. Heart disease was the most frequent recorded cause of death (51%) of the amputee whereas only 28.1% of the Tayside group died from this pathology (p less than 0.01). Carcinomatosis was reported as a cause of death in 14% of the amputees and 23.5% of the Tayside group. Cerebrovascular disease caused death in 6% of the amputees and in 12.3% of the Tayside group (both p less than 0.01). These findings confirm earlier suggestions that vascular amputees die from heart disease more often than the general population.