Cell preservation in University of Wisconsin solution during isolation of canine islets of Langerhans

Improved yield of canine islet isolation from deceased donors

BACKGROUND

Canine diabetes is a strikingly prevalent and growing disease, and yet the standard treatment of a twice-daily insulin injection is both cumbersome to pet owners and only moderately effective. Islet transplantation has been performed with repeated success in canine research models, but has unfortunately not been made available to companion animals. Standard protocols for islet isolation, developed primarily for human islet transplantation, include beating-heart organ donation, vascular perfusion of preservation solutions, specialized equipment. Unfortunately, these processes are prohibitively complex and expensive for veterinary use. The aim of the study was to develop a simplified approach for isolating canine islets that is compatible with the financial and logistical restrictions inherent to veterinary medicine for the purpose of translating islet transplantation to a clinical treatment for canine diabetes.

RESULTS

Here, we describe simplified strategies for isolating quality islets from deceased canine donors without vascular preservation and with up to 90 min of cold ischemia time. An average of more than 1500 islet equivalents per kg of donor bodyweight was obtained with a purity of 70% (N = 6 animals). Islets were 95% viable and responsive to glucose stimulation for a week. We found that processing only the body and tail of the pancreas increased isolation efficiency without sacrificing islet total yield. Islet yield per gram of tissue increased from 773 to 1868 islet equivalents when the head of the pancreas was discarded (N = 3/group).

CONCLUSIONS

In summary, this study resulted in the development of an efficient and readily accessible method for obtaining viable and functional canine islets from deceased donors. These strategies provide an ethical means for obtaining donor islets.

Evaluation of a high-yield technique for pancreatic islet isolation from deceased canine donors

Type 1 diabetes mellitus is one of the most frequently diagnosed endocrinopathies in dogs, and prevalence continues to increase. Pancreatic islet transplantation is a noninvasive and potentially curative treatment for type 1 diabetes mellitus. Institution of this treatment in dogs will require a readily available source of canine islets. We hypothesized that clinically acceptable islet yield and purity could be achieved by using deceased canine donors and standard centrifugation equipment. Pancreata were procured from dogs euthanized for reasons unrelated to this study. Initial anatomic studies were performed to evaluate efficacy of pancreatic perfusion. Infusion into the accessory pancreatic duct resulted in perfusion of approximately 75% of the pancreas. Additional cannulation of the distal right limb of the pancreas allowed complete perfusion. Collagenase digestion was performed with a Ricordi chamber and temperature-controlled perfusion circuit. Islets were separated from the exocrine tissue with the use of a discontinuous density gradient and a standard laboratory centrifuge. After isolation, islet yield was calculated and viability was assessed with dual fluorescent staining techniques. Islet isolation was completed in 6 dogs. Median (interquartile range) islet yield was 36,756 (28,527) islet equivalents per pancreas. A high degree of islet purity (percentage of endocrine tissue; 87.5% [10%]) and viability (87.4% [12.4%]) were achieved. The islet yield achieved with this technique would require approximately 1 pancreas per 5 kg body weight of the recipient dog. Purity and viability of the isolated islets were comparable with those achieved in human islet transplantation program. According to initial results, clinically relevant islet yield and quality can be obtained from deceased canine donors with the use of standard laboratory equipment.

Islet transplantation: factors in short-term islet survival

Islet transplantation has the potential to cure type 1 diabetes. In recent years, the proportion of patients achieving initial insulin independence has improved, but longer term outcomes remain poor compared to those for whole pancreas transplants. This review article will discuss factors affecting islet yield and viability leading up to transplantation and in the immediate post-transplant period.

Isolation, density purification, and in vitro culture maintenance of functional caprine islets of Langerhans as an alternative islet source for diabetes study

BACKGROUND

Insufficient availability of human donors makes the search for alternative source of islet cells mandatory for future developments in pancreatic transplantation. The present study investigates the potential of caprine as an alternative source of pancreatic islets. The objectives of the study were to optimize techniques for caprine islet isolation and purification for culture establishment, and to subsequently assess their viable and functional potential.

METHODS

Caprine pancreatic tissues were collected from a local slaughterhouse and prior transported to the laboratory by maintaining the cold chain. Islets were obtained by a collagenase-based digestion and optimized isolation technique. Islet cell purity and viability were determined by dithizone and trypan blue staining, respectively. Islet clusters of different sizes were positively identified by staining methods and demonstrated 90% viability in the culture system. Following static incubation, an in vitro insulin secretion assay was carried out and analyzed by ELISA.

RESULTS

The islets remained satisfactorily viable for 5 days in the culture system following regular media changes. The current study has successfully optimized the isolation, purification and culture maintenance of caprine islets.

CONCLUSION

The successful yield, viability and functionality of islets isolated from the optimized protocol provide promising potential as an alternative source of islets for diabetes and transplantation researches.