Parameters for successful pig islet isolation as determined using 68 specific-pathogen-free miniature pigs.
BACKGROUND
Islet cell transplantation is a novel therapeutic modality for the cure of diabetes. Pig islet cells are an attractive substitute for human islet cells; however, they are known to be particularly difficult to isolate because of a weak islet capsule and a tendency to be fragmented during enzymatic digestion. Therefore, parameters favoring successful pig islet isolation were investigated using specific-pathogen-free (SPF) miniature pigs.


METHODS
Sixty-eight SPF miniature pigs were used for islet isolation. Birth weight, body weight, age, sex, pregnancy history, and the fasting blood glucose levels of each pig were determined. Each pig's general condition was assessed with regard to feeding status and physical activity. Pancreas procurement was performed by one surgical team. Anesthesia duration, operation duration, procedure quality, and perfusate type were recorded. After pancreatectomy, a biopsy was performed for islet density analysis. Decapsulation, cannulation duration, degree of distension, and cold ischemic time were assessed. During islet isolation, pancreas weight, digestion time, and digested tissue proportion were recorded. Isolation results were evaluated by total islet equivalents (IEQ), islet equivalents per gram of pancreas (IEQ/g), isolation index, islet recovery rate, purity, and visual grade. To identify the predictors of higher islet isolation yield, we performed binary logistic regression analysis with significant (P < 0.05) variables from the univariate analysis.


RESULTS
The pigs were categorized into high (n = 34) and low yield (n = 34) groups according to the median IEQ/g or total IEQ values. Body weight and age were significantly different between the two groups. Being male or a positive history of pregnancy in females was factors favoring successful islet isolation. General condition assessments failed to estimate islet isolation results. Long anesthesia duration, which might have caused ischemic injury to the pancreas, negatively affected islet isolation results. Decapsulation, cannulation duration, and subsequent pancreas distension were significantly important in successful islet isolation. Inter-lot variability of Liberase was not observed because of screening processes performed before purchase. Isolation index and islet recovery rate correlated well with islet yields.


CONCLUSIONS
Multivariate analysis using total IEQ and IEQ/g as outcome variables indicated that age older than 2, being male and moderate distension by Liberase injection are major determinants influencing successful islet isolation.
Kim
Hyoung-Il
HI
Xenotransplantation Research Center, Jongno-gu, Seoul, Korea.
Lee
Song-Yi
SY
Jin
Sang Man
SM
Kim
Kang Seok
KS
Yu
Jae Eun
JE
Yeom
Su-Cheong
SC
Yoon
Tai Wook
TW
Kim
Jae Hyeon
JH
Ha
Jongwon
J
Park
Chung-Gyu
CG
Kim
Sang-Joon
SJ
D000818:Animals; D001706:Biopsy; D017364:Collagenases / Q000494:pharmacology; D005260:Female; D006801:Humans; D007515:Islets of Langerhans / Q000187:drug effects / Q000473:pathology / Q000601:surgery*; D016381:Islets of Langerhans Transplantation; D008297:Male; D015999:Multivariate Analysis; D012044:Regression Analysis; D012727:Sex Characteristics; D013047:Specific Pathogen-Free Organisms; D013552:Swine; D013556:Swine, Miniature / Q000601:surgery*; D013820:Thermolysin / Q000494:pharmacology; D020858:Tissue and Organ Harvesting / Q000379:methods*; D014183:Transplantation, Heterologous
D017364:Collagenases; C106635:Liberase; D013820:Thermolysin