Critical Factors Determined Islet Graft Function In Canine Islet Autotransplantation

Yang, Tae Young; Jeong, In Kyung; Oh, Seung Hoon; Lee, Sang Hoon; Kim, Dong Jun; Hahm, Jong Ryul; Kim, Byung Joon; Ahn, Kyu Jeung; Kim, Sung Joo; Chung, Jae Hoon; Min, Yong Ki; Lee, Myung Shik; Lee, Moon Kyu; Kim, Kwang Won

Abstract

BACKGROUND: Islet cell transplantation is an attractive alternative to whole organ pancreas transplantation, since it is clearly safer and simpler surgical procedure for the reciplents. However, several obstacles still remain, because the free islets appear to be more susceptible to non-specific inflammatory damage or immune mediated destruction than islets in an intact pancreas. Therefore, the purpose of this study is to examine the functional outcome of islet autograft and the factors related to the islets graft survival in mongrel dogs.
METHODS
Twelve adult mongrel dogs weighting 12~16 kg were used for the experiment of total pancratectomy and islet autotransplantation. The islets were properly isolated by a modified Recordi method. The obtained islets were further purified by centrifugation on discontinuous gradients using cell separation system (Model 2991, Cobe, Lakewood Colo). After the heparization(50U/kg), the islets were injected slowly into the liver through the portal vain for 30 minutes. The post-transplantation intravenous glucose tolerence test (IVGTT) with glucose disappearance rate (K), liver function test (LFT), fasting plasma glucose (FPG) ware measured periodically.
RESULTS
I) The median of Ks were 1.3%/min (range 0.3~2.1) and the lEq/kg (150 m equivalents/kg of recipient body weight) was 3520 (range 1350-6550). The Ks in recipients with high lEq/kg (> or =5,000) were significantly higher than those in recipients with low lEq/kg (<5,000)(r=0.78, p<0.05). 2) The islet cell viability were estimated to be 95% and the median of the required insulin dosage for the maintenance of normal FPG were 0.7 (range 0~1.6) U/kg/day, The insulin requirement correlated well with the level of lEq/kg (r=-0.90, p<0.01). 3) The median of the volume of the transplanted pancreatic islet cell were 2.1 mL (range 0.7~5.0) and the purity was 60k (range 10~95), The portal pressure gradients of during the transplant procedure were 4.0(range 0.5~12.0) cmH20. The portal pressure gradients in recipients with high purity were significantly lower than those in recipients with low purity (r=-0,80, p<0,05).
CONCLUSIONS
In this study, we confirmed that autotransplantation of islet cell on the pancreatectomized dogs can render nearly normoglycemia, and transplanted islet mass was most critical factor to successful autotransplantation in canine model.