Iodixanol-controlled density gradient during islet purification improves recovery rate in human islet isolation.
BACKGROUND
For pancreatic islet transplantation, islet purification minimizes the risks associated with islet infusion through the portal vein by reducing the amount of transplanted tissue. However, the purification step may result in decreased numbers of islets recovered from digested tissue and be traumatic to the islets. In this study, we evaluated the effectiveness of iodixanol-controlled density gradients on the islet purification step.


METHODS
For 14.3% of the isolations, the density was 1.085 g/cm3, 32.1% were 1.090 g/cm3, 46.4% were 1.095 g/cm3, 3.6% were 1.100 g/cm3, and 3.6% were 1.105 g/cm3, indicating that the density varies with each isolation. This has profound implications for the difficulty of islet purification. According to the density of digested tissue before purification, the density of the purification solutions was controlled by changing the volumetric ratio of iodixanol and the purification solutions (iodixanol-Kyoto [IK] solutions).


RESULTS
Islet yield after purification and rate of postpurification recovery were significantly higher in the IK group than with standard continuous gradient purification by Ficoll solutions (islet yield=Ficoll group: 377,230+/-50,207 islet equivalents, IK group: 594,136+/-50,570 islet equivalents, P less than 0.01; percentage of recovery=Ficoll group: 55.6%+/-5.8%, IK group: 84.9%+/-4.2%, P less than 0.01). In vitro and in vivo assays suggest that the quality of islets was similar between the two groups.


CONCLUSIONS
Our data suggest that using an iodixanol-controlled density gradient improves the islet recovery rate in human islet isolation. On the basis of these data, we now use this purification method for clinical islet transplantation.
Noguchi
Hirofumi
H
Baylor All Saints Medical Center, Baylor Research Institute, Fort Worth, TX 76104, USA. hirofumn@baylorhealth.edu
Ikemoto
Tetsuya
T
Naziruddin
Bashoo
B
Jackson
Andrew
A
Shimoda
Masayuki
M
Fujita
Yasutaka
Y
Chujo
Daisuke
D
Takita
Morihito
M
Kobayashi
Naoya
N
Onaca
Nicholas
N
Levy
Marlon F
MF
Matsumoto
Shinichi
S
D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D002469:Cell Separation / Q000379:methods*; D002470:Cell Survival / Q000187:drug effects; D003287:Contrast Media; D005260:Female; D005362:Ficoll; D006801:Humans; D007515:Islets of Langerhans / Q000166:cytology* / Q000187:drug effects; D007700:Kinetics; D008297:Male; D010179:Pancreas / Q000166:cytology; D012996:Solutions; D014283:Triiodobenzoic Acids / Q000494:pharmacology*
D003287:Contrast Media; D012996:Solutions; D014283:Triiodobenzoic Acids; D005362:Ficoll; D000255:Adenosine Triphosphate; C044834:iodixanol