A model to evaluate toxic factors influencing islets during collagenase digestion: the role of serine protease inhibitor in the protection of islets.
The recovery of all of the islets contained in a pancreas is the goal of islet isolation for transplantation. This study reveals an environment that injures the isolated islets during digestion and proposes a new model for optimal islet isolation. Islets were isolated from Wistar rat  pancreases by stationary collagenase digestion while the digestion time was varied at 15, 30, 60, and 120 min. The digested pancreas and islets were analyzed histologically and adenosine nucleotides were measured. Overnight cultured islets (40 islets) were cocultured for 30 min with the supernatants  obtained from pancreatic collagenase digestion at different digestion periods in order to assess the toxic environment. The peak yields of islets were obtained at 30 min of digestion. The histological study of digested pancreas showed that the exocrine cells lost their cellular integrity at  120 min of digestion, but the islet cells were left intact. Accordingly, the ATP levels of the pancreatic tissue decreased during the digestion period. The coculture experiment demonstrated that the islets cultured with the supernatants from the collagenase digestion showed digestion time-dependent  disruption of the cellular integrity of islets in accordance with a rapid decrease of ATP levels in the islets. The addition of serine protease inhibitors into this coculture clearly showed protection of islets, which maintained high ATP levels in association with intact membrane integrity  as assessed by AO/PI staining. Morphological deterioration of islets as well as a marked ATP decrease was evident in the entire digested pancreas as well as in islets cocultured in the supernatants from the collagenase digestion. Various factors toxic to the islets can therefore be analyzed  in future experiments using this coculture model for obtaining a good yield of viable islets.
Department of Surgery, Fukushima Medical University, Fukushima City, Fukushima, Japan.
Manabu
M
Tsukada
Takuro
T
Saito
Kazuya
K
Ise
Akira
A
Kenjo
Takashi
T
Kimura
Yoshihiro
Y
Satoh
Takaharu
T
Saito
Takayuki
T
Anazawa
Ikuro
I
Oshibe
Shigeya
S
Suzuki
Yasuhiro
Y
Hashimoto
Mitsukazu
M
Gotoh
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002469:Cell Separation / Q000379:methods*; D018920:Coculture Techniques; D017364:Collagenases / Q000494:pharmacology*; D006023:Glycoproteins / Q000494:pharmacology; D007515:Islets of Langerhans / Q000166:cytology* / Q000187:drug effects / Q000473:pathology; D008297:Male; D008954:Models, Biological; D010179:Pancreas / Q000166:cytology / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D013450:Sulfones / Q000494:pharmacology; D013997:Time Factors; D014357:Trypsin / Q000737:chemistry / Q000378:metabolism
D006023:Glycoproteins; D015842:Serine Proteinase Inhibitors; D013450:Sulfones; C002010:4-(2-aminoethyl)benzenesulfonylfluoride; D000255:Adenosine Triphosphate; D014357:Trypsin; D017364:Collagenases; C028665:urinastatin