title: Direct comparison of Cryotop®vitrification and Bicell®freezing on recovery of functional rat pancreatic islets.
abstract: Two protocols, Bicell®freeze-thawing and Cryotop®vitrification-warming, were compared for suitability in cryopreserving rat pancreatic islets (101-150 μm in mean diameter). Immediate survival rates of post-thaw and post-warm islets (50 and 57%, respectively), assessed by FDA/PI double staining, were lower than that of fresh control islets (90%). Most of the PI-positive dead cells were detected in peripheral area of post-warm islets, and were removed after subsequent 24 h culture (survival rate; 85% vs 59% in post-thaw islets). Quantitative PCR analysis showed that Bicell®freeze-thawing compromised expression of genes relating to β-cell function (Pdx1 and Glut2), but not to one of apoptotic pathways (Bax/Bcl2 ratio). Expression of these genes was maintained in islets before and after the Cryotop®vitrification-warming. Values of stimulus index (SI) for 20 mM/3 mM glucose-stimulated insulin secretion were 6.7, 1.9 and 3.9 in fresh control, post-thaw and post-warm islets, respectively. The SI values after 24 h culture were 4.1, 1.9 and 3.1, respectively. Larger islets (>150 μm in diameter) had comparable survival rates, but lower SI values after Cryotop®vitrification-warming when compared to smaller counterparts. These results suggest that rat pancreatic islets can be cryopreserved by Cryotop®vitrification-warming rather than Bicell®freeze-thawing, without considerable loss of in vitro β-cell function.
authors.affiliation: Graduate School of Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamanaka
authors.affiliation: Graduate School of Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Tashima
authors.affiliation: Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan.
authors.forename: Rio
authors.initials: R
authors.lastname: Takahashi
authors.affiliation: Graduate School of Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan; Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Takashima
authors.affiliation: National Institute for Physiological Sciences, Okazaki, Aichi, 444-8787, Japan.
authors.forename: Teppei
authors.initials: T
authors.lastname: Goto
authors.affiliation: National Institute for Physiological Sciences, Okazaki, Aichi, 444-8787, Japan; School of Life Science, The Graduate University for Advanced Studies, Okazaki, Aichi, 444-8787, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Hirabayashi
authors.affiliation: Graduate School of Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan; Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano, 386-8567, Japan. Electronic address: shochi@shinshu-u.ac.jp.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Hochi
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000379:methods*; D005615:Freezing; D007515:Islets of Langerhans / Q000166:cytology*; D051381:Rats; D058989:Vitrification
keywords: Bicell(®) freezing; Cryotop(®) vitrification; Insulin secretion; Rat Langerhans islets; qPCR