title: Glass transition temperature of dried lens tissue pretreated with trehalose, maltose, or cyclic tetrasaccharide.
abstract: OBJECTIVE
  Glass transition temperature is a main indicator for amorphous polymers and biological macromolecules as materials, and would be a key for understanding the role of trehalose in protecting proteins and cells against desiccation. In this study, we measured the glass transition temperature by differential scanning calorimetry of dried lens tissues as a model of a whole biological tissue to know the effect of pretreatment by trehalose and other sugars.
  
  
  METHODS
  Isolated porcine lenses were incubated with saline, 100 or 1000 mM concentration of trehalose, maltose, or cyclic tetrasaccharide dissolved in saline at room temperature for 150 minutes. The solutions were removed and all samples were dried at room temperature in a desiccator until no weight change. The dried tissues were ground into powder and placed in a measuring pan for differential scanning calorimetry.
  
  
  RESULTS
  The glass transition temperature of the dried lens tissues, as a mean and standard deviation, was 63.0 ± 6.4°C (n = 3) with saline pretreatment; 53.0 ± 0.8°C and 56.3 ± 2.7°C (n = 3), respectively, with 100 and 1000 mM trehalose pretreatment; 56.0 ± 1.6°C and 55.8 ± 1.1°C (n = 3), respectively, with 100 and 1000 mM maltose pretreatment; 60.0 ± 8.8°C and 59.2 ± 6.3°C (n = 3), respectively, with 100 and 1000 mM cyclic tetrasaccharide pretreatment. The glass transition temperature appeared lower, although not significantly, with trehalose and maltose pretreatments than with saline and cyclic tetrasaccharide pretreatments (P > 0.05, Kruskal-Wallis test). The glass transition temperature of the dried lens tissues with trehalose pretreatment appeared more noticeable on the thermogram, compared with other pretreatments.
  
  
  CONCLUSIONS
  The glass transition temperature was measured for the first time in the dried lens tissues as an example of a whole biological tissue and might provide a basis for tissue preservation in the dried condition.
authors.affiliation: Department of Ophthalmology, Okayama University Medical School and Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, 700-8558 Japan.
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Kawata
authors.affiliation: Department of Ophthalmology, Okayama University Medical School and Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, 700-8558 Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Matsuo
authors.affiliation: Division of Polymer Materials Science, Faculty of Engineering and Okayama University Graduate School of Natural Science and Technology, Okayama, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Uchida
keywords: Biological tissue; Cyclic tetrasaccharide; Desiccation; Differential scanning calorimetry; Glass transition temperature; Lens; Maltose; Regenerative medicine; Tissue preservation; Trehalose