title: Cryopreservation of insulin-producing cells microencapsulated in sodium cellulose sulfate.
abstract: BACKGROUND
  Diabetes mellitus may be treated with pancreatic islet cell transplantation. The use of xenogenic islet cells may overcome the shortage of human donor organs. Microencapsulation seems to be a promising method for immunoprotection. Since isolation, purification, encapsulation, and transplantation of islet cells are labor-intensive, cryopreservation has emerged as an attractive system for islet banking. In this study sodium cellulose sulfate (NaCS), a novel method for microencapsulation of islet cells, was tested for its capability to protect cells during cryopreservation.
  
  
  METHODS
  HIT-T15 cells were microencapsulated in NaCS. Cells were frozen and thawed using three different media containing varying amounts of dimethylsulfoxide (DMSO) and glycerol. Cell viability and cell growth were monitored using 3-(-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide before freezing and 1 week after thawing.
  
  
  RESULTS
  NaCS did not show any negative impact on the growth rates of encapsulated HIT-T15 cells compared with nonencapsulated controls. Nonencapsulated cells were adequately cryopreserved by both DMSO- and glycerol-containing freezing media. DMSO was not suitable for cryopreservation of encapsulated HIT-T15 cells, whereas glycerol seemed to produce no considerable cell loss during freezing and thawing.
  
  
  CONCLUSIONS
  Islet banking of cells encapsulated in NaCS was feasible. Microencapsulation did not harm islet cell recovery. As NaCS is less immunogenic and more biocompatible than other materials used for microencapsulation, it may be a promising method for immunoisolation of islet cells to replace the endocrine pancreas in a physiological way.
authors.affiliation: Department of Surgery, Division of Transplantation Surgery, Medical University Graz, Graz, Austria. philipp.stiegler@klinikum-graz.at
authors.forename: P B
authors.initials: PB
authors.lastname: Stiegler
authors.forename: V
authors.initials: V
authors.lastname: Stadlbauer
authors.forename: S
authors.initials: S
authors.lastname: Schaffellner
authors.forename: G
authors.initials: G
authors.lastname: Halwachs
authors.forename: C
authors.initials: C
authors.lastname: Lackner
authors.forename: O
authors.initials: O
authors.lastname: Hauser
authors.forename: F
authors.initials: F
authors.lastname: Iberer
authors.forename: K
authors.initials: K
authors.lastname: Tscheliessnigg
mesh_terms: D000818:Animals; D002214:Capsules; D002452:Cell Count; D002455:Cell Division; D002460:Cell Line; D002482:Cellulose / Q000031:analogs & derivatives; D006224:Cricetinae; D015925:Cryopreservation / Q000379:methods*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology* / Q000378:metabolism; D016381:Islets of Langerhans Transplantation; D014183:Transplantation, Heterologous / Q000379:methods
chemical_list: D002214:Capsules; D007328:Insulin; D002482:Cellulose; C020254:cellulose sulfate