title: Effects of growth regulation on conditionally-transformed alginate-entrapped insulin secreting cell lines in vitro.
abstract: The ability to control cell growth is an issue of critical importance for the use of transformed beta-cell lines within a bioartificial pancreas. Such control can be achieved either by entrapping the cells in a biomaterial that can inhibit cell proliferation or by genetically modifying the cells to regulate growth. Integrating tetracycline-off or -on operon systems into murine insulinoma cell lines (betaTC-tet and R7T1, respectively) allows cell growth regulation upon exposure to tetracycline (TC) or its derivative doxycycline (Dox), respectively. However, the effects of this regulatory approach on the long-term phenotypic metabolic and secretory stability of alginate-entrapped cells have yet to be thoroughly investigated. In this study, cultures of betaTC-tet and R7T1 cells entrapped in alginate beads were allowed to grow freely, or were growth-regulated, either at the onset, or after 20 days of growth. The data show that growth regulation of alginate-entrapped cells is achievable with chronic administration of the regulatory compound in a concentration-dependent manner. However, as these cultures age, the amount of insulin released does not always reflect the metabolic and histological characteristics of the cultures. This change, coupled with a loss of glucose stimulated insulin secretion in the Dox treated R7T1 cell line, indicate a phenotypic shift of cells with an activated tet-operon. These observations have implications on the selection and long-term function of three-dimensional bioartificial pancreatic constructs that include conditionally transformed beta-cell lines.
authors.affiliation: The Laboratory for Tissue Engineering, Department of Medicine, Division of Endocrinology, University of Florida, 1600 SW Archer Rd, P.O. Box 100226, Gainesville, FL 32610-0226, USA.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Simpson
authors.forename: Nata
authors.initials: N
authors.lastname: Khokhlova
authors.forename: Jose A
authors.initials: JA
authors.lastname: Oca-Cossio
authors.forename: Scott S
authors.initials: SS
authors.lastname: McFarlane
authors.forename: Chiab P
authors.initials: CP
authors.lastname: Simpson
authors.forename: Ioannis
authors.initials: I
authors.lastname: Constantinidis
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000818:Animals; D001187:Artificial Organs; D002455:Cell Division; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D020723:Glucuronic Acid / Q000737:chemistry*; D006603:Hexuronic Acids / Q000737:chemistry*; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007340:Insulinoma / Q000378:metabolism*; D051379:Mice; D010179:Pancreas / Q000378:metabolism
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D007328:Insulin; D004317:Doxorubicin; D020723:Glucuronic Acid; D005947:Glucose