TY - JOUR
T1 - Extracellular matrix for a rechargeable cell delivery system
AU - Bae, You Han
AU - Vernon, Brent
AU - Han, Chang Kwon
AU - Kim, Sung Wan
N1 - Funding Information:
This work was supported by STEPI, RR-07, Korea and NIH DK46458 and GM 08393, USA. The authors thank Moon Kyu Lee, MD (Samsung Medical Center, Korea) for his help in isolating the islets.
PY - 1998/4/30
Y1 - 1998/4/30
N2 - Above a critical concentration, aqueous polymer solutions of N- isopropylacrylamide copolymers with small amounts of acrylic acid, synthesized in benzene by radical polymerization, exhibited four distinct phases as the temperature increased; clear solution, opaque solution, gel and shrunken gel. The transition between the opaque solution phase and the gel phase was in the range of 30-34°C and was reversible without syneresis and noticeable hysteresis under the experimental conditions used in this study. Islets of Langerhans, isolated from Sprague-Dawley rat pancreata and entrapped in the gel matrix, remained viable, with no significant decrease in insulin secretion function in vitro for one month. When islets were encapsulated with the gel matrix in hollow fibers [molecular weight cut-off (MWCO)=~400 000] and were exposed to dynamic changes in glucose and theophylline concentrations, their insulin secretion patterns demonstrated a smaller lag time and higher amplitude in insulin release than islets entrapped in a conventional alginate matrix under the same experimental conditions. From these two observations, i.e. gel reversibility and islet functionality in the matrix observed in in vitro experiments, the N- isopropylacrylamide copolymers with acrylic acid synthesized in this study are optimum candidates for the extracellular matrix in a diffusion chamber- type cell delivery system in order to recharge the entrapped cells when cell functionality in the system decreases.
AB - Above a critical concentration, aqueous polymer solutions of N- isopropylacrylamide copolymers with small amounts of acrylic acid, synthesized in benzene by radical polymerization, exhibited four distinct phases as the temperature increased; clear solution, opaque solution, gel and shrunken gel. The transition between the opaque solution phase and the gel phase was in the range of 30-34°C and was reversible without syneresis and noticeable hysteresis under the experimental conditions used in this study. Islets of Langerhans, isolated from Sprague-Dawley rat pancreata and entrapped in the gel matrix, remained viable, with no significant decrease in insulin secretion function in vitro for one month. When islets were encapsulated with the gel matrix in hollow fibers [molecular weight cut-off (MWCO)=~400 000] and were exposed to dynamic changes in glucose and theophylline concentrations, their insulin secretion patterns demonstrated a smaller lag time and higher amplitude in insulin release than islets entrapped in a conventional alginate matrix under the same experimental conditions. From these two observations, i.e. gel reversibility and islet functionality in the matrix observed in in vitro experiments, the N- isopropylacrylamide copolymers with acrylic acid synthesized in this study are optimum candidates for the extracellular matrix in a diffusion chamber- type cell delivery system in order to recharge the entrapped cells when cell functionality in the system decreases.
KW - Biohybrid artificial pancreas
KW - Hysteresis
KW - Islets
KW - N-Isopropylacrylamide copolymers
KW - Thermoreversible gelation
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U2 - 10.1016/S0168-3659(97)00258-7
DO - 10.1016/S0168-3659(97)00258-7
M3 - Article
C2 - 9741932
AN - SCOPUS:0032580443
SN - 0168-3659
VL - 53
SP - 249
EP - 258
JO - Journal of Controlled Release
JF - Journal of Controlled Release
IS - 1-3
ER -