A sensitivity study of the key parameters in the interfacial photopolymerization of poly(ethylene glycol) diacrylate upon porcine islets.

A method has been defined to interfacially photopolymerize poly(ethylene glycol) diacrylates (PEG diacrylates) to form a crosslinked hydrogel membrane upon the surfaces of porcine islets of Langerhans to serve as an immune barrier for allo- and xenotransplantation. A sensitivity study of six key parameters in the interfacial photopolymerization process was performed to aid in determination of the optimal encapsulation conditions, leading to the most uniform hydrogel membranes and viable islets. The key parameters included the concentrations of the components of the initiation scheme, namely eosin Y, triethanolamine, and 1-vinyl 2-pyrrolidinone. Other parameters investigated included the duration and flux of laser irradiation and the PEG diacrylate molecular weight. Each parameter was doubled and halved from the standard conditions used in the encapsulation process while holding all the remaining parameters at the standard conditions. The effects of changing each parameter on islet viability, encapsulation efficiency, and gel thickness were quantified. Islet viability was sensitive to the duration of laser illumination, viability significantly increasing as the duration was reduced. Encapsulation efficiency was sensitive to the concentrations of eosin Y, triethanolamine, and 1-vinyl 2-pyrrolidinone, to the laser flux, and to the PEG diacrylate molecular weight. Increasing the concentration of eosin Y significantly improved the encapsulation efficiency, while decreasing the concentration of 1-vinyl 2-pyrrolidinone and increasing the concentration of triethanolamine had the greatest effects in significantly reducing the encapsulation efficiency. Gel thickness was sensitive to the concentrations of triethanolamine and 1-vinyl 2-pyrrolidinone, to the duration of laser illumination, and to the PEG diacrylate molecular weight. Increasing the PEG diacrylate molecular weight significantly increased the gel thickness, while decreasing the concentration of 1-vinyl 2-pyrrolidinone and increasing the concentration of triethanolamine had the greatest effects in significantly reducing the gel thickness. From this sensitivity study, conditions were determined to encapsulate porcine islets, resulting in greater than 90% islet viability and greater than 90% encapsulation efficiency.

[1]  M. Field,et al.  PURIFIED CANINE ISLET AUTOGRAFTS: FUNCTIONAL OUTCOME AS INFLUENCED BY ISLET NUMBER AND IMPLANTATION SITE , 1990, Transplantation.

[2]  T I Karu,et al.  EFFECTS OF VISIBLE RADIATION ON CULTURED CELLS , 1990, Photochemistry and photobiology.

[3]  P. Lacy,et al.  Effect of transplantation site and alpha L3T4 treatment on survival of rat, hamster, and rabbit islet xenografts in mice. , 1989, Transplantation.

[4]  R. Turner,et al.  Metabolic Function of Intraportal and Intrasplenic Islet Autografts in Cynomolgus Monkeys , 1989, Diabetes.

[5]  H. Amemiya,et al.  Feasibility of agarose microbeads with xenogeneic islets as a bioartificial pancreas. , 1994, Journal of biomedical materials research.

[6]  J. A. Hubbell,et al.  Modification of islet of langerhans surfaces with immunoprotective poly(ethylene glycol) coatings via interfacial photopolymerization. , 1994, Biotechnology and bioengineering.

[7]  D. Neckers,et al.  Photopolymerization studies using visible light photoinitiators , 1992 .

[8]  J. M. Harris,et al.  Proton NMR characterization of poly(ethylene glycols) and derivatives , 1990 .

[9]  Kazuo Tanaka,et al.  Poly(ethylene oxide) macromonomers. 7. Micellar polymerization in water , 1991 .

[10]  P. Lacy,et al.  A Method for the Mass Isolation of Islets From the Adult Pig Pancreas , 1986, Diabetes.

[11]  D. Ducassou,et al.  In situ polymerization of a microencapsulating medium round living cells. , 1988, Journal of biomedical materials research.

[12]  P. Lacy,et al.  Method for the Isolation of Intact Islets of Langerhans from the Rat Pancreas , 1967, Diabetes.

[13]  Jeffrey A. Hubbell,et al.  Rapid photopolymerization of immunoprotective gels in contact with cells and tissue , 1992 .

[14]  R. L. Broughton,et al.  Microencapsulation of mammalian cells in a HEMA-MMA copolymer: effects on capsule morphology and permeability. , 1990, Journal of biomedical materials research.

[15]  I. Goldfine,et al.  Mechanisms of Insulin-Induced Insulin-Receptor Downregulation: Decrease of Receptor Biosynthesis and mRNA Levels , 1989, Diabetes.

[16]  D. Ecker,et al.  Xenotransplantation of porcine and bovine islets without immunosuppression using uncoated alginate microspheres. , 1995, Transplantation.

[17]  C. Colton,et al.  Implantable biohybrid artificial organs. , 1995, Cell transplantation.

[18]  A. Sun,et al.  Prolonged Reversal of Diabetic State in NOD Mice by Xenografts of Microencapsulated Rat Islets , 1991, Diabetes.

[19]  H Iwata,et al.  Strategy for developing microbeads applicable to islet xenotransplantation into a spontaneous diabetic NOD mouse. , 1994, Journal of biomedical materials research.

[20]  F. Lim,et al.  Microencapsulated islets as bioartificial endocrine pancreas. , 1980, Science.