Transport characterization of membranes for immunoisolation.
This study relates to the diffusive transport characterization of hollow fibre membranes used in implantable bio-hybrid organs and other immunoisolatory devices. Techniques were developed to accurately determine the mass transfer coefficients for diffusing species in the 10(2)-10(5) MW range, validated and then used to study one membrane type known to effectively immunoisolate both allografts and xenografts in vivo. Low-molecular-weight diffusing markers included glucose, vitamin B12 and cytochrome C; higher-molecular-weight molecules were bovine serum albumin, immunoglobulin G, apoferritin and a range of fluorescein-tagged dextrans. Overall and fractional mass transfer coefficients through the hollow fibres were determined using a resistance-in-series model for transport. A flowing dialysis-type apparatus was used for the small-molecular-weight diffusants, whereas a static diffusion chamber was used for large-molecular-weight markers. For diffusion measurements of small-molecular-weight solutes, convective artefacts were minimized and the effect of boundary layers on both sides of the membrane were accounted for in the model. In measuring diffusion coefficients of large-molecular-weight species, boundary layer effects were shown to be negligible. Results showed that for small-molecular-weight species (< 13,000 MW) the diffusion coefficient in the membrane was reduced relative to diffusion in water by two to four times. The diffusion rate of large-molecular-weight species was hindered by several thousand-fold over their rate of diffusion in water.
Dionne
K E
KE
CytoTherapeutics Inc., Providence, RI 02906, USA.
Cain
B M
BM
Li
R H
RH
Bell
W J
WJ
Doherty
E J
EJ
Rein
D H
DH
Lysaght
M J
MJ
Gentile
F T
FT
D000818:Animals; D001052:Apoferritins; D001187:Artificial Organs; D001672:Biocompatible Materials; D003574:Cytochrome c Group; D003956:Dialysis; D004058:Diffusion; D005947:Glucose; D006801:Humans; D007074:Immunoglobulin G; D008433:Mathematics; D008567:Membranes, Artificial; D008962:Models, Theoretical; D012710:Serum Albumin, Bovine; D014183:Transplantation, Heterologous; D014184:Transplantation, Homologous; D014805:Vitamin B 12
D001672:Biocompatible Materials; D003574:Cytochrome c Group; D007074:Immunoglobulin G; D008567:Membranes, Artificial; D012710:Serum Albumin, Bovine; D001052:Apoferritins; D005947:Glucose; D014805:Vitamin B 12