IN-VIVO BIOSTABILITY OF A POLYMERIC HOLLOW-FIBER MEMBRANE FOR CELL ENCAPSULATION

The biostability of poly(acrylonitrile-co-vinyl chloride) (P(AN/VC)) h ollow fibre membranes was assessed in the rat peritoneal cavity over a 12 month period. The mechanical and chemical stabilities of the hollo w fibre membrane (HFM) were characterized by measuring its tensile str ength and molecular weight (by gel permeation chromatography) pre-impl antation and post-explantation. The stability of the HFM transport pro perties was determined by molecular weight cut-off (MWCO) and hydrauli c permeability (HP). Explanted HFMs were treated with 4 M NaOH to remo ve adsorbed protein before measuring mechanical, chemical and transpor t properties. The HFM was stable in vivo for at least 12 months: (i) w eight average molecular weight (M(W)) at t = 0 was 143 000 g mol(-1) ( with a polydispersity index (PDI) of 2.3) and at t = 12 months it was 128 000 g mol(-1) (with a PDI of 2.8); and (ii) tensile strength at t = 0, 52 +/- 2 mdyne, did not change significantly over time and was 46 +/- 7 mdyne at t = 15 months (P > 0.05 by a two-tailed Student's t-te st); and (iii) no significant differences, with respect to standard de viation, were observed in the transport properties: HP was 7.4 +/- 1.5 ml min(-1) m(-2) mmHg(-1) at t = 0 and 7.5 +/- 1.5 mi min(-1) m(-2) m mHg(-1) at t = 12 months, while MWCO (at 90% rejection) was initially 40 000 +/- 8000 g mol(-1) and then 54 000 +/- 10 000 g mol(-1) at t = 12 months.