Permeability of alginate microcapsules to secretory recombinant gene products

D. E. Awrey, M. Tse, G. Hortelano, P. L. Chang

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


Non-autologous somatic gene therapy is an alternate approach to delivering recombinant gene products through implantation of a 'universal' donor cell line engineered to produce a therapeutic gene product. The cells are immunologically isolated by enclosure in immunoprotective microcapsules fabricated from alginate-poly-L-lysine-alginate. The molecular weight cutoff of these microcapsules was thought to be <100 kd, thus, excluding the immunoglobulins. However, when such microcapsules are fabricated to enclose cells, they show a higher permeability threshold than expected. The secretion rates of recombinant gene products ranging from 21 through 150 to 300 kd (human growth hormone, rat serum albumin, human arylsulfatase A, human immunoglobulin, mouse β-hexosaminidase, mouse β-glucuronidase) were similar between the nonencapsulated and encapsulated recombinant cells with the exception of the largest molecular species, the 300-kd β-glucuronidase. Its secretion was reduced about eightfold after encapsulation. Increasing the thickness of the membrane by prolonging the coating time with poly-L-lysine did not provide a lower molecular weight cutoff. An additional coating with alginate, however, reduced the leakage of the larger molecular species, but the effect was short lived: After 2 weeks in culture, the double- and single- coated microcapsules were equally permeable. Both the increased poly-L- lysine and alginate coating were detrimental to the long-term viability and proliferation of the encapsulated cells. Hence, immunoisolation of encapsulated cells with alginate-poly-L-lysine-alginate microcapsules cannot provide a molecular weight cutoff below 300 kd.

Original languageEnglish
Pages (from-to)472-484
Number of pages13
JournalBiotechnology and Bioengineering
Issue number4
Publication statusPublished - Nov 20 1996


  • albumin
  • gene therapy
  • growth hormone
  • immunoglobulin
  • lysosomal enzymes

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology

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