Poly(L-lactide)acid/alginate composite membranes for guided tissue regeneration

The barrier membranes for guided tissue regeneration (GTR) to treat bone de fects have to satisfy the critera of biocompatibility, cell-occlusiveness, space-making, tissue integration and clinical manageability. In this study a system constituted of a poly(L-lactide) acid (PLLA) asymmetric membrane c ombined with an alginate film was prepared. The PLLA membrane functions to both support the alginate film and separate the soft tissue; the alginate f ilm is intended to act as potential vehicle for the growth factors to promo te osteogenesis. The structural, morphological, and mechanical properties o f the bilamellar membrane and its stability in culture medium were evaluate d. Moreover, the feasibility of using the alginate membranes as controlled- release delivery vehicles of TGF-beta was monitored. Finally, the bacterial adhesion and permeability of Streptococcus mutans, selected for the high a dhesive affinity, were monitored. The results showed that the Surfaces of t he alginate side, to be used in contact with the bone defect, were rougher than PLLA ones. When in contact with complete culture medium, the PLLA-algi nate membrane retained its mechanical and structural properties for more th an 100 days. Then, the degradation processes occurred but the membrane cont inued to be stable and manageable for 6 months. Growth factors such as TGF- beta can be incorporated into alginate membranes functioning as drug delive ry vehicle, and retain the biological activity when tested in an in vitro m odel system. The obtained membrane acted as a barrier to the passage of S. mutans bacteria and showed to promote a lower bacterial adhesion with respe ct to commercial GTR membranes. (C) 2001 John Wiley & Sons, Inc.