title: Neovascularization of synthetic membranes directed by membrane microarchitecture.
abstract: Transplantation of tissues enclosed within a membrane device designed to protect the cells from immune rejection (immunoisolation) provides an opportunity to treat a variety of disease conditions. Successful implementation of immunoisolation has been hampered by the foreign-body reaction to biomaterials. We screened a variety of commercially available membranes for foreign-body reactions following implantation under the skin of rats. Histologic analysis revealed that neovascularization at the membrane-tissue interface occurred in several membranes that had pore sizes large enough to allow complete penetration by host cells (0.8-8 microns pore size). When the vascularization of the membrane-tissue interface of 5-microns-pore-size polytetrafluoroethylene (PTFE) membranes was compared to 0.02-microns-pore-size PTFE membranes, it was found that the larger pore membranes had 80-100-fold more vascular structures. The increased vascularization was observed even though the larger pore membrane was laminated to a smaller pore inner membrane to prevent cell entry into the prototype immunoisolation device. This significantly higher level of vascularization was maintained for 1 year in the subcutaneous site in rats.
authors.affiliation: Baxter Healthcare Corp., Baxter Technology Park, Round Lake, Illinois 60073, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Brauker
authors.forename: V E
authors.initials: VE
authors.lastname: Carr-Brendel
authors.forename: L A
authors.initials: LA
authors.lastname: Martinson
authors.forename: J
authors.initials: J
authors.lastname: Crudele
authors.forename: W D
authors.initials: WD
authors.lastname: Johnston
authors.forename: R C
authors.initials: RC
authors.lastname: Johnson
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001808:Blood Vessels / Q000166:cytology / Q000502:physiology; D005549:Foreign-Body Reaction / Q000276:immunology; D008297:Male; D008567:Membranes, Artificial; D018919:Neovascularization, Physiologic / Q000502:physiology*; D011138:Polytetrafluoroethylene; D016062:Porosity; D019736:Prostheses and Implants; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001672:Biocompatible Materials; D008567:Membranes, Artificial; D011138:Polytetrafluoroethylene