title: Solute diffusion through fibrotic tissue formed around protective cage system for implantable devices.
abstract: This article presents the concept of an implantable cage system that can house and protect implanted biomedical sensing and therapeutic devices in the body. Cylinder-shaped cages made of porous polyvinyl alcohol (PVA) sheets with an 80-µm pore size and/or stainless steel meshes with 0.54-mm openings were implanted subcutaneously in the dorsal region of rats for 5 weeks. Analysis of the explanted cages showed the formation of fibrosis tissue around the cages. PVA cages had fibrotic tissue growing mostly along the outer surface of cages, while stainless steel cages had fibrotic tissue growing into the inside surface of the cage structure, due to the larger porosity of the stainless steel meshes. As the detection of target molecules with short time lags for biosensors and mass transport with low diffusion resistance into and out of certain therapeutic devices are critical for the success of such devices, we examined whether the fibrous tissue formed around the cages were permeable to molecules of our interest. For that purpose, bath diffusion and microfluidic chamber diffusion experiments using solutions containing the target molecules were performed. Diffusion of sodium, potassium and urea through the fibrosis tissue was confirmed, thus suggesting the potential of these cylindrical cages surrounded by fibrosis tissue to successfully encase implantable sensors and therapeutic apparatus.
authors.affiliation: Department of Mechanical Engineering, Keio University, Yokoahama, Kanagawa, Japan.
authors.forename: Gunawan Setia
authors.initials: GS
authors.lastname: Prihandana
authors.affiliation: Department of Mechanical Engineering, Keio University, Yokoahama, Kanagawa, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Ito
authors.affiliation: Department of System Design Engineering, Keio University, Yokoahama, Kanagawa, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Tanimura
authors.affiliation: Department of Surgery, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yagi
authors.affiliation: Department of Strategy and Business Development, Medtronic Japan, Co., Ltd., Minato-ku, Tokyo, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hori
authors.affiliation: Department of Ventures and New Therapies, Medtronic, Inc., Fridley, Minnesota, USA.
authors.forename: Orhan
authors.initials: O
authors.lastname: Soykan
authors.affiliation: Department of System Design Engineering, Keio University, Yokoahama, Kanagawa, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Sudo
authors.affiliation: Department of Mechanical Engineering, Keio University, Yokoahama, Kanagawa, Japan.
authors.forename: Norihisa
authors.initials: N
authors.lastname: Miki
mesh_terms: D000818:Animals; D005355:Fibrosis / Q000209:etiology / Q000503:physiopathology; D020007:Implants, Experimental; D008297:Male; D011142:Polyvinyl Alcohol; D016062:Porosity; D051381:Rats; D017207:Rats, Sprague-Dawley; D013193:Stainless Steel; D013526:Surgical Mesh
chemical_list: D013193:Stainless Steel; D011142:Polyvinyl Alcohol
keywords: cage; diffusion; fibrotic tissue; implant; micro