Solute diffusion through fibrotic tissue formed around protective cage system for implantable devices

Area of Science:

• Biomaterials Science
• Biomedical Engineering
• Tissue Engineering

Background:

• Developing implantable systems to protect biomedical sensors and therapeutic devices is crucial.
• Biocompatible materials are needed for long-term implantation with minimal adverse tissue reactions.
• Understanding foreign body response and tissue integration is key for device efficacy.

Purpose of the Study:

• To evaluate the biocompatibility and tissue integration of implantable porous cages.
• To assess the permeability of the formed fibrotic tissue for molecular transport.
• To determine the suitability of these cages for housing biomedical sensing and therapeutic devices.

Main Methods:

• Cylindrical cages of porous polyvinyl alcohol (PVA) and stainless steel meshes were implanted subcutaneously in rats for 5 weeks.
• Explanted cages were analyzed for fibrotic tissue formation and its location relative to cage porosity.
• Diffusion experiments using sodium, potassium, and urea were conducted to assess tissue permeability.

Main Results:

• Fibrosis tissue formed around both PVA and stainless steel cages.
• Stainless steel cages showed fibrotic tissue ingrowth due to larger pore size.
• Diffusion of sodium, potassium, and urea through the fibrosis tissue was confirmed.

Conclusions:

• Implantable porous cages elicit a fibrotic response that allows for molecular diffusion.
• The tested cage materials and resulting tissue integration support their potential use for encasing implantable sensors and therapeutic devices.
• This study demonstrates a promising approach for protecting and enabling function of implanted biomedical technologies.