Surface chemistry influences implant-mediated host tissue responses

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Surface Chemistry

Background:

• Implant-mediated fibrotic reactions negatively impact the performance and longevity of various medical devices, including cell encapsulation systems, drug delivery devices, and biosensors.
• While surface functional groups influence short-term cellular responses, their effect on long-term in vivo fibrotic reactions is limited due to insufficient host cell-implant interactions.
• Maximizing the impact of surface functionality on cellular responses requires strategies that enhance interactions, similar to drug release microspheres.

Purpose of the Study:

• To investigate the ability of functionalized micron-sized particles to modulate host tissue responses to biomaterial implants.
• To evaluate the effect of different surface functional groups (-OH, -NH(2), -CF(x), -COOH) on the inflammatory and fibrotic reactions following subcutaneous implantation.
• To determine if increasing functionalized surface area and spatial distribution can enhance the influence of surface chemistry on tissue reactivity.

Main Methods:

• Polypropylene particles were functionalized with four distinct chemical groups (-OH, -NH(2), -CF(x), -COOH) using radio frequency glow discharge plasma polymerization.
• The functionalized particles were implanted subcutaneously in a mice model to evaluate host tissue responses.
• Histological analysis was performed to assess capsule thickness, cellular infiltration, and overall inflammatory/fibrotic reactions.

Main Results:

• Significant differences in tissue response were observed based on surface chemistry.
• -OH and -NH(2) functionalized surfaces induced the thickest fibrous capsules and highest cellular infiltration.
• -CF(x) and -COOH functionalized surfaces exhibited the least inflammatory/fibrotic responses and cellular infiltration.

Conclusions:

• Surface chemistry of biomaterial implants plays a crucial role in modulating host tissue responses.
• Increasing the available functionalized surface area and spatial distribution can substantially enhance the effect of surface chemistry on tissue reactivity.
• Surfaces with -CF(x) and -COOH functionalities show promise for reducing adverse fibrotic reactions, potentially improving implant performance and longevity.