Gas Bubbles from Biodegradable Magnesium Implants Convey Mechanical Cues and Promote Immune Cell Stimulation

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Cell Biology

Background:

• Biodegradable magnesium implants are increasingly used in medical treatments.
• Gas bubble formation in adjacent soft tissues is a common but poorly understood phenomenon.
• Understanding bubble-related biological implications is vital for patient outcomes.

Purpose of the Study:

• To investigate the biological effects of gas bubble accumulation and evolution around magnesium implants.
• To analyze the influence of bubble dynamics on tissue and cell behavior over time and distance.
• To elucidate the cellular and molecular mechanisms underlying the tissue response to implant-generated bubbles.

Main Methods:

• In vivo study using rats with biodegradable magnesium implants.
• Observation of bubble accumulation, resorption, and tissue morphology.
• Analysis of cellular infiltration, macrophage phenotypes, and mechanosensitive ion channel expression (Piezo1).
• Spatially resolved transcriptomics to identify gene expression patterns and pathway activation.

Main Results:

• Bubbles formed around implants in early postimplantation stages and subsequently resorbed.
• Tissue and cell geometry changes were observed near bubbles, with macrophage accumulation and increased Piezo1 expression.
• Spatially resolved transcriptomics revealed proinflammatory pathway activation and expression of Spp1 (proliferative macrophage marker).
• Significant enrichment of cytoskeletal rearrangement genes indicated cellular response to mechanical cues from bubbles.
• Bubble-implant distance and time significantly modulated the cellular response, with distant bubbles correlating with declining regeneration and predominant inflammation.

Conclusions:

• Degradation-induced bubbles from magnesium implants elicit complex local responses involving inflammatory and mechanical pathways.
• Cellular behavior and tissue healing are significantly influenced by bubble dynamics, including their proximity to the implant and temporal evolution.
• Controlled gas release from magnesium implants and careful monitoring of bubble evolution are necessary for optimizing tissue healing and clinical application.