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Mast cells and tissue reaction to intraperitoneally implanted polymer capsules.
L Christenson1, L Wahlberg, P Aebischer
1Artificial Organ Laboratory, Brown University, Providence, Rhode Island 02912.
Journal of Biomedical Materials Research
|September 1, 1991
Summary
Local delivery of dexamethasone (dms) from ethylene vinyl acetate (EVAc) rods significantly reduced the inflammatory tissue reaction to implanted biomaterials in rats. This localized approach offers a promising alternative to systemic dms treatment for implantable devices.
Area of Science:
- Biomaterials Science
- Immunology
- Drug Delivery Systems
Background:
- Inflammatory responses to biomaterials impede implant functionality.
- Dexamethasone (dms) is an anti-inflammatory drug that modulates macrophage and mast cell activity.
- Systemic dms administration reduces tissue reactions but carries side effects.
Purpose of the Study:
- To investigate the local effect of dexamethasone (dms) released from ethylene vinyl acetate (EVAc) rods on the tissue reaction to implanted biomaterials.
- To evaluate a localized drug delivery system for controlling inflammatory responses around implants.
- To compare local dms delivery with systemic administration and implants without dms.
Main Methods:
- Dexamethasone (dms) was loaded into ethylene vinyl acetate (EVAc) rods.
- EVAc/dms rods were placed within acrylic copolymer capsules and implanted intraperitoneally in rats.
- In vitro release of dms from EVAc rods was characterized.
- Tissue reactions around capsules with EVAc/dms rods were compared to those with pure EVAc rods at various time points.
- Histological analysis quantified fibroblast and collagen layers and mast cell presence.
Main Results:
- In vitro, dms release from EVAc rods was quasilinear for 5 weeks.
- Intraperitoneally implanted capsules with EVAc/dms rods showed significantly thinner tissue reaction layers compared to controls (pure EVAc rods).
- The local dms delivery resulted in a thinner tissue reaction than previously observed with systemic dms treatment.
- Implants with dms-loaded EVAc rods had more intact mast cells, suggesting their role in the inflammatory process.
Conclusions:
- Local release of dexamethasone (dms) from EVAc rods effectively mitigates the foreign body response to intraperitoneal polymer implants.
- This localized drug delivery system controls inflammation while potentially avoiding systemic side effects.
- Mast cell degranulation appears to be a key component of the tissue reaction to these polymer implants.