Calcification of polyurethanes implanted subdermally in rats is enhanced by calciphylaxis

Area of Science:

• Biomaterials Science
• Medical Device Engineering
• Pathology

Background:

• Polyurethane (PU) use in cardiovascular implants is limited by calcification.
• Existing animal models for studying PU calcification are costly and complex.
• A novel, cost-effective rat subdermal implant model is needed.

Purpose of the Study:

• To investigate polyurethane calcification in a rat subdermal implant model.
• To evaluate the efficacy of ethanehydroxy-bisphosphonate (EHBP) modification in preventing calcification.
• To establish a new model for assessing the calcification potential of biomedical polymers.

Main Methods:

• Induction of calciphylaxis in rats using dihydrotachysterol (a vitamin-D analog).
• Subdermal implantation of four polyurethanes (Biomer, Mitrathane, PEU-2000, PEU-100) for 60 days.
• Analysis of explant calcium and phosphate levels, somatic growth, and serum calcium.
• Morphological examination using scanning electron microscopy, energy dispersive X-ray spectroscopy, and light microscopy.

Main Results:

• Calciphylaxis significantly increased calcium levels in Biomer, Mitrathane, and PEU-2000 implants compared to controls.
• PEU-100, modified with EHBP, exhibited resistance to calcification under calciphylaxis conditions.
• Calciphylaxis did not affect somatic growth or serum calcium levels in the rats.
• Calcification was predominantly observed on the surface of the explants.

Conclusions:

• Calciphylaxis enhances superficial calcification of polyurethanes in rat subdermal implants.
• EHBP-modified polyurethane demonstrates resistance to calcification induced by calciphylaxis.
• Rat subdermal implants with induced calciphylaxis offer a viable model for evaluating polymer calcification potential.