Development of new injectable bulking agents: Biocompatibility of radiopaque polymeric microspheres studies in a mouse model

PJ Emans, K Saralidze, MLW Knetsch, MJJ Gijbels, LH Koole*, Roelof Kuijer

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

22 Citations (Scopus)


Radiopaque polymeric microspheres have a potential as new bulking agents for treatment of stress urinary incontinence (SUI). The advantage over existing bulking agents ties in their X-ray visibility in situ; other polymeric bulking agents (e.g., PTFE or silicone rubbers) are practically radiolucent (i.e., incapable of absorbing X-radiation). Radiopacity is useful in practice because of the high spatial accuracy of X-ray imaging. For instance, X-ray fluoroscopy can be used to assess possible migration of the bulking agent over time or to provide guidance in cases in which a second injection of a bulking agent is necessary (repeated treatment of SUI). Biocompatibility of injected radiopaque microspheres was investigated in vivo by using the mouse as a model. Microspheres were injected subcutaneously (9 animals) or intramuscularly (9 animals), and follow-up was 8 days or 3 months. X-ray fluoroscopy gave clear images of the miscrospheres as an ensemble, and it was found that no migration occurred during 3 months. Histopathology confirmed that all microspheres stayed close to the site of the injection. The microspheres appeared to be well tolerated; only a few giant cells, manifesting a mild inflammatory reaction, were encountered. At 3 months, cappillary blood vessels were observed throughout the microsphere beds, and macrophages and fibroblast cells were seen in between the microspheres. This is encouraging with respect to the intended application, although it must be acknowledged that the data refer merely to a mouse model. Further experiments with larger, more representative models (rabbit and goat) are in progress. © 2005 Wiley Periodicals, Inc.

Original languageEnglish
Pages (from-to)430-436
Number of pages7
JournalJournal of Biomedical Materials Research. Part B: Applied Biomaterials
Issue number4
Publication statusPublished - 15-Jun-2005


  • radiopacity
  • microsphere
  • bulking agent
  • stress urinary incontinence
  • biocompatibility

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