Changes of Tissue Reactions on Various HA Filler Under Immune Stress Status: An In Vivo Study

Background

Post-COVID-19, there has been an increase in reports of anaphylaxis to hyaluronic acid (HA) filler injections.

Objective

This study aimed to investigate the differences in tissue reactions induced by HA fillers produced via various cross-linking technologies under conditions of immune stress.

Methods

A sensitized guinea pig model was utilized to evaluate the anaphylactic responses to different HA fillers. The biological reactions at the injection sites were assessed through hematoxylin and eosin staining. Material properties of the HA fillers were characterized using rheological testing.

Results

Upon injection into sensitized guinea pigs, anaphylactic reactions varied in intensity. The probability of anaphylaxis increased with the degree of cross-linking in the HA fillers, with the reactions predominantly localized to the intradermal injection sites. Histopathological analysis revealed varying degrees of lymphocyte infiltration and other pathological changes across the experimental groups. HA gels produced using different technologies exhibited distinct rheological properties.

Conclusion

The degree of cross-linking and the manufacturing technologies employed in the production of HA fillers significantly impact the occurrence of clinical reactions during immune stimulation. These findings suggest that the administration of HA fillers should be meticulously contemplated in the context of immune stress.

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