The histologic reaction and permanence of hyaluronic acid gel, calcium hydroxylapatite microspheres, and extracellular matrix bio gel.

Background: The filling materials on the beauty market can be classified into three types: natural biological materials, synthetic polymer materials, and composites containing bioactive substances. However, comparative experimental data is lacking to compare their biological responses and permanence.

Aims: The main object of this study was to evaluate the biological response of these three types of fillers to provide a theoretical basis for clinical application.

Methods: Six-week-old female mice were injected subcutaneously with hyaluronic acid (HA) gel, calcium hydroxylapatite (CaHA) microspheres, and extracellular matrix (ECM) bio gel to observe the body reaction and permanence. At 1, 4, 8, and 16 weeks, the test sites were excised and analyzed by histopathology and proteomics.

Results: Extracellular matrix had a minimal foreign body response. HA had a good volume effect at the early stage but the volume retention rate was lower than CaHA in the long term. CaHA could stimulate neo-collagen formation.

Conclusion: This study has proven the effectiveness and safety of these fillers and could provide clinical guidance for the plastic surgeon.