Intradermal Delivery of Calcium Hydroxylapatite With Fractionated Ablation

Area of Science:

• Dermatology and Biomedical Imaging
• Tissue Engineering and Regenerative Medicine

Background:

• The in vivo behavior and tissue integration of biostimulatory particulate matter, such as calcium hydroxylapatite (CaHA), after fractional laser treatment are not well understood.
• Fractional laser treatments create microchannels in the skin, potentially facilitating the penetration and integration of topically applied substances.

Purpose of the Study:

• To evaluate the penetration of calcium hydroxylapatite (CaHA) into skin defects created by fractional laser treatment.
• To assess the efficacy of reflectance confocal microscopy (RCM) and multiphoton microscopy (MPM) in monitoring CaHA treatment effects over time.

Main Methods:

• A volunteer's arm received fractional erbium laser treatment, with one area also receiving topical CaHA application.
• Noninvasive imaging using RCM and MPM was employed to visualize beneath the skin surface at baseline and over a 6-week period.
• Microscopy techniques were used to track laser-induced channels, CaHA microsphere distribution, and tissue response.

Main Results:

• Both RCM and MPM visualized laser-induced channels within an hour of treatment, providing complementary information on CaHA microsphere distribution.
• RCM showed CaHA microspheres as bright spheres within healing tissue, while MPM depicted them as dark spheres and highlighted collagen regeneration via second harmonic generation (SHG).
• CaHA microspheres were observed to be incorporated into healing tissue and remained present in the mid-dermis for at least 6 weeks.

Conclusions:

• Calcium hydroxylapatite (CaHA) can be delivered into the dermis via fractional laser treatment and persists for at least 6 weeks.
• Reflectance confocal microscopy (RCM) and multiphoton microscopy (MPM) are effective noninvasive tools for monitoring CaHA presence and tissue response, including new collagen production.
• These imaging modalities offer valuable insights into the in vivo integration and efficacy of CaHA as a dermal filler in conjunction with fractional laser therapy.