OBJECTIVE: The absorption of biostimulatory particulate matter following its application to fractional skin defects remains poorly understood, and even less is known about its in vivo impact in terms of tissue integration. The objectives of this study are twofold: (1) to evaluate the potential of calcium hydroxylapatite (CaHA) to penetrate through skin treated with a fractional laser; and (2) to assess the effectiveness of clinical laser scanning microscopy technologies in monitoring the effects of such treatment over time.
METHODS: One area on a volunteer\'s arm was treated with a fractional erbium laser (Sciton Inc., Palo Alto, CA), while a second area received the same laser treatment followed by CaHA topical application. We used reflectance confocal microscopy (RCM) and multiphoton microscopy (MPM) to noninvasively image beneath the surface of the treated skin to study and monitor the effects of these treatments within 1 h of treatment and at four additional time points over a 6-week period.
RESULTS: One hour posttreatment, at different depths beneath the skin surface, MPM and RCM provided similar visualizations of laser-induced channels. In skin treated by both laser and CaHA, these two imaging methods provided complementary information. RCM captured the lateral and depth distribution of CaHA microspheres and were seen as bright spheres as they became incorporated into the healing tissue. MPM, meanwhile, visualized the CaHA microparticles as dark shadow spheres within the laser-induced channels and encroaching healing tissue. Furthermore, MPM provided critical information about collagen regeneration around the microspheres, with the collagen visually marked by its distinct second harmonic generation (SHG) signal.
CONCLUSIONS: This observational pilot study demonstrates that CaHA, a collagen stimulator used as a dermal filler, can not only be inserted into the dermis after fractional laser treatment but remains in the healing skin for at least 6 weeks posttreatment. The noninvasive imaging techniques RCM and MPM successfully captured the presence of CaHA microspheres mid-dermis during the healing phase. They also demonstrated new collagen production around the microspheres, highlighting the effectiveness of these imaging approaches in monitoring such treatment over time.

BACKGROUND: Acne vulgaris (AV) is a widespread inflammatory skin condition associated with increased sebum production, abnormal keratinization, bacterial overgrowth, and inflammation. Overactive sebaceous glands (SGs) produce excess sebum, promote Cutibacterium acnes growth, and affect acne development. Energy-based treatments (EBDs), including light therapy, photodynamic therapy (PDT), lasers, and radiofrequency (RF) devices, have emerged as effective treatment options. As the use of EBDs becomes more widespread, it is imperative to understand their effects on skin parameters, such as sebum, in AV.
METHODS: Searches were conducted in Embase, PubMed, Web of Science, and the Cochrane Library. The studies included were randomized and nonrandomized trials on facial AV that used EBDs and featured objective casual sebum level (CSL) measurements via Sebumeter. Data synthesis involved percentage reductions in CSL at follow-ups compared to baseline.
RESULTS: Twenty-three studies were analyzed. PDT and RF consistently reduced CSL by 30%-40% and 30%-35%, respectively. Laser therapy showed lesser reductions, whereas light therapy varied significantly and studies had a high risk of bias. All EBD therapies were more effective than no treatment and PDT was superior to light monotherapy. Laser therapy combined with fractional microneedling radiofrequency (FMR) or as a standalone was more effective than laser alone.
CONCLUSIONS: Noninvasive sebum measurement provides valuable insights into AV treatment efficacy. PDT, lasers, especially the 1450-nm diode laser, and FMR are promising for reducing sebum. Standardization of measurement techniques and further research are vital for enhancing treatment personalization, reducing side effects, and improving AV management.

Botulinum toxin A (BTX) and microwave thermolysis (MWT) are standard axillary hyperhidrosis treatments, but comparison of their subclinical effects is lacking. Line-field confocal optical coherence tomography (LC-OCT) is a promising non-invasive imaging tool for visualizing tissue-interactions. This study aimed to describe subclinical effects of BTX and MWT for axillary hyperhidrosis with LC-OCT-imaging compared to histology. This study derived from an intra-individual, randomized, controlled trial, treating axillary hyperhidrosis with BTX versus MWT. Subclinical effects based on LC-OCT images from baseline and 6-month follow-up (n = 8 patients) were evaluated and compared to corresponding histological samples. At baseline, LC-OCT visualized eccrine pores at the skin surface and ducts in the upper dermis (500 μm), but not deeper-lying sweat glands. Histology identified entire sweat glands. Six months post-treatment, LC-OCT revealed no detectable morphology changes in any BTX-treated axillae (100%), while recognizing obstructed eccrine pores and atrophy of eccrine ducts in most MWT-treated axillae (75%). Histology corroborated LC-OCT findings, while also showing substantial changes to entire sweat glands. LC-OCT enabled visualization of subclinical alterations of superficial eccrine ducts after MWT and unchanged morphology after BTX. LC-OCT is a promising tool for non-invasive assessment of treatment-specific tissue-interactions that can be complementary to histology.