Facial aging is primarily characterized by the loss and disorganization of the dermal extracellular matrix (ECM), particularly collagen. Injectable biostimulators, such as calcium hydroxyapatite (CaHA), represent a vital non-surgical strategy to counteract these changes by inducing neocollagenesis. This 90-day clinical trial was designed to comparatively evaluate the efficacy of a novel regenerative solution (RS) diluent, formulated to potentially enhance the biostimulatory effects of standard CaHA (STIIM product), against a conventional diluent (control) for the treatment of facial laxity. Twenty-one subjects (N = 21) were randomized to receive CaHA diluted with either RS or control formulation. Efficacy was assessed using histological analysis (collagen I area percentage), ultrasound (US) for dermal density, and clinical laxity scoring. Histological analysis, although limited by a small subsample size (N = 3), showed qualitative and exploratory evidence of collagen remodeling in both groups. However, the RS group showed enhanced dermal thickening via US (15% increase vs. 5% control, p-value = 0.012), and improvement in clinical laxity. Furthermore, histological findings, including Picrosirius red staining, indicated that the RS group resulted in qualitatively greater ECM organization and more robust type I collagen fibers compared to the control. The novel regenerative solution is safe and demonstrates enhanced neocollagenesis and clinical efficacy over the conventional formulation, validating its potential as a diluent for CaHA for optimized facial rejuvenation.

Background/Objectives: Cervical integument aging is a complex, multifactorial process characterized by thinning dermis, loss of elasticity, and platysmal band prominence. Multimodal treatments targeting these distinct anatomical layers simultaneously remain limited. This study aimed to evaluate the clinical efficacy, safety, and rejuvenation potential of the STIIM UP Protocol, a single-session treatment combining calcium hydroxyapatite (CaHA), hyaluronic acid (HA), and botulinum toxin type A (BoNT-A) for neck rejuvenation. Methods: This prospective, open-label, exploratory clinical study enrolled 13 healthy women (n = 13) presenting with cervical laxity. The STIIM UP suspension was delivered bilaterally into the subdermal plane of the anterior neck region using a retro-injection fanning technique with a 22G cannula at Day 0 (D0). Evaluated outcomes included the IBSA Neck Grading Scale, Global Aesthetic Improvement Scale (GAIS), FACE-Q module scores, and high-frequency ultrasound (USG) tissue thickness measurements at baseline and Day 120 (D120). Safety was monitored throughout. Results: The median consensus IBSA scores decreased significantly from 4.0 at baseline to 2.0 at both D30 and D120 (p-value < 0.01), indicating a rapid and sustained reduction in laxity. At D120, the GAIS responder rate reached 100% according to independent evaluators and 90.9% based on patient self-assessments. Quantitative USG confirmed statistically significant bilateral tissue thickening across the epidermis, dermis, and subcutaneous strata (p-value < 0.05). Progressive, clinically meaningful improvements were captured via the FACE-Q scales. No local or systemic adverse events were observed. Conclusions: The STIIM UP Protocol is a safe and effective multilayer intervention that successfully achieves comprehensive neck rejuvenation, bridging immediate clinical enhancement with sustained, tissue-proven structural remodeling.