Preclinical Comparison of an Injectable In-Situ Scaffold-Forming Oligomeric Collagen for Soft Tissue Volume Augmentation in a Rat Model

Introduction: Dermal fillers are widely used to restore facial volume, yet current materials often exhibit swelling, inflammatory responses, or limited persistence. Objective: To compare rheological and extrusion properties, volumetric persistence, and local tissue response of an injectable, in-situ scaffold-forming oligomeric collagen with a commercially available hyaluronic acid filler and saline in a rat model. Methods: Oligomeric collagen was administered by subcutaneous injection, with commercial filler and saline as controls. Animals were evaluated at 1, 6, and 12 weeks using three-dimensional volumetric scanning and histopathological analyses. Rheological, compressive, and extrusion properties were measured. Statistical comparisons used one-way analysis of variance or Student’s t -tests. Results: In this 12-week rat study, oligomer demonstrated low extrusion force and stable scaffold volumes after equilibration. Extrusion force was similar to saline and ∼15-fold lower than the commercial filler. Scaffold volumes were ∼25% of the injected volume and remained stable from 1 to 12 weeks. The commercial filler exhibited swelling (∼400%) at 1 week, followed by ∼83% volume loss. Histological analysis showed minimal inflammatory response with scaffold integration, whereas the commercial filler exhibited regional inflammation and fibrous capsule formation. Conclusions: Injectable scaffold-forming oligomer exhibited low extrusion force, persistent volume, and minimal local tissue response over 12 weeks.