The regenerative potential of mesenchymal stem cell (MSC) secretomes in peripheral nerve injuries warrants rigorous evaluation. This systematic review analyzes their effectiveness in preclinical models of neurotmesis, a complete transection of a nerve. Neurophysiological recovery was assessed through nerve conduction velocity (NCV), a measure of the speed at which electrical impulses travel along a nerve. Following PRISMA guidelines, a systematic search was conducted in PubMed, Scopus, Web of Science, and ScienceDirect (last search July 2024). From 640 initially identified studies, 13 met inclusion criteria, encompassing 514 animals (rats). experimental designs published since 2014 in English or Spanish, focusing on MSC secretomes for nerve regeneration. Exclusion criteria included reviews, case reports, and incomplete data. The risk of bias was assessed using Joanna Briggs Institute tools. Results were synthesized narratively, focusing on functional and structural outcomes. The included studies employed various MSC sources, including adipose tissue, olfactory mucosa, and umbilical cord. Nine studies reported enhanced SFI, favoring secretome-treated groups over controls (mean difference +20.5%, p < 0.01). Seven studies documented increased NCV, with up to 35% higher conduction velocities in treated groups (p < 0.05). Histological outcomes reported in 12 studies showed increased axonal diameter (+25%, p < 0.01), myelin sheath thickness (+30%, p < 0.05), and Schwann cell proliferation. Limitations of the included evidence include methodological heterogeneity and variability in outcome measurement tools. MSC-derived secretomes demonstrate potential as advanced therapeutic strategies for nerve injuries. Personalized approaches considering injury type and clinical context are essential for optimizing outcomes.

Background and Clinical Significance: Hyaluronic acid fillers are currently the most widely used materials in aesthetic medicine and represent one of the most frequently performed minimally invasive procedures worldwide. Vascular occlusion is the most severe complication associated with this type if filler injections due to the risk of tissue necrosis and permanent sequelae. Early recognition and precise identification of the affected vascular territory are essential to prevent irreversible damage. Case Presentation: his report describes a case of infraorbital artery occlusion with retrograde extension to the anterior superior alveolar artery and associated gingival ischemia, highlighting the role of high-frequency ultrasound in diagnosis and management. A 60-year-old woman developed vascular occlusion following supraperiosteal HA injection in the medial cheek. Clinical findings included livedo reticularis in the infraorbital and nasal regions, along with ipsilateral gingival anesthesia and mucosal ischemia. High-frequency ultrasound was used to assess the extent and mechanism of vascular involvement. A targeted treatment approach was implemented using low-dose hyaluronidase (100 IU/mL), with 200 IU administered in the infraorbital region and an additional 100 IU delivered under ultrasound guidance to the affected alveolar branch. Ultrasound examination revealed extrinsic compression of the infraorbital artery and secondary occlusion of the anterior superior alveolar artery consistent with retrograde embolization. Following image-guided administration of hyaluronidase, complete reperfusion was achieved, with resolution of both cutaneous and gingival ischemia and no functional or aesthetic sequelae. Conclusions: High-frequency ultrasound provides critical diagnostic information in vascular complications after HA filler injection, allowing for accurate identification of the mechanism and extent of vascular involvement. Ultrasound-guided low-dose hyaluronidase may represent an effective and safe strategy to restore perfusion while minimizing unnecessary enzyme exposure and associated adverse effects.