Mechanical Stress Improves Fat Graft Survival by Promoting Adipose-Derived Stem Cells Proliferation.

Cell-assisted lipotransfer (CAL), defined as co-transplantation of aspirated fat with enrichment of adipose-derived stem cells (ASCs), is a novel technique for cosmetic and reconstructive surgery to overcome the low survival rate of traditional fat grafting. However, clinically approved techniques for increasing the potency of ASCs in CAL have not been developed yet. As a more clinically applicable method, we used mechanical stress to reinforce the potency of ASCs. Mechanical stress was applied to the inguinal fat pad by needling . Morphological and cellular changes in adipose tissues were examined by flow cytometric analysis 1, 3, 5, and 7 days after the procedure. The proliferation and adipogenesis potencies of ASCs were evaluated. CAL with ASCs treated with mechanical stress or sham control were performed, and engraftment was determined at 4 weeks post-operation. Flow cytometry analysis revealed that mechanical stress significantly increased the number as well as the frequency of ASC proliferation in fat. Proliferation assays and adipocyte-specific marker gene analysis revealed that mechanical stress promoted proliferation potential but did not affect the differentiation capacity of ASCs. Moreover, CAL with cells derived from mechanical stress-treated fat increased the engraftment. Our results indicate that mechanical stress may be a simple method for improving the efficacy of CAL by enhancing the proliferation potency of ASCs.

Embolization for treating posttraumatic pseudoaneurysm of the sphenopalatine artery.

Posttraumatic pseudoaneurysms of the sphenopalatine artery are rare. Only a few cases have been reported. We report two cases of hemorrhage due to pseudoaneurysm of the sphenopalatine artery. The hemorrhage was uncontrollable. It required embolization. Two patients visited our hospital for treatment of zygomaticomaxillary complex fracture. At the emergency room, patients presented with massive nasal bleeding which ceased shortly. After reduction of the fracture, patients presented persistent nasopharyngeal bleeding. Under suspicion of intracranial vessel injury, we performed angiography. Angiograms revealed pseudoaneurysms of the sphenopalatine artery. Endovascular embolization was performed, leading to successful hemostasis in both patients. Due to close proximity to pterygoid plates, zygomaticomaxillary complex fracture involving pterygoid plates may cause injury of the sphenopalatine artery. The only presentation of sphenopalatine artery injury is nasopharyngeal bleeding which is common. Based on our clinical experience, although pseudoaneurysm of maxillary artery branch after maxillofacial trauma has a low incidence, suspicion of injury involving deeply located arteries and early imaging via angiogram are recommended to manage recurrent bleeding after facial trauma or surgery.