HUMAN AMNIOTIC MEMBRANE POTENTIAL FOR BONE REPAIR: FROM THE LAB TO THE CLINIC - ROLE OF ITS IMMUNOGENICITY

F. Gindraux^1,2 | ¹CHU Besançon, Service de Chirurgie Maxillo-Faciale et Stomatologie, Besançon, France; ²Université Marie et Louis Pasteur, SINERGIES UR 4662, Besançon, France

The human amniotic membrane (hAM) has low immunogenicity and offers anti-inflammatory, anti-fibrotic, antimicrobial, antiviral, and analgesic effects. It contains stem cells and growth factors that support tissue regeneration, with preservation methods including cryopreservation, lyophilization, and dehydration. We evaluated hAM in orthopedic and maxillofacial bone surgery, focusing on its potential to improve the induced membrane technique Our studies assessed cell survival, osteodifferentiation, and osteogenic potential both in vitro and in vivo, and tested various processing methods in collaboration with Inserm U1026 BioTis (Bordeaux)). Results indicated limited effectiveness of hAM for bone defect repair. Given these findings, we explored hAM for medication-related osteonecrosis of the jaw (MRONJ). In a 6-month prospective study of eight MRONJ patients treated with cryopreserved hAM, 80% showed complete or partial wound healing and all experienced pain relief and improved quality of life. Radiological follow-up confirmed lesion stability or new bone formation in most cases. A multicenter randomized clinical trial (NCT05664815) involving 57 patients is currently underway. In parallel, we investigated the humoral immune response following hAM transplantation. We prospectively followed 23 patients undergoing cryopreserved hAM transplantation between August 2022 and September 2023, collecting sera at transplantation, 1-, and 3-months post-transplant. Nine patients had prior immunizing events. Anti-HLA class I and II antibodies were assessed by Luminex, and anti-HLA-G by ELISA. No de novo immunization or change in anti-HLA antibody profiles was observed post-transplant, and no anti-HLA-G antibodies were detected. These results confirm the absence of humoral immunization after hAM transplantation, supporting its immunological safety and excellent clinical tolerance.