Organ transplantation represents the optimal therapeutic tool for patients with end-stage organ failure. Hematopoietic stem cell transplantation (HSCT) is likewise an effective therapy for a wide range of malignant and non-malignant diseases. Better understanding of transplantation immunology and the use of multi-modal immunosuppression protocols, can decrease the risk of graft failure and graft-versus-host disease (GVHD) after HSCT. Nevertheless, a major challenge of modern transplantology still seems to be finding non-invasive biomarkers for recipients selection, monitoring of allograft function, and diagnosis of rejection. Since proinflammatory cytokine osteopontin (OPN) is closely involved in regulating both adaptive and innate immune responses, as well as the pathogenesis of inflammatory and autoimmune diseases, it is likely to play an important role in organ and HSC transplantation. This review is to summarize recent advances in our knowledge about OPN function in the kidney, heart, liver, lung, and HSC transplantation. Most studies found that elevated OPN is associated with poorer graft function in kidney, heart, liver and lung recipients. Moreover, some reports suggested that this protein can play role in GVHD pathogenesis. However, due to relatively small number of similar studies, as well as some inconclusive results, future investigation in this field is needed to verify if OPN can serve as a biomarker of organ and HSC transplantation. The knowledge about such markers will promote our understanding of the mechanisms underlying graft dysfunction and posttransplant mortality. In addition, such knowledge may be helpful in the development of new treatment strategies and identification of recipients with increased risk of allograft failure.

器官移植是终末期器官衰竭患者的最佳治疗工具。造血干细胞移植（HSCT）同样是治疗多种恶性和非恶性疾病的有效方法。更好地了解移植免疫学和使用多模式免疫抑制方案，可以降低 HSCT 后移植失败和移植物抗宿主病 (GVHD) 的风险。然而，现代移植学的一个主要挑战似乎仍然是寻找用于受体选择、同种异体移植物功能监测和排斥诊断的非侵入性生物标志物。由于促炎细胞因子骨桥蛋白 (OPN) 与调节适应性和先天免疫反应以及炎症和自身免疫疾病的发病机制密切相关，它可能在器官和 HSC 移植中发挥重要作用。本综述旨在总结我们对肾脏、心脏、肝脏、肺和 HSC 移植中 OPN 功能的认识的最新进展。大多数研究发现，OPN 升高与肾脏、心脏、肝脏和肺受者的移植功能较差有关。此外，一些报道表明这种蛋白质可以在 GVHD 发病机制中发挥作用。然而，由于类似研究数量相对较少，以及一些不确定的结果，需要在该领域进行进一步的研究，以验证 OPN 是否可以作为器官和 HSC 移植的生物标志物。对这些标志物的了解将促进我们对移植物功能障碍和移植后死亡率的潜在机制的理解。此外，