PDLSC-CM targets HAPLN1 in macrophages to reduce root resorption in delayed replanted teeth.

Abstract

Background: Tooth avulsion is the most serious dental trauma, mainly affecting anterior teeth in adolescents. Delayed tooth replantation is the most common situation in clinical, but root resorption is a common complication that can lead to tooth loss. As implant is not feasible in adolescents, strategies to mitigate root resorption remain a major challenge in dentistry. We aim to evaluate the therapeutic effect and potential target of periodontal ligament stem cell-conditioned medium (PDLSC-CM) to reduce root resorption in delayed replanted tooth.

Methods: Clinical samples from delayed tooth replantation patients were analyzed by X-ray and histological staining. A rat model of delayed tooth replantation was established, with PDLSC-CM applied as the tooth preservative and irrigating solution. Root resorption was assessed by micro-CT and histopathology. Proteomic screening followed by Western blot and immunofluorescence was used to identify and validate key molecules. Macrophage polarization and osteoclastogenesis were examined in vitro using RAW264.7 and bone marrow-derived macrophages. Recombinant adeno-associated virus (rAAV) was used to validate the key protein molecules.

Results: Human avulsed tooth with delayed replantation shows obvious root resorption and high expressions of inflammatory cytokines and osteoclast-related factors in periapical tissue. PDLSC-CM reduces the root resorption and inhibits the expressions of inflammatory cytokines and osteoclast-related factors in root and periapical tissue of delayed replantation of avulsed tooth in rats. PDLSC-CM downregulates the expression of HAPLN1 mainly in macrophages, thereby inhibits inflammation and osteoclastogenesis of delayed replanted tooth root. Overexpression of HAPLN1 abolishes the protective effect of PDLSC-CM on delayed replanted tooth root.

Conclusion: HAPLN1 reduction in macrophages plays a pivotal role in PDLSC-CM reducing root resorption. PDLSC-CM is a promising preservation medium for avulsed teeth with potential clinical applications, and the development of drug candidate targeting HAPLN1 has favorable clinical prospects.