DLP printed hDPSC-loaded GelMA microsphere regenerates dental pulp and repairs spinal cord.

Dental pulp regeneration is ideal for irreversible pulp or periapical lesions, and in situ stem cell therapy is one of the most effective therapies for pulp regeneration. In this study, we provided an atlas of the non-cultured and monolayer cultured dental pulp cells with single-cell RNA sequencing and analysis. Monolayer cultured dental pulp cells cluster more closely together than non-cultured dental pulp cells, suggesting a lower heterogeneous population with relatively consistent clusters and similar cellular composition. We successfully fabricated hDPSC-loaded microspheres by layer-by-layer photocuring with a digital light processing (DLP) printer. These hDPSC-loaded microspheres have improved stemness and higher multi-directional differentiation potential, including angiogenic, neurogenic, and odontogenic differentiation. The hDPSC-loaded microspheres could promote spinal cord regeneration in rat spinal cord injury models. Moreover, in heterotopic implantation tests on nude mice, CD31, MAP2, and DSPP immunofluorescence signals were observed, implying the formation of vascular, neural, and odontogenetic tissues. In situ experiments in minipigs demonstrated highly vascularized dental pulp and uniformly arranged odontoblast-like cells in root canals of incisors. In short, hDPSC-loaded microspheres can promote full-length dental pulp regeneration at the root canals' coronal, middle, and apical sections, particularly for blood vessels and nerve formation, which is a promising therapeutic strategy for necrotic pulp.

A hierarchical vascularized engineered bone inspired by intramembranous ossification for mandibular regeneration.

Mandibular defects caused by injuries, tumors, and infections are common and can severely affect mandibular function and the patient's appearance. However, mandible reconstruction with a mandibular bionic structure remains challenging. Inspired by the process of intramembranous ossification in mandibular development, a hierarchical vascularized engineered bone consisting of angiogenesis and osteogenesis modules has been produced. Moreover, the hierarchical vascular network and bone structure generated by these hierarchical vascularized engineered bone modules match the particular anatomical structure of the mandible. The ultra-tough polyion complex has been used as the basic scaffold for hierarchical vascularized engineered bone for ensuring better reconstruction of mandible function. According to the results of in vivo experiments, the bone regenerated using hierarchical vascularized engineered bone is similar to the natural mandibular bone in terms of morphology and genomics. The sonic hedgehog signaling pathway is specifically activated in hierarchical vascularized engineered bone, indicating that the new bone in hierarchical vascularized engineered bone underwent a process of intramembranous ossification identical to that of mandible development. Thus, hierarchical vascularized engineered bone has a high potential for clinical application in mandibular defect reconstruction. Moreover, the concept based on developmental processes and bionic structures provides an effective strategy for tissue regeneration.

Surface Modification by Divalent Main-Group-Elemental Ions for Improved Bone Remodeling To Instruct Implant Biofabrication.

Divalent main-group-elemental ions are widely used to improve osteogenic capacity of implants biofabricated from Ti and its alloys. However, the conclusions regarding their osseointegration and immunogenicity are always inconsistent because of the multiple bone remodeling processes as well as the distinct material surface features arising from processing. Here we successfully manufactured the porous micro/nanostructured surface topography with divalent main-group-elemental ions (Mg2+, Ca2+, Sr2+, Ba2+) on substrates through hydrothermal treatment and comprehensively evaluated the complex bone remodeling processes, including osseointegration, immunogenicity, and fibrosis of substrates and implants. We found that Sr-modified implants not only upregulated the adhesion and proliferation of mesenchymal stem cells but also the differentiation of osteogenic markers compared with those modified by other divalent main-group-elemental ions (Mg2+, Ca2+, Ba2+). More importantly, the osteoclastogenesis, immunogenicity, and fibrosis of Sr-modified implants were also significantly downregulated. In vivo, evaluations of new bone formation and histological morphology at the interface of implant and host as well as the removal torque similarly indicated the improved osseointegration of Sr-modified implants as well as the absence of immunogenicity, fibrosis, or necrosis. Our results suggested that among various divalent main-group-elemental ions, Sr2+ might be a promising one for enhancing bone remodeling, which can be used to instruct functionalization of the surfaces of biofabricated Ti-based orthopedic and dental implants in the future.