Alkali-extracted proteins from the tooth dentin matrix as a mixture of bioactive molecules for cartilage repair and regeneration.

Introduction: Dentin matrix extracted protein (DMEP) is a mixture of proteins extracted from the organic matrix of a natural demineralized dentin matrix that is rich in a variety of growth factors. However, the effect of DMEP on cartilage regeneration is unclear. The aim of this study was to investigate the efficacy of DMEP extracted via a novel alkali conditioning method in promoting cartilage regeneration. Methods: Alkali-extracted DMEP (a-DMEP) was obtained from human dentin fragments using pH 10 bicarbonate buffer. The concentration of chondrogenesis-related growth factors in a-DMEP was measured via enzyme-linked immunosorbent assay (ELISA). Human bone marrow mesenchymal stem cells (hBMMSCs) in pellet form were induced with a-DMEP. Alcian blue and Safranin O staining were performed to detect cartilage matrix formation, and quantitative real-time polymerase chain reaction (qRT-PCR) was used to assess chondrogenic-related gene expression in the pellets. Rabbit articular osteochondral defects were implanted with collagen and a-DMEP. Cartilage regeneration was assessed with histological staining 4 weeks after surgery. Results: Compared with traditional neutral-extracted DMEP, a-DMEP significantly increased the levels of transforming growth factor beta 1(TGF-ß1), insulin-like growth factor-1(IGF-1) and basic fibroblast growth factor (bFGF). After coculture with hBMMSC pellets, a-DMEP significantly promoted the expression of the collagen type II alpha 1(COL2A1) and aggrecan (ACAN) genes and the formation of cartilage extracellular matrix in cell pellets. Moreover, compared with equivalent amounts of exogenous human recombinant TGF-ß1, a-DMEP had a stronger chondrogenic ability. In vivo, a-DMEP induced osteochondral regeneration with hyaline cartilage-like structures. Conclusions: Our results showed that a-DMEP, a compound of various proteins derived from natural tissues, is a promising material for cartilage repair and regeneration.

Polydopamine-coated bioactive glass for immunomodulation and odontogenesis in pulpitis.

Preserving vital pulp in cases of dental pulpitis is desired but remains challenging. Previous research has shown that bioactive glass (BG) possesses notable capabilities for odontogenic differentiation. However, the immunoregulatory potential of BG for inflamed pulp is still controversial, which is essential for preserving vital pulp in the context of pulpitis. This study introduces a novel approach utilizing polydopamine-coated BG (BG-PDA) which demonstrates the ability to alleviate inflammation and promote odontogenesis for vital pulp therapy. In vitro, BG-PDA has the potential to induce M2 polarization of macrophages, resulting in decreased intracellular reactive oxygen species levels, inhibition of pro-inflammatory factor, and enhancement of anti-inflammatory factor expression. Furthermore, BG-PDA can strengthen the mitochondrial function in macrophages and facilitate odontogenic differentiation of human dental pulp cells. In a rat model of pulpitis, BG-PDA exhibits the capacity to promote M2 polarization of macrophages, alleviate inflammation, and facilitate dentin bridge formation. This study highlights the notable immunomodulatory and odontogenesis-inducing properties of BG-PDA for treating dental pulpitis, as evidenced by both in vitro and in vivo experiments. These results imply that BG-PDA could serve as a promising biomaterial for vital pulp therapy.

Heparin-Functionalized Bioactive Glass to Harvest Endogenous Growth Factors for Pulp Regeneration.

Pulp and periapical diseases can lead to the cessation of tooth development, resulting in compromised tooth structure and functions. Despite numerous efforts to induce pulp regeneration, effective strategies are still lacking. Growth factors (GFs) hold considerable promise in pulp regeneration due to their diverse cellular regulatory properties. However, the limited half-lives and susceptibility to degradation of exogenous GFs necessitate the administration of supra-physiological doses, leading to undesirable side effects. In this research, a heparin-functionalized bioactive glass (CaO-P2O5-SiO2-Heparin, abbreviated as PSC-Heparin) with strong bioactivity and a stable neutral pH is developed as a promising candidate to addressing challenges in pulp regeneration. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis reveal the successful synthesis of PSC-Heparin. Scanning electron microscopy and X-ray diffraction show the hydroxyapatite formation can be observed on the surface of PSC-Heparin after soaking in simulated body fluid for 12 h. PSC-Heparin is capable of harvesting various endogenous GFs and sustainably releasing them over an extended duration by the enzyme-linked immunosorbent assay. Cytological experiments show that developed PSC-Heparin can facilitate the adhesion, migration, proliferation, and odontogenic differentiation of stem cells from apical papillae. Notably, the histological analysis of subcutaneous implantation in nude mice demonstrates PSC-Heparin is capable of promoting the odontoblast-like layers and pulp-dentin complex formation without the addition of exogenous GFs, which is vital for clinical applications. This work highlights an effective strategy of harvesting endogenous GFs and avoiding the involvement of exogenous GFs to achieve pulp-dentin complex regeneration, which may open a new horizon for regenerative endodontic therapy.

Induction of Cartilage Regeneration by Nanoparticles Loaded with Dentin Matrix Extracted Proteins.

Due to the limited self-repair capacity of articular cartilage, tissue engineering has good application prospects for cartilage regeneration. Dentin contains several key growth factors involved in cartilage regeneration. However, it remains unknown whether dentin matrix extracted proteins (DMEP) can be utilized as a complex growth factor mixture to induce cartilage regeneration. In this work, we extracted DMEP from human dentin and improved the content and activity of chondrogenic-related growth factors in DMEP by alkaline conditioning. Afterward, mesoporous silica nanoparticles (MSNs) with particular physical and chemical properties were composed to selectively load and sustain the release of proteins in DMEP. MSN-DMEP promoted chondrogenic differentiation of rat bone marrow-derived mesenchymal stem cells with fewer growth factors than exogenously added transforming growth factor-ß1 (TGF-ß1). Therefore, MSN-DMEP may serve as a promising candidate for cartilage regeneration as an alternative to expensive synthetic growth factors. Impact statement Several growth factors embedded in dentin matrix could be involved in cartilage regeneration. This article reports that alkaline conditioning could improve the content and activity of chondrogenic-related growth factors in dentin matrix extracted proteins (DMEP). Mesoporous silica nanoparticles (MSNs) with particular physical and chemical properties performed well in loading and sustained releasing of proteins in DMEP. In vitro and in vivo studies suggest that MSN-DMEP could be a promising candidate for cartilage regeneration as an alternative to expensive synthetic growth factors.