Improved physical and osteoinductive properties of demineralized bone matrix by gelatin methacryloyl formulation

Photothermal Effect and Biomineralization of Black Phosphorus Nanosheet-Composited Hydrogel Boosts Synergistic Treatment of Dentin Hypersensitivity

Dentin hypersensitivity (DH), marked by exposed dentinal tubules, presents as a sharp toothache triggered by stimuli and subsides when the stimuli are removed. To address the limitations of current commercial desensitizers in terms of acid resistance, friction resistance, and stability, a black phosphorus nanosheet-composited methacrylate gelatin hydrogel (GelMA/BP) is developed for DH treatment, leveraging the synergistic effects of photothermal therapy and biomineralization. Incorporating the BP nanosheet provided GelMA/BP with a stable photothermal response and the continuous release of phosphate anions, which blocked dentinal tubules by converting light energy into heat and initiating biomineralization. In vitro desensitizing therapy showed that the dentinal tubule diameter in the GelMA/BP50 group (0-1.13 µm) is significantly reduced compared to that in the DH-model group (0-3.14 µm). The GelMA/BP50 group achieved an 86% tubule occlusion rate, with acid resistance of 80%, friction resistance of 76%, and long-term stability of 74%. In vivo studies further validated the efficacy of GelMA/BP50, showing a reduction in tubule diameter (0-0.37 µm) and an occlusion rate of 79%, which alleviated toothache and increased intake and weight. These results demonstrate that this desensitizing hydrogel acts as an effective dentinal tubule sealant, offering promising clinical benefits for the topical treatment of DH.

Combined use of deproteinized bovine bone mineral and α-tricalcium phosphate using gelatin carriers

OBJECTIVE

To study the effect on biomaterial degradation and bone formation of different ratios between α-tricalcium phosphate (α-TCP) and deproteinized bovine bone mineral (DBBM) using various gelatins as a carrier.

MATERIALS AND METHODS

Thirty-six critical-sized calvarial bone defects were randomly treated in 18 animals. Four biomaterials with different compositional relations of DBBM to α-TCP and granules to carrier were investigated: (1) 40 ± 10% DBBM/40 ± 10% α-TCP with 20 ± 10% gelatin type 1 in ratio 4:1 (B1/G1), (2) 20 ± 10% DBBM/60 ± 10% α-TCP with 20 ± 10% gelatin type 1 in ratio 4:1 (B2/G1), (3) 20 ± 10% DBBM/60 ± 10% α-TCP with 15 ± 10%/5 ± 5% gelatin type 2/ glycerine (B2/G2) and 4), 10 ± 10% DBBM/60 ± 10% α-TCP with 20 ± 10%/10 ± 10% gelatin type 2/ glycerine (B3/G2). As a positive control 50 ± 10% DBBM/50 ± 10% α-TCP without gelatin (PC, B1/G0) and as a negative control (NC) empty defects were chosen. All defects were covered with a collagen membrane. The samples were harvested 4 weeks post-surgically and examined by micro-CT and histomorphometric analysis.

RESULTS

New bone formation was evident in all defects. The mineralized tissue volume was significantly higher in the four tested biomaterials than in the NC group, but lower compared to the PC group. Histomorphometry showed similar levels of bone formation in all groups, whereas only the PC group reached a significantly higher total augmentation area than that of the NC. The PC group showed significantly higher mineralized tissue density and residual material area compared to the B3/G2 group, and more residual DBBM than the four tested biomaterials.

CONCLUSIONS

New bone formation was not significantly affected either by different DBBM:α-TCP compositional ratios nor the presence of various gelatin carriers.

CLINICAL RELEVANCE

Similar levels of osteoconductivity indicates the presumptive use of combined products in alveolar ridge augmentation to support bone formation. Gelatin with or without glycerine may be considered for its use as a carrier to the biomaterials frequently applied in peri-implant surgery.

Research Progress on Biomaterials for Spinal Cord Repair

Spinal cord injury (SCI) is a very destructive disease of the central nervous system that often causes irreversible nerve damage. Unfortunately, the adult mammalian spinal cord displays little regenerative capacity after injury. In addition, the glial scars and inflammatory responses around the lesion site are another major obstacle for successful axon regeneration after SCI. However, biomaterials are highly biocompatible, and they could provide physical guidance to allow regenerating axon growth over the lesion site and restore functional neural circuits. In addition, combined or synergistic effects of spinal cord repair can be achieved by integrating different strategies, including the use of various biomaterials and microstructures, as well as combining bioactive molecules and living cells. Therefore, it is possible to use tissue engineering scaffolds to regulate the local microenvironment of the injured spinal cord, which may achieve better functional recovery in spinal cord injury repair. In this review, we summarize the latest progress in the treatment of SCI by biomaterials, and discussed its potential mechanism.

The Future of Bone Repair: Emerging Technologies and Biomaterials in Bone Regeneration

Bone defects and fractures present significant clinical challenges, particularly in orthopedic and maxillofacial applications. While minor bone defects may be capable of healing naturally, those of a critical size necessitate intervention through the use of implants or grafts. The utilization of traditional methodologies, encompassing autografts and allografts, is constrained by several factors. These include the potential for donor site morbidity, the restricted availability of suitable donors, and the possibility of immune rejection. This has prompted extensive research in the field of bone tissue engineering to develop advanced synthetic and bio-derived materials that can support bone regeneration. The optimal bone substitute must achieve a balance between biocompatibility, bioresorbability, osteoconductivity, and osteoinductivity while simultaneously providing mechanical support during the healing process. Recent innovations include the utilization of three-dimensional printing, nanotechnology, and bioactive coatings to create scaffolds that mimic the structure of natural bone and enhance cell proliferation and differentiation. Notwithstanding the advancements above, challenges remain in optimizing the controlled release of growth factors and adapting materials to various clinical contexts. This review provides a comprehensive overview of the current advancements in bone substitute materials, focusing on their biological mechanisms, design considerations, and clinical applications. It explores the role of emerging technologies, such as additive manufacturing and stem cell-based therapies, in advancing the field. Future research highlights the need for multidisciplinary collaboration and rigorous testing to develop advanced bone graft substitutes, improving outcomes and quality of life for patients with complex defects.

Demineralized bone matrix for repair and regeneration of maxillofacial defects: A narrative review

OBJECTIVES

Demineralized bone matrix (DBM) is a well-established bone graft material widely accepted by dentists and the public for its favorable osteoconductivity and osteoinductive potential. This article aimed to provide a narrative review of the current therapeutic applications and limitations of DBM in maxillofacial bone defects.

STUDY SELECTION, DATA, AND SOURCES

Randomized controlled trials, prospective or retrospective clinical studies, case series and reports, and systematic reviews. MEDLINE, PubMed, and Google Scholar were searched using keywords.

CONCLUSIONS

Some evidence supported the therapeutic application of DBM in periodontal intrabony defects, maxillary sinus lifts, ridge preservation, ridge augmentation, alveolar cleft repair, orthognathic surgery, and other regional maxillofacial bone defects. However, the limitations of DBM should be considered when using it, including potential low immunogenicity, instability of osteoinductive potential, handling of the graft material, and patient acceptance.

CLINICAL SIGNIFICANCE

With the increasing demand for the treatment of maxillofacial bone defects, DBM is likely to play a greater role as a promising bone graft material. Safe and effective combination treatment strategies and how to maintain a stable osteoinductive potential will be the future challenges of DBM research.

Development of photoreactive demineralized bone matrix 3D printing colloidal inks for bone tissue engineering

Demineralized bone matrix (DBM) has been widely used clinically for dental, craniofacial and skeletal bone repair, as an osteoinductive and osteoconductive material. 3D printing (3DP) enables the creation of bone tissue engineering scaffolds with complex geometries and porosity. Photoreactive methacryloylated gelatin nanoparticles (GNP-MAs) 3DP inks have been developed, which display gel-like behavior for high print fidelity and are capable of post-printing photocrosslinking for control of scaffold swelling and degradation. Here, novel DBM nanoparticles (DBM-NPs, ∼400 nm) were fabricated and characterized prior to incorporation in 3DP inks. The objectives of this study were to determine how these DBM-NPs would influence the printability of composite colloidal 3DP inks, assess the impact of ultraviolet (UV) crosslinking on 3DP scaffold swelling and degradation and evaluate the osteogenic potential of DBM-NP-containing composite colloidal scaffolds. The addition of methacryloylated DBM-NPs (DBM-NP-MAs) to composite colloidal inks (100:0, 95:5 and 75:25 GNP-MA:DBM-NP-MA) did not significantly impact the rheological properties associated with printability, such as viscosity and shear recovery or photocrosslinking. UV crosslinking with a UV dosage of 3 J/cm2 directly impacted the rate of 3DP scaffold swelling for all GNP-MA:DBM-NP-MA ratios with an ∼40% greater increase in scaffold area and pore area in uncrosslinked versus photocrosslinked scaffolds over 21 days in phosphate-buffered saline (PBS). Likewise, degradation (hydrolytic and enzymatic) over 21 days for all DBM-NP-MA content groups was significantly decreased, ∼45% less in PBS and collagenase-containing PBS, in UV-crosslinked versus uncrosslinked groups. The incorporation of DBM-NP-MAs into scaffolds decreased mass loss compared to GNP-MA-only scaffolds during collagenase degradation. An in vitro osteogenic study with bone marrow-derived mesenchymal stem cells demonstrated osteoconductive properties of 3DP scaffolds for the DBM-NP-MA contents examined. The creation of photoreactive DBM-NP-MAs and their application in 3DP provide a platform for the development of ECM-derived colloidal materials and tailored control of biochemical cue presentation with broad tissue engineering applications.

Construction of a decellularized spinal cord matrix/GelMA composite scaffold and its effects on neuronal differentiation of neural stem cells

Spinal cord injury (SCI) leads to severe loss of motor and sensory functions, and the rehabilitation of SCI is a worldwide problem. Tissue-engineered scaffolds offer new hope for SCI patients, while the newly developed materials encountered a challenge in modeling the microenvironment around the lesion site. We constructed a new composite scaffold by mixing decellularized spinal cord extracellular matrix (dECM) with gelatin methacryloyl (GelMA). The dECM, as a natural biological material, retained a large number of proteins and growth factors related to neurogenesis. GelMA was a photopolymerizable material, harbored a polymer network structure, soft texture, certain shape and plenty of water. The viability, proliferation, and differentiation of neural stem cells (NSCs) on the composite scaffold were evaluated by cell count kit-8 (CCK8), Live/Dead assay, phalloidin staining, 5-Ethynyl-2'-deoxyurdine (EdU), immunofluorescence staining and western blot. The Live/Dead assay, phalloidin staining, EdU, and CCK8 assay showed that the composite scaffold had good biocompatibility and provided better support for proliferation of NSCs. Results of immunocytochemistry and western blot showed that the composite scaffolds promoted the specific differentiation of NSCs into neuron cells. Together, this dECM/GelMA composite scaffold can be used as a cell culture coating, the isolated NSCs seeded on the surface of composite scaffold expressed neuronal markers and assumed neuronal morphology. Our work provided a new method that would be widely used in tissue engineering of SCI.

3D printed hybrid bone constructs of PCL and dental pulp stem cells loaded GelMA

Fabrication of scaffolds using polymers and then cell seeding is a routine protocol of tissue engineering applications. Synthetic polymers have adequate mechanical properties to substitute for some bone tissue, but they are generally hydrophobic and have no specific cell recognition sites, which leads to poor cell affinity and adhesion. Some natural polymers, have high cell affinity but are mechanically weak and do not have the strength required as a bone supporting material. In the present study, 3D printed hybrid scaffolds were fabricated using PCL and GelMA carrying dental pulp stem cells (DPSCs), which is printed in the gaps between the PCL struts. This cell loaded GelMA was shown to support osteoinductivity, while the PCL provided mechanical strength needed to mimic the bone tissue. 3D printed PCL/GelMA and GelMA scaffolds were highly stable during 21 days of incubation in PBS. The compressive moduli of the hybrid scaffolds were in the range of the compressive moduli of trabecular bone. DPSCs were homogeneously distributed throughout the entire hydrogel component and exhibited high cell viability in both scaffolds during 21 days of incubation. Upon osteogenic differentiation DPSCs expressed two key matrix proteins, osteopontin and osteocalcin. Alizarin red staining showed mineralized nodules, which demonstrates osteogenic differentiation of DPSCs within GelMA. This construct yielded a very high cell viability, osteogenic differentiation and mineralization comparable to cell culture without compromising mechanical strength suitable for bone tissue engineering applications. Thus, 3D printed, cell loaded PCL/GelMA hybrid scaffolds have a great potential for use in bone tissue engineering applications.

Bone Graft Materials for Alveolar Bone Defects in Orthodontic Tooth Movement

Clinically, orthodontic tooth movement (OTM) across the narrow alveolar ridge area inevitably entails some adverse reactions such as limited movement and periodontal tissue damage. Hence, it is essential to reconstruct the morphology of the alveolar crest before the tooth movement. Unlike the routine reconstruction of alveolar ridge in the field of implant, the orthodontic practices are distinctive, which require dental movement across the constructed alveolar ridge with safety and stability. Herein, we addressed the pros and cons of reconstruction of the defected orthodontic alveolar ridge with different bone graft materials. Attention is also paid to other factors such as the postgraft initiation time of OTM that can substantially influence the bone reconstruction and tooth movement effect. Rather, considering the lack of a unified standard in orthodontic clinics related to bone reconstruction for OTM, we provide some recommendations and guidance for OTM through alveolar ridge defect area.

Biomedical application of photo-crosslinked gelatin hydrogels

Abstract

During the past decades, photo-crosslinked gelatin hydrogel (methacrylated gelatin, GelMA) has gained a lot of attention due to its remarkable application in the biomedical field. It has been widely used in cell transplantation, cell culture and drug delivery, based on its crosslinking to form hydrogels with tunable mechanical properties and excellent bio-compatibility when exposed to light irradiation to mimic the micro-environment of native extracellular matrix (ECM). Because of its unique biofunctionality and mechanical tenability, it has also been widely applied in the repair and regeneration of bone, heart, cornea, epidermal tissue, cartilage, vascular, peripheral nerve, oral mucosa, and skeletal muscle et al. The purpose of this review is to summarize the recent application of GelMA in drug delivery and tissue engineering field. Moreover, this review article will briefly introduce both the development of GelMA and the characterization of GelMA. Finally, we discuss the challenges and future development prospects of GelMA as a tissue engineering material and drug or gene delivery carrier, hoping to contribute to accelerating the development of GelMA in the biomedical field.

Graphical abstract