Osteogenic Capability Research Articles

Synthesis and preclinical evaluation of a novel Oxy133-infused biomimetic bone graft using a rat model of posterolateral spinal fusion.

To (1) create a novel tissue-engineered bone graft comprising the osteoinductive oxysterol Oxy133 and (2) compare the osteogenic capability of this novel bone graft with bone graft substitutes previously examined. Oxy133 was homogeneously incorporated into a biomimetic bone graft substitute (BioMim) comprising extracellular matrix and calcium phosphates. Two iterations of the graft were created: one corresponding to an implant-dose of 2.0mg Oxy133 (BioMim-Oxy133-Lo) and the other corresponding to an implant-dose of 20mg Oxy133 (BioMim-Oxy133-Hi). Thirty-two male Sprague Dawley rats were allocated randomly to four equally sized groups: 1) BioMim-Oxy133-Lo, 2) BioMim-Oxy133-Hi, 3) absorbable collagen sponge (ACS) with topically applied Oxy133 dissolved in dimethyl sulfoxide (ACS-Oxy133; 20mg Oxy133/graft), and 4) ACS with topically applied rhBMP-2 dissolved in water (ACS-rhBMP-2; 5.0μg rhBMP-2/graft). All animals underwent L4-L5 posterolateral spinal fusion. Spines were harvested 8 weeks postoperatively and analyzed using micro-CT imaging. Successful fusion was achieved in all animals. Grafts containing Oxy133 had significantly greater bone volume, percentage bone volume (%BV), bone surface density (BSD), and trabecular number (TbN) compared to ACS-rhBMP-2 (p<0.01 for each). Animals treated with BioMim-Oxy133-Lo had the greatest %BV, BSD, and TbN (p<0.001 for each), whereas animals treated with ACS-rhBMP-2 had the lowest %BV, BSD, TbN, and trabecular thickness (p<0.001 for each). BioMim-Oxy133 is a novel bone graft that led to superior bone volume and quality compared to ACS-rhBMP-2 in a clinically translatable rat model of spinal fusion. Future work is needed to further evaluate this material as a safe and efficacious bone graft substitute.

3D-Printed Polymer Scaffolds for Vascularized Bone Regeneration Using Mineral and Extracellular Matrix Deposition

Abstract Purpose Trauma, injury, disease, infection, congenital deformities, and non-union after a fracture can lead to significant loss of bone tissue resulting in large bone defects. If left untreated, this can lead to decreased bone strength, stability, and function as well as long-term malformations. We present a novel, pre-vascularized 3D-printed biodegradable scaffold mimicking the architecture of native bone as a bone graft alternative to promote vascularized bone regeneration. Methods Scaffolds with a highly porous central trabecular section surrounded by an outer cortical section modeled after the bone’s osteons were 3D printed in polylactic acid (PLA). Hydroxyapatite (HA) posts were incorporated to improve mechanical strength. A soak-freeze technique was used to introduce additional porosity to support the recruitment, proliferation, and differentiation of stem cells. Scaffolds were mineralized to provide cues for osteoconduction and osteoinduction. They were also pre-vascularized to promote the differentiation of stem cells along the vascular lineage. Results Compression mechanical testing showed the addition of HA posts improved mechanical strength. Using the soak-freeze technique, micropores in the range of 0–10 µm were introduced. Osteogenic differentiation capability of the scaffolds was verified in vitro through the estimation of osteocalcin (OC) produced by the cells seeded on them and by staining for alkaline phosphatase. Differentiation of stem cells along the vascular lineage within the scaffold was confirmed via the estimation of vascular endothelial growth factor (VEGF-A) and by staining for CD31, a marker for vascular differentiation. Conclusion This novel scaffold incorporated with cues necessary to promote the regeneration of bone and its vasculature shows promise as an alternative to currently used bone grafts. Lay Summary Significant bone loss caused by trauma, infection, or disease results in large defects that are currently treated using bone grafts—autografts (taken from the same patient), allografts and xenografts (donor tissue), or synthetic grafts. We have developed a tissue-engineered alternative that mimics the architecture of natural bone and has cues to promote both the regeneration of bone and its vasculature. These are fabricated using 3D printing (3DP) technology, providing cost-effective, customizable alternatives to conventional bone grafts.

Bone regeneration in rabbit cranial defects: 3D printed polylactic acid scaffolds gradually enriched with marine bioderived calcium phosphate

ObjectiveThis study aimed to evaluate the in vivo biocompatibility, mechanical performance and osteoconductive potential of 3D-printed polylactic acid (PLA) scaffolds enriched with marine bioderived calcium phosphate (bioCaP) for bone tissue engineering. Materials and MethodsPLA-bioCaP composite scaffolds were specifically designed for the rabbit cranial defect model by 3D printing, with a uniform distribution of open square-shaped pores and contributions in bioCaP. Physicochemical and mechanical characterization and the evaluation of biological response are presented. ResultsThe scaffolds demonstrated mechanical properties comparable to human bones, integration with the host bone, and osteoconductive behavior promoting cell ingrowth from the defect edge. Strong mineralized tissue ingrowth through the scaffolds’ pores was observed, providing notable support to the host bone. In quantitative terms, micro-CT and histomorphometry analysis post-implantation revealed no significant differences in bone regeneration across all groups. ConclusionThe 3D-printed scaffolds with perpendicular patterning, open porosity, and proposed composition displayed satisfactory mechanical properties, biocompatibility, and osteoconductive response. The scaffolds promoted bone regeneration at similar levels as the PLA. The highest contribution of bioCaP promoted a positive influence in certain histomorphometric parameters; however, it did not significantly improve their osteogenic capability. Further research is required to optimize scaffold composition and enhance their osteogenic potential. Clinical RelevanceThis study presents a significant advancement in bone tissue engineering through the development of personalized composite scaffolds for bone-related applications. The clinical implications of this research are profound, especially considering the increasing demand for functional bone regeneration technologies capable of producing cost-effective producing cost-effective customized scaffolds.

γ-Fe2O3/Polydopamine/TiO2 nano-porous array composite coating (FPTCC) to modulate antibacterial, osteogenesis, and osseointegration through photothermal-magnetic response

Delayed-union or non-union of fractures due to infection and localized low osteogenic activity is a great physical, psychological and financial burden for patients. Therefore, there is an urgent need to find an economical and effective solution. In this study, a γ-Fe2O3/polydopamine/TiO2 nano-porous arrays composite coating (FPTCC) with photothermal-magnetic responsiveness was fabricated. The characterization of FPTCC was analyzed by FT-IR, SEM, and EDS. The photothermal ability, photothermal stability and magnetic hysteresis curves were examined to evaluate photothermal-magnetic response properties of FPTCC. The results demonstrated that FPTCC has outstanding hydrophilicity, strong substrate bonding and stable remotely controlled photothermal-magnetic response properties. Furthermore, in vitro and in vivo biological experiments were performed to verify the capability of FPTCC to modulate antibacterial, osteogenesis and osseointegration under the intervention of NIR irradiation and static magnetic field. In conclusion, the FPTCC with biocompatibility, antibacterial, and osteogenic capabilities may provide a potential strategy for the prevention and treatment of delayed-union or non-union of fracture.

Establishment of immortalized rabbit bone marrow mesenchymal stem cells and a preliminary study of their osteogenic differentiation capability.

A stable and standardized source of mesenchymal stem cells is a prerequisite for bone repair tissue engineering research and application. We aimed to establish a stable cell line of bone marrow mesenchymal stem cells from New Zealand rabbits and explore their osteogenic differentiation capacity. Primary rabbit bone marrow mesenchymal stem cells (RBMSCs) were isolated and immortalized via retroviral expression of SV40 Large T antigen (LTA). To assess the osteogenic differentiation capacity of the cells invitro, we studied the alkaline phosphatase (ALP) expression level and calcium deposition in bone morphogenetic protein 9 (BMP9)-induced immortalized cells using ALP staining and quantification, as well as alizarin red staining. Ectopic bone formation by the cells was assessed using micro-computed tomography (μCT) and histological examination. The immortalized cell line we established using SV40 LTA, which we termed iRBMSCs, was non-tumorigenic and maintained long-term proliferative activity. We further discovered that BMP9 (MOI = 30) effectively induced the osteogenic differentiation capacity of iRBMSCs invitro, and there was a synergy with GelMA hydrogel in inducing osteogenic differentiation of the iRBMSCs invivo. We confirmed that iRBMSCs are promising as a stable cell line source for bone defect repair engineering.

Injectable and adhesive MgO2-potentiated hydrogel with sequential tumor synergistic therapy and osteogenesis for challenging postsurgical osteosarcoma treatment

The clinical treatment of osteosarcoma faces great challenges of residual tumor cells leading to tumor recurrence and irregular bone defects difficult to repair after surgery removal of the primary tumor tissue. We developed an injectable and in-situ cross-linkable hydrogel (named MOG hydrogel) using MgO2 nanoparticles and dopamine-conjugated gelatin as main components. MgO2 was rationally designed as a multifunctional active ingredient to mediate in situ gelation, tumor therapy, and bone repair sequentially. The 10MOG (with 10 mg/mL MgO2 content) showed excellent gel stability, injectability, shape adaptability, tissue adhesion, and rapid hemostatic ability. Importantly, 10MOG exhibited ideal sequential H2O2 and Mg2+ release property. The released H2O2 synergized with photothermal therapy for enhanced tumor recurrence suppression, and the sustainable Mg2+ release efficiently promoted bone regeneration. The MOG hydrogel, possessing excellent on-demand antitumor and osteogenic capabilities in vitro and in vivo, exhibited tremendous potential in the clinical application for challenging postsurgical osteosarcoma treatment.

Dental pulp stem cell‑derived extracellular vesicles loaded with hydrogels promote osteogenesis in rats with alveolar bone defects.

Alveolar bone defects caused by inflammation, trauma and tumors adversely affect periodontal health, causing tooth loosening or dentition defects, thus affecting denture or implant repair. Advancements in tissue engineering technology and stem cell biology have significantly improved the regenerative reconstruction of alveolar bone defects. The multiple trophic activities of extracellular vesicles (EVs) produced by mesenchymal stem cells play important roles in exerting their therapeutic effects. Several studies have reported the role of dental pulp stem cells (DPSCs) in bone regeneration, but the regenerative effects of DPSC‑EVs on alveolar bone defects are unclear. In the present study, the osteogenic effects of DPSC‑EVs on Hertwig's epithelial root sheath (HERS) cells in vitro and their osteoinductive effects in an alveolar bone defect rat model were investigated. The results showed that DPSC‑EVs significantly promoted the expression of osteogenic genes, such as runt‑related transcription factor 2 and alkaline phosphatase, and increased the osteogenic differentiation capability of HERS. These findings suggested that transforming growth factor β1 inhibition decreased DPSC‑EV‑induced Smad, MAPK and ERK phosphorylation in HERS. In vivo, DPSC‑EV‑loaded hydrogels were transplanted into the alveolar sockets of Sprague‑Dawley rats and observed for eight weeks. The new bone grew concentrically in the DPSC‑EV or DPSC‑EV‑loaded hydrogel group, with greater bone mass than that in the control group, and the bone volume/total volume increased notably. The results confirmed the osteogenic and osteoinductive effects of DPSC‑EVs and DPSC‑Exo‑loaded hydrogels on alveolar bone defects. Due to their low immunogenicity, high stability, good biocompatibility and osteogenic propensity, DPSC‑EV‑loaded hydrogels are a safe cell‑free therapeutic approach for defective alveolar bone regeneration.

Synergy of engineered gelatin methacrylate-based porous microspheres and multicellular assembly to promote osteogenesis and angiogenesis in bone tissue reconstruction

One of the key challenges in bone defects treatment is providing adequate and stable blood supply during new tissue regeneration. Mesenchymal stem cells (MSCs) and endothelial cells (ECs) have great potential to promote osteogenesis and angiogenesis during bone defect repair through paracrine effects, but their therapeutic efficacy depends on effective cellular assembly and delivery. In this work, we developed various microspheres with different pore sizes for multi-cellular delivery to enhance the angiogenic and osteogenic capability via combining microfluidic and gradient freeze-drying techniques. The particle and pore size of fabricated porous gelatin methacrylate (GelMA)-based hydrogel microspheres (PGMS) could be controllable through adjusting the freezing time of hydrogel microspheres, the range of particles and pores size are 150–250 μm and 10–100 μm with different freezing time from 0 min to 30 min. The optimized particle size (200.8 ± 14.2 μm) and pore size (11.2 ± 1.9 μm) were explored to promote cell assemble, adhesion, growth, and proliferation in the PGMS. Furthermore, the co-assembly and delivery of bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) on the PGMS was achieved and an optimal cellular ratio of BMSCs to HUVECs (20:2) was established for co-culturing of them to achieve optimal paracrine effects, further promoting osteogenic differentiation and angiogenesis. Finally, results from both in vitro and in vivo experiments showed that the developed PGMS with co-assembly of BMSCs to HUVECs contributed to accelerate bone regeneration and vascularization process daringly, exhibited great potential in vascularized bone tissue reconstruction.

Extracellular vesicle-laden hybrid cryogel-interpenetrating network scaffold for improved osteogenesis in bone tissue engineering

Bone tissue engineering (BTE) aims to regenerate the damaged or diseased bone by combining cells, growth factors, and biomaterials. Synthetic bone tissue, which is widely available, is a promising alternative to autografts, allografts, and natural fillers. Biomaterials like 3D scaffolds mimic the extracellular matrix, supporting cell growth and tissue regeneration. However, clinical applications face challenges such as limited osteogenic and angiogenic capabilities, weak mechanical strength, and risks of infection and immune reactions. The current work introduces a mechanically robust cryogel-hydrogel hybrid scaffold, loaded with extracellular vesicles (EVs) and cell secretomes as osteoinductive cues. The scaffold’s mechanical strength was assessed against its individual components. Its physical characteristics, including swelling capacity and porous structure, were analyzed using field emission scanning electron microscopy (FESEM), and the incorporation of nano-hydroxyapatite (nHAp) was confirmed through Fourier transform infrared (FTIR) spectroscopy. Three scaffolds were tested: a cryogel scaffold of gelatin and nano-hydroxyapatite (nHAp), a hydrogel scaffold of poly(ethylene glycol) diacrylate (PEGDA), and a hybrid cryogel scaffold of gelatin and nano-hydroxyapatite with a PEGDA interpenetrating network (IPN). The results indicated that the hybrid cryogel scaffold with IPN had the greatest normalized ALP content and lowest cytotoxicity, making it the best choice for further study. To explore the osteoinductive potential of Mesenchymal Stem Cell-derived EVs, three scaffold variations were tested: a hybrid IPN scaffold, IPN + nHAp scaffold, and IPN + nHAp + EVs scaffold. These were evaluated for viable cell count, ALP activity, DNA content, and calcium accumulation. The IPN + nHAp + EVs scaffold demonstrated the greatest potential for BTE, with the highest mechanical strength—20.82-fold greater than the single-network cryogel and 1.75-fold stronger than the PEGDA hydrogel. It also showed the highest normalized ALP content, 3.39-fold and 1.47-fold greater than the IPN and IPN + nHAp scaffolds, respectively, and the highest calcium deposition, 1.30-fold higher than the IPN + nHAp scaffold. In conclusion, this study successfully developed a hybrid scaffold system with improved mechanical characteristics and osteogenesis potential, advancing the field of bone tissue engineering.

Early anti-inflammatory polarization of macrophages ameliorates post-surgical inflammation and osseointegration around titanium implants in mice

Dental implants are considered a superior option for the replacement of missing teeth. However, the invasive nature of the surgical procedure often results in significant postoperative inflammation, and the prolonged healing period of 3–6 months presents a notable disadvantage. High mobility group box 1 (HMGB1) is a critical mediator of acute inflammation following surgical injury, which can hinder the onset of osseointegration. This study aims to examine whether the inhibition of HMGB1 can mitigate acute inflammation and subsequently enhance osseointegration. The findings indicate that HMGB1 inhibition markedly reduces inflammation and promotes bone repair in murine models. Further in vitro investigations into the regulatory mechanisms of HMGB1 in macrophages reveal its role in increasing Yes-associated protein (YAP) activity, which contributes to pro-inflammatory polarization. Additionally, conditioned media derived from macrophages influenced by HMGB1 significantly impair the migratory and osteogenic capabilities of bone marrow-derived mesenchymal stem cells, which are essential for bone regeneration. In vivo experiments further validate that the administration of exogenous HMGB1 exacerbates postoperative acute inflammation and obstructs osseointegration. The study concludes that inhibiting HMGB1 fosters an anti-inflammatory polarization of macrophages, leading to diminished postoperative acute inflammation and expedited osseointegration around dental implants in mice.

Lockd Enhances Mandibular Mesenchymal Stem Cell Proliferation While Inhibiting Osteogenic Capability via Binding With SUZ12 in the Inflammatory Microenvironment.

To investigate the role of lncRNA Lockd in mandibular mesenchymal stem cell (M-MSC) proliferation and osteogenic capability in the inflammatory microenvironment, focusing on its interaction with SUZ12. Using lncR Lockd knockdown/overexpression cell models and a murine periodontitis model, we explored Lockd's effects on M-MSC proliferation and osteogenic capability in the inflammatory microenvironment. Predictions from multiple databases and a series of rescue experiments revealed the regulatory role of the Lockd/SUZ12 signalling axis of M-MSC in the inflammatory microenvironment. Lockd was found to stimulate M-MSC proliferation but impair osteogenic differentiation. The in vitro studies suggested that the activation of Lockd negatively inhibited the osteogenic differentiation process and may ultimately impact bone formation in periodontitis. Mechanistically, it was elucidated that Lockd interacts with SUZ12, a core component of the polycomb repressive complex 2 (PRC2), and may affect the PRC2 complex's role in osteogenic gene expression. Lockd boosts the proliferation of M-MSCs but inhibits their osteogenic differentiation by interacting with SUZ12, potentially inhibiting osteogenic capability in the inflammatory microenvironment.

Multifunctional sericin-based biomineralized nanoplatforms with immunomodulatory and angio/osteo-genic activity for accelerated bone regeneration in periodontitis

Periodontitis is a chronic inflammation caused by dental plaque. It is characterized by the accumulation of excessive reactive oxygen species (ROS) and inflammatory mediators in the periodontal area. This affects the function of host cells, activates osteoclasts, and destroys periodontal tissue. Treatments such as local debridement or antibiotic therapy for ameliorating the overactive inflammatory microenvironment and repairing periodontal tissues are challenging. This paper reports multifunctional nanoplatforms (Se-CuSrHA@EGCG) based on sericin with ROS-scavenging, immunomodulatory, angiogenic, and osteogenic capabilities. The natural protein sericin, derived from silk cocoons, is used in water/oil emulsification and cross-linking processes to create sericin nanoparticles (Se NPs). Numerous binding sites are present on the surface of Se NPs. Ion-doped hydroxyapatite nanoparticles (Se-CuSrHA NPs) can be constructed using the force between positive and negative charges. After mineralization, an antioxidant coating is formed on the surface using polyethyleneimine (PEI)/epigallocatechin gallate (EGCG). Research conducted both in vitro and in vivo demonstrates that Se-CuSrHA@EGCG NPs can efficiently scavenge ROS, regulate macrophage polarization, increase the secretion of anti-inflammatory cytokines, and balance the immune microenvironment. In addition, Se-CuSrHA@EGCG stimulates angiogenesis, inhibits osteoclasts, and accelerates periodontal tissue repair. Therefore, this is a preferable strategy to accelerate bone regeneration in patients with periodontitis.

Biocompatible chitin-based Janus hydrogel membranes for periodontal repair

Periodontal defects caused by severe periodontitis are a widespread issue globally. Guided tissue regeneration (GTR) using barrier membranes for alveolar bone repair is a common clinical treatment. However, most commercially available collagen barrier membranes are expensive and lack the antibacterial properties essential for effective bone regeneration. Herein, we report a natural polysaccharide chitin hydrogel barrier membrane with a Janus structure (ChT-PDA-p-HAP), featuring high antibacterial and protein-repelling activity on the outer side and good osteogenesis ability on the inner side. This multifunctional membrane is fabricated though a three-step process: (i) dissolution and regeneration of chitin, (ii) co-deposition with polydopamine (PDA) and poly(sulfobetaine methacrylate) (pSBMA), and (iii) coating with gelatin-hydroxyapatite (gelatin-HAP). In vitro cell experiments demonstrated the membrane's high biocompatibility and significant osteogenic activity. In vivo implantation in rats with periodontal defects revealed that the cemento-enamel junction index of the ChT-PDA-p-HAP membrane (1.165 mm) was superior to that of the commercial Bio-Gide® membrane (1.350 mm). This work presents a method for fabricating a chitin-based Janus barrier membrane, potentially expanding the use of chitin in tissue engineering. Statement of significanceThis study introduces a Janus hydrogel membrane based on chitin, tailored for guided tissue regeneration in periodontal defects. By combining antibacterial properties and osteogenic capabilities in a single membrane, the ChT-PDA-p-HAP membrane represents a significant advancement over traditional collagen barriers. Its outer surface, enhanced by Cu2+ and PDA-pSBMA coatings, resists bacterial colonization and protein adhesion effectively, while the inner side, coated with gelatin-HAP, promotes robust bone formation. In vitro experiments demonstrate high biocompatibility and substantial osteogenic differentiation, while in vivo testing in rat models confirms good therapeutic efficacy compared to commercial membranes. This multifunctional approach not only utilizes chitin's abundant natural resource but also integrates simple coating techniques to enhance therapeutic outcomes in periodontal tissue engineering, offering promising avenues for broader biomedical applications.

Self-cascade ROS-trapping bioreaction system reverses stem cell oxidative stress fate for osteogenesis

eactive oxygen species (ROS) scavenging is essential for periodontal regeneration. However, the dynamic change of the applied materials within the ROS-rich environment and the residual oxidation products in the host highly impact periodontal regeneration. This study successfully constructs a bioreaction system via thiol-ene click chemistry, leveraging the high affinity of glutathione (GSH) for ROS to attract excess ROS to the crosslinking points. Two minutes after hydrogen peroxide (H2O2) treatment, the ROS level in the G8-0 hydrogel acutely decreases, reaching a 4.4% reduction within 10minutes, confirming the ROS-trapping efficacy. Through a ‘bait switch-on’ mechanism, hexagonal boron nitride (hBN) takes over the captured ROS and the oxidation products of pectin further drive the reduction reaction, ultimately restoring the extracellular environment. The self-cascade products, oxidized hBN, reshape the intracellular oxidative stress (OS) environment, achieving a synergistic extra- and intra-cellular treatment. The significantly high reduced to oxidized glutathione (GSH/GSSG) ratio in G8-10 hydrogel (~80%) illustrates a reversal of oxidative stress in bone marrow stem cells (BMSCs). On a molecular level, the bioreaction system inhibits the NF-κB pathway, promoting the expression of key antioxidant genes (Nqo1 and Nrf2) and osteogenic molecules (ALP and OCN), thereby reversing the detrimental effects of OS on BMSCs. In vivo application demonstrated the system’s strong redox-balancing and osteogenic capabilities in the periodontal inflammation environment. This novel antioxidant bioreaction system, characterized by self-cascade ROS-trapping and product utilization, offers innovative treatment strategies for tissue regeneration under conditions of excessive OS.

Functionalized 3D-printed GelMA/Laponite hydrogel scaffold promotes BMSCs recruitment through osteoimmunomodulatory enhance osteogenic via AMPK/mTOR signaling pathway

The migration and differentiation of bone marrow mesenchymal stem cells (BMSCs) play crucial roles in bone repair processes. However, conventional scaffolds often lack of effectively inducing and recruiting BMSCs. In our study, we present a novel approach by introducing a 3D-bioprinted scaffold composed of hydrogels, with the addition of laponite to the GelMA solution, aimed at enhancing scaffold performance. Both in vivo and in vitro experiments have confirmed the outstanding biocompatibility of the scaffold. Furthermore, for the first time, Apt19s has been chemically modified onto the surface of the hydrogel scaffold, resulting in a remarkable enhancement in the migration and adhesion of BMSCs. Moreover, the scaffold has demonstrated robust osteogenic differentiation capability in both in vivo and in vitro environments. Additionally, the hydrogel scaffold has shown the ability to induce the polarization of macrophages from M1 to M2, thereby facilitating the osteogenic differentiation of BMSCs via the bone immune pathway. Through RNA-seq analysis, it has been revealed that macrophages regulate the osteogenic differentiation of BMSCs through the AMPK/mTOR signaling pathway. In summary, the functionalized GelMA/Laponite scaffold offers a cost-effective approach for tailored in situ bone regeneration.

Implication of CXCR2-Src axis in the angiogenic and osteogenic effects of FP-TEB

Application of tissue-engineered bones (TEBs) is hindered by challenges associated with incorporated viable cells. Previously, we employed freeze-drying techniques on TEBs to devitalize mesenchymal stem cells (MSCs) while preserving functional proteins, yielding functional proteins-based TEBs (FP-TEBs). Here, we aimed to elucidate their in vivo angiogenic and osteogenic capabilities and the mechanisms. qPCR arrays were employed to evaluate chemokines and receptors governing EC migration. Identified C-X-C chemokine receptors (CXCRs) were substantiated using shRNAs, and the pivotal role of CXCR2 was validated via conditional knockout mice. Finally, signaling molecules downstream of CXCR2 were identified. Additionally, Src, MAP4K4, and p38 MAPK were identified indispensable for CXCR2 function. Further investigations revealed that regulation of p38 MAPK by Src was mediated by MAP4K4. In conclusion, FP-TEBs promoted EC migration, angiogenesis, and osteogenesis via the CXCR2-Src-Map4k4-p38 MAPK axis.

Application of Mg-MOF-loaded gelatin microspheres with osteogenic, angiogenic, and ROS scavenging capabilities in bone defect repair

The management of bone defects, particularly those with irregular geometries resulting from osteoporotic fractures, remains fraught with challenges. Microspheres have emerged as a promising vehicle for tissue engineering, distinguished by their controlled release, safety, and ease of application. Various bioactive components are integrated into microspheres to improve their performance. Metal-organic frameworks, formed from metal ions interconnected by organic ligands, are increasingly utilized in tissue engineering. Specifically, magnesium-based MOFs are notable for their broad applicability; Mg2+ ions are instrumental in bone reconstruction and repair, facilitating osteogenesis, angiogenesis, antibacterial effects, and anti-inflammatory properties. Mg-MOF was synthesized using magnesium chloride and gallic acid, and it was incorporated into gelatin microspheres to create Gel@Mg-MOF composite microspheres. Leveraging gelatin's biocompatibility, controlled release, and biodegradability, the composites' biocompatibility was evaluated through toxicity and adhesion assays. Moreover, the osteogenic and angiogenic potentials of the Gel@Mg-MOF microspheres were assessed, alongside their capacity for ROS scavenging. Results suggest that controlled Mg2+ release from Gel@Mg-MOF microspheres promotes osteogenic activity in RBMSCs and enhances angiogenic potential in HUVECs. Additionally, the gallic acid-containing composite microspheres exhibited antioxidative properties. Collectively, the findings suggest that Gel@Mg-MOF microspheres could provide effective support for bone defect repair, with potential for clinical deployment.

Cytotoxicity and genotoxic impacts of LAPONITE® on murine adipose stem cells

This study comprehensively characterized LAPONITE® and evaluated its cytotoxic and genotoxic effects on rat adipose-derived stem cells (ADSCs). Chemical analyses included Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. Cytotoxic screening using the Artemia salina lethality test indicated low toxicity. ADSCs exhibited mesenchymal stem cell chracteristics. LAPONITE® demonstrated osteogenic induction capability. MTT assays revealed increased cell viability across concentrations and exposure times. The comet assay for genotoxicity showed no significant differences in damage index between experimental groups, except for a distinction in the frequency of damage between LAPONITE® concentrations at the longest exposure time. This comprehensive assessment provides valuable insights into the safety and potential applications of LAPONITE® in regenerative medicine.

Cu/Gd co-doped hydroxyapatite/poly lactic-co-glycolic acid composites enhance MRI imaging and bone defect regeneration.

Background: The hydroxyapatite (HA)/poly(lactide-co-glycolide) acid (PLGA) composite material is a widely used orthopedic implant due to its excellent biocompatibility and plasticity. Recent advancements in cation doping have expanded its potential biological applications. However, conventional HA/PLGA composites are not visible under X-rays post-implantation and have limited osteogenic induction capabilities. Copper (Cu) is known to regulate osteoblast proliferation and differentiation, while gadolinium (Gd) can significantly enhance the magnetic resonance imaging (MRI) capabilities of materials. Methods: This study aimed to investigate whether incorporating Cu and Gd into an HA/PLGA composite could enhance the osteogenic properties, in vivo bone defect repair, and MRI characteristics. We prepared a Cu/Gd@HA/PLGA composite and assessed its performance. Results: Material characterization confirmed that Cu/Gd@HA retained the morphology and crystal structure of HA. The Cu/Gd@HA/PLGA composite exhibited excellent nuclear magnetic imaging capabilities, porosity, and hydrophilicity, which are conducive to cell adhesion and implant detection. In vitro experiments demonstrated that the Cu/Gd@HA/PLGA composite enhanced the proliferation, differentiation, and adhesion of MC3T3-E1 cells, and upregulated COL-1 and BMP-2 expression at both gene and protein levels. In vivo studies showed that the Cu/Gd@HA/PLGA composite maintained strong T1-weighted MRI signals and significantly improved the bone defect healing rate in rats. Conclusion: These findings indicate that the Cu/Gd@HA/PLGA composites significantly enhance T1-weighted MRI capabilities, promote osteoblast proliferation and differentiation in vitro, and accelerate bone defect healing in vivo.

Osteogenic differentiation capabilities of multiarm PEG hydrogels: involvement of gel–gel-phase separation in cell differentiation

AbstractThe development of bioactive scaffolds is essential for tissue engineering because of the influence of material physicochemical properties on cellular activities. Recently, we discovered that percolation-induced 4-arm polyethylene glycol (PEG) hydrogels achieved gel–gel phase separation (GGPS), which has tissue affinity in vivo. However, whether the 4-arm structure is the optimal configuration for the use of PEG hydrogels as scaffolds remains unclear. In this study, we investigated the effect of an increased branching factor on GGPS. Compared with the 4-arm PEG hydrogel, the 8-arm PEG hydrogel presented a greater degree of GGPS and increased hydrophobicity. We introduced the RGD sequence into PEG hydrogels to directly assess the biological activity of GGPS, with a particular focus on its effects on the activity of bone-forming osteoblasts. Although the 8-arm PEG hydrogel did not enhance cell adhesion, it enhanced osteoblast differentiation compared with the 4-arm PEG hydrogel. Therefore, the 8-arm PEG hydrogel mediated by GGPS shows promise as a scaffold for osteoblast differentiation and holds potential as a foundation for future advancements in bone tissue engineering.