Characterization and intracellular mechanism of electrospun poly (ε-caprolactone) (PCL) fibers incorporated with bone-dECM powder as a potential membrane for guided bone regeneration

Incorporating Bone-Derived ECM into Macroporous Microribbon Scaffolds Accelerates Bone Regeneration

Tissue-derived extracellular matrix (tdECM) hydrogels serve as effective scaffolds for tissue regeneration by promoting a regenerative immune response. While most tdECM hydrogels are nanoporous and tailored for soft tissue, macroporosity is crucial for bone regeneration. Yet, there's a shortage of macroporous ECM-based hydrogels for this purpose. The study aims to address this gap by developing a co-spinning technique to integrate bone-derived ECM (bECM) into gelatin-based, macroporous microribbon (µRB) scaffolds. The effect of varying doses of bECM on scaffold properties was characterized. In vitro studies revealed 15% bECM as optimal for promoting MSC osteogenesis and macrophage (Mφ) polarization. When implanted in a mouse critical-sized cranial bone defect model, 15% bECM with tricalcium phosphate (TCP) microparticles significantly accelerated bone regeneration and vascularization, filling over 55% of the void by week 2. Increasing bECM to 25% enhanced mesenchymal stem cell (MSC) recruitment and decreased M1 Mφ polarization but reduced overall bone formation and vascularization. The findings demonstrate co-spun gelatin/bECM hydrogels as promising macroporous scaffolds for robust endogenous bone regeneration, without the need for exogenous cells or growth factors. While this study focused on bone regeneration, this platform holds the potential for incorporating various tdECM into macroporous scaffolds for diverse tissue regeneration applications.

Pulmonary decellularized extracellular matrix (dECM) modified polyethylene terephthalate three-dimensional cell carriers regulate the proliferation and paracrine activity of mesenchymal stem cells

Introduction: Mesenchymal stem cells (MSCs) possess a high degree of self-renewal capacity and in vitro multi-lineage differentiation potential. Decellularized materials have garnered considerable attention due to their elevated biocompatibility, reduced immunogenicity, excellent biodegradability, and the ability to partially mimic the in vivo microenvironment conducive to cell growth. To address the issue of mesenchymal stem cells losing their stem cell characteristics during two-dimensional (2D) cultivation, this study established three-dimensional cell carriers modified with lung decellularized extracellular matrix and assessed its impact on the life activities of mesenchymal stem cells. Methods: This study employed PET as a substrate material, grafting with polydopamine (PDA), and constructing a decellularized extracellular matrix (dECM) coating on its surface, thus creating the PET/PDA/dECM three-dimensional (3D) composite carrier. Subsequently, material characterization of the cellular carriers was conducted, followed by co-culturing with human umbilical cord mesenchymal stem cells in vitro, aiming to investigate the material's impact on the proliferation and paracrine activity of mesenchymal stem cells. Results and Discussion: Material characterization demonstrated successful grafting of PDA and dECM materials, and it had complete hydrophilicity, high porosity, and excellent mechanical properties. The material was rich in various ECM proteins (collagen I, collagen IV , laminin, fibronectin, elastin), indicating good biocompatibility. In long-term in vitro cultivation (14 days) experiments, the PET/PDA/dECM three-dimensional composite carrier significantly enhanced adhesion and proliferation of human umbilical cord-derived mesenchymal stem cells (HUCMSCs), with a proliferation rate 1.9 times higher than that of cells cultured on tissue culture polystyrene (TCPS) at day 14. Furthermore, it effectively maintained the stem cell characteristics, expressing specific antigens for HUCMSCs. Through qPCR, Western blot, and ELISA experiments, the composite carrier markedly promoted the expression and secretion of key cell factors in HUCMSCs. These results demonstrate that the PET/PDA/dECM composite carrier holds great potential for scaling up MSCs' long-term in vitro cultivation and the production of paracrine factors.

Efficacy of positive space acquiring membrane and antimicrobial membrane combined with granular bone substitute implantation in guiding oral bone regeneration

Augmentation of the alveolar bone is important before oral implantation. For large bone defects, it becomes necessary to apply guided bone regeneration (GBR) materials, accompanied by filling defect sites with autologous or allogeneic bone, or bone substitutes such as acellular bone powder. In this study, we tested a granular bone substitute and GBR membrane combination therapy in treating MC3T3-E1 and L929 cells in vitro and rat calvarial and alveolar defects in vivo. The recovery conditions of bone defects were monitored by micro-CT, and 3D reconstruction of the CT images was applied to evaluate the bone augmentation semi-quantitatively. Test GBR materials could support the proliferation of MC3T3-E1 cells, poly (p-dioxanone-co-L-phenylalanine) (PDPA)-based membrane could induce apoptosis of L929 cells. Among GBR membranes applied groups, the regeneration condition of defected calvarial defects of PDPA based membrane applied group was the best and this may be caused by its excellent positive space acquiring effect. However, in a complex bacteriogenic environment, the oral bone regeneration-guided efficacy of the PDPA membrane decreased in the post-repair stage with the aggravation of infections. By contrast, the antimicrobial membrane combined with the PDPA membrane exhibited continually increasing GBR efficacy at the later stage of repair owing to its multifunctional properties, which are infection-inhibiting and positive space acquiring. Therefore, multifunctional GBR membranes are preferable for GBR in complex oral environments, and further research should be conducted to determine their efficacy in other models.

Recent developments in nanomaterials for upgrading treatment of orthopedics diseases

Nanotechnology has changed science in the last three decades. Recent applications of nanotechnology in the disciplines of medicine and biology have enhanced medical diagnostics, manufacturing, and drug delivery. The latest studies have demonstrated this modern technology's potential for developing novel methods of disease detection and treatment, particularly in orthopedics. According to recent developments in bone tissue engineering, implantable substances, diagnostics and treatment, and surface adhesives, nanomedicine has revolutionized orthopedics. Numerous nanomaterials with distinctive chemical, physical, and biological properties have been engineered to generate innovative medication delivery methods for the local, sustained, and targeted delivery of drugs with enhanced therapeutic efficacy and minimal or no toxicity, indicating a very promising strategy for effectively controlling illnesses. Extensive study has been carried out on the applications of nanotechnology, particularly in orthopedics. Nanotechnology can revolutionize orthopedics cure, diagnosis, and research. Drug delivery precision employing nanotechnology using gold and liposome nanoparticles has shown especially encouraging results. Moreover, the delivery of drugs and biologics for osteosarcoma is actively investigated. Different kind of biosensors and nanoparticles has been used in the diagnosis of bone disorders, for example, renal osteodystrophy, Paget's disease, and osteoporosis. The major hurdles to the commercialization of nanotechnology-based composite are eventually examined, thus helping in eliminating the limits in connection to some pre-existing biomaterials for orthopedics, important variables like implant life, quality, cure cost, and pain and relief from pain. The potential for nanotechnology in orthopedics is tremendous, and most of it looks to remain unexplored, but not without challenges. This review aims to highlight the up tp date developments in nanotechnology for boosting the treatment modalities for orthopedic ailments. Moreover, we also highlighted unmet requirements and present barriers to the practical adoption of biomimetic nanotechnology-based orthopedic treatments.

In Silico Study of Novel Cyclodextrin Inclusion Complexes of Polycaprolactone and Its Correlation with Skin Regeneration

Three novel biomaterials obtained via inclusion complexes of β-cyclodextrin, 6-deoxi-6-amino-β-cyclodextrin and epithelial growth factor grafted to 6-deoxi-6-amino-β-cyclodextrin with polycaprolactone. Furthermore, some physicochemical, toxicological and absorption properties were predicted using bioinformatics tools. The electronic, geometrical and spectroscopical calculated properties agree with the properties obtained via experimental methods, explaining the behaviors observed in each case. The interaction energy was obtained, and its values were -60.6, -20.9 and -17.1 kcal/mol for β-cyclodextrin/polycaprolactone followed by the 6-amino-β-cyclodextrin-polycaprolactone complex and finally the complex of epithelial growth factor anchored to 6-deoxy-6-amino-β-cyclodextrin/polycaprolactone. Additionally, the dipolar moments were calculated, achieving values of 3.2688, 5.9249 and 5.0998 Debye, respectively, and in addition the experimental wettability behavior of the studied materials has also been explained. It is important to note that the toxicological predictions suggested no mutagenic, tumorigenic or reproductive effects; moreover, an anti-inflammatory effect has been shown. Finally, the improvement in the cicatricial effect of the novel materials has been conveniently explained by comparing the poly-caprolactone data obtained in the experimental assessments.

Comprehensive reparative effects of bacteriostatic poly(L-lactide-co-glycolide)/poly(L-lactide-co-ε-caprolactone) electrospinning membrane on alveolar bone defects in progressive periodontitis

Periodontitis is a chronic inflammatory disease that leads to the loss of alveolar bone, among several studies focusing on reconstructing periodontal bone caused by periodontitis, guided bone regeneration (GBR) is a promising approach. In this study a serial clinically applied antibiotics loaded poly(L-lactide-co-glycolide)/poly(L-lactide-co-ε-caprolactone) (PLGA/PLCA) fibrous mesh to prevent and reconstruct defective bone in periodontitis were prepared by electrospinning. Incorporation of antibiotics promoted the hydrophilicity but decreased the crystallinity of PLGA/PLCA membranes. Antibiotics could be sustained released from membranes. Metronidazole, minocycline, and doxycycline incorporated membranes could suppress Porphyromonas gingivalis (P. gingivalis) within 21 days in vitro. Metronidazole and minocycline incorporated membranes decreased 41% and 55.5% colony counts in rat gingival crevicular fluid in vivo. Minocycline-loaded membrane could support the proliferation of MC3T3-E1 cells and maintained 79% viability of human ligament fibroblasts cultured on it. And MC3T3-E1 cells could undergo osteoblastic differentiation when cultured with pure PLGA/PLCA membrane and minocycline incorporated membrane. Then in vivo repairable effects of those antibiotics loaded membranes were evaluated in alveolar bone defected P. gingivalis infected model. The application of minocycline loaded membranes, effectively prevented the bone resorption of periodontitis caused by P. gingivalis. After been treated with minocycline incorporated membrane, volume of defected bone of maintained at about 50% level of control rats. 8 weeks post-operation, newly regenerated bone was observed in the operative alveolar bone of the pure PLGA/PLCA membrane, metronidazole and minocycline incorporated PLGA/PLCA membrane treated groups. Minocycline/PLGA/PLCA electrospinning membrane is a promising GBR material that can be applied to guide regeneration of periodontitis-induced alveolar bone damage.

Positive space acquiring asymmetric membranes for guiding alveolar bone regeneration under infectious conditions

To obtain multifunctional materials suitable for guiding alveolar bone regeneration under infectious conditions, we prepared asymmetric membranes comprising space acquiring layer that involves fibroblast inhibitor poly(p-dioxanone-co-L-phenylalanine) (PDPA), an isolating dense layer that forms barrier between two layers and an osteogenesis inducing electrospinning layer which involves hydroxyapatite or hydroxyapatite & minocycline. Then the composition, crystallization, morphology, and hydrophilicity of asymmetric membranes were analyzed. Minocycline incorporated membranes controlled the expansion of Porphyromonas gingivalis (P. gingivalis) in vitro. Hydroxyapatite-incorporated asymmetric membranes promoted the expression of osteogenesis related genes RUNX2, OPN, ALP of MC3T3-E1 cells in vitro. The mineralization of MC3T3-E1 cells cultured with hydroxyapatite-incorporated asymmetric membranes were also promoted in vitro. Asymmetric membranes especially hydroxyapatite-incorporated ones guided the regeneration of the mandibular bone defect in vivo. Bone regeneration guided under infectious conditions was evaluated in a P. gingivalis infected alveolar bone defect model. Specifically, space acquiring layer containing asymmetric membranes effectively controlled connective tissue hyperplasia at defect sites. The excellent guided bone regeneration achieved by applying a single space acquiring layer membrane further indicates the importance of acquiring space actively to induce bone regeneration. Hydroxyapatite-minocycline incorporated symmetric membranes could simultaneously suppress alveolar bone reabsorption caused by infection and guide regeneration of defects. Therefore, the hydroxyapatite-minocycline incorporated asymmetric membrane may be more suitable to be applied in guiding regeneration of bone defects under complex infectious conditions.

Bovine dentin collagen/poly(lactic acid) scaffolds for teeth tissue regeneration

Electrospun scaffolds with diameter fibers compared to those in the extracellular matrix were produced with poly(lactic acid) (PLA) and non-denatured collagen from bovine dentin (DCol). DCol was obtained through an improved version of the Longin method by acid erosion of the hydroxyapatite of the roots of teeth from a 2-year-old cattle. The dentin collagen was characterized by energy dispersive X-ray spectroscopy (EDS), and carbon, nitrogen, and oxygen were found to be the main elements of the protein. Infrared analysis revealed the typical bands of collagen at about 3300, 1631, 1539, and 1234 cm−1 for amides A, I, II, and III, respectively. Calorimetric and infrared analyses also demonstrated that the collagen was non-denatured. With scanning electron microscopy, it was found that the thinnest fibers with a diameter comparable to that of fibers in the extracellular matrix were obtained when dentin collagen and acetic acid (AAc) were added to the solution of PLA in trifluoroethanol (TFE). The scaffolds with the thinnest diameter had also the highest porosity, and we considered that they could be beneficial in the growth of dentin cell. Human placenta-derived mesenchymal stem cells were seeded onto electrospun scaffolds. After 24, 48 and 96 h of culture, cell proliferation was evaluated by two independent strategies. In both assays, it was found that the pl-MSCs were capable of adhering and proliferating in different scaffolds. It was also observed that cell adhesion and proliferation increased significantly in scaffolds containing collagen, although the addition of AAc slightly decreased this effect on all scaffolds.

Graphical abstract

Recent advances in biofunctional guided bone regeneration materials for repairing defective alveolar and maxillofacial bone: A review

The anatomy of the oral and maxillofacial sites is complex, and bone defects caused by trauma, tumors, and inflammation in these zones are extremely difficult to repair. Among the most effective and reliable methods to attain osteogenesis, the guided bone regeneration (GBR) technique is extensively applied in defective oral and maxillofacial GBR. Furthermore, endowing biofunctions is crucial for GBR materials applied in repairing defective alveolar and maxillofacial bones. In this review, recent advances in designing and fabricating GBR materials applied in oral and maxillofacial sites are classified and discussed according to their biofunctions, including maintaining space for bone growth; facilitating the adhesion, migration, and proliferation of osteoblasts; facilitating the migration and differentiation of progenitor cells; promoting vascularization; providing immunoregulation to induce osteogenesis; suppressing infection; and effectively mimicking natural tissues using graded biomimetic materials. In addition, new processing strategies (e.g., 3D printing) and new design concepts (e.g., developing bone mimetic extracellular matrix niches and preparing scaffolds to suppress connective tissue to actively acquire space for bone regeneration), are particularly worthy of further study. In the future, GBR materials with richer biological functions are expected to be developed based on an in-depth understanding of the mechanism of bone-GBR-material interactions.

Electrospinning porcine decellularized nerve matrix scaffold for peripheral nerve regeneration

The composition and spatial structure of bioscaffold materials are essential for constructing tissue regeneration microenvironments. In this study, by using an electrospinning technique without any other additives, we successfully developed pure porcine decellularized nerve matrix (xDNME) conduits. The developed xDNME was composed of an obvious decellularized matrix fiber structure and effectively retained the natural components in the decellularized matrix of the nerve tissue. The xDNME conduit exhibited superior biocompatibility and the ability to overcome inter-species barriers. In vivo, after 12 weeks of implantation, xDNME significantly promoted the regeneration of rat sciatic nerve. The regenerated nerve fibers completely connected the two ends of the nerve defect, which were about 8 mm apart. The xDNME and xDNME-OPC groups showed myelin structures in the regenerated nerve fibers. In the xDNME group, the average thickness of the regenerated myelin sheath was 0.640 ± 0.013 μm, which was almost comparable to that in the autologous nerve group (0.646 ± 0.017 μm). Electrophysiological experiments revealed that both of the regenerated nerve fibers in the xDNME and xDNME-OPC groups had excellent abilities to transmit electrical signals. Respectively, the average conduction velocities of xDNME and xDNME-OPC were 8.86 ± 3.57 m/s and 6.99 ± 3.43 m/s. In conclusion, the xDNME conduits have a great potential for clinical treatment of peripheral nerve injuries, which may clinically transform peripheral nerve related regenerative medicine.

The advances in nanomedicine for bone and cartilage repair

With the gradual demographic shift toward an aging and obese society, an increasing number of patients are suffering from bone and cartilage injuries. However, conventional therapies are hindered by the defects of materials, failing to adequately stimulate the necessary cellular response to promote sufficient cartilage regeneration, bone remodeling and osseointegration. In recent years, the rapid development of nanomedicine has initiated a revolution in orthopedics, especially in tissue engineering and regenerative medicine, due to their capacity to effectively stimulate cellular responses on a nanoscale with enhanced drug loading efficiency, targeted capability, increased mechanical properties and improved uptake rate, resulting in an improved therapeutic effect. Therefore, a comprehensive review of advancements in nanomedicine for bone and cartilage diseases is timely and beneficial. This review firstly summarized the wide range of existing nanotechnology applications in the medical field. The progressive development of nano delivery systems in nanomedicine, including nanoparticles and biomimetic techniques, which are lacking in the current literature, is further described. More importantly, we also highlighted the research advancements of nanomedicine in bone and cartilage repair using the latest preclinical and clinical examples, and further discussed the research directions of nano-therapies in future clinical practice.

A long-lasting guided bone regeneration membrane from sequentially functionalised photoactive atelocollagen

The fast degradation of collagen-based membranes in the biological environment remains a critical challenge, resulting in underperforming Guided Bone Regeneration (GBR) therapy leading to compromised clinical results. Photoactive atelocollagen (AC) systems functionalised with ethylenically unsaturated monomers, such as 4-vinylbenzyl chloride (4VBC), have been shown to generate mechanically competent materials for wound healing, inflammation control and drug delivery, whereby control of the molecular architecture of the AC network is key. Building on this platform, the sequential functionalisation with 4VBC and methacrylic anhydride (MA) was hypothesised to generate UV-cured AC hydrogels with reduced swelling ratio, increased proteolytic stability and barrier functionality for GBR therapy. The sequentially functionalised atelocollagen precursor (SAP) was characterised via TNBS and ninhydrin colourimetric assays, circular dichroism and UV-curing rheometry, which confirmed nearly complete consumption of collagen's primary amino groups, preserved triple helices and fast (< 180 s) gelation kinetics, respectively. Hydrogel's swelling ratio and compression modulus were adjusted depending on the aqueous environment used for UV-curing, whilst the sequential functionalisation of AC successfully generated hydrogels with superior proteolytic stability in vitro compared to both 4VBC-functionalised control and the commercial dental membrane Bio-Gide®. These in vitro results were confirmed in vivo via both subcutaneous implantation and a proof-of-concept study in a GBR calvarial model, indicating integrity of the hydrogel and barrier defect, as well as tissue formation following 1-month implantation in rats. STATEMENT OF SIGNIFICANCE: Collagen-based membranes remain a key component in Guided Bone Regeneration (GBR) therapy, but their properties, e.g. proteolytic stability and soft tissue barrier functionality, are still far from optimal. This is largely attributed to the complex molecular configuration of collagen, which makes chemical accessibility and structure-function relations challenging. Here, we fabricated a UV-cured hydrogel network of atelocollagen, whereby triple helices were sequentially functionalised with two distinct ethylenically unsaturated monomers. The effects of the sequential functionalisation and UV-curing on the macroscopic properties, degradation behaviour and GBR capability were investigated in vitro and in vivo. The results highlight the key role of the sequential functionalisation and provide important insights for the design of future, longer-lasting resorbable membranes for GBR therapy.

Fibers by Electrospinning and Their Emerging Applications in Bone Tissue Engineering

Bone tissue engineering (BTE) is an optimized approach for bone regeneration to overcome the disadvantages of lacking donors. Biocompatibility, biodegradability, simulation of extracellular matrix (ECM), and excellent mechanical properties are essential characteristics of BTE scaffold, sometimes including drug loading capacity. Electrospinning is a simple technique to prepare fibrous scaffolds because of its efficiency, adaptability, and flexible preparation of electrospinning solution. Recent studies about electrospinning in BTE are summarized in this review. First, we summarized various types of polymers used in electrospinning and methods of electrospinning in recent work. Then, we divided them into three parts according to their main role in BTE, (1) ECM simulation, (2) mechanical support, and (3) drug delivery system.

Recent applications of electrical, centrifugal, and pressurised emerging technologies for fibrous structure engineering in drug delivery, regenerative medicine and theranostics

Advancements in technology and material development in recent years has led to significant breakthroughs in the remit of fiber engineering. Conventional methods such as wet spinning, melt spinning, phase separation and template synthesis have been reported to develop fibrous structures for an array of applications. However, these methods have limitations with respect to processing conditions (e.g. high processing temperatures, shear stresses) and production (e.g. non-continuous fibers). The materials that can be processed using these methods are also limited, deterring their use in practical applications. Producing fibrous structures on a nanometer scale, in sync with the advancements in nanotechnology is another challenge met by these conventional methods. In this review we aim to present a brief overview of conventional methods of fiber fabrication and focus on the emerging fiber engineering techniques namely electrospinning, centrifugal spinning and pressurised gyration. This review will discuss the fundamental principles and factors governing each fabrication method and converge on the applications of the resulting spun fibers; specifically, in the drug delivery remit and in regenerative medicine.