Biomimetic Scaffolds Research Articles

Biomimetically ordered ultralong hydroxyapatite nanowires-based hierarchical hydrogel scaffold with osteoimmunomodulatory and osteogenesis abilities for augmenting bone regeneration

Artificial construction of tissue engineering implants with bone-mimicking structure and osteogenic function is of great significance for bone regeneration, but it remains a formidable challenge. Herein, inspired by natural bone, a biomimetically hierarchical hydrogel scaffold with highly ordered arrangement and multi-layered concentric circular structure is constructed by a convenient free-injection method for osteoimmunomodulation and bone defect regeneration. Ultralong hydroxyapatite nanowires act as skeleton unit to assemble into the hierarchically ordered nanowire bundles and further hybridization with hyaluronic acid methacrylate and loading with layered double hydroxide nanosheets to form the stable biomimetic scaffold. The biomimetic scaffold exhibits anisotropic structure, high water content and porosity, mechanical robustness, and sustained release of bioactive ions. In particular, the excellent biocompatibility together with ordered topography and biochemical cue can guide recruitment and directional migration of stem cells, and effectively promote osteogenic differentiation and vascularization in vitro. Moreover, the biomimetic scaffold induces M2 phenotype polarization of macrophages, thus creating a favorable osteoimmune environment. The in vivo study proves that the biomimetic scaffold can attenuate inflammation, promote vascularized ossification, and further accelerate new bone formation. This study provides an innovative strategy to construct multifunctional anisotropic biomaterials for bone tissue engineering.

Synergistic large segmental bone repair by 3D printed bionic scaffolds and engineered ADSC nanovesicles: Towards an optimized regenerative microenvironment

Achieving sufficient bone regeneration in large segmental defects is challenging, with the structure of bone repair scaffolds and their loaded bioactive substances crucial for modulating the local osteogenic microenvironment. This study utilized digital laser processing (DLP)-based 3D printing technology to successfully fabricate high-precision methacryloylated polycaprolactone (PCLMA) bionic bone scaffold structures. Adipose-derived stem cell-engineered nanovesicles (ADSC-ENs) were uniformly and stably modified onto the bionic scaffold surface using a perfusion device, constructing a conducive microenvironment for tissue regeneration and long bone defect repair through the scaffold's structural design and the vesicles' biological functions. Scanning electron microscopy (SEM) examination of the scaffold surface confirmed the efficient loading of ADSC-ENs. The material group loaded with vesicles (PCLMA-BAS-ENs) demonstrated good cell compatibility and osteogenic potential when analyzed for the adhesion and osteogenesis of primary rabbit bone marrow mesenchymal stem cells (BMSCs) on the material surface. Tested in a 15 mm critical rabbit radial defect model, the PCLMA-BAS-ENs scaffold facilitated near-complete bone defect repair after 12 weeks. Immunofluorescence and proteomic results indicated that the PCLMA-BAS-ENs scaffold significantly improved the osteogenic microenvironment at the defect site in vivo, promoted angiogenesis, and enhanced the polarization of macrophages towards M2 phenotype, and facilitated the recruitment of BMSCs. Thus, the PCLMA-BAS-ENs scaffold was proven to significantly promote the repair of large segmental bone defects. Overall, this strategy of combining engineered vesicles with highly biomimetic scaffolds to promote large-segment bone tissue regeneration holds great potential in orthopedic and other regenerative medicine applications.

Therapeutic applications of biological macromolecules and scaffolds for skeletal muscle regeneration: A review

Skeletal muscle (SM) mass and strength maintenance are important requirements for human well-being. SM regeneration to repair minor injuries depends upon the myogenic activities of muscle satellite (stem) cells. However, losses of regenerative properties following volumetric muscle loss or severe trauma or due to congenital muscular abnormalities are not self-restorable, and thus, these conditions have major healthcare implications and pose clinical challenges. In this context, tissue engineering based on different types of biomaterials and scaffolds provides an encouraging means of structural and functional SM reconstruction. In particular, biomimetic (able to transmit biological signals) and several porous scaffolds are rapidly evolving. Several biological macromolecules/biomaterials (collagen, gelatin, alginate, chitosan, and fibrin etc.) are being widely used for SM regeneration. However, available alternatives for SM regeneration must be redesigned to make them more user-friendly and economically feasible with longer shelf lives. This review aimed to explore the biological aspects of SM regeneration and the roles played by several biological macromolecules and scaffolds in SM regeneration in cases of volumetric muscle loss.

Cover Picture: Three‐dimensional printed biomimetic multilayer scaffolds coordinated with sleep‐related small extracellular vesicles: A strategy for extracellular matrix homeostasis and macrophage polarization to enhance osteochondral regeneration (View 2/2024)

Cover Picture: Three‐dimensional printed biomimetic multilayer scaffolds coordinated with sleep‐related small extracellular vesicles: A strategy for extracellular matrix homeostasis and macrophage polarization to enhance osteochondral regeneration (View 2/2024)

Design of Biomimetic Porous Scaffolds for Bone Tissue Engineering

Design of Biomimetic Porous Scaffolds for Bone Tissue Engineering

Melt Electrowriting Combined with Fused Deposition Modeling Printing for the Fabrication of Three-Dimensional Biomimetic Scaffolds for Osteotendinous Junction Regeneration.

This study aims to explore a novel scaffold for osteotendinous junction regeneration and to preliminarily verify its osteogenic and tenogenic abilities in vitro. A polycaprolactone (PCL) scaffold with aligned and orthogonal fibers was created using melt electrowriting (MEW) and fused deposition modeling (FDM). The scaffold was coated with Type I collagen, and hydroxyapatite was carefully added to separate the regions intended for bone and tendon regeneration, before being rolled into a cylindrical shape. Human adipose-derived stem cells (hADSCs) were seeded to evaluate viability and differentiation. Scaffold characterization was performed with Scanning Electron Microscope (SEM). Osteogenesis was assessed by alkaline phosphatase (ALP) and Alizarin red staining, while immunostaining and transcription-quantitative polymerase chain reaction (RT-qPCR) evaluated osteogenic and tendogenic markers. Scaffolds were developed in four variations: aligned (A), collagen-coated aligned (A+C), orthogonal (O), and mineral-coated orthogonal (O+M). SEM analysis confirmed surface morphology and energy-dispersive X-ray spectroscopy (EDS) verified mineral coating on O+M types. Hydrophilicity and mechanical properties were optimized in modified scaffolds, with A+C showing increased tensile strength and O+M improved in compression. hADSCs demonstrated good viability and morphology across scaffolds, withO+M scaffolds showing higher cell proliferation and osteogenic potential, and A and A+C scaffolds supporting tenogenic differentiation. This study confirms the potential of a novel PCL scaffold with distinct regions for osteogenic and tenogenic differentiation, supporting the regeneration of osteotendinous junctions in vitro.

Hydrogel bioink formulation for 3D bioprinting: Sustained delivery of PDGF-BB and VEGF in biomimetic scaffolds for tendon partial rupture repair

Hydrogel bioink formulation for 3D bioprinting: Sustained delivery of PDGF-BB and VEGF in biomimetic scaffolds for tendon partial rupture repair

Designing of a Multifunctional 3D-Printed Biomimetic Theragenerative Aerogel Scaffold via Mussel-Inspired Chemistry: Bioactive Glass Nanofiber-Incorporated Self-Assembled Silk Fibroin with Antibacterial, Antiosteosarcoma, and Osteoinductive Properties.

Biomaterial-mediated bone tissue engineering (BTE) offers an alternative, interesting approach for the restoration of damaged bone tissues in postsurgery osteosarcoma treatment. This study focused on synthesizing innovative composite inks, integrating self-assembled silk fibroin (SF), tannic acids (TA), and electrospun bioactive glass nanofibers 70SiO2-25CaO-5P2O5 (BGNF). By synergistically combining the unique characteristics of these three components through self-assembly and microextrusion-based three-dimensional (3D) printing, our goal was to produce durable and versatile aerogel-based 3D composite scaffolds. These scaffolds were designed to exhibit hierarchical porosity along with antibacterial, antiosteosarcoma, and bone regeneration properties. Taking inspiration from mussel foot protein attachment chemistry involving the coordination of dihydroxyphenylalanine (DOPA) amino acids with ferric ions (Fe3+), we synthesized a tris-complex catecholate-iron self-assembled composite gel. This gel formation occurred through the coordination of oxidized SF (SFO) with TA and polydopamine-modified BGNF (BGNF-PDA). The dynamic nature of the coordination ligand-metal bonds within the self-assembled SFO matrix provided excellent shear-thinning properties, allowing the SFO-TA-BGNF complex gel to be extruded through a nozzle, facilitating 3D printing into scaffolds with outstanding shape fidelity. Moreover, the developed composite aerogels exhibited multifaceted features, including NIR-triggered photothermal antibacterial and in vitro photothermal antiosteosarcoma properties. In vitro studies showcased their excellent biocompatibility and osteogenic features as seeded cells successfully differentiated into osteoblasts, promoting bone regeneration in 21 days. Through comprehensive characterizations and biological validations, our antibacterial scaffold demonstrated promise as an exceptional platform for concurrent bone regeneration and bone cancer therapy, setting the stage for their potential clinical application.

Kuragel: A biomimetic hydrogel scaffold designed to promote corneal regeneration

Cornea-related injuries are the most common cause of blindness worldwide. Transplantation remains the primary approach for addressing corneal blindness, though the demand for donor corneas outmatches the supply by millions. Tissue adhesives employed to seal corneal wounds have shown inefficient healing and incomplete vision restoration. We have developed a biodegradable hydrogel- Kuragel, with the ability to promote corneal regeneration. Functionalized gelatin and hyaluronic acid form photo-crosslinkable hydrogel with transparency and compressive modulus similar to healthy human cornea. Kuragel composition was tuned to achieve sufficient adhesive strength for sutureless integration to host tissue, with minimal swelling post-administration. Studies in the New Zealand rabbit mechanical injury model affecting corneal epithelium and stroma demonstrate that Kuragel efficiently promotes re-epithelialization within 1month of administration, while stroma and sub-basal nerve plexus regenerate within 3months. We propose Kuragel as a regenerative treatment for patients suffering from corneal defects including thinning, by restoration of transparency and thickness.

Biomimetic Bone-Like Composite Hydrogel Scaffolds Composed of Collagen Fibrils and Natural Hydroxyapatite for Promoting Bone Repair.

Bone is a complex organic-inorganic composite tissue composed of ∼30% organics and ∼70% hydroxyapatite (HAp). Inspired by this, we used 30% collagen and 70% HAp extracted from natural bone using the calcination method to generate a biomimetic bone composite hydrogel scaffold (BBCHS). In one respect, BBCHS, with a fixed proportion of inorganic and organic components similar to natural bone, exhibits good physical properties. In another respect, the highly biologically active and biocompatible HAp from natural bone effectively promotes osteogenic differentiation, and type I collagen facilitates cell adhesion and spreading. Additionally, the well-structured porosity of the BBCHS provides sufficient growth space for bone marrow mesenchymal stem cells (BMSCs) while promoting substance exchange. Compared to the control group, the new bone surface of the defective location in the B-HA70+Col group is increased by 3.4-fold after 8 weeks of in vivo experiments. This strategy enables the BBCHS to closely imitate the chemical makeup and physical structure of natural bone. With its robust biocompatibility and osteogenic activity, the BBCHS can be easily adapted for a wide range of bone repair applications and offers promising potential for future research and development.

Mechanical properties of native and decellularized reproductive tissues: insights for tissue engineering strategies

Understanding the mechanical properties and porosity of reproductive tissues is vital for regenerative medicine and tissue engineering. This study investigated the changes in Young's modulus (YM), storage modulus (E′), loss modulus (Eʺ), and porosity of native and decellularized bovine reproductive tissues during the estrous cycle. Testis tunica albuginea had significantly higher YM, E′, and Eʺ than the inner testis, indicating greater stiffness and viscoelasticity. Endometrium showed no distinct differences in YM, E′, or Eʺ across the estrous cycle or between horns. Ovaries exhibited significant variations in YM, E′, Eʺ, and porosity, with higher YM and E′ in the ipsilateral cortex and medulla during the luteal phase. Decellularized ovarian tissues displayed increased porosity. The oviduct displayed no significant differences in YM or E′ in the isthmus, but the contralateral ampulla had reduced YM and E′ in the luteal phase. These findings offer valuable insights into the dynamic mechanical properties and porosity of reproductive tissues, facilitating the development of biomimetic scaffolds for tissue engineering applications.

3D cotton-type anisotropic biomimetic scaffold with low fiber motion electrospun via a sharply inclined array collector for induced osteogenesis

Electrospinning is an effective method to fabricate fibrous scaffolds that mimic the ECM of bone tissue on a nano- to macro-scale. However, a limitation of electrospun fibrous scaffolds for bone tissue engineering is the structure formed by densely compacted fibers, which significantly impedes cell infiltration and tissue ingrowth. To address this problem, several researchers have developed numerous techniques for fabricating 3D fibrous scaffolds with customized topography and pore size. Despite the success in developing various 3D electrospun scaffolds based on fiber repulsion, the lack of contact points between fibers in those scaffolds has been shown to hinder cell attachment, migration, proliferation, and differentiation due to excessive movement of the fibers. In this article, we introduce a Dianthus caryophyllus-inspired scaffold fabricated using SIAC-PE, a modified collector under specific viscosity conditions of PCL/LA solution. The developed scaffold mimicking the structural similarities of the nature-inspired design presented enhanced cell proliferation, infiltration, and increased expression of bone-related factors by reducing fiber movements, presenting high space interconnection, high porosity, and controlled fiber topography.

Indirect co-culture of osteoblasts and endothelial cells in vitro based on a biomimetic 3D composite hydrogel scaffold to promote the proliferation and differentiation of osteoblasts.

The field of orthopedics has long struggled with the challenge of repairing and regenerating bone defects, which involves a complex process of osteogenesis requiring coordinated interactions among different types of cells. The crucial role of endothelial cells and osteoblasts in bone vascularization and osteogenesis underscores the importance of their intimate interaction. However, efforts to bioengineer bone tissue have been impeded by the difficulty in establishing proper angiogenesis and osteogenesis in tissue structures. This study presents a novel approach to bone tissue engineering, involving a three-dimensional composite hydrogel scaffold composed of sodium alginate microspheres encapsulated in type I collagen. Using this scaffold, a three-dimensional indirect co-culture system was established for osteoblasts and endothelial cells to evaluate the osteogenic differentiation potential of osteoblasts. Results demonstrate that the non-contact co-culture system of endothelial cells and osteoblasts constructed by the composite hydrogel scaffold loaded with microspheres holds promise for bone tissue engineering. The innovative concept of an indirect co-culture system presents exciting prospects for conducting intercellular communication studies and offers a valuable in vitro tissue platform to investigate tissue regeneration.

Hierarchically Biomimetic Scaffolds with Anisotropic Micropores and Nanotopological Patterns to Promote Bone Regeneration via Geometric Modulation.

Structural engineering is an appealing means to modulate osteogenesis without the intervention of exogenous cells or therapeutic agents. In this work, a novel 3D scaffold with anisotropic micropores and nanotopographical patterns is developed. Scaffolds with oriented pores are fabricated via the selective extraction of water-soluble polyethylene oxide from its poly(ε-caprolactone) co-continuous mixture and uniaxial stretching. The plate apatite-like lamellae are subsequently hatched on the pore walls through surface-induced epitaxial crystallization. Such a unique geometric architecture yields a synergistic effect on the osteogenic capability. The prepared scaffold leads to a 19.2% and 128.0% increase in the alkaline phosphatase activity of rat bone mesenchymal stem cells compared to that of the scaffolds with only oriented pores and only nanotopographical patterns, respectively. It also induces the greatest upregulation of osteogenic-related gene expression in vitro. The cranial defect repair results demonstrate that the prepared scaffold effectively promotes new bone regeneration, as indicated by a 350% increase in collagen I expression in vivo compared to the isotropic porous scaffold without surface nanotopology after implantation for 14weeks. Overall, this work provides geometric motifs for the transduction of biophysical cues in 3D porous scaffolds, which is a promising option for tissue engineering applications.

Biomimetic multilayer scaffolds with prolonged retention of stem cells-recruiting and angiogenic peptides for promoting bladder regeneration

The complications of enterocystoplasy have challenged traditional bladder reconstruction methods. Tissue engineering scaffolds, involving stem cells implantation and vascularization strategies, emerge as promising alternatives. However, their applications are hindered by issues regarding the source of stem cells and the rapid loss of bioactive factors in a urinary environment. Here, a multilayer biomimetic scaffold consisting of polycaprolactone (PCL) nanofibrous mats and oxidized dextran/carboxymethyl chitosan hydrogel has been synthesized. Bone marrow homing peptide (BMHP) and vascular endothelial growth factor-mimicking peptide (VP) were incorporated into the hydrogel to recruit endogenous stem cells and promote vascularization, respectively. The results indicated that PCL mats not only reinforced the mechanical properties of composite scaffolds but also prolonged the retention of peptides via the hydrophobic surface. In vivo experiments demonstrated that BMHP and VP had crosstalk effects, amplifying their functions to accelerate bladder regeneration, enhance contractility of smooth muscle cells, inhibit fibrosis, and improve innervation. Overall, the novel functionalized scaffolds are potentially viable for urologic tissue reconstruction.

Combined nucleus pulposus and annulus fibrosus bioactive scaffolds enhance intervertebral disc defect regeneration

Combined repair of nucleus pulposus (NP) and annulus fibrosus (AF) is an effective treatment method after discectomy. Tissue engineering techniques for the treatment of discectomy defects typically employ the use of hydrogels. However, this poses challenges due to inadequate mechanical properties and the inability to restore the natural cross-lamellar structure of the AF. Here, we utilized a blend of 3 %(w/v) gelatin methacryloyl (GelMA) hydrogel and biomimetic polycaprolactone (PCL) scaffolds loaded with transforming growth factor β1 (TGF-β1) to repair trapezoidal defects in the AF. The biomimetic PCL microfiber scaffolds significantly improved the compressive strength of the GelMA hydrogel. Additionally, we employed 5 %(w/v) GelMA hydrogel delivered with growth differentiation factor 5 (GDF5) to restore the hydration of the NP following discectomy. The addition of GDF5 and TGF-β1 to the GelMA hydrogel effectively induced stem cell differentiation into NP and AF, respectively. This combined reparative strategy demonstrated favorable outcomes in ovine lumbar spine defects. Magnetic Resonance Imaging (MRI) taken at 1 and 3 months revealed the restoration of NP hydration, while histological staining indicated increased extracellular matrix deposition and preservation of intervertebral disc (IVD) integrity. Our combined treatment strategy offers a promising avenue for achieving endogenous regeneration of IVD following discectomy.

Biomimetic Scaffolds-A Novel Approach to Three Dimensional Cell Culture Techniques for Potential Implementation in Tissue Engineering.

Biomimetic scaffolds imitate native tissue and can take a multidimensional form. They are biocompatible and can influence cellular metabolism, making them attractive bioengineering platforms. The use of biomimetic scaffolds adds complexity to traditional cell cultivation methods. The most commonly used technique involves cultivating cells on a flat surface in a two-dimensional format due to its simplicity. A three-dimensional (3D) format can provide a microenvironment for surrounding cells. There are two main techniques for obtaining 3D structures based on the presence of scaffolding. Scaffold-free techniques consist of spheroid technologies. Meanwhile, scaffold techniques contain organoids and all constructs that use various types of scaffolds, ranging from decellularized extracellular matrix (dECM) through hydrogels that are one of the most extensively studied forms of potential scaffolds for 3D culture up to 4D bioprinted biomaterials. 3D bioprinting is one of the most important techniques used to create biomimetic scaffolds. The versatility of this technique allows the use of many different types of inks, mainly hydrogels, as well as cells and inorganic substances. Increasing amounts of data provide evidence of vast potential of biomimetic scaffolds usage in tissue engineering and personalized medicine, with the main area of potential application being the regeneration of skin and musculoskeletal systems. Recent papers also indicate increasing amounts of in vivo tests of products based on biomimetic scaffolds, which further strengthen the importance of this branch of tissue engineering and emphasize the need for extensive research to provide safe for humansbiomimetic tissues and organs. In this review article, we provide a review of the recent advancements in the field of biomimetic scaffolds preceded by an overview of cell culture technologies that led to the development of biomimetic scaffold techniques as the most complex type of cell culture.

Fabrication of biomimetic scaffold through hybrid forming technique

AbstractBone tissue engineering procedures require the use of a scaffold with a sufficiently porous structure, which serves as a three‐dimensional template for cell attachment, followed by tissue regeneration and vascularization both in vitro and in vivo. This study aimed to create scaffold material with a unique hybrid forming that met these parameters. Slip casting and freeze‐drying processes were used with a hybrid forming approach to create a bone scaffold based on hydroxyapatite (HA) mimicking the structure of cortical and cancellous bones, respectively. HA was synthesized by the wet chemical precipitation method. Fourier‐transform infrared spectroscopy, dynamic light scattering, X‐ray diffraction, thermogravimetric analysis‐differential thermal analysis, Brunauer‐Emmett‐Teller, He Pycnometer, and scanning electron microscope analyses were performed to characterize the scaffold. According to analysis results, HA particle size was found at 137.8 nm. The optimum sintering temperature was determined to be 1300°C. The specific surface area of the HA powder was measured as 55.11 m2/g. The total open porosity of the hybrid scaffold was calculated as 70%. Scaffold successfully substituted both cancellous and cortical layers of bone regarding structural characteristics, porosity, and mechanical strength. Considering morphological characteristics, a hybrid scaffold might facilitate vascularization, osteoinduction, and osteoconduction. Research findings suggest that the hybrid design strongly resembled natural bone and is suitable for both load‐bearing and non‐bearing bones.

Designing Biomimetic 3D-Printed Osteochondral Scaffolds for Enhanced Load-Bearing Capacity.

Osteoarthritis is a debilitating chronic joint disorder that affects millions of people worldwide. Since palliative and surgical treatments cannot completely regenerate hyaline cartilage within the articulating joint, osteochondral (OC) tissue engineering has been explored to heal OC defects. Utilizing computational simulations and three-dimensional (3D) printing, we aimed to build rationale around fabricating OC scaffolds with enhanced biomechanics. First, computational simulations revealed that interfacial fibrils within a bilayer alter OC scaffold deformation patterns by redirecting load-induced stresses toward the top of the cartilage layer. Principal component analysis revealed that scaffolds with 800 μm long fibrils (scaffolds 8A-8H) possessed optimal biomechanical properties to withstand compression and shear forces. While compression testing indicated that OC scaffolds with 800 μm fibrils did not have greater compressive moduli than other scaffolds, interfacial shear tests indicated that scaffold 8H possessed the greatest shear strength. Lastly, failure analysis demonstrated that yielding or buckling models describe interfacial fibril failure depending on fibril slenderness S. Specifically for scaffolds with packing density n = 6 and n = 8, the yielding failure model fits experimental loads with S < 10, while the buckling model fitted scaffolds with S < 10 slenderness. The research presented provides critical insights into designing 3D printed interfacial scaffolds with refined biomechanics toward improving OC tissue engineering outcomes.

Cell-free biomimetic scaffold for chondral and osteochondral lesions: surgical technique for custom and standardized implantation

IntroductionCell-free chondral and osteochondral scaffolds have been introduced to address lesions of the articular surface. A proper implantation technique is key to favor scaffold integration, regenerative processes, and positive clinical outcomes. ObjectivesThe purpose of this article is to describe indications and surgical steps for both the custom traditional free-hand implantation approach and an innovative minimally invasive technique for the standardized implantation of this biomimetic cell-free scaffold (MaioRegen; Fin-Ceramica Faenza Spa). MethodsIndications and contraindications for this scaffold implantation have been provided. The required steps for surgical preparation, implantation technique, and postoperative management have been described as well to address articular surface lesions of the knee. ResultsA dedicated instrumentation for circular implants of different sizes has been developed to allow more precise preparation of the depth and width of the defect, reducing the invasiveness and increasing implant stability. The custom free-hand technique with chisels and osteotomes remains useful when the lesion does not allow the use of the standardized instrumented technique. In case further stability of the implant is needed, fibrin glue addition should be considered. ConclusionsBy guiding the readers with the key perioperative and intraoperative steps, chondral and osteochondral defects can be addressed with the use of a cell-free scaffold, maximizing implant stability.