Periosteum-Inspired Membranes Integrated with Bioactive Magnesium Oxychloride Ceramic Nanoneedles for Guided Bone Regeneration

Tissue Mimetic Membranes for Healing Augmentation of Tendon-Bone Interface in Rotator Cuff Repair

The globally prevalent rotator cuff tear has a high re-rupture rate, attributing to the failure to reproduce the interfacial fibrocartilaginous enthesis. Herein, a hierarchically organized membrane is developed that mimics the heterogeneous anatomy and properties of the natural enthesis and finely facilitates the reconstruction of tendon-bone interface. A biphasic membrane consisting of a microporous layer and a mineralized fibrous layer is constructed through the non-solvent induced phase separation (NIPS) strategy followed by a co-axial electrospinning procedure. Cationic kartogenin (KGN)-conjugated nanogel (nGel-KGN) and osteo-promotive struvite are incorporated within the membranes in a region-specific manner. During in vivo repair, the nGel-KGN-functionalized microporous layer is adjacent to the tendon which intends to suppress scar tissue formation at the lesion and simultaneously heightens chondrogenesis. Meanwhile, the struvite-containing fibrous layer covers the tubercula minus to enhance stem cell aggregation and bony ingrowth. Such tissue-specific features and spatiotemporal release behaviors contribute to effective guidance of specific defect-healing events at the transitional region, further leading to the remarkably promoted regenerative outcome in terms of the fibrocartilaginous tissue formation, collagen fiber alignment, and optimized functional motion of rotator cuff. These findings render a novel biomimetic membrane as a promising material for clinical rotator cuff repair.

Scalable fabrication of porous membrane incorporating human extracellular matrix-like collagen for guided bone regeneration

Guided bone regeneration (GBR) is an extensively used technique for the treatment of maxillofacial bone defects and bone mass deficiency in clinical practice. However, to date, studies on membranes for GBR have not achieved the combination of suitable properties and cost-effective membrane production. Herein, we developed a polycaprolactone/human extracellular matrix-like collagen (PCL/hCol) membrane with an asymmetric porous structure via the nonsolvent-induced phase separation (NIPS) method, which is a highly efficient procedure with simple operation, scalable fabrication and low cost. This membrane possessed a porous rough surface, which is conducive to cell attachment and proliferation for guiding osteogenesis, together with a relatively smooth surface with micropores, which allows the passage of nutrients and is unfavorable for the adhesion of cells, thus preventing fibroblast invasion and overall meeting the demands for GBR. Besides, we evaluated the characteristics and biological properties of the membrane and compared them with those of commercially available membranes. Results showed that the PCL/hCol membrane exhibited excellent mechanical properties, degradation characteristics, barrier function, biocompatibility and osteoinductive potential. Furthermore, our in vivo study demonstrated the promotive effect of the PCL/hCol membrane on bone formation in rat calvarial defects. Taken together, our NIPS-prepared PCL/hCol membrane with promising properties and production advantages offers a new perspective for its development and potential use in GBR application.

Barrier Membrane with Janus Function and Structure for Guided Bone Regeneration

Guided bone regeneration (GBR) technology has been demonstrated to be an effective method for reconstructing bone defects. A membrane is used to cover the bone defect to stop soft tissue from growing into it. The biosurface design of the barrier membrane is key to the technology. In this work, an asymmetric functional gradient Janus membrane was designed to address the bidirectional environment of the bone and soft tissue during bone reconstruction. The Janus membrane was simply and efficiently prepared by the multilayer self-assembly technique, and it was divided into the polycaprolactone isolation layer (PCL layer, GBR-A) and the nanohydroxyapatite/polycaprolactone/polyethylene glycol osteogenic layer (HAn/PCL/PEG layer, GBR-B). The morphology, composition, roughness, hydrophilicity, biocompatibility, cell attachment, and osteogenic mineralization ability of the double surfaces of the Janus membrane were systematically evaluated. The GBR-A layer was smooth, dense, and hydrophobic, which could inhibit cell adhesion and resist soft tissue invasion. The GBR-B layer was rough, porous, hydrophilic, and bioactive, promoting cell adhesion, proliferation, matrix mineralization, and expression of alkaline phosphatase and RUNX2. In vitro and in vivo results showed that the membrane could bind tightly to bone, maintain long-term space stability, and significantly promote new bone formation. Moreover, the membrane could fix the bone filling material in the defect for a better healing effect. This work presents a straightforward and viable methodology for the fabrication of GBR membranes with Janus-based bioactive surfaces. This work may provide insights for the design of biomaterial surfaces and treatment of bone defects.

A multifunctional collagen-base bilayer membrane integrated with a bimetallic/polydopamine network for enhanced guided bone regeneration

The guided bone regeneration (GBR) technique is an effective treatment for small and medium-sized bone defects in the oral and maxillofacial region. However, currently available collagen membranes have limited functionality and are inadequate for clinical requirements. To address this challenge, this study pioneeringly developed a multifunctional bilayer membrane. Specifically, a bimetallic/polydopamine network (BPN), consisting of silver, magnesium, and dopamine, was successfully synthesized for the first time and integrated with collagen and hydroxyapatite. The resulting material was characterized, and its physicochemical properties, along with its barrier, osteogenic, angiogenic, antibacterial, hemostatic, and biosafety effects, were evaluated through both in vitro and in vivo studies. The results indicated that the BPN, composed of magnesium ions, silver nanoparticles (Ag NPs), and polydopamine (PDA), exhibited excellent thermal stability and slow release of silver and magnesium elements. The BPN/Col-HA membrane featured a bilayer structure with uniform distribution of silver and magnesium. It also demonstrated good hydrophilicity, suitable degradation and mechanical properties, as well as sustained release of silver and magnesium. In vitro experiments showed that the BPN/Col-HA membrane possessed desirable barrier, osteogenic, angiogenic, antibacterial, hemostatic, and biocompatible properties. In vivo results further confirmed its biosafety, hemostatic efficacy, and ability to effectively promote bone defect repair and angiogenesis. Thus, the BPN/Col-HA membrane emerges as a multifunctional GBR membrane with potential for clinical translation.

Shear Flow-Assembled Janus Membrane with Bifunctional Osteogenic and Antibacterial Effects for Guided Bone Regeneration

Guided bone regeneration (GBR) membranes that reside at the interface between the bone and soft tissues for bone repair attract increasing attention, but currently developed GBR membranes suffer from relatively poor osteogenic and antibacterial effects as well as limited mechanical property and biodegradability. We present here the design and fabrication of a bifunctional Janus GBR membrane based on a shear flow-driven layer by a layer self-assembly approach. The Janus GBR membrane comprises a calcium phosphate-collagen/polyethylene glycol (CaP@COL/PEG) layer and a chitosan/poly(acrylic acid) (CHI/PAA) layer on different sides of a collagen membrane to form a sandwich structure. The membrane exhibits good mechanical stability and tailored biodegradability. It is found that the CaP@COL/PEG layer and CHI/PAA layer contribute to the osteogenic differentiation and antibacterial function, respectively. In comparison with the control group, the Janus GBR membrane displays a 2.52-time and 1.84-time enhancement in respective volume and density of newly generated bone. The greatly improved bone repair ability of the Janus GBR membrane is further confirmed through histological analysis, and it has great potential for practical applications in bone tissue engineering.

Green synthetic sodium alginate-glycerol-MXene nanocomposite membrane with excellent flexibility and mineralization ability for guided bone regeneration

Developing a novel bioactive material as a barrier membrane for guided bone regeneration (GBR) surgery remains challenging. As a new member of two-dimensional (2D) material family, MXene is a promising candidate component for barrier membranes due to its high specific surface area and osteogenic differentiation ability. In this work, a green and simple SA/glycerol/MXene (SgM) composite membrane was prepared via solvent casting method by using sodium alginate (SA) and MXene (M) as raw materials while employing glycerol (g) as a plasticizer. The addition of glycerol significantly increased the elongation at the break of SA from 10%-20% to 240%-360%, while the introduction of MXene promoted the deposition of calcium and phosphorus to form hydroxyapatite. At the same time, the roughness of the SgM composite membrane is apparently improved, which is conducive to cell adhesion and proliferation. This work provides a basis for further research on SgM composite membrane as GBR membrane for the treatment of bone defects.

Metal ions: the unfading stars of bone regeneration-from bone metabolism regulation to biomaterial applications

In recent years, bone regeneration has emerged as a remarkable field that offers promising guidance for treating bone-related diseases, such as bone defects, bone infections, and osteosarcoma. Among various bone regeneration approaches, the metal ion-based strategy has surfaced as a prospective candidate approach owing to the extensive regulatory role of metal ions in bone metabolism and the diversity of corresponding delivery strategies. Various metal ions can promote bone regeneration through three primary strategies: balancing the effects of osteoblasts and osteoclasts, regulating the immune microenvironment, and promoting bone angiogenesis. In the meantime, the complex molecular mechanisms behind these strategies are being consistently explored. Moreover, the accelerated development of biomaterials broadens the prospect of metal ions applied to bone regeneration. This review highlights the potential of metal ions for bone regeneration and their underlying mechanisms. We propose that future investigations focus on refining the clinical utilization of metal ions using both mechanistic inquiry and materials engineering to bolster the clinical effectiveness of metal ion-based approaches for bone regeneration.

Accumulative Rolling Mg/PLLA Composite Membrane with Lamellar Heterostructure for Enhanced Bacteria Inhibition and Rapid Bone Regeneration

Developing composite materials with optimized mechanics, degradation, and bioactivity for bone regeneration has long been a crucial mission. Herein, a multifunctional Mg/Poly-l-lactic acid (Mg/PLLA) composite membrane based on the "materials plain" concept through the accumulative rolling (AR) method is proposed. Results show that at a rolling ratio of 75%, the comprehensive mechanical properties of the membrane in the rolling direction are self-reinforced significantly (elongation at break ≈53.2%, tensile strength ≈104.0 MPa, Young's modulus ≈2.13 GPa). This enhancement is attributed to the directional arrangement and increased crystallization of PLLA molecular chains, as demonstrated by SAXS and DSC results. Furthermore, the AR composite membrane presents a lamellar heterostructure, which not only avoids the accumulation of Mg microparticles (MgMPs) but also regulates the degradation rate. Through the contribution of bioactive MgMPs and their photothermal effect synergistically, the membrane effectively eliminates bacterial infection and accelerates vascularized bone regeneration both in vitro and in vivo. Notably, the membrane exhibits outstanding rat skull bone regeneration performance in only 4 weeks, surpassing most literature reports. In short, this work develops a composite membrane with a "one stone, four birds" effect, opening an efficient avenue toward high-performance orthopedic materials.

Decellularized periosteum promotes guided bone regeneration via manipulation of macrophage polarization

Periosteum has shown potential as an effective barrier membrane for guided bone regeneration (GBR). However, if recognized as a "foreign body," insertion of a barrier membrane in GBR treatment will inevitably alter the local immune microenvironment and subsequently influence bone regeneration. The aim of this investigation was to fabricate decellularized periosteum (DP) and investigate its immunomodulatory properties in GBR. DP was successfully fabricated from periosteum from the mini-pig cranium. In vitro experiments indicated that the DP scaffold modulated macrophage polarization toward a pro-regenerative M2 phenotype, which in turn facilitated migration and osteogenic differentiation of bone marrow-derived mesenchymal stem cells. A rat GBR model with a cranial critical-size defect was established, and our in vivo experiment confirmed the beneficial effects of DP on the local immune microenvironment and bone regeneration. Collectively, the findings of this study indicate that the prepared DP possesses immunomodulatory properties and represents a promising barrier membrane for GBR procedures.

Injectable magnesium oxychloride cement foam-derived scaffold for augmenting osteoporotic defect repair

HYPOTHESIS

Cement augmentation has been widely applied to promote osteoporotic fracture healing, whereas the existing calcium-based products suffer from the excessively slow degradation, which may impede bone regeneration. Magnesium oxychloride cement (MOC) shows promising biodegradation tendency and bioactivity, which is expected to be a potential alternative to the classic calcium-based cement for hard-tissue-engineering applications.

EXPERIMENTS

Here, a hierarchical porous MOC foam (MOCF)-derived scaffold with favorable bio-resorption kinetic and superior bioactivity is fabricated through Pickering foaming technique. Then, a systematic characterization in terms of material properties and in vitro biological performance have been conducted to evaluate the feasibility of the as-prepared MOCF scaffold to be a bone-augmenting material for treating osteoporotic defects.

FINDINGS

The developed MOCF shows excellent handling performance in the paste state, while exhibiting sufficient load-bearing capacity after solidification. In comparison with the traditional bone cement, calcium deficient hydroxyapatite (CDHA), our porous MOCF scaffold demonstrates a much higher biodegradation tendency and better cell recruitment ability. Additionally, the eluted bioactive ions by MOCF commits to a biologically inductive microenvironment, where the in vitro osteogenesis is significantly enhanced. It is anticipated that this advanced MOCF scaffold will be competitive for clinical therapies to augment osteoporotic bone regeneration.