Alloy Scaffolds Research Articles

Reduction in the Corrosion Rate of Magnesium and Magnesium Alloy Specimens and Implications for Plain Fully Bioresorbable Coronary Artery Stents: A Review

The most popular treatment/management modality for coronary artery disease, which is one of the leading causes of death, is percutaneous transluminal coronary intervention (popularly known as “plain old balloon angioplasty”) followed by implantation of a stent (“stenting”). Stent types have evolved from bare metal stents through first-generation drug-eluting stents to fully bioresorbable stents (FBRSs). Two examples of FBRSs are 1) Mg scaffold with no coating; and 2) Mg alloy scaffold coated with a bioresorbable polymer in which an anti-proliferative drug is embedded. In the case of Mg/Mg alloy FBRSs, one of the reported clinical results is that the resorption time of the stent is too short (in vivo resorption time (and, hence, improving the clinical efficacy) of the current generation of fully-bioresorbable Mg/Mg-alloy stents as well as guide the development of the next generation of these stents.

Interplay between self-assembled structure of bone morphogenetic protein-2 (BMP-2) and osteoblast functions in three-dimensional titanium alloy scaffolds: Stimulation of osteogenic activity.

Three-dimensional cellular scaffolds are receiving significant attention in bone tissue engineering to treat segmental bone defects. However, there are indications of lack of significant osteoinductive ability of three-dimensional cellular scaffolds. In this regard, the objective of the study is to elucidate the interplay between bone morphogenetic protein (BMP-2) and osteoblast functions on 3D mesh structures with different porosities and pore size that were fabricated by electron beam melting. Self-assembled dendritic microstructure with interconnected cellular-type morphology of BMP-2 on 3D scaffolds stimulated osteoblast functions including adhesion, proliferation, and mineralization, with prominent effect on 2-mm mesh. Furthermore, immunofluorescence studies demonstrated higher density and viability of osteoblasts on lower porosity mesh structure (2 mm) as compared to 3- and 4-mm mesh structures. Enhanced filopodia cellular extensions with extensive cell spreading was observed on BMP-2 treated mesh structures, a behavior that is attributed to the unique self-assembled structure of BMP-2 that effectively communicates with the cells. The study underscores the potential of BMP-2 in imparting osteoinductive capability to the 3D printed scaffolds.

P17: Antitumor activity of allogeneic bone marrow cells immobilized in porous-permeable TiNi-based alloy scaffold

The most effective method in treatment of inoperable cancer is currently miniallogeneic transplantation. This type of treatment focuses on reaction of “graft-versus-tumor”. According to preliminary data, such treatment leads to long-term remission in patients with metastatic cancer, who did not respond to previous therapy. Anti-tumor immune response after transplant may be extended or enhanced by additional infusion of donor lymphocytes. Research has shown that introduction of donor lymphocytes achieves complete remission of the tumor, even in case of relapse after allogeneic transplantation from the same donor, but these effects are unstable and not so long because of rapid elimination of donor lymphocytes [1] . The main problem is the preservation of cell transplantation viability and functional activity of the cells in patient’s body, and protecting them from recipient’s immune system. In recent years, most suitable for this purpose are the three-dimensional porous biomaterials (3D-scaffold). Specific pore space does not allow immunity effectors quickly destroy the cells in scaffold [2] , [3] . Research Institute of medical materials and implants with shape memory at the Tomsk State University created a porous-permeable incubators (scaffold) of TiNi-based shape memory alloy (TiNi). The material has unique properties: permeable porous structure by open interconnected pores, characterized by high degree of wettability with tissue media and nanoporous inner surface of the pore walls, exhibits high adhesion to various cell types, so all mentioned meet requirements of the bio-chemical and bio-mechanical compatibility. Porous TiNi-based scaffolds allow continually to keep the functionality cells and prolong their action [4] , [5] . The purpose of this study was to investigate possibility of modulation of antitumor response in allogeneic bone marrow transplantation in porous-permeable incubator of TiNi. Results Intraperitoneal injection of allogeneic bone marrow (BM) reduces metastasis by 30% and has easy 10%-antitumor effect. At the same time, the implantation of bone marrow cells on incubator of TiNi (BM + TiNi) leads to more pronounced antitumor (25%) and significant antimetastatic effects (45%). Life span of animals with tumors and implanted bone marrow cells on incubator TiNi is increased by 60% Since bone marrow cells do not have direct antiproliferative effect on tumor target cells in vitro, it is assumed that one of the mechanisms effecting the bone marrow transplantation on neoplastic process is the stimulation of endogenous effectors of antitumor immunity. The study of morphological parameters immunocompetent organs showed that administration of allogeneic bone marrow cells can reduce thymic regression, decrease splenomegaly at animals with transplanted tumors. Conclusion Allogeneic transplantation of bone marrow cells on porous incubator was shown to prolong and enhance antitumor and antimetastatic action compared to injecting the cells. This effect is directly due to the stimulation of antitumor immunity, that is described by the study of immunity factors. The results show perspectives of porous TiNi-based scaffolds in complex treatment of neoplastic diseases.

Effects Of Infrared And Ultraviolet Radiation On The Viability Of Cells Immobilized In Porous TiNi-based Alloy Scaffold

Cell responses to electromagnetic radiation are due to many factors including the cellular microenvironment. The aim of the present study was to explore the effects of ultraviolet (UV) and infrared (IR) irradiation of low intensity on cultured cells derived from different biological tissues (spleen, bone marrow, and Ehrlich's adenocarcinoma), which were immobilized in a porous TiNi-based alloy scaffold. Accordingly, the following objectives were set: i) to evaluate the impact of low-intensity radiation on cell suspensions, and ii) to carry out a comparative analysis of the viability of cells immobilized in porous TiNi-based alloy and IR- and UV-irradiated. The data show that the extracellular environment of bone marrow, tumor and spleen cell populations affects their viability and proliferative potency in porous TiNi-based scaffolds. IR- and UV irradiation of cell cultures immobilized in the scaffold affects the cell viability in populations of bone marrow, tumor, and spleen cells. In case of IR irradiation, cell viability was significantly improved, at the same time UV irradiation suppressed cell proliferation activity. The effect of IR irradiation can be used to resuscitate the cell area. The effect of UV irradiation can be used to destroy residual tumor lesions or other pathological cell populations. Effects of low-intensity infrared (IR) and ultraviolet (UV) radiation on the number of viable cells were evaluated against the control group in which cells were exposed to natural daylight. The results showed that IR irradiation led to a 4.6-, 2.5-, and 1.3-fold increase in viable Ehrlich tumor, bone marrow, and spleen cells, respectively, while UV exposure led to a 3.9-, 1.5-, and 1.2-fold increase, respectively.

Processing and properties of topologically optimised biomedical Ti–24Nb–4Zr–8Sn scaffolds manufactured by selective laser melting

This study investigated the effect of the processing parameters on the quality and mechanical properties of a biomedical titanium alloy (Ti–24Nb–4Zr–8Sn) scaffolds fabricated by selective laser melting. Optimal manufacturing parameters were then determined through analysing the pores distribution, geometrical accuracy and the mechanical properties of the produced components. The evaporation of tin during the process is thought to be the main cause of pore generation at higher incident energy densities. Using the optimal processing conditions, the strength of the scaffold reached 51MPa at a scaffold density of <1g/cm3 and a high solid strut relative density of ~99.3%. Fracture surface analysis found that the main reason for strut early failure was the weaknesses of struts caused by the presence of pores as well the thickness of strut and internal unmelted powders.**Co-corresponding author.

In vitro and in vivo evaluation of porous TiNi-based alloy as a scaffold for cell tissue engineering

This study aims to look into the applicability of a porous TiNi-based shape memory alloy (SMA) scaffold as an incubator for bone marrow mesenchymal cells, hepatocytes, and pancreatic islet cells. The porous TiNi-based SMA used was fabricated using a self-propagating high-temperature synthesis (SHS) technique, in which scaffold blocks measuring 4 × 4 × 10 mm were prepared. In vitro tests were done using mesenchymal stem cells (MSC) isolated from mature bone marrow of CBA/j inbred mice, and cultured in 3 different culture media – Control medium, Osteogenic medium, and Chondrogenic medium. Hepatocytes and islet cells were isolated from the livers and pancreatic glands of Wistar rats respectively, seeded on porous TiNi-based SMA scaffolds, and cultured. The scaffolds were then implanted into the abdominal cavity of Wistar rats and later harvested, at days 7, 14, 21, and 28, post-implantation. SEM imaging was performed with pre-implanted scaffolds at day 0 and harvested scaffolds at days 7, 14, 21, and 28, post-implantation. Based on weight increase percentages, the in vitro study revealed that the osteogenic group showed a 2-fold increase, and the chondrogenic group showed a 1.33-fold increase, compared to the control group. The in vivo study, on the other hand, showed that from day 7 post-implantation, the cellular in-growth gradually invaded the inner porous structure from the periphery towards the center, and at day-28 post-implantation, all pores were closed and completely filled with cells and the extracellular matrix. The results show that porous TiNi-based SMA is a unique biocompatible incubator for cell cultures and can be successfully used for tissue bioengineering and artificial organs.

Analysis of Gene Expression Signatures for Osteogenic 3D Perfusion-Bioreactor Cell Cultures Based on a Multifactorial DoE Approach

The use of multifactorial design of experiments (DoE) in tissue engineering bioprocess development will contribute to the robust manufacturing of tissue engineered constructs by linking their quality characteristics to bioprocess operating parameters. In this work, perfusion bioreactors were used for the in vitro culture and osteogenic differentiation of human periosteum-derived cells (hPDCs) seeded on three-dimensional titanium (Ti) alloy scaffolds. A CaP-supplemented medium was used to induce differentiation of the cultured hPDCs. A two-level, three-factor fractional factorial design was employed to evaluate a range of bioreactor operating conditions by changing the levels of the following parameters: flow rate (0.5–2 mL/min), cell culture duration (7–21 days) and cell seeding density (1.5 × 103–3 × 103 cells/cm2). This approach allowed for evaluating the individual impact of the aforementioned process parameters upon a range of genes that are related to the osteogenic lineage, such as collagen type I, alkaline phosphatase, osterix, osteopontin and osteocalcin. Furthermore, by overlaying gene-specific response surfaces, an integrated operating process space was highlighted within which predetermined values of the six genes of interest (i.e., gene signature) could be minimally met over the course of the bioreactor culture time.

Microstructure, mechanical property and corrosion behavior of co-continuous β-TCP/MgCa composite manufactured by suction casting

The co-continuous β-TCP/MgCa composite was fabricated by infiltrating MgCa alloy into porous β-TCP using suction casting technique. The microstructure, mechanical property and corrosion behaviors of the composite have been evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical testing, electrochemical and immersion tests. It was shown that the composite structure was compact and the interfacial combination between MgCa alloy and β-TCP scaffold was very well. The composite had an ultimate compressive strength of (147±13) MPa, which was near with the natural bone (2–180MPa) and about 1000-fold higher than that of the original porous β-TCP scaffold, but it still retained over half of the strength of the MgCa bulk alloy. The electrochemical and immersion tests indicated that the corrosion resistance of the composite was better than that of the MgCa bulk alloy, and the corrosion rate of the MgCa matrix alloy was quicker than that of the porous scaffold for the composite. The corrosion products of the composite surface were mainly Mg(OH)2, hydroxyapatite (HA) and Ca3(PO4)2.

Microstructure and characteristics of interpenetrating β-TCP/Mg–Zn–Mn composite fabricated by suction casting

A novel interpenetrating β-TCP/Mg–Zn–Mn composite was fabricated by infiltrating Mg–Zn–Mn alloy into porous β-TCP using suction casting technique. The microstructure, mechanical property and corrosion behaviors of the composite have been evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical testing, electrochemical and immersion test. It was shown that the composite had a compact structure and the interfacial bonding between Mg–Zn–Mn alloy and β-TCP scaffold was very well. The composite had an ultimate compressive strength of 140±20MPa, which is near with the natural bone (2–180MPa) and about 1000-fold higher than that of the original porous β-TCP scaffold, and it still retained about two fifths of the strength of the bulk Mg–Zn–Mn alloy. The electrochemical and immersion tests indicated that the corrosion resistance of the composite was better than that of the Mg–Zn–Mn matrix alloy, and the corrosion products on the composite surface were mainly Mg(OH)2, Ca3(PO4)2 and HA.

Process Quality Engineering for Bioreactor-Driven Manufacturing of Tissue-Engineered Constructs for Bone Regeneration

The incorporation of Quality-by-Design (QbD) principles in tissue-engineering bioprocess development toward clinical use will ensure that manufactured constructs possess prerequisite quality characteristics addressing emerging regulatory requirements and ensuring the functional in vivo behavior. In this work, the QbD principles were applied on a manufacturing process step for the in vitro production of osteogenic three-dimensional (3D) hybrid scaffolds that involves cell matrix deposition on a 3D titanium (Ti) alloy scaffold. An osteogenic cell source (human periosteum-derived cells) cultured in a bioinstructive medium was used to functionalize regular Ti scaffolds in a perfusion bioreactor, resulting in an osteogenic hybrid carrier. A two-level three-factor fractional factorial design of experiments was employed to explore a range of production-relevant process conditions by simultaneously changing value levels of the following parameters: flow rate (0.5-2 mL/min), cell culture duration (7-21 days), and cell-seeding density (1.5×10(3)-3×10(3) cells/cm(2)). This approach allowed to evaluate the individual impact of the aforementioned process parameters upon key quality attributes of the produced hybrids, such as collagen production, mineralization level, and cell number. The use of a fractional factorial design approach helped create a design space in which hybrid scaffolds of predefined quality attributes may be robustly manufactured while minimizing the number of required experiments.

Fabrication and characterization of porous Ti–7.5Mo alloy scaffolds for biomedical applications

Porous titanium and titanium alloys are promising scaffolds for bone tissue engineering, since they have the potential to provide new bone tissue ingrowth abilities and low elastic modulus to match that of natural bone. In the present study, porous Ti-7.5Mo alloy scaffolds with various porosities from 30 to 75 % were successfully prepared through a space-holder sintering method. The yield strength and elastic modulus of a Ti-7.5Mo scaffold with a porosity of 50 % are 127 MPa and 4.2 GPa, respectively, being relatively comparable to the reported mechanical properties of natural bone. In addition, the porous Ti-7.5Mo alloy exhibited improved apatite-forming abilities after pretreatment (with NaOH or NaOH + water) and subsequent immersion in simulated body fluid (SBF) at 37 °C. After soaking in an SBF solution for 21 days, a dense apatite layer covered the inner and outer surfaces of the pretreated porous Ti-7.5Mo substrates, thereby providing favorable bioactive conditions for bone bonding and growth. The preliminary cell culturing result revealed that the porous Ti-7.5Mo alloy supported cell attachment.

Biomechanical behavior of bone scaffolds made of additive manufactured tricalciumphosphate and titanium alloy under different loading conditions

The repair of large segmental bone defects caused by fracture, tumor or infection remains challenging in orthopedic surgery. The capability of two different bone scaffold materials, sintered tricalciumphosphate and a titanium alloy (Ti6Al4V), were determined by mechanical and biomechanical testing. All scaffolds were fabricated by means of additive manufacturing techniques with identical design and controlled pore geometry. Small-sized sintered TCP scaffolds (10 mm diameter, 21 mm length) were fabricated as dense and open-porous samples and tested in an axial loading procedure. Material properties for titanium alloy were determined by using both tensile (dense) and compressive test samples (open-porous). Furthermore, large-sized open-porous TCP and titanium alloy scaffolds (30 mm in height and diameter, 700 µm pore size) were tested in a biomechanical setup simulating a large segmental bone defect using a composite femur stabilized with an osteosynthesis plate. Static physiologic loads (1.9 kN) were applied within these tests. Ultimate compressive strength of the TCP samples was 11.2 ± 0.7 MPa and 2.2 ± 0.3 MPa, respectively, for the dense and the open-porous samples. Tensile strength and ultimate compressive strength was 909.8 ± 4.9 MPa and 183.3 ± 3.7 MPa, respectively, for the dense and the open-porous titanium alloy samples. Furthermore, the biomechanical results showed good mechanical stability for the titanium alloy scaffolds. TCP scaffolds failed at 30% of the maximum load. Based on recent data, the 3D printed TCP scaffolds tested cannot currently be recommended for high load-bearing situations. Scaffolds made of titanium could be optimized by adapting the biomechanical requirements.

In vivo degradation of magnesium alloy LA63 scaffolds for temporary stabilization of biological myocardial grafts in a swine model

Synthetic or biological patch materials used for surgical myocardial reconstruction are often fragile. Therefore, a transient support by degradable magnesium scaffolds can reduce the risk of dilation or rupture of the patch until physiological remodeling has led to a sufficient mechanical durability. However, there is evidence that magnesium implants can influence the growth and physiological behavior of the host's cells and tissue. Hence, we epicardially implanted scaffolds of the magnesium fluoride-coated magnesium alloy LA63 in a swine model to assess biocompatibility and degradation kinetics. Chemical analysis of the pigs' organs revealed no toxic accumulation of magnesium ions in the skeletal muscle, myocardium, liver, kidney, and bone of the pigs 1, 3, and 6 months postimplantation. The implants were surrounded by a fibrous granulation tissue, but no signs of necrosis were histologically evaluable. A sufficiently slow degradation rate of the magnesium alloy scaffold can be demonstrated via micro-computed tomography investigation. We conclude that stabilizing scaffolds of the magnesium fluoride-coated magnesium alloy LA63 can be used for epicardial application because no significant adverse effects to myocardial tissue were noted. Thus, degradable stabilizing scaffolds of this magnesium alloy with a slow degradation rate can extend the indication of innovative biological and synthetic patch materials.

Processing and mechanical properties of porous Ti–7.5Mo alloy

Titanium (Ti) and its alloys continue to be utilized extensively for skeletal repair and dental implants. Most metallic implant materials including pure Ti and Ti alloys used today are in their solid forms and are often much stiffer than human bone. However, the elastic modulus of Ti and Ti alloys can be reduced through the introduction of a porous structure, which may also provide new bone tissue integration and vascularization abilities. In the present study, porous Ti–7.5Mo alloy scaffolds made from ball-milled alloy particles and sintered at 1100°C for 10, 15 and 20h respectively were successfully prepared through a space-holder sintering method. In the sintered Ti–7.5Mo, no obvious diffraction peaks of elemental Mo remained after the sintering, and a duplex α+β microstructure was confirmed from the XRD pattern. The samples made from BM15 (the alloy particles ball-milled for 15h) had higher relative density, compressive strength and elastic modulus performance than those from BM3 and BM30 (the alloy particles ball-milled for 3 and 30h, respectively) when they were sintered under the same conditions. Moreover, the longer sintering time lead to the higher relative density and the greater compressive strength and modulus of the sample. In this work, the strength and modulus of the sintered porous Ti–7.5Mo conforms to the basic mechanical property requirement of cancellous bones.

Evaluation of Biological Properties of Electron Beam Melted Ti6Al4V Implant with Biomimetic Coating In Vitro and In Vivo

BackgroundHigh strength porous titanium implants are widely used for the reconstruction of craniofacial defects because of their similar mechanical properties to those of bone. The recent introduction of electron beam melting (EBM) technique allows a direct digitally enabled fabrication of patient specific porous titanium implants, whereas both their in vitro and in vivo biological performance need further investigation.MethodsIn the present study, we fabricated porous Ti6Al4V implants with controlled porous structure by EBM process, analyzed their mechanical properties, and conducted the surface modification with biomimetic approach. The bioactivities of EBM porous titanium in vitro and in vivo were evaluated between implants with and without biomimetic apatite coating.ResultsThe physical property of the porous implants, containing the compressive strength being 163 - 286 MPa and the Young’s modulus being 14.5–38.5 GPa, is similar to cortical bone. The in vitro culture of osteoblasts on the porous Ti6Al4V implants has shown a favorable circumstance for cell attachment and proliferation as well as cell morphology and spreading, which were comparable with the implants coating with bone-like apatite. In vivo, histological analysis has obtained a rapid ingrowth of bone tissue from calvarial margins toward the center of bone defect in 12 weeks. We observed similar increasing rate of bone ingrowth and percentage of bone formation within coated and uncoated implants, all of which achieved a successful bridging of the defect in 12 weeks after the implantation.ConclusionsThis study demonstrated that the EBM porous Ti6Al4V implant not only reduced the stress-shielding but also exerted appropriate osteoconductive properties, as well as the apatite coated group. The results opened up the possibility of using purely porous titanium alloy scaffolds to reconstruct specific bone defects in the maxillofacial and orthopedic fields.

Microstructure, mechanical property and corrosion behaviors of interpenetrating C/Mg-Zn-Mn composite fabricated by suction casting

A novel interpenetrating C/Mg-Zn-Mn composite was fabricated by infiltrating Mg-Zn-Mn alloy into porous carbon using suction casting technique. The microstructure, mechanical properties and corrosion behaviors of the composite have been evaluated by means of SEM, XRD, mechanical testing and immersion test. It was shown that the composite had a compact structure and the interfacial bonding between Mg-Zn-Mn alloy and carbon scaffold was very well. The composite had an ultimate compressive strength of (195±15) MPa, which is near with the natural bone (2–180MPa) and about 150-fold higher than that of the original porous carbon scaffold, and it still retained half of the strength of the bulk Mg-Zn-Mn alloy. The corrosion test indicated that the mass loss percentage of the composite was 52.9% after 30days′ immersion in simulated body fluid (SBF) at 37±0.5°C, and the corrosion rates were 0.043mg/cm2h and 0.028mg/cm2h after 3 and 7days′ immersion, respectively. The corrosion products on the composite surface were mainly Mg(OH)2 and hydroxyapatite (HA).

Wear Properties of Porous NiTi Orthopedic Shape Memory Alloy

Porous NiTi shape memory alloy (SMA) scaffolds have great potential to be used as orthopedic implants because of their porous structure and superior physical properties. Its metallic nature provides it with better mechanical properties and Young’s modulus close to that of natural bones. Besides allowing tissue ingrowth and transfer of nutrients, porous SMA possesses unique pseudoelastic properties compatible to natural hard tissues like bones and tendons, thus expediting in vivo osseointegration. However, the nickel release from debris and the metal surface may cause osteocytic osteolysis at the interface between the artificial implants and bone tissues. Subsequent mobilization may finally lead to implant failure. In this study, the wear properties of porous NiTi with different porosities processed at different treatment temperatures are determined. The results of the study show that the porosity, phase transformation temperature, and annealing temperature are major factors influencing the wear characteristics of porous NiTi SMA.

A Newly Developed Biocompatible Titanium Alloy and its Scaffolding by Powder Metallurgy

Titanium and some of its alloys have received considerable attention for biomedical applications in recent years due to their excellent biocompatibility, high corrosion resistance and relatively low elastic modulus when compared to other metallic implant materials such as Co-Cr alloys and stainless steels. However, these alloys can still suffer from inadequate biocompatibility; lack of biological fixation and biomechanical mismatch with the properties of bone in vivo. In this study, a new biocompatible Ti alloy, Ti4Ta4Sn, consisting of alpha and beta phases was fabricated and their mechanical properties were investigated. Moreover, the Ti alloy was scaffolded into a porous structure using powder metallurgy with an architecture and elastic modulus mimicking those of cancellous bone. Cell culture results indicated that the new porous Ti alloy scaffold possesses excellent in vitro biocompatibility.

Fabrication of Ti14Nb4Sn Alloys for Bone Tissue Engineering Applications

In this paper, porous Ti14Nb4Sn alloys were fabricated using a space holder sintering method, resulting in a porosity of ~70%. Scanning electron microscopy (SEM) analyses revealed a combination of both macropore and micropore structures. The fabricated titanium alloy scaffolds exhibited a similar structure to that of natural bone, which is expected to improve bone implant longevity. Bacterial cells of Pseudomonas aeruginosa ATCC 9027 were employed for the in vitro test.

Design and assessment of a wrapped cylindrical Ca‐P AZ31 Mg alloy for critical‐size ulna defect repair

Recently, magnesium has been investigated as a promising bioresorbable orthopedic biomaterial. Its mechanical properties are very similar to natural bone, making it appropriate for load-bearing orthopedic fracture repair applications. However, significant hurdles remain regarding the design of practical implants and methods to control degradation and enhance biocompatibility. Although attempts have been made to hinder magnesium's rapid corrosion via alloying and coating, these studies have used solid monoliths. In an effort to reduce the amount of alloy used for implantation in a shape that mimics cortical bone shape, this study used a thin sheet of Mg AZ31 which was rolled into hollow cylindrical scaffolds. The scaffold was coated with different amounts of Ca-P; this implant demonstrated slowed corrosion in simulated body fluid (SBF) as well as enhanced biocompatibility for mesenchymal stem cells (MSC). In vivo implantation of magnesium alloy scaffold adjacent to the rat femur showed significant biointegration with further deposition of complex Mg-Ca phosphates/carbonates typical of natural bone. Finally, the implant was placed in a critical-size ulna defect in live rabbits, which lead to radiographic union and partial restoration of biomechanical strength in the defect. This study demonstrated that a thin sheet of coated Mg alloy that was spirally wrapped wound be a promising orthopedic biomaterial for bone repair.