The Construction and Investigation of PLGA Artificial Bone by Biomimetic Mineralization

To modify the surface property of poly lactide-co-glycolide （PLGA） by biomimetic mineralization to construct a new kind of artificial bone. PLGA films and 3-diamensional （3-D） porous scaffolds hydrolyzed in alkaline solution were minerilized in SBF for 14 days. The morphology and composition of the mineral grown on PLGA were analyzed with SEM, FTIR and XRD. The porosity of the scaffolds was detected by using the liquid displacement method. The compressive strength of the scaffolds was detected by using a Shimadzu universal mechanic tester. An obvious mineral coating was detected on the surface of films and scaffolds. The main compqnent of the mineral was carbonated hydroxyapatite （HA） similar to the major mineral component of bone tissues. The porosity of the un-mineralized and mineralized porous scaffolds was （84.86±8.52） % and （79.70 ± 7.70） % respectively. The compressive strength was 0. 784±0. 156 N/mm^2 in un-mineralized 3-D porous PLGA and 0. 858±0. 145 N/mm^2 in mineralized 3-D porous PLGA. There were no significant differences between the mineralized and un-mineralized scaffolds （P〉0, 05） in porosity and biomechanics. Biomimetic mineralization is a suitable method to construct artificial bone.

Experimental Study on Polymer Artificial Bone with HA Coated and Fiber Liners

Layers of ante-polymerized PMMA （ Polymethylmethacrylate ） ore manually smeared on both sides of carbon fiber and polyester fiber to a certain thickness. It was pre-solidified, stripped and cut for sterilization. Based on the results of a series of experiments, HA coated artificial bone is considered to be a non-senshizing, non- irritant, and non- toxic biomaterial for medical applications. The artificial bone has excellent mechanical and biological property. And it conforms to the national standard requirement. Safety analysis guarantees h a prosperous future of clinical application.

MACROPHAGES IN DEGRADATION OF COLLAGEN / HYDROXYLAPATITE(CHA), BETA-TRICALCIUM PHOSPHATE CERAMICS (TCP) ARTIFICIAL BONE GRAFT AN IN VIVO STUDY

The macrophages mediated biodegradation of two biomaterials, collagen / hydroxylapatite (CHA) and beta-tricalcium phosphate ceramics (TCP), was studied in 24 male Kunming mice and 20 male C57BL / 6 mice with histopathologic, histochemical and ultrastructural observation. It was demonstrated that macrophages infiltrated after CHA, TCP were implanted. The macrophages could be differentiated from fibroblasts and the other infiltrated cells for special cellular profile and strong acid phosphatase activity. Morphologically, monocyte macrophages and infused multinuclear giant cell degraded CHA and TCP by phagocytosis and extracellular resorption. The carbonic anhydrase activity of macrophages was demonstrated by histochemical technique. It suggested that macrophages secreted H+ and accomplished the decalcification of calcium phosphate compound of CHA and TCP. We conclude that macrophages are the main mediating cells which degraded CHA and TCP intracellularly and extracellularly.

Clinical observation of biomimetic mineralized collagen artificial bone putty for bone reconstruction of calcaneus fracture

This study investigated clinical outcomes of biomimetic mineralized collagen artificial bone putty for bone reconstruction in the treatment of calcaneus fracture.Sixty cases of calcaneal fractures surgically treated with open reduction and internal fixation in our hospital from June 2014–2015 were chosen and randomly divided into two groups,including 30 cases treated with biomimetic mineralized collagen artificial bone putty as treatment group,and 30 cases treated with autogenous ilia as control group.The average follow-up time was 17.263.0 months.The results showed that the surgery duration and postoperative drainage volume of treatment group were significantly lower than control group;there were no statistically significant differences in the fracture healing time,American Orthopaedic Foot and Ankle Society scores at 3 and 12 months after surgery,Bo¨hler’s angle,Gissane’s angle and height of calcaneus between the two groups.There were no significant differences in wound complication and reject reaction between the two groups,while significant difference in donor site complication.As a conclusion,the implantation of biomimetic mineralized collagen artificial bone putty in the open reduction of calcaneal fracture resulted in reliable effect and less complications,which is suitable for clinical applications in the treatment of bone defect in calcaneal fractures.

A comparative study of autogenous, allograft and artificial bone substitutes on bone regeneration and immunotoxicity in rat femur defect model

Repair and reconstruction of large bone defect were often difficult,and bone substitute materials,including autogenous bone,allogenic bone and artificial bone,were common treatment strategies.The key to elucidate the clinical effect of these bone repair materials was to study their osteogenic capacity and immunotoxicological compatibility.In this paper,the mechanical properties,micro-CT imaging analysis,digital image analysis and histological slice analysis of the three bone grafts were investigated and compared after different time points of implantation in rat femur defect model.Autogenous bone and biphasic calcium phosphate particular artificial bone containing 61.4% HA and 38.6%β-tricalcium phosphate with 61.64%porosity and 0.8617±0.0068 g/cm^(3) den-sity(d≤2 mm)had similar and strong bone repair ability,but autogenous bone implant materials caused greater secondary damage to experimental animals;allogenic bone exhibited poor bone defect repair ability.At the early stage of implantation,the immunological indexes such as Immunoglobulin G,Immunoglobulin M concentration and CD4 cells'population of allogenic bone significantly increased in compared with those of autologous bone and artificial bone.Although the repair process of artificial bone was relatively inefficient than autologous bone graft,the low immunotoxicological indexes and acceptable therapeutic effects endowed it as an excellent alter-native material to solve the problems with insufficient source and secondary trauma of autogenous bone.

Macrophages in Degradation of Calcium Phosphate Compound Artificial Bone： An in vitro Study

The isolated mice peritoneal macrophages in degradation of calcium phosphate compound artificial bone - collagen/hydroxylapatite (CHA). hydroxylapatite (HA), beta-tricalcium phosphate (TCP) ceramics, have been studied by use of both Ca++, P concentration assay in cultured supernatant and scanning electron microscopy (SEM). The solubility of Ca++ . composition of materials increased more significantly when macrophages were inoculated than when macrophages were not seeded (P< 0.001), and it was shown that the ground materials were wrapped and phagocytized or resorbed extracellularly by macrophages under SEM, suggesting that macrophages could mediate the degradation of calcium phosphate compound artificial bone by phagocytizing and/or degrading extracellularly.

An investigation on plasma spraying with artificial bone powder and bonding characteristics of coating

Artificial bone powder is satisfactorily deposited onto the surface of synthetic metal arthrosis(Co-Cr-Mo) with plasma spraying process. Factors influencing the quality of coating are investigated. Bond of artificial bone powder coating sprayed with different parameters is measured. and the coatings are anlyzed with metallographic examination and electron probe analysis. Experiments show that artificial bone powder coating sprayed onto synthetic metal arthrosis with satisfactory bond strength can be obtained by manipulating plasma spraying.

Percutaneous reduction combined with bone graft in treatment of displaced intra-articular calcaneal fractures

Objective： To introduce the experience and key points of percutaneous reduction combined with bone graft to treat calcaneal fractures. Methods： Percutaneous reduction and internal fixation combined with bone graft was performed from April 2004 to April 2006 on 15 cases （16 sides） with intra-articular calcaneal fractures including 13 males （14 feet） and 2 females （2 feet） ,with average age of 36. 6 years （24-61 years）. All patients underwent radiography including lateral and axial views for calcaneus, oblique view for foot and three-dimensional CT imaging reconstruction. According to Sanders classification, there were 12 feet of type Ⅱ （3 type Ⅱa, 3 type Ⅱb and 8 type Ⅱc） and 2 feet of type Illac. The length of calcaneus was recovered through traction by Steinmann pin which passed through calcaneal tubercle perpendicularly and the posterior facet was elevated until reduction by a curve scissors through an 0.5 cm incision along the primary fracture line of lateral calcaneus. The calcaneus was fixed with different cannulated cancellous screws according to the type of fractures. Then bone graft was injected to fill the defect of calcaneus through lateral incision. Results： All patients were followed up for an average of 18.4 months （ranged, 12 to 34 months）. No complication such as wound infection, screw breakage and calcaneum varus was found postoperatively. The average time for bone healing was 10 weeks. The results were excellent in 12 cases, good in 4 cases according to the American Orthopaedic Foot and Ankle Society （AOFAS） hindfoot score. The rate of excellent and good clinical results was 100%. The mean AOFAS hindfoot score in tongue type group （86.5±4.4） was better than in joint depression type group （81.2±1.7, P〈0.05）. Radiography showed basic restoration of Bohler＇s angle, Gissane＇s angle and calcaneal shape. Conclusion： The combination of percutaneous reduction and injectable bone graft is suitable for surgical treatment of Sanders Ⅱ and Ⅲ type calcaneal fractures, with advantages of simple operation, fewer complications and good clinical results.

Recent Progress in the Construction of Functional Artificial Bone by Cytokine-Controlled Strategies

Objective： Combining artificial scaffolds with stimulatory factors to reconstruct lost bone tissues is one of the hottest research directions. The purpose of this review was to conduct a retrospective survey on the latest reports on artificial bone fabrication with functional cytokines. Data Sources： The status of related scientific research from the year 2005 to 2018 was analyzed through the mode of literature retrieval in PubMed and VIP Database. The retrieval words are as follows： ＂bone tissue engineering,＂ ＂angiogenesis,＇＂ ＂cytokines,＂ ＂osteogenesis,＂ ＂biomimetic bone marrow,＂ ＂sol-gel,＂ ＂delivery system,＂ and the corresponding Chinese words. Study Selection： After reading through the title and abstract/br early screening, the lull text of relevant studies was evaluated and those not related with this review had been ruled out. Results： According to the literature retrospective survey, there were three key points for the successful construction of functional artificial bones： （1） the continuous supply of relatively low concentration ofcytokines during the required period; （2） the delivery of two or more cytokines essential to the process and ensure the relatively spatial independence to reduce the unnecessary interference： and （3） supporting the early-stage angiogenesis and late-stage osteogenesis, respectively, regulating and balancing the crosslinking of both to avoid the surface ossification that would probably block the osteogenesis inside. Conclusions： The synergistic effect of both angiogenic factors and osteogenic factors applied in bone regeneration is a key point in the combined functional artificial bone. Through analysis, comparison, and summary of the current strategies, we proposed that the most promising one is to mimic the natural bone marrow function to facilitate the regeneration process and ensure the efficient repair of large weight-bearing bone defect.

Artificial periosteum in bone defect repair--A review

Periosteum is a thin membrane that encases the surfaces of most bones.It is composed of an outer fibrous layer contains longitudinally oriented cells and collagen fibers and an inner cambial layer that consists of multipotent mesenchymal stem cells（MSCs）and osteogenic progenitor cells.Periosteum has a function of regulating cell and collagen arrangement,which is important to the integrity,modelling and remodelling of bone,particularly during bone defect repair.Apart from autograft and allograft,artificial periosteum,or tissue-engineered periosteum mimicking native periosteum in structure or function,made up of small intestinal submucosa,acellular dermis,induced membrane,cell sheets,and polymeric scaffolds,and so on,has been developed to be used in bone defect repair.In this review,we classify the artificial periosteum into three approaches based on the material source,that is,native tissues,scaffoldfree cell sheets and scaffold-cell composites.Mechanisms,methods and efficacy of each approach are provided.Existing obstacles and enabling technologies for future directions are also discussed.

Study of gelatinized marrow stroma osteoblasts and true bone ceramic active bone

Objective: To investigate a new method to construct tissue-engineering bone that will be applicable clinically. Methods: The cultured 5th generation rabbit bone marrow stroma osteoblasts (MSO) was dissolved in 3% sodium alginate solution (the final concentration of sodium alginate in the solution being 1%, and MSO, 5×106/L), and then inoculated into prepared true bone ceramic (TBC) and gelatinized the bone by dribbling with calcium gluconate. The standard bone defect models were made in 48 adult New Zealand rabbit’s both radius. Among the 48 rabbits, 24 were in Groups A and B, in which the left radius was implanted with gelatinized MSO-TBC (Group A) and right radius implanted with autograft-bone (Group B); and the other 24 were in control group whose left radius was implanted with non-gelatinized MSO-TBC (Group C) and right radius implanted with gelatinized TBC (Group D). Outcomes of the implanted bones were assessed by radiology, pathological histology, osteogenetic quantitative analysis, and biomechanics at 2, 4, 8,12 weeks postoperatively. Results: In Groups A and B, a satisfactory bone reparation and bony union was noted within 12 weeks. In Groups C and D, bone reparation was not satisfied compared with Group A in terms of ostogenetic quantity and biomechanics. Conclusions: Gelatinized MSO-TBC is an ideal artificial active bone that overcomes TBC shortcomings of fragileness and smooth surface that is not eligible for seed cell’s adhesion. It is promising to put into clinical use extensively.

Preparation and Characterization of 3D Printed Hydroxyapatite-Whisker-Strengthened Hydroxyapatite Scaffold Coated with Biphasic Calcium Phosphate

This study investigates the in vitro degradation of calcium-deficient hydroxyapatite powder after heat treatment at different temperatures and analyzes the calculated phase composition,particle size distribution,degradation rate,and bioactivity of the powder after heat treatment.A mixture of hydroxyapatite and𝛽-tricalcium phosphate(BCP)coatings was prepared on the surface of a 3D-printed hydroxyapatite-whisker-strengthened hydroxyapatite scaf-fold(HAw/HA)by vacuum impregnation and ultraviolet light curing combined with an optimized heat treatment process.The performance of the coatings under different methods was characterized.The composite scaffolds with highly interconnected pores and excellent mechanical properties were prepared,and their biodegradation performance,bioactivity,osteoconductivity,and osteoinductivity of the scaffolds were improved.The results showed that calcium-deficient hydroxyapatite began to transform into BCP between 600℃and 800℃,and the powder treated at 800℃has better bioactivity.The BCP coating prepared by light curing was more uniform,resulting in a higher interfacial bonding strength,and has better osteoconductivity and osteoinductivity than that prepared by vacuum impregnation.

Ca^(2+)-supplying black phosphorus-based scaffolds fabricated with microfluidic technology for osteogenesis

Effective osteogenesis remains a challenge in the treatment of bone defects.The emergence of artificial bone scaffolds provides an attractive solution.In this work,a new biomineralization strategy is proposed to facilitate osteogenesis through sustaining supply of nutrients including phosphorus(P),calcium(Ca),and silicon(Si).We developed black phosphorus(BP)-based,three-dimensional nanocomposite fibrous scaffolds via microfluidic technology to provide a wealth of essential ions for bone defect treatment.The fibrous scaffolds were fabricated from 3D poly(L-lactic acid)(PLLA)nanofibers(3D NFs),BP nanosheets,and hydroxyapatite(HA)-porous SiO2 nanoparticles.The 3D BP@HA NFs possess three advantages:i)stably connected pores allow the easy entrance of bone marrow-derived mesenchymal stem cells(BMSCs)into the interior of the 3D fibrous scaffolds for bone repair and osteogenesis;ii)plentiful nutrients in the NFs strongly improve osteogenic differentiation in the bone repair area;iii)the photothermal effect of fibrous scaffolds promotes the release of elements necessary for bone formation,thus achieving accelerated osteogenesis.Both in vitro and in vivo results demonstrated that the 3D BP@HA NFs,with the assistance of NIR laser,exhibited good performance in promoting bone regeneration.Furthermore,microfluidic technology makes it possible to obtain high-quality 3D BP@HA NFs with low costs,rapid processing,high throughput and mass production,greatly improving the prospects for clinical application.This is also the first BP-based bone scaffold platform that can self-supply Ca^(2+),which may be the blessedness for older patients with bone defects or patients with damaged bones as a result of calcium loss.