Preparation and characterization of hemihydrate calcium sulfate-calcium hydroxide composite bone repair materials

Objective:To prepare a bone repair material with certain mechanical strength and biological activity,this paper used calcium sulfate hemihydrate(CSH)powder compounded with calcium hydroxide(Ca(OH)2)powder to prepare a bone repair scaffold material for physicochemical property characterization and testing.Methods:The physical and chemical properties and characterization of the dried and cured bone repair materials were determined by Fourier infrared spectroscopy(FT-IR),X-ray diffraction(XRD),and scanning electron microscopy;Universal material testing machine to determine the mechanical and mechanical strength of composite materials.Results:XRD showed that the structure of the composite material phase at 5%concentration was calcium sulfate hemihydrate and calcium hydroxide after hydration.The FT-IR and XRD analyses were consistent.Scanning electron microscopy(SEM)results showed that calcium hydroxide was uniformly dispersed in the hemihydrate calcium sulfate material.0%,1%,5%,and 10%specimen groups had compressive strengths of 3.86±3.1,5.27±1.28,8.22±0.96,and 14.4±3.28 MPa.10%addition of calcium hydroxide significantly improved the mechanical strength of the composites,but also reduced the the porosity of the material.Conclusion:With the addition of calcium hydroxide,the CSH-Ca(OH)2 composite was improved in terms of mechanical material and is expected to be a new type of bone repair material.

Editor's Choice—Application of tissue-engineered materials in the repair of spinal cord injury

The development of tissue-engineered technology brings hope to the treatment of spinal cord injury. Preparation of a tissue-engineered spinal cord stent with three-dimensional bionic structure has important value in the construction of tissue-engineered spinal cord and the repair of spinal cord injury. Acellular scaffolds can be produced with chemical extraction,

A Systematic Review of Animal and Clinical Studies on the Use of Scaffolds for Urethral Repair

Replacing urethral tissue with functional scaffolds has been one of the challenging problems in the field of urethra reconstruction or repair over the last several decades. Various scaffold materials have been used in animal studies, but clinical studies on use of scaffolds for urethral repair are scarce. The aim of this study was to review recent animal and clinical studies on the use of different scaffolds for urethral repair, and to evaluate these scaffolds based on the evidence from these studies. Pub Med and OVID databases were searched to identify relevant studies, in conjunction with further manual search. Studies that met the inclusion criteria were systematically evaluated. Of 555 identified studies, 38 were included for analysis. It was found that in both animal and clinical studies, scaffolds seeded with cells were used for repair of large segmental defects of the urethra, such as in tubular urethroplasty. When the defect area was small, cell-free scaffolds were more likely to be applied. A lot of pre-clinical and limited clinical evidence showed that natural or artificial materials could be used as scaffolds for urethral repair. Urinary tissue engineering is still in the immature stage, and the safety, efficacy, cost-effectiveness of the scaffolds are needed for further study.

Recent progress in injectable bone repair materials research

Minimally invasive injectable self-setting materials are useful for bone repairs and for bone tissue regeneration in situ. Due to the potential advantages of these materials, such as causing minimal tissue injury, nearly no influence on blood supply, easy operation and negligible postoperative pain, they have shown great promises and successes in clinical applications. It has been proposed that an ideal injectable bone repair material should have features similar to that of natural bones, in terms of both the microstructure and the composition, so that it not only provides adequate stimulus to facilitate cell adhesion, proliferation and differentiation but also offers a satisfactory biological environment for new bone to grow at the implantation site. This article reviews the properties and applications of injectable bone repair materials, including those that are based on natural and synthetic polymers, calcium phosphate, calcium phosphate/ polymer composites and calcium sulfate, to orthopedics and bone tissue repairs, as well as the progress made in biomimetic fabrication of injectable bone repair materials.

Bio-inspired Cell Membrane Ingredient Cholesterol-conjugated Chitosan as a Potential Material for Bone Tissue Repair

We prepared a cholesterol-conjugated chitosan（CHCS） material and evaluated its potential application as a bone tissue repair material by in vitro cell experiments. Cell proliferation, differentiation and morphology on CHCS membrane surfaces with different graft degrees were assessed in mouse pre-osteoblasts MC3T3-E1 cells. The results indicate that CHCS materials could promote the proliferation of MC3T3-E1 cells at low graft degrees, but the CHCS material with high graft degree inhibits the proliferation of cells in contrast to the pure chitosan membrane. However, the alkaline phosphatase（ALP） activity of MC3T3-E1 ceils on different CHCS membrane surface increased with in- creasing graft degrees of cholesterol. The area of cells stretched onto the surface of CHCS materials was larger than on the surface of CS materials, and more microfilaments and stress fibers in cells were observed on CHCS materials than on the pure chitosan material surface. After 7 d, the expression of related osteogenic marker genes, such as rum-related transcription factor 2（Runx2）, osterix（OSX）, osteocalcin（OCN）, osteopontin（OPN）, ALP and collagen I（COL-I） were all up-regulated in CHCS materials to different degrees compared to pure chitosan material, which in- dicated that the CHCS materials facilitated MC3T3-EI cell differentiation and maturation, Characterizing CHCS materials is useful in designing and developing strategies for bone tissue engineering.

The use of bioactive peptides to modify materials for bone tissue repair

It has been well recognized that the modification of biomaterials with appropriate bioactive peptides could further enhance their functions.Especially,it has been shown that peptide-modified bone repair materials could promote new bone formation more efficiently compared with conventional ones.The purpose of this article is to give a general review of recent studies on bioactive peptide-modified materials for bone tissue repair.Firstly,the main peptides for inducing bone regeneration and commonly used methods to prepare peptide-modified bone repair materials are introduced.Then,current in vitro and in vivo research progress of peptide-modified composites used as potential bone repair materials are reviewed and discussed.Generally speaking,the recent related studies have fully suggested that the modification of bone repair materials with osteogenicrelated peptides provide promising strategies for the development of bioactive materials and substrates for enhanced bone regeneration and the therapy of bone tissue diseases.Furthermore,we have proposed some research trends in the conclusion and perspectives part.

Skull repair materials applied in cranioplasty: History and progress

The skull provides protection and mechanical support, and acts as a container for the brain and its accessory organs. Some defects in the skull can fatally threaten human life.Many efforts have been taken to repair defects in the skull, among which cranioplasty is the most prominent technique. To repair the injury, numerous natural and artificial materials have been adopted by neurosurgeons. Many cranioprostheses have been tried in the past decades, from autoplast to bioceramics. Neurosurgeons have been evaluating their advantages and shortages through clinical practice. Among those prostheses, surgeons gradually prefer bionic ones due to their marvelous osteoconductivity,osteoinductivity, biocompatibility, and biodegradability. Autogeneic bone has been widely recognized as the "gold standard" for renovating large-sized bone defects. However, the access to this technique is restricted by limited availability and complications associated with its use. Many metal and polymeric materials with mechanical characteristics analogous to natural bones were consequently applied to cranioplasty. But most of them were unsatisfactory concerning osteoconductiion and biodegradability owe to their intrinsic properties. With the microstructures almost identical to natural bones, mineralized collagen has biological performance nearly identical to autogeneic bone, such as osteoconduction. Implants made of mineralized collagen can integrate themselves into the newly formed bones through a process called "creeping substitution". In this review, the authors retrospect the evolution of skull repair material applied in cranioplasty. The ultimate skull repair material should have microstructure and bioactive qualities that enable osteogenesis induction and intramembranous ossification.

Biodegradable Zn-Sr alloy for bone regeneration in rat femoral condyle defect model: In vitro and in vivo studies

Bone defects are commonly caused by severe trauma,malignant tumors,or congenital diseases and remain among the toughest clinical problems faced by orthopedic surgeons,especially when of critical size.Biodegradable zinc-based metals have recently gained popularity for their desirable biocompatibility,suitable degradation rate,and favorable osteogenesis-promoting properties.The biphasic activity of Sr promotes osteogenesis and inhibits osteoclastogenesis,which imparts Zn-Sr alloys with the ideal theoretical osteogenic properties.Herein,a biodegradable Zn-Sr binary alloy system was fabricated.The cytocompatibility and osteogenesis of the Zn-Sr alloys were significantly better than those of pure Zn in MC3T3-E1 cells.RNA-sequencing illustrated that the Zn-0.8Sr alloy promoted osteogenesis by activating the wnt/β-catenin,PI3K/Akt,and MAPK/Erk signaling pathways.Furthermore,rat femoral condyle defects were repaired using Zn-0.8Sr alloy scaffolds,with pure Ti as a control.The scaffold-bone integration and bone ingrowth confirmed the favorable in vivo repair properties of the Zn-Sr alloy,which was verified to offer satisfactory biosafety based on the hematoxylin-eosin(H&E)staining and ion concentration testing of important organs.The Zn-0.8Sr alloy was identified as an ideal bone repair material candidate,especially for application in critical-sized defects on load-bearing sites due to its favorable biocompatibility and osteogenic properties in vitro and in vivo.

The effect of carbon nanotubes on osteogenic functions of adipose-derived mesenchymal stem cells in vitro and bone formation in vivo compared with that of nano-hydroxyapatite and the possible mechanism

It has been well recognized that the development and use of artificial materials with high osteogenic ability is one of the most promising means to replace bone grafting that has exhibited various negative effects.The biomimetic features and unique physiochemical properties of nanomaterials play important roles in stimulating cellular functions and guiding tissue regeneration.But efficacy degree of some nanomaterials to promote specific tissue formation is still not clear.We hereby comparatively studied the osteogenic ability of our treated multiwalled carbon nanotubes(MCNTs)and the main inorganic mineral component of natural bone,nano-hydroxyapatite(nHA)in the same system,and tried to tell the related mechanism.In vitro culture of human adiposederived mesenchymal stem cells(HASCs)on the MCNTs and nHA demonstrated that although there was no significant difference in the cell adhesion amount between on the MCNTs and nHA,the cell attachment strength and proliferation on the MCNTs were better.Most importantly,the MCNTs could induce osteogenic differentiation of the HASCs better than the nHA,the possible mechanism of which was found to be that the MCNTs could activate Notch involved signaling pathways by concentrating more proteins,including specific bone-inducing ones.Moreover,the MCNTs could induce ectopic bone formation in vivo while the nHA could not,which might be because MCNTs could stimulate inducible cells in tissues to form inductive bone better than nHA by concentrating more proteins including specific bone-inducing ones secreted from M2 macrophages.Therefore,MCNTs might be more effective materials for accelerating bone formation even than nHA.