Tissue Response of an Osteoinductive Bioceramic in Bone Defect Rabbit Model

HA/TCP and HA rods （φ5 mm×10 mm） were made for implantation in New Zealand white rabbit with different condition. Sixty three rabbit were divided into three groups： group 1 （n=18）, group 2 （n=27） and group 3 （n=18）. In group 1, 10 mm radius was defected, and one HA/TCP rod was implanted in the muscle a distant away from the bone defect area. In group 2, also, 10 mm radius was defected, one HA rod was implanted in the muscle a distant away from the bone defect area. In group 3, two HA/TCP rods were implanted in the dorsal muscle of the rabbit with bone intact. Histological observation showed that in group 1, some new bone was found only two months after implantation （n=2）, and obvious immature woven bone could be observed in these bioceramics from the 3rd month on. However, in group 3, bone began to be found 6 months after implantation （n=2）. In group 2, we could not find any bone tissue up to 9 month’s observation. These results suggest that, first, the bone defect model could significantly accelerate bone formation at non-osseous sites in rabbits; second,. HA/TCP bioceramics were confirmed with osteoinductive property while HA bioceramics without osteoinductive property nearly. Thus, bone defect might be a good animal model for further researches for osteoinductive bioceramics.

Application of osteoinductive calcium phosphate ceramics in children’s endoscopic neurosurgery:report of five cases

This work aimed at investigating the possibility and effectiveness of osteoinductive calcium phosphate(CaP)ceramics to close the drilled skull holes and prevent the postoperative cerebrospinal fluid(CSF)leaking in children’s endoscopic neurosurgery.Five children patients(four boys and one girl,3-to 8-years old)underwent the surgery,in which the endoscopic third ventriculostomy(ETV)was operated in four cases of hydrocephalus,and biopsy and ETV were both performed in one case of pineal tumor.The drilled skull holes were filled with the commercial osteoinductive CaP ceramics.The patients were followed up by CT scan at 1,7 days,3 and 6 months postoperatively.All the five cases were successful,and the holes were closed well after filled with the ceramics.The follow-up survey showed that no CSF leaking or rejection reaction was found.The CT scan indicated that the drilled holes began healing at 7 days postoperatively,and a relatively complete healing happened at 6 months postoperatively.The excellent ability of the CaP ceramics to induce bone regeneration was also confirmed by repairing the skull defects in a monkey model.The results of μ-CT and histological analysis showed that a bony structure with irregular array occurred at the defect area,and the newly formed bone volume density reached 65.7%.In conclusion,the osteoinductive CaP ceramics could be an ideal material to treat the drilled skull holes in children’s endoscopic neurosurgery and prevent CSF leaking afterwards.However,further investigation with more cases and longer follow-up was required to evaluate the clinical effect.

The material and biological characteristics of osteoinductive calcium phosphate ceramics

The discovery of osteoinductivity of calcium phosphate(Ca-P)ceramics has set an enduring paradigm of conferring biological regenerative activity to materials with carefully designed structural characteristics.The unique phase composition and porous structural features of osteoinductive Ca-P ceramics allow it to interact with signaling molecules and extracellular matrices in the host system,creating a local environment conducive to new bone formation.Mounting evidence now indicate that the osteoinductive activity of Ca-P ceramics is linked to their physicochemical and three-dimensional structural properties.Inspired by this conceptual breakthrough,many laboratories have shown that other materials can be also enticed to join the rank of tissue-inducing biomaterials,and besides the bones,other tissues such as cartilage,nerves and blood vessels were also regenerated with the assistance of biomaterials.Here,we give a brief historical recount about the discovery of the osteoinductivity of Ca-P ceramics,summarize the underlying material factors and biological characteristics,and discuss the mechanism of osteoinduction concerning protein adsorption,and the interaction with different types of cells,and the involvement of the vascular and immune systems.

Optimal regenerative repair of large segmental bone defect in a goat model with osteoinductive calcium phosphate bioceramic implants

So far,how to achieve the optimal regenerative repair of large load-bearing bone defects using artificial bone grafts is a huge challenge in clinic.In this study,a strategy of combining osteoinductive biphasic calcium phosphate(BCP)bioceramic scaffolds with intramedullary nail fixation for creating stable osteogenic microenvironment was applied to repair large segmental bone defects(3.0 cm in length)in goat femur model.The material characterization results showed that the BCP scaffold had the initial compressive strength of over 2.0 MPa,and total porosity of 84%.The cell culture experiments demonstrated that the scaffold had the excellent ability to promote the proliferation and osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells(BMSCs).The in vivo results showed that the intramedullary nail fixation maintained the initial stability and structural integrity of the implants at early stage,promoting the osteogenic process both guided and induced by the BCP scaffolds.At 9 months postoperatively,good integration between the implants and host bone was observed,and a large amount of newborn bones formed,accompanying with the degradation of the material.At 18 months postoperatively,almost the complete new bone substitution in the defect area was achieved.The maximum bending strength of the repaired bone defects reached to the 100% of normal femur at 18 months post-surgery.Our results demonstrated the good potential of osteoinductive BCP bioceramics in the regenerative repair of large load-bearing bone defects.The current study could provide an effective method to treat the clinical large segmental bone defects.

Continuously released Zn^(2+)in 3D-printed PLGA/β-TCP/Zn scaffolds for bone defect repair by improving osteoinductive and anti-inflammatory properties

Long-term nonunion of bone defects has always been a major problem in orthopedic treatment.Artificial bone graft materials such as Poly(lactic-co-glycolic acid)/β-tricalcium phosphate(PLGA/β-TCP)scaffolds are expected to solve this problem due to their suitable degradation rate and good osteoconductivity.However,insufficient mechanical properties,lack of osteoinductivity and infections after implanted limit its large-scale clinical application.Hence,we proposed a novel bone repair bioscaffold by adding zinc submicron particles to PLGA/β-TCP using low temperature rapid prototyping 3D printing technology.We first screened the scaffolds with 1 wt%Zn that had good biocompatibility and could stably release a safe dose of zinc ions within 16 weeks to ensure long-term non-toxicity.As designed,the scaffold had a multi-level porous structure of biomimetic cancellous bone,and the Young’s modulus(63.41±1.89 MPa)and compressive strength(2.887±0.025 MPa)of the scaffold were close to those of cancellous bone.In addition,after a series of in vitro and in vivo experiments,the scaffolds proved to have no adverse effects on the viability of BMSCs and promoted their adhesion and osteogenic differentiation,as well as exhibiting higher osteogenic and anti-inflammatory properties than PLGA/β-TCP scaffold without zinc particles.We also found that this osteogenic and anti-inflammatory effect might be related to Wnt/β-catenin,P38 MAPK and NFkB pathways.This study lay a foundation for the follow-up study of bone regeneration mechanism of Zn-containing biomaterials.We envision that this scaffold may become a new strategy for clinical treatment of bone defects.

Triple-functional bone adhesive with enhanced internal fixation,bacteriostasis and osteoinductive properties for open fracture repair

At present,effective fixation and anti-infection implant materials represent the mainstay for the treatment of open fractures.However,external fixation can cause nail tract infections and is ineffective for fixing small fracture fragments.Moreover,closed reduction and internal fixation during the early stage of injury can lead to potential bone infection,conducive to bone nonunion and delayed healing.Herein,we designed a bone adhesive with anti-infection,osteogenic and bone adhesion fixation properties to promote reduction and fixation of open fractures and subsequent soft tissue repair.It was prepared by the reaction of gelatin(Gel)and oxidized starch(OS)with vancomycin(VAN)-loaded mesoporous bioactive glass nanoparticles(MBGNs)covalently cross-linked with Schiff bases.Characterization and adhesion experiments were conducted to validate the successful preparation of the Gel-OS/VAN@MBGNs(GOVM-gel)adhesive.Meanwhile,in vitro cell experiments demonstrated its good antibacterial effects with the ability to stimulate bone marrow mesenchymal stem cell(BMSCs)proliferation,upregulate the expression of alkaline phosphatase(ALP)and osteogenic proteins(RunX2 and OPN)and enhance the deposition of calcium nodules.Additionally,we established a rat skull fracture model and a subcutaneous infection model.The histological analysis showed that bone adhesive enhanced osteogenesis,and in vivo experiments demonstrated that the number of inflammatory cells and bacteria was significantly reduced.Overall,the adhesive could promote early reduction of fractures and antibacterial and osteogenic effects,providing the foothold for treatment of this patient population.

Strategies of strengthening mechanical properties in the osteoinductive calcium phosphate bioceramics

Calcium phosphate(CaP)bioceramics are widely applied in the bone repairing field attributing to their excellent biological properties,especially osteoinductivity.However,their applications in load-bearing or segmental bone defects are severely restricted by the poor mechanical properties.It is generally considered that it is challenging to improve mechanical and biological properties of CaP bioceramics simultaneously.Up to now,various strategies have been developed to enhance mechanical strengths of CaP ceramics,the achievements in recent researches need to be urgently summarized.In this review,the effective and current means of enhancing mechanical properties of CaP ceramics were comprehensively summarized from the perspectives of fine-grain strengthening,second phase strengthening,and sintering process optimization.What’s more,the further improvement of mechanical properties for CaP ceramics was prospectively proposed including heat treatment and biomimetic.Therefore,this review put forward the direction about how to compatibly improve mechanical properties of CaP ceramics,which can provide data and ideas for expanding the range of their clinical applications.

One-step co-doping of ZnO and Zn^(2+)in osteoinductive calcium phosphate ceramics with synergistic antibacterial activity for regenerative repair of infected bone defect

How to endow bone grafts with long-term antibacterial activity and good bone regenerative ability to achieve the regenerative repair of infected bone defects has been the focus of the clinical treatment of osteomyelitis.The present study introduced a novel one-step route to realizing the co-doping of zinc oxide(ZnO)and zinc ion(Zn^(2+))in biphasic calcium phosphate(BCP)ceramics to utilize their synergistic antibacterial.Compared with the conventional BCP ceramics(BCP-Ca),the ZnO/Zn^(2+)co-doping ones(BCP-Zn)possessed strong antibacterial ability on E.coli and S.aureus as well as stimulated the osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs)effectively.The synergistic antibacterial mechanism of ZnO and Zn^(2+)was also investigated.BCP-Zn showed excellent osteoinductivity and angiogenesis at three months postoperatively in the canine intramuscular implantation model.Moreover,BCP-Zn exhibited excellent anti-infective ability and bone regenerative repair compared to BCP-Ca and control groups in the infected bone defect model of rat femur.Collectively,these findings suggest that the simultaneous introduction of ZnO/Zn^(2+)could have immense potential to expand the application of osteoinductive BCP ceramics in the regenerative repair of infected bone defects.

Application of osteoinductive calcium phosphate ceramics in giant cell tumor of the sacrum:report of six cases

This study aimed at evaluating the possibility and effectiveness of osteoinductive bioceramics to fill the tumor cavity following the curettage of sacral giant cell tumor(GCT).Six patients(four females and two males,25–45 years old)underwent nervesparing surgery,in which the tumor was treated by denosumab,preoperative arterial embolization and extensive curettage.The remaining cavity was filled with commercial osteoinductive calcium phosphate(CaP)bioceramics,whose excellent osteoinductivity was confirmed by intramuscular implantation in beagle canine.All patients were followed by computed tomography(CT)scans postoperatively.According to the modified Neer criterion,five cases obtained Type I healing status,and one case had Type II.At the latest follow-up,no graft-related complications and local recurrence were found.The CT scan indicated a median time of healing initiation of 3months postoperatively,and the median time for relatively complete healing was 12months.The excellent bone regenerative ability of the ceramics was also confirmed by increased CT attenuation value,blurred boundary and cortical rim rebuilding.In conclusion,osteoinductive CaP bioceramics could be an ideal biomaterial to treat the large remaining cavity following extensive curettage of sacral GCT.However,further investigation with more cases and longer follow-up was required to confirm the final clinical effect.

Osteoinductive intramedullary implant as an adjunctive therapy for bone transport:A promising approach to accelerate bone defect healing

A recent study published in Nature Communications presents a unique approach using an osteoinductive intra-medullary(IM)implant as an adjunctive therapy for bone transport distraction osteogenesis.The study demon-strates that this innovative technique achieves early bony bridging,eliminates pin tract infections,and prevents docking site non-union,offering significant potential for the treatment of large bone defects.The study also highlights an additive effect of the osteoinductive IM implant on distraction osteogenesis for managing bone defect.

Preparation and osteoinduction of active micro-arc oxidation films on Ti-3Zr-2Sn-3Mo-25Nb alloy

A layer of porous film containing Ca and P was prepared by the micro-arc oxidation method on the surface of a novel near β biomedical Ti-3Zr-2Sn-3Mo-25Nb alloy, and then NH2- active group was introduced to the films by activation treatment. The phase composition, surface micro-topography and elemental characteristics of the micro-arc oxidation films were investigated with XRD, SEM, EDS and XPS, and the osteoinduction of the micro-arc oxidation films was tested using the simulated body fluid immersion, the in-vitro osteoblast cultivation test and animal experiment. The results show that the oxide layer is a kind of porous ceramic intermixture and contains Ca and P. The films in the simulated body fluid can induce apatite formation, resulting in excellent bioactivity. The cell test discovers that osteoblasts can grow well on the surface of micro-arc oxidation films. And the Ti-3Zr-2Sn-3Mo-25Nb biomedical alloy coated with active porous calcium-phosphate films shows better osteoinduction in vivo.

Ectopic Bone Formation in vivo Induced by a Novel Synthetic Peptide Derived from BMP-2 Using Porous Collagen Scaffolds

To investigate the osteoinductive and ectopicly osteogenic effects of a novel peptide P24 derived from bone morphogenetic protein 2 （BMP2）, biodegradable collagen scaffolds （CS） were used to load BMP-2-derived peptide solutions with different concentrations （0.4 mg peptide/CS, 0.1 mg peptide/CS and pure CS, respectively）, and the implants were implanted into muscular pockets on the back of Wistar rats. Radiographs and histological analysis were performed to evaluate the ectopic bone effects. Active ectopic bone formation was seen in both groups containing the peptide at different concentration （0.4 mg and 0.1 mg）, whereas no bone formation and only fibrous tissue was seen in the pure CS group. The new bone formation induced by the peptide P24 displayed a dose-dependent and time-dependent efficiency. The new bone formation in the 0.4 mg peptide/CS group significantly increased than that of the 0.1 mg peptide/CS group. This novel BMP-2-derived peptide had excellent osteoinductive and ectopicly osteogenic properties which were similar to those of BMP2.

Porous Calcium Phosphate Ceramic Scaffolds for Tissue Engineering

This study examined the biological response of two porous calcium phosphate ceramics, hydroxyapntite （ HA ） and hydroxyapaptite/β-tricalcium phosphate （ HA/β- TCP ） scaffolds. Three different cell types , a human osteoblastic cell line （ HOS ） , primary human osteoblasts （HOB） and human mesenehymal stem cells （MSCs）, were used to examine biocompatibility and osteoinductive capacity. The experimental results showed both materials were highly biocompatible and proliferation was significantly greater on pure HA （ P 〈 0.01 ）, with a peak in proliferation at day 7. Protein levels were significantly higher （ P 〈 0.05） than the control Thermanox（ TMX （ tm） ） for both test materials. Osteoinduction of MSCs was observed on both test materials, with cells seeded on HA/ β-TCP showing greater alkaline phosphatase activity compared to HA alone, indicating an enhancement in osteoinductive property. Both materials show good potential for use as tissue engineered scaffolds.

Immobilization of RGD Peptide onto the Surface of Apatite-Wollastonite Ceramic for Enhanced Osteoblast Adhesion and Bone Regeneration

The arginine-glycine-aspartic （RGD） acid peptide was grafted to the surface of apatitewollastonite （AW） ceramic in an effort to improve its cell adhesion, proliferation and osteoinduction. RGD peptide was covalently immobilized onto the surface of AW ceramic via the synthetic cross linker AA.PTS-E and 1-ethyl-3-（3-dimethylaminopropyl）carbodiimide （EDC）. The modified surfaces were characterized by attenuated total reflectance Fourier transform infrared spectroscopy （ATR-FTIR） and X-ray photoelectron spectroscopy （XPS）. The chemical analysis indicated that RGD peptide had been immobilized onto the AW surface successfully. The growth of osteoblast-like cells （MG63） showed that modifying the AW surface with RGD peptide enhanced the cell adhesion and proliferation. And the histological evaluation of RGD-AW showed that the bone regeneration and remodeling process were significantly enhanced compared to the original AW ceramics after 2, 4 and 8 weeks implantation in rabbit＇s femoral condyles.

In Vitro Characterizations of PLLA/β-TCP Porous Matrix Materials and RMSC-PLLA-β-TCP Composite Scaffolds

To develop a novel degradable poly (L-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) bioactive materials for bone tissueengineering, β-TCP powder was produced by a new wet process. Porous scaffolds were prepared by three steps, i.e. solventcasting, compression molding and leaching stage. Factors influencing the compressive strength and the degradation behaviorof the porous scaffold, e.g. weight fraction of pore forming agent-sodium chloride (NaCl), weight ratio of PLLA: β-TCP,the particle size of β-TCP and the porosity, were discussed in details. Rat marrow stromal cells (RMSC) were incorporatedinto the composite by tissue engineering approach. Biological and osteogenesis potential of the composite scaffold weredetermined with MTT assay, alkaline phosphatase (ALP) activity and bone osteocalcin (OCN) content evaluation. Resultsshow that PLLA/β-TCP bioactive porous scaffold has good mechanical and pore structure with adjustable compressive strengthneeded for surgery. RMSCs seeding on porous PLLA/β-TCP composite behaves good seeding efficacy, biocompatibility andosteoinductive potential. Osteoprogenitor cells could well penetrate into the material matrix and begin cell proliferation andosteogenic differentiation. Osseous matrix could be formed on the surface of the composite after culturing in vitro. It isexpected that the PLLA/β-TCP porous composites are promising scaffolds for bone tissue engineering in prosthesis surgery.

Heterotopic ossification after the use of recombinant human bone morphogenetic protein-7

AIM To present the incidence of heterotopic ossification after the use of recombinant human bone morphogenetic protein-7(rhB MP-7) for the treatment of nonunions.METHODS Bone morphogenetic proteins(BMPs) promote bone formation by auto-induction. Recombinant human BMP-7 in combination with bone grafts was used in 84 patients for the treatment of long bone nonunions. All patients were evaluated radiographicaly for the development of heterotopic ossification during the standard assessment for the nonunion healing. In all patients(80.9%) with radiographic signs of heterotopic ossification, a CT scan was performed. Nonunion site palpation and ROM evaluation of the adjacent jointswere also carried out. Factors related to the patient(age, gender), the nonunion(location, size, chronicity, number of previous procedures, infection, surrounding tissues condition) and the surgical procedure(graft and fixation type, amount of rhB MP-7) were correlated with the development of heterotopic ossification and statistical analysis with Pearsons χ~2 test was performed.RESULTS Eighty point nine percent of the nonunions treated with rh BMP-7, healed with no need for further procedures. Heterotopic bone formation occurred in 15 of 84 patients(17.8%) and it was apparent in the routine radiologi-cal evaluation of the nonunion site, in a mean time of 5.5 mo after the rh BMP-7 application(range 3-12). The heterotopic ossification was located at the femur in 8 cases, at the tibia in 6, and at the humerus in οne patient. In 4 patients a palpable mass was present and only in one patient, with a para-articular knee nonunion treated with rhB MP-7, the size of heterotopic ossification affected the knee range of motion. All the patients with heterotopic ossification were male. Statistical analysis proved that patient's gender was the only important factor for the development of heterotopic ossification(P = 0.007). CONCLUSION Heterotopic ossification after the use of rh BMP-7 in nonunions was common but it did not compromise the final clinical outcome in most cases, and affected only male patients.

Dual-Wavelength Photosensitive Nano-in-Micro Scaffold Regulates Innate and Adaptive Immune Responses for Osteogenesis

The immune response of a biomaterial determines its osteoinductive effect.Although the mechanisms by which some immune cells promote regeneration have been revealed,the biomaterial-induced immune response is a dynamic process involving multiple cells.Currently,it is challenging to accurately regulate the innate and adaptive immune responses to promote osteoinduction in biomaterials.Herein,we investigated the roles of macrophages and dendritic cells(DCs)during the osteoinduction of biphasic calcium phosphate(BCP)scaffolds.We found that osteoinductive BCP directed M2 macrophage polarization and inhibited DC maturation,resulting in low T cell response and efficient osteogenesis.Accordingly,a dual-targeting nano-in-micro scaffold(BCP loaded with gold nanocage,BCP-GNC)was designed to regulate the immune responses of macrophages and DCs.Through a dual-wavelength photosensitive switch,BCP-GNC releases interleukin-4 in the early stage of osteoinduction to target M2 macrophages and then releases dexamethasone in the later stage to target immature DCs,creating a desirable inflammatory environment for osteogenesis.This study demonstrates that biomaterials developed to have specific regulatory capacities for immune cells can be used to control the early inflammatory responses of implanted materials and induce osteogenesis.

The Clinical Application of Human Bone Matrix Gelatin

This paper reports the results of 24 cases of bone defect resulting from bone tumor or tumor condition excision, and of posterior spinal fusion, treated by human bone matrix gelatin. The success rate of bone defect repair and spinal fusion is 91. 67 %. The results suggest that human bone matrix gelatin has. excellent osteoinductive effect and is ideal substitute for bone autografts.

The Role of Microstructure of Highly Purified Beta-Tricalcium Phosphate for Osteoinduction in Canine Dorsal Muscles

Porous β-tricalcium phosphate (TCP) displays osteoinductivity in certain animals in the absence of osteoinductive agents. We evaluated whether the microstructure may be an important determinant of osteoinduction, and also investigated how bone formation was promoted using β-TCP combined with bone marrow aspirates. We prepared two types of β-TCP, namely, β-TCP A, which possessed interconnected macropores and micropores, and β-TCP B, which possessed macropores but had less detectable micropores. These were implanted with or without marrow in canine muscles. Bone formation and the resorption of each β-TCP implant were evaluated histologically. Newly formed bone began to appear at day 42 in the implants of β-TCP A alone, but the implants of β-TCP B alone did not show any bone formation by day 42. Meanwhile, bone formation was already evident on day 14 by loading with bone marrow aspirates with or without micropores. By immunohistochemistry, the number of cathepsin K-positive cells (osteoclasts) increased as time passed in the implants of β-TCP A alone, while the number of the osteoclasts did not change obviously in the implants of β-TCP B alone from day 14 to 56. Reticular fibrils were evident within the β-TCP A, and were barely observed in the β-TCP B in the silver impregnation. The present result would bring about the possible role to enhance the importance of the surface microstructure for the better osteoinductivity. Our findings suggest that the combination of porous β-TCP and bone marrow facilitates bone formation.

Osteoinduction and Osteoconduction with Porous Beta-Tricalcium Phosphate Implanted after Fibular Resection in Humans

Osteoinductive properties of β-TCP remain unknown in humans. It is important to improve the bone grafts which have been the standard treatment for bone defect due to their biocompatibility and bone-healing properties. The purpose of this study was to radiologically clarify the bone forming property of β-TCP by evaluating the replacement of β-TCP by newly formed bone in the defect after fibular resection and to examine the histological features of a β-TCP specimen three months after grafting. Radiographs of 17 patients who underwent β-TCP grafting were evaluated. Osteoinductive and osteoconductive properties were assessed by examining bone formation from the remnant fibula, periosteum, and β-TCP alone. In one case, β-TCP was removed later because of postoperative complications and was evaluated histologically. Twenty two of 34 sites between the remnant fibula and β-TCP had achieved good bone regeneration. Five of 14 sites between the periosteum and β-TCP had achieved good bone regeneration. We found immature but evident bone formation in three cases with no osseous and periosteal sites. Histological analysis revealed bone formation on the outer macropore surface of β-TCP. Some blood vessels formed in the macropores expressed CD31 and CD34, while a few lymphatic vessels expressed CD34 and podoplanin. Thus, the osteoinductive ability of β-TCP alone was demonstrated in humans radiographically for the first time. The histological morphology of β-TCP was demonstrated at an early stage after grafting in humans.