Treatment Of Large Bone Defects Research Articles

Mild Thermotherapy-Assisted GelMA/HA/MPDA@Roxadustat 3D-Printed Scaffolds with Combined Angiogenesis-Osteogenesis Functions for Bone Regeneration.

Early reconstruction of the vascular network is a prerequisite to the effective treatment of substantial bone defects. Traditional 3D printed tissue engineering scaffolds designed to repair large bone defects do not effectively regenerate the vascular network, and rely only on the porous structure within the scaffold for nutrient transfer and metabolic waste removal. This leads to delayed bone restoration and hence functional recovery. Therefore, strategies for generation scaffolds with the capacity to efficiently regenerate vascularization should be developed. This study loads roxarestat (RD), which can stabilize HIF-1α expression in a normoxic environment, onto the mesopore polydopamine nanoparticles (MPDA@RD) to enhance the reconstruction of vascular network in large bone defects. Subsequently, MPDA@RD is mixed with GelMA/HA hydrogel bioink to fabricate a multifunctional hydrogel scaffold (GHM@RD) through 3D printing. In vitro results show that the GHM@RD scaffolds achieve good angiogenic-osteogenic coupling by activating the PI3K/AKT/HSP90 pathway in BMSCs and the PI3K/AKT/HIF-1α pathway in HUVECs under mild thermotherapy. In vivo experiments reveal that RD and mild hyperthermia synergistically induce early vascularization and bone regeneration of critical bone defects. In conclusion, the designed GHM@RD drug delivery scaffold with mild hyperthermia holds great therapeutic value for future treatment of large bone defects.

Fabrication of 3D printed trabecular bone-templated scaffolds modified with rare earth europium (III)-based complex for enhancing mitochondrial function in bone regeneration

Bone defects have been a tough clinical challenge. The natural trabecular tissue reflects a balance between the minimal metabolic cost of maintenance and maximal network stability, with mitochondria being the energy suppliers for osteogenesis. Herein, a 3D printed trabecular bone-templated scaffold composed of polylactide (PLA) modified with europium (III)-organic ligands (polydopamine and chitooligosaccharide, PDA/COS@Eu) was fabricated (denoted as Tra-PLA/PDA/COS@Eu) to augment bone repair by facilitating mitochondrial function. First, the trabecular bone templated-scaffold provides superior mechanical performance and permeability in contrast to a computer aided designed (CAD) scaffold under a same volume fraction. Tra-PLA/PDA/COS@Eu scaffold up regulated PI3K/AKT/S6K/HIF-1α pathway and significantly promoted BMSCs proliferation and osteogenic differentiation. In addition, Tra-PLA/PDA/COS@Eu scaffold provided anti-inflammatory environment by promoting macrophages M2 polarization through COS, and significantly stimulated BMSCs osteogenesis with enhanced mitochondrial function and biosynthesis. Remarkably, Eu ions are the key ingredient in enhancing mitochondrial function and biosynthesis in BMSCs. Further studies showed that the above-mentioned facilitations in a rabbit bone defect model were found to be more significant with trabecular bone-templated scaffolds, as opposed to CAD scaffolds. In summary, this novel trabecular bone-templated scaffold targeting mitochondrial function has the potential to become an effective method in the treatment of large bone defects.

Can locking plate fixation and free Vascularised fibular transfer with skin island achieve good functional outcome in the treatment of large bone defects of Tibia ? A study of 26 cases

BackgroundDespite the availability of multiple treatment options, management of tibial bone loss continues to be a challenge. Free vascularized fibula graft (FVFG) with a skin paddle offers better advantages over the other methods. We aimed to study the functional outcomes and QALY of patients with large tibial bone defects following FVFG with a locking plate in 26 patients. Materials and MethodsWe analyzed 26 consecutive patients with large tibial bone defects treated by free vascularized fibular graft (FVFG) and stabilization using a long locking plate between 2009 and 2018. All were followed up for a mean period of 42 months (24 months to 120 months). Bony union, graft hypertrophy, and complications such as stress fracture and infections were assessed. Multivariate regression analysis was performed to identify any association between demographic factors, injury characteristics, treatment-related factors, and fibular hypertrophy. Additionally, The EQ-5D quality-of-life (QOL) indices were obtained using the SF-12 score to evaluate the patients' overall quality of life. ResultsThe mean age of the patients at the time of presentation was 36.26 yrs (range, 18–60 years). The cause of bone loss was open injury in 16 patients and infected nonunion in 10 patients. Complete union was achieved in 25 patients (96 %) without any requirement of additional surgical procedures. The mean union time of the graft was 4.04 months (range, 3–6 months). The mean fibular hypertrophy calculated by De Boer index was 0.61 %, 11 %, 28.24 % and 52.52 % at 3,6 months and 1 and 2 years respectively. Patients with metaphyseal bone loss have significant fibular hypertrophy. Participants in our study experienced a quality of life equivalent to 0.88 (range 0.79–0.99) of perfect health. ConclusionsFVFG with skin paddle and LCP fixation for massive tibial bone loss achieved satisfactory outcome and QALY even in the challenging healthcare environment of South India, a developing country.It maintains alignment, promotes graft hypertrophy, and prevents stress fractures. Level of evidenceLevel 4 Level of clinical careLevel I Tertiary trauma centre

Osteogenic Potential of a Biomaterial Enriched with Osteostatin and Mesenchymal Stem Cells in Osteoporotic Rabbits.

Mesoporous bioactive glasses (MBGs) of the SiO2-CaO-P2O5 system are biocompatible materials with a quick and effective in vitro and in vivo bioactive response. MBGs can be enhanced by including therapeutically active ions in their composition, by hosting osteogenic molecules within their mesopores, or by decorating their surfaces with mesenchymal stem cells (MSCs). In previous studies, our group showed that MBGs, ZnO-enriched and loaded with the osteogenic peptide osteostatin (OST), and MSCs exhibited osteogenic features under in vitro conditions. The aim of the present study was to evaluate bone repair capability after large bone defect treatment in distal femur osteoporotic rabbits using MBGs (76%SiO2-15%CaO-5%P2O5-4%ZnO (mol-%)) before and after loading with OST and MSCs from a donor rabbit. MSCs presence and/or OST in scaffolds significantly improved bone repair capacity at 6 and 12 weeks, as confirmed by variations observed in trabecular and cortical bone parameters obtained by micro-CT as well as histological analysis results. A greater effect was observed when OST and MSCs were combined. These findings may indicate the great potential for treating critical bone defects by combining MBGs with MSCs and osteogenic peptides such as OST, with good prospects for translation to clinical practice.

Evaluation of post-extraction alveolar regeneration time in advanced periodontal disease employing novel hydroxyapatitepolymeric (FlexiOss®Vet) in dogs.

The purpose of the study was to demonstrate bone regeneration and the time of formation of new alveolar bone based on implanted FlexiOss®Vet bone substitute material. The study attempted to determine the time taken to fill bone defects with newly formed osseous bone compared to alveoli with a standard method of filling the post-extraction alveolus with a collagen sponge. The study was conducted on a group of 12 dogs with advanced periodontal disease (stage IV) in which polymeric hydroxyapatite bone substitute material (FlexiOss®Vet) was implanted into alveoli on the right side, and collagen sponge was implanted into alveoli on the left side in the same patient. The patients underwent macroscopic inspection and X-ray examination at different periods of regeneration after the procedure. On the right side, macroscopically, the alveoli showed features of marked enlargement, and on X-ray examination they gave opacity to X-rays and there was no clear border between the alveolus and alveolar bone. On the left side, the alveoli were clearly penetrable to X-rays, and hollow alveoli filled mainly with connective tissue were observed. The study also showed a significant reduction in bone healing time in alveoli with implants compared to self-healing alveoli. These results suggest that the implanted material is significantly beneficial in the process of bone regeneration in large bone defects in dogs and notably shortens the process of bone regeneration after tooth extractions. It is presumed that this could reflect a model for the treatment of large bone defects in not only the maxilla and mandible, but also long bones, and that it could be a model for alveolar healing in humans.

Docking site complications analysis of Ilizarov bone transport technique in the treatment of tibial bone defects

BackgroundTreating long bone defects of the extremities caused by trauma, infection, tumours, and nonunion has been challenging for clinical orthopaedic surgeons. Bone transport techniques have the potential to treat bone defects. However, inevitable docking site complications related to bone transport techniques have been reported in many studies. The purpose of this study was to investigate the risk factors associated with docking site complications in patients who underwent the Ilizarov bone transport technique for the treatment of tibial bone defects.MethodsThis retrospective study included 103 patients who underwent bone transport for the treatment of large bone defects in the tibia from October 2012 to October 2019. Patient demographic data, complications and clinical outcomes after a minimum of 2 years of follow-up were collected and retrospectively analysed. Additionally, univariate analysis and logistic regression analysis were used to analyse the factors that may affect the development of docking site complications in patients with tibial bone defects treated with the Ilizarov bone transport technique. The clinical outcomes were evaluated using the Association for the Study and Application of the Ilizarov criteria (ASAMI) at the last clinical follow-up.ResultsAll 103 patients with an average follow-up of 27.5 months. The docking site complications rate per patient was 0.53, and delayed union occurred in 22 cases (21.4%), axial deviation occurred in 19 cases (18.4%) and soft tissue incarceration occurred in 10 cases (9.7%). According to the results of the logistic regression analysis, the bone defect length (P = 0.001, OR = 1.976), and bone defect of distal 1/3 (P = 0.01, OR = 1.976) were significantly correlated with delayed union. Bone defect length (P < 0.001, OR = 1.981) and external fixation time (P = 0.012, OR = 1.017) were significantly correlated with axial deviation. Soft tissue defects (P = 0.047, OR = 6.766) and the number of previous operations (P = 0.001, OR = 2.920) were significantly correlated with soft tissue incarceration. The ASAMI bone score at the last follow-up showed a rate of excellent and good bone results of 95.1% and a rate of excellent functional results of 90.3%.ConclusionThe Ilizarov bone transport technique is a practical and effective method for the treatment of tibial bone defects. However, the incidence of complications at the docking site is high, of which bone defect length, external fixation time, the number of previous operations, soft tissue defects and the bone defect of distal 1/3 are statistically significantly associated with the occurrence of docking site complications.

Accelerated bone defect repairment by carbon nitride photoelectric conversion material in core–shell nanofibrous depended on neurogenesis

Highly efficient bone repair materials are essential for the clinical treatment of large bone defects. This study aimed to develop nanofibrous scaffolds for bone defect repairment. Here, we reported that insulin like growth factor (IGF) adsorbed into phosphorus doped graphite phase carbon nitride (C3N4(P)) as core, and nerve growth factor (NGF) adsorbed into silk fibroin (SF) as shell to prepare nanofibrous scaffolds (IGF@C3N4(P)/NGF@SF) by coaxial electrospining for accelerating bone formation. Additionally, C3N4(P) was employed as a photoelectric conversion material capable of achieving the mutual conversion of light and electricity. Remarkably, we found that red light + IGF@C3N4(P)/NGF@SF scaffold may enhance osteogenesis in bone mesenchymal stem cells (BMSCs) by activating the extracellular regulated protein kinases1/2 (Erk1/2), which subsequently activated runt-related transcription factor 2 (Runx2) and the mammalian target of rapamycin (mTOR) pathway. Consequently, the mRNA expression levels of downstream osteogenic related genes were increased. Furthermore, we observed that red light + IGF@C3N4(P)/NGF@SF scaffold promoted BMSCs induced neural differentiation cells differentiated into neuron and upregulated the mRNA expression levels of neuron specific related genes. Interestingly, we also demonstrated the formation of new neurons in the Haversian canal within the cranial defect area in mice, indicating that red light + IGF@C3N4(P)/NGF@SF scaffold promoted osteogenesis with neurogenesis. Moreover, our RNA sequencing results supported the activation of neurogenesis along with osteogenesis. Based on these novel findings, we conclude that red light + IGF@C3N4(P)/NGF@SF scaffold exhibits great potential as a prospective biomaterial for promoting bone defect repairment with neurogenesis, and the utilization of red light is crucial in facilitating this process.

Cold physical plasma treatment optimization for improved bone allograft processing.

In musculoskeletal surgery, the treatment of large bone defects is challenging and can require the use of bone graft substitutes to restore mechanical stability and promote host-mediated regeneration. The use of bone allografts is well-established in many bone regenerative procedures, but is associated with low rates of ingrowth due to pre-therapeutic graft processing. Cold physical plasma (CPP), a partially ionized gas that simultaneously generates reactive oxygen (O2) and nitrogen (N2) species, is suggested to be advantageous in biomedical implant processing. CPP is a promising tool in allograft processing for improving surface characteristics of bone allografts towards enhanced cellularization and osteoconduction. However, a preclinical assessment regarding the feasibility of pre-therapeutic processing of allogeneic bone grafts with CPP has not yet been performed. Thus, this pilot study aimed to analyze the bone morphology of CPP processed allografts using synchrotron radiation-based microcomputed tomography (SR-µCT) and to analyze the effects of CPP processing on human bone cell viability and function. The analyzes, including co-registration of pre- and post-treatment SR-µCT scans, revealed that the main bone morphological properties (total volume, mineralized volume, surface area, and porosity) remained unaffected by CPP treatment if compared to allografts not treated with CPP. Varying effects on cellular metabolic activity and alkaline phosphatase activity were found in response to different gas mixtures and treatment durations employed for CPP application. It was found that 3min CPP treatment using a He + 0.1% N2 gas mixture led to the most favourable outcome regarding a significant increase in bone cell viability and alkaline phosphatase activity. This study highlights the promising potential of pre-therapeuthic bone allograft processing by CPP prior to intraoperative application and emphasizes the need for gas source and treatment time optimization for specific applications.

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 intramedullary (IM) implant as an adjunctive therapy for bone transport distraction osteogenesis. The study demonstrates 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.

Silicone rubber sealed channel induced self-healing of large bone defects: Where is the limit of self-healing of bone?

BackgroundLarge defects of long tubular bones due to severe trauma, bone tumor resection, or osteomyelitis debridement are challenging in orthopedics. Bone non-union and other complications often lead to serious consequences. At present, autologous bone graft is still the gold standard for the treatment of large bone defects. However, autologous bone graft sources are limited. Silicon rubber (SR) materials are widely used in biomedical fields, due to their safety and biocompatibility, and even shown to induce nerve regeneration. Materials and methodsWe extracted rat bone marrow mesenchymal stem cells (BMMSCs) in vitro and verified the biocompatibility of silicone rubber through cell experiments. Then we designed a rabbit radius critical sized bone defect model to verify the effect of silicone rubber sealed channel inducing bone repair in vivo. ResultsSR sealed channel could prevent the fibrous tissue from entering the fracture end and forming bone nonunion, thereby inducing self-healing of long tubular bone through endochondral osteogenesis. The hematoma tissue formed in the early stage was rich in osteogenesis and angiogenesis related proteins, and gradually turned into vascularization and endochondral osteogenesis, and finally realized bone regeneration. ConclusionsIn summary, our study proved that SR sealed channel could prevent the fibrous tissue from entering the fracture end and induce self-healing of long tubular bone through endochondral osteogenesis. In this process, the sealed environment provided by the SR channel was key, and this might indicate that the limit of self-healing of bone exceeded the previously thought. The translational potential of this articleThis study investigated a new concept to induce the self-healing of large bone defects. It could avoid trauma caused by autologous bone extraction and possible rejection reactions caused by bone graft materials. Further research based on this study, including the innovation of induction materials, might invent a new type of bone inducing production, which could bring convenience to patients. We believed that this study had significant meaning for the treatment of large bone defects in clinical practice.

Research Progress of Bone Implant Additive Manufacturing

Bone implants are currently a solution for the treatment of large bone defects. The structural design and manufacture of complex bone tissue engineering scaffolds can be realized by using additive manufacturing technology. Advances in additive manufacturing techniques and the continued emergence of related materials provide different opportunities for new bone implant techniques to achieve the challenging requirements of proposed bone implants. The purpose of this review is to present the current status and analyze the advantages and disadvantages of various additive manufacturing for the manufacturing of bone implants. Five different manufacturing techniques (multilayer deposition forming, ink direct writing, laser melting, laser sintering, and light curing are reviewed.) and the currently required bone implants technology, and thus put forward the research and development direction of additive manufacturing suitable for bone implants.

Microenvironment-targeted strategy steers advanced bone regeneration.

Treatment of large bone defects represents a great challenge in orthopedic and craniomaxillofacial surgery. Traditional strategies in bone tissue engineering have focused primarily on mimicking the extracellular matrix (ECM) of bone in terms of structure and composition. However, the synergistic effects of other cues from the microenvironment during bone regeneration are often neglected. The bone microenvironment is a sophisticated system that includes physiological (e.g., neighboring cells such as macrophages), chemical (e.g., oxygen, pH), and physical factors (e.g., mechanics, acoustics) that dynamically interact with each other. Microenvironment-targeted strategies are increasingly recognized as crucial for successful bone regeneration and offer promising solutions for advancing bone tissue engineering. This review provides a comprehensive overview of current microenvironment-targeted strategies and challenges for bone regeneration and further outlines prospective directions of the approaches in construction of bone organoids.

Development of a novel thermogelling PEC-based ECM mimicking nanocomposite bioink for bone tissue engineering

Non-union of large bone defects has been an existing clinical problem. 3D extrusion-based bioprinting provides an efficient approach to tackle such problems. This approach enables the use of various biomaterials, cell types and growth factors in developing a superior bone graft that is specific to the defect. In this article, we have designed and printed an ECM mimicking, self-assembled polyelectrolyte complex (PEC) based fibrous bioink using natural polymers like chitosan-polygalacturonic acid (PGA) and other biomaterials – gelatin, laponite and nanohydroxyapatite with a modified 3D printer. The developed bioink possesses a thermo-reversible sol-gel transition at physiological pH and temperature. Here, we demonstrated that post-printing, our fiber-reinforced bioink had significant cell proliferation with cell viability of >80% and negligible cell morbidity. The practicability of developing this self-assembled PEC-based bioink was assessed. Bioink with 4% gelatin (PECHLG4) had optimal printability with a minimal swelling ratio of approximately 3%. The printed scaffold had integrity for a period of 8 days under 0.5 mg/mL lysozyme concentration. We also evaluated the mechanical property of the bioink using compression analysis which gave an elastic modulus of 16 KPa. This combination of natural polymers and nanocomposite, along with a fibrous network of PECs, is itself a novel approach for 3D bioprinting and can be a preliminary proposition for the treatment of large bone defects.

Spatiotemporalized Hydrogel Microspheres Promote Vascularized Osteogenesis via Ultrasound Oxygen Delivery

AbstractDisturbance of spatiotemporal oxygen balance is the main cause of delayed healing or nonhealing of large bone defects. The accurate administration of oxygen to regulate disruptions in the spatiotemporal oxygen equilibrium during 9 h of hypoxia is imperative for bone tissue regeneration. Herein, oxygen‐loaded nanobubbles prepared by double emulsification are successfully embedded in GelMA/HepMA microsphere macromolecular meshwork by microfluidic techniques, and a spatiotemporalized hydrogel microsphere is constructed by noncovalently binding bone morphogenetic protein 2 (BMP‐2). The spatiotemporalized hydrogel microspheres precisely “remote control” oxygen release by ultrasound in vitro 9 h after bone injury to regulate spatiotemporal oxygen homeostasis disorder, maintain a high level of vascular endothelial growth factor (VEGF) expression, and accelerate bone repair. The spatiotemporalized hydrogel microspheres possess good oxygen‐carrying capacity and ultrasonic responsiveness, and the oxygen concentration increases to 1.63, 1.95, 2.11, and 2.29 times under the ultrasound action at different intensities of 1, 2, 3, and 4 W, respectively, providing the conditions for the precise regulation of spatiotemporal oxygen balance disorder by ultrasound. In the in vitro hypoxia model and in vivo rat femoral defect model, the spatiotemporal hydrogel microspheres show good vascularization and osteogenesis capabilities, which provide a new strategy for the clinical treatment of large bone defects.

An osteoinductive and biodegradable intramedullary implant accelerates bone healing and mitigates complications of bone transport in male rats.

Bone transport is a surgery-driven procedure for the treatment of large bone defects. However, challenging complications include prolonged consolidation, docking site nonunion and pin tract infection. Here, we develop an osteoinductive and biodegradable intramedullary implant by a hybrid tissue engineering construct technique to enable sustained delivery of bone morphogenetic protein-2 as an adjunctive therapy. In a male rat bone transport model, the eluting bone morphogenetic protein-2 from the implants accelerates bone formation and remodeling, leading to early bony fusion as shown by imaging, mechanical testing, histological analysis, and microarray assays. Moreover, no pin tract infection but tight osseointegration are observed. In contrast, conventional treatments show higher proportion of docking site nonunion and pin tract infection. The findings of this study demonstrate that the novel intramedullary implant holds great promise for advancing bone transport techniques by promoting bone regeneration and reducing complications in the treatment of bone defects.

Combination therapy with BMSCs‑exosomes and porous tantalum for the repair of femur supracondylar defects.

In the field of orthopedics, defects in large bones have proven challenging to resolve. The aim of the present study was to address this problem through the combination of tantalum metal (pTa) with exosomes derived from bone marrow mesenchymal stem cells (BMSCs), which have the potential to enhance regeneration of full thickness femoral bone defects in rats. Cell culture results demonstrated that exosomes improved the proliferation and differentiation of BMSCs. Following establishment of a supracondylar femoral bone defect, exosomes and pTa were implanted into the defect area. Results demonstrated that pTa acts as a core scaffold for cell adhesion and exhibits good biocompatibility. Moreover, micro‑CT scan results as well as histological examination demonstrated that pTa had a significant effect on osteogenesis, with the addition of exosomes further promoting bone tissue regeneration and repair. In conclusion, this novel composite scaffold can effectively promote bone regeneration in large bone defect areas, providing a new approach for the treatment of large bone defects.

One Stage Masquelets Technique: Evaluation of Different Forms of Membrane Filling with and without Bone Marrow Mononuclear Cells (BMC) in Large Femoral Bone Defects in Rats.

The classic two-stage masquelet technique is an effective procedure for the treatment of large bone defects. Our group recently showed that one surgery could be saved by using a decellularized dermis membrane (DCD, Epiflex, DIZG). In addition, studies with bone substitute materials for defect filling show that it also appears possible to dispense with the removal of syngeneic cancellous bone (SCB), which is fraught with complications. The focus of this work was to clarify whether the SCB can be replaced by the granular demineralized bone matrix (g-DBM) or fibrous demineralized bone matrix (f-DBM) demineralized bone matrix and whether the colonization of the DCD and/or the DBM defect filling with bone marrow mononuclear cells (BMC) can lead to improved bone healing. In 100 Sprague Dawley rats, a critical femoral bone defect 5 mm in length was stabilized with a plate and then encased in DCD. Subsequently, the defect was filled with SCB (control), g-DBM, or f-DBM, with or without BMC. After 8 weeks, the femurs were harvested and subjected to histological, radiological, and biomechanical analysis. The analyses showed the incipient bony bridging of the defect zone in both groups for g-DBM and f-DBM. Stability and bone formation were not affected compared to the control group. The addition of BMCs showed no further improvement in bone healing. In conclusion, DBM offers a new perspective on defect filling; however, the addition of BMC did not lead to better results.

Effect of low-intensity pulsed ultrasound on osteogenic differentiation of human induced membrane-derived cells in Masquelet technique

IntroductionThe Masquelet technique is a relatively new method for large bone defect treatment. In this technique, grafted bone tissue is used, and after the cement is removed, the induced membrane (IM; that form around the cement spacers placed in the bone defect region) is thought to play an important role in promoting bone formation. On the other hand, low-intensity pulsed ultrasound (LIPUS) is known to promote fracture healing and angiogenesis through mechanical stimulation. This study aimed to investigate the in vitro effects of LIPUS on the osteogenic differentiation of human induced membrane-derived cells (IMCs). MethodsSeven patients who had been treated using the Masquelet technique were enrolled. The IM was harvested during the second stage of the technique. IMCs were isolated, cultured in growth medium, and then divided into two groups: (1) control group, IMCs cultured in osteogenic medium without LIPUS, and (2) LIPUS group, IMCs cultured in osteogenic medium with LIPUS treatment. Adherent cells from the IM samples were harvested after the first passage and evaluated for cell surface protein expression using immunostaining. A cell proliferation assay was used to count the number of IMCs using a hemocytometer. Osteogenic differentiation capability was assessed using an alkaline phosphatase (ALP) activity assay, Alizarin Red S staining, and real-time reverse transcription-polymerase chain reaction. ResultsCell surface antigen profiling revealed that the IMCs contained cells positive for the mesenchymal stem cell–related markers CD73, CD90, and CD105. No significant difference in cell numbers was found between the control and LIPUS groups. The ALP activity of IMCs in the LIPUS group was significantly higher than that in the control group on days 7 and 14. Alizarin red S staining intensity was significantly higher in the LIPUS group than in the control group on day 21. Runx2 and VEGF expression was significantly upregulated on days 7 and 14, respectively, compared with levels in the control group. ConclusionWe demonstrated the significant effect of LIPUS on the osteogenic differentiation of human IMCs. This study indicates that LIPUS can be used as an additional tool for the enhancement of the healing process of the Masquelet technique.

Rat bone marrow mesenchymal stem cells induced by rrPDGF-BB promotes bone regeneration during distraction osteogenesis.

Background: In the clinical treatment of large bone defects, distraction osteogenesis can be used. However, some patients may suffer from poor bone regeneration, or even delayed healing or non-union. Problems with the aggregation and proliferation of primary osteoblasts, or problems with the differentiation of primary osteoblasts will lead to poor bone regeneration. Therefore, supplementing exogenous primary osteoblasts and growth factors when using distraction osteogenesis may be a treatment plan with great potential. Methods: Bone marrow mesenchymal stem cells (BMSCs) were extracted from rats and cultured. Subsequently, Recombinant Rat Platelet-derived Growth Factor BB (rrPDGF-BB) was used to induce bone marrow mesenchymal stem cells. At the same time, male adult rats were selected to make the right femoral distraction osteogenesis model. During the mineralization period, phosphate buffer salt solution (control group), non-induction bone marrow mesenchymal stem cells (group 1) and recombinant rat platelet-derived growth factor BB intervened bone marrow mesenchymal stem cells (group 2) were injected into the distraction areas of each group. Then, the experimental results were evaluated with imaging and histology. Statistical analysis of the data showed that the difference was statistically significant if p < 0.05. Results: After intervention with recombinant rat platelet-derived growth factor BB on bone marrow mesenchymal stem cells, the cell morphology changed into a thin strip. After the cells were injected in the mineralization period, the samples showed that the callus in group 2 had greater hardness and the color close to the normal bone tissue; X-ray examination showed that there were more new callus in the distraction space of group 2; Micro-CT examination showed that there were more new bone tissues in group 2; Micro-CT data at week eight showed that the tissue volume, bone volume, percent bone volume, bone trabecular thickness, bone trabecular number and bone mineral density in group 2 were the largest, and the bone trabecular separation in group 2 was the smallest. There was a statistical difference between the groups (p < 0.05); HE staining confirmed that group 2 formed more blood vessels and chondrocytes earlier than the control group. At 8weeks, the bone marrow cavity of group 2 was obvious, and some of them had been fused. Conclusion: The study confirmed that injecting bone marrow mesenchymal stem cellsBB into the distraction space of rats can promote the formation of new bone in the distraction area and promote the healing of distraction osteogenesis.

Flowerbed-Inspired Biomimetic Scaffold with Rapid Internal Tissue Infiltration and Vascularization Capacity for Bone Repair.

The favorable microstructure and bioactivity of tissue-engineered bone scaffolds are closely associated with the regenerative efficacy of bone defects. For the treatment of large bone defects, however, most of them fail to meet requirements such as adequate mechanical strength, highly porous structure, and excellent angiogenic and osteogenic activities. Herein, inspired by the characteristics of a "flowerbed", we construct a short nanofiber aggregates-enriched dual-factor delivery scaffold via 3D printing and electrospinning techniques for guiding vascularized bone regeneration. By the assembly of short nanofibers containing dimethyloxalylglycine (DMOG)-loaded mesoporous silica nanoparticles with a 3D printed strontium-contained hydroxyapatite/polycaprolactone (SrHA@PCL) scaffold, an adjustable porous structure can be easily realized by changing the density of nanofibers, while strong compressive strength will be acquired due to the framework role of SrHA@PCL. Owing to the different degradation performance between electrospun nanofibers and 3D printed microfilaments, a sequential release behavior of DMOG and Sr ions is achieved. Both in vivo and in vitro results demonstrate that the dual-factor delivery scaffold has excellent biocompatibility, significantly promotes angiogenesis and osteogenesis by stimulating endothelial cells and osteoblasts, and effectively accelerates tissue ingrowth and vascularized bone regeneration through activating the hypoxia inducible factor-1α pathway and immunoregulatory effect. Overall, this study has provided a promising strategy for constructing a bone microenvironment-matched biomimetic scaffold for bone regeneration.