Endogenous Electric Field-Coupled PD@BP Biomimetic Periosteum Promotes Bone Regeneration through Sensory Nerve via Fanconi Anemia Signaling Pathway.

To treat bone defects, repairing the nerve-rich periosteum is critical for repairing the local electric field. In this study, an endogenous electric field is coupled with 2D black phosphorus electroactive periosteum to explore its role in promoting bone regeneration through nerves. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize the electrically active biomimetic periosteum. Here, the in vitro effects exerted by the electrically active periosteum on the transformation of Schwann cells into the repair phenotype, axon initial segment (AIS) and dense core vesicle (DCV) of sensory neurons, and bone marrow mesenchymal stem cells are assessed using SEM, immunofluorescence, RNA-sequencing, and calcium ion probes. The electrically active periosteum stimulates Schwann cells into a neuroprotective phenotype via the Fanconi anemia pathway, enhances the AIS effect of sensory neurons, regulates DCV transport, and releases neurotransmitters, promoting the osteogenic transformation of bone marrow mesenchymal stem cells. Microcomputed tomography and other in vivo techniques are used to study the effects of the electrically active periosteum on bone regeneration. The results show that the electrically active periosteum promotes nerve-induced osteogenic repair, providing a potential clinical strategy for bone regeneration.

Biphasic mineralized collagen-based composite scaffold for cranial bone regeneration in developing sheep.

Appropriate mechanical support and excellent osteogenic capability are two essential prerequisites of customized implants for regenerating large-sized cranial bone defect. Although porous bone scaffolds have been widely proven to promote bone regeneration, their weak mechanical properties limit the clinical applications in cranioplasty. Herein, we applied two previously developed mineralized collagen-based bone scaffolds (MC), porous MC (pMC) and compact MC (cMC) to construct a biphasic MC composite bone scaffold (bMC) to repair the large-sized cranial bone defect in developing sheep. A supporting frame composed of cMC phase in the shape of tic-tac-toe structure was fabricated first and then embedded in pMC phase. The two phases had good interfacial bond, attributing to the formation of an interfacial zone. The in vivo performance of the bMC scaffold was evaluated by using a cranial bone defect model in 1-month-old sheep. The computed tomography imaging, X-ray scanning and histological evaluation showed that the pMC phase in the bMC scaffold, similar to the pMC scaffold, was gradually replaced by the regenerative bone tissues with comprehensively increased bone mineral density and complete connection of bone bridge in the whole region. The cMC frame promoted new bone formation beneath the frame without obvious degradation, thus providing appropriate mechanical protection and ensuring the structural integrity of the implant. In general, the sheep with bMC implantation exhibited the best status of survival, growth and the repair effect. The biphasic structural design may be a prospective strategy for developing new generation of cranioplasty materials to regenerate cranial bone defect in clinic.

One-Step Fabrication of a Micro/Nanosphere-Coordinated Dual Stimulus-Responsive Nanofibrous Membrane for Intelligent Antifouling and Ultrahigh Permeability of Viscous Water-in-Oil Emulsions.

Membrane fouling is a major challenge for long-term oil/water separation. The incomplete degradation of organic pollutants or membrane damage exists in the common methods of membrane regeneration. Herein, a dual-responsive nanofibrous membrane with high water-in-oil emulsion separation efficiency and smart cleaning properties is reported, which shows complete restoration of its original separation performance. The pH-responsive and upper critical solution temperature (UCST)-type thermoresponsive nanofibrous membrane with a micro/nanosphere structure was developed via a one-step-blending electrospinning strategy. The membrane displays high hydrophobicity/oleophilicity at pH 7 and 25 °C and hydrophilicity/oleophobicity at pH 3 and 55 °C. As a result, it exhibits an ultrahigh permeability of 60528.76 L m-2 h-1 bar-1 and a separation efficiency of 99.5% for water-in-D5 emulsions at room temperature (25 °C). Moreover, the contaminated membranes could be easily reclaimed by being rinsed with warm acidic water (pH 3 and 55 °C). The membrane maintained high separation performance after being used for multiple cycles, indicating its scalable application for purifying emulsified oil. This study provides a facial method of constructing membranes with multiscale hierarchical structures and a new idea for the design of recyclable oil/water separation membranes.

The clinical results of treating Kummell's disease with mineralized collagen modified polymethyl methacrylate.

To investigate the clinical results of treating Kummell's Disease by using mineralized collagen modified polymethyl methacrylate bone cement, 23 cases (23 vertebras) who sustained Kummell's Disease treated with mineralized collagen modified polymethyl methacrylate bone cement from July 2017 to February 2019 were reviewed retrospectively. The visual analogue scale, vertebral body height, Cobb angle, CT values pre-operation and post-operation as well as incidence of complications were observed. All the patients were successfully followed up with an average period of 11.3 months (ranging from 6 to 12 months). The patients could ambulate on the second day after the operation. The visual analogue scale scores significantly decreased from two days after the operation to the last follow-up compared with that before the operation (p < 0.05); the average vertebral height and local Cobb angle had significant recovery (p < 0.05); the CT value of the treated vertebra significantly increased compared with that before the operation (p < 0.05). Bone cement leakage occurred in one case, anterior edge leakage occurred in one case, and no clinical symptoms caused by bone cement leakage occurred. No re-fracture of the treated vertebral body or adjacent vertebral bodies were observed in the follow-ups. With good osteogenic activity and degradable absorption characteristics, mineralized collagen was compounded with the existing polymethyl methacrylate bone cement to reduce its strength in the vertebral body and enhance biocompatibility, the incidence of adjacent vertebral fractures and re-fractures within the injured vertebrae is significantly reduced, and good clinical results are obtained, which is worthy of popularization.

The study of mechanical and drug release properties of the mineralized collagen/polylactic acid scaffold by tuning the crystalline structure of polylactic acid.

Open bone fractures in clinical are not only difficult to heal but also at a high risk of infections. Annual cases of fractures which result from osteoporosis amount to approximately 9 million. The objective of this study is to load the antibiotic drug of vancomycin and tune its controlled delivery on a bone repair scaffold material of Mineralized Collagen/poly(lactic acid) (MCP) via changing the crystallinity of poly(lactic acid) to achieve inhibiting infection while repairing defects. We explored the crystallization process of the material during molding and prepared non-crystalline MCP1, MCP2, MCP3 and MCP4 by rapid freeze forming and crystalline MCP5 by tuning temperature decreasing rate. This method can control the micropore structure of the material; and the material changes from brittleness to toughness, which greatly enhances the control of mechanical properties. The drug release behavior of the material was studied for 28 days. Furthermore, the antibacterial property of the material was tested by the zone of inhibition, which shows the material good bacteriostasis. The controllable MCPs are expected to be substitutes for the treatment of infectious bone defects applying to clinical practical treatment.

Clinical observation of mineralized collagen bone grafting after curettage of benign bone tumors.

Curettage of benign bone tumor is a common cause for bone defect. For such bone defect repair, autogenous bone, allogeneic bone and traditional artificial bone graft substitutes have many disadvantages. In recent years, a biomimetic mineralized collagen (MC) with similar composition and microstructures to the natural bone matrix was developed and used for treating various bone defects. In this work, a retrospective study analyzed clinical outcomes of patients treated with curettage of benign bone tumors and bone grafting with MC, in comparison to another group treated with the same surgical method and autogenous bone. Lane-Sandhu X-ray score of the autogenous bone group was superior to the MC group at 1 month after the operation, but the two groups had no statistical difference at 6 and 12 months. The MC group was better in Musculoskeletal Tumor Society scoring at 1 and 6 months after the operation, and the two groups had no statistical difference at 12 month. Therefore, the MC performed not as good as autogenous bone in early stage of bone healing but achieved comparable outcomes in long-term follow-ups. Moreover, the MC has advantages in function recovery and avoided potential complications induced by harvesting autogenous bone.

Bioactive poly (methyl methacrylate) bone cement for the treatment of osteoporotic vertebral compression fractures.

Rationale: Poly (methyl methacrylate) (PMMA) bone cement is one of the most commonly used biomaterials for augmenting/stabilizing osteoporosis-induced vertebral compression fractures (OVCFs), such as percutaneous vertebroplasty (PVP) and balloon kyphoplasty (BKP). However, its clinical applications are limited by its poor performance in high compressive modulus and weak bonding to bone. To address these issues, a bioactive composite bone cement was developed for the treatment of osteoporotic vertebral compression fractures, in which mineralized collagen (MC) was incorporated into the PMMA bone cement (MC-PMMA). Methods: The in vitro properties of PMMA and MC-PMMA composite bone cement were determined, including setting time, compressive modulus, adherence, proliferation, and osteogenic differentiation of rat bone mesenchymal stem cells. The in vivo properties of both cements were evaluated in an animal study (36 osteoporotic New Zealand female rabbits divided equally between the two bone cement groups; PVP at L5) and a small-scale and short-term clinical study (12 patients in each of the two bone cement groups; follow-up: 2 years). Results: In terms of value for PMMA bone cement, the handling properties of MC-PMMA bone cement were not significantly different. However, both compressive strength and compressive modulus were found to be significantly lower. In the rabbit model study, at 8 and 12 weeks post-surgery, bone regeneration was more significant in MC-PMMA bone cement (cortical bone thickness, osteoblast area, new bone area, and bone ingrowth %; each significantly higher). In the clinical study, at a follow-up of 2 years, both the Visual Analogue Score and Oswestry Disability Index were significantly reduced when MC-PMMA cement was used. Conclusions: MC-PMMA bone cement demonstrated good adaptive mechanical properties and biocompatibility and may be a promising alternative to commercial PMMA bone cements for the treatment of osteoporotic vertebral fractures in clinical settings. While the present results for MC-PMMA bone cement are encouraging, further study of this cement is needed to explore its viability as an ideal alternative for use in PVP and BKP.

Minimally invasive injectable lumbar interbody fusion with mineralized collagen-modified PMMA bone cement: A new animal model.

This study was to develop a feasible and safe animal model for minimally invasive injectable lumbar interbody fusion using a novel biomaterial, mineralized collagen-polymethylmethacrylate bone cement (MC-PMMA), with unilateral pedicle screw fixation in an in vivo goat model. Eight goats (Capra aegagrus hircus) were divided into three groups: MC-PMMA, unmodified commercial-polymethylmethacrylate bone cement (UC-PMMA), and a control group (titanium cage filled with autogenous bone, TC-AB). Each group of goats was treated with minimally invasive lumbar interbody fusion at the L3/L4 and L5/L6 disc spaces (injected for MC-PMMA and UC-PMMA, implanted for TC-AB). The pedicle screws were inserted at the L3, L4, L5, and L6 vertebrae, respectively, and fixed on the left side. The characteristics of osteogenesis and bone growth were assessed at the third and the sixth month, respectively. The methods of evaluation included the survival of each animal, X-ray imaging, and 256-layer spiral computed tomography (256-CT) scanning, imaged with three-dimensional microfocus computed tomography (micro-CT), and histological analysis. The results showed that PMMA bone cement can be extruded smoothly after doping MC, the MC-PMMA integrates better with bone than the UC-PMMA, and all goats recovered after surgery without nerve damage. After 3 and 6 months, the implants were stable. New trabecular bone was observed in the TC-AB group. In the UC-PMMA group a thick fibrous capsule had formed around the implants. The MC-PMMA was observed to have perfect osteogenesis and bone ingrowth to adjacent bone surface. Minimally invasive injectable lumbar interbody fusion using MC-PMMA bone cement was shown to have profound clinical value, and the MC-PMMA showed potential application prospects.

Mineralized collagen-modified PMMA cement enhances bone integration and reduces fibrous encapsulation in the treatment of lumbar degenerative disc disease.

As a minimally invasive surgery, percutaneous cement discoplasty (PCD) is now contemplated to treat lumbar disc degeneration disease in elder population. Here, we investigated whether the osteogenic mineralized collagen (MC) modified polymethylmethacrylate (PMMA) cement could be a suitable material in PCD surgery. Injectability, hydrophilicity and mechanical properties of the MC-modified PMMA (PMMA-MC) was characterized. The introduction of MC did not change the application and setting time of PMMA and was easy to be handled in minimally invasive operation. Hydrophilicity of PMMA-MC was greatly improved and its elastic modulus was tailored to complement mechanical performance of bone under dynamic stress. Then, PCD surgery in a goat model with induced disc degeneration was performed with implantation of PMMA-MC or PMMA. Three months after implantation, micro-computed tomography analysis revealed a 36.4% higher circumferential contact index between PMMA-MC and bone, as compared to PMMA alone. Histological staining confirmed that the surface of PMMA-MC was in direct contact with new bone, while the PMMA was covered by fibrous tissue. The observed gathering of macrophages around the implant was suspected to be the cause of fibrous encapsulation. Therefore, the interactions of PMMA and PMMA-MC with macrophages were investigated in vitro. We discovered that the addition of MC could hinder the proliferation and fusion of the macrophages. Moreover, expressions of fibroblast-stimulating growth factors, insulin-like growth factor, basic fibroblast growth factor and tumor necrosis factor-ß were significantly down-regulated in the macrophages cocultured with PMMA-MC. Together, the promoted osteointegration and reduced fibrous tissue formation observed with PMMA-MC material makes it a promising candidate for PCD surgery.

Tuning pore features of mineralized collagen/PCL scaffolds for cranial bone regeneration in a rat model.

Porosity is indispensable for a bone tissue-engineered scaffold for facilitating endogenous cell migration and nascent bone ingrowth. In large-sized cranial bone defect repair, porous scaffolds meet great challenges to match cranial bone regeneration and provide sufficient protection with structural integrity. Therefore, the pore features of the scaffolds for cranial bone regeneration should differ from those typical porous scaffolds used in tubular bone repair and be finely tuned. In this study, a series of porous mineralized collagen/PCL scaffolds with different pore features were fabricated via freeze-drying and applied in a Sprague Dawley rat cranial bone calvarial defect model. The pore size for four groups increased from 10-45 µm to 40-130 µm. As scaffold porosity increased, the compressive strength decreased from 2.09 ±â€¯0.12 MPa to 0.51 ±â€¯0.04 MPa. The micro-computed tomography three-dimensional reconstruction images showed that as pore size and porosity increased, the amount of new bone formation had a maximum in group 3 (pore size: 20-100 µm, compressive strength: 1.06 ±â€¯0.03 MPa). In addition, the histological and histomorphometric analyses showed a consistent tendency which confirmed the Micro-CT results. Meanwhile, histological findings including bony bridging, tissue response at the bone-implant interface and fibrous capsule thickness indicated that the dura mater pathway played the most important role in the regenerative process of this calvarial defect model.

Mineralized Collagen Modified Polymethyl Methacrylate Bone Cement for Osteoporotic Compression Vertebral Fracture at 1-Year Follow-up.

STUDY DESIGN: Retrospective comparative study. OBJECTIVE: This study aimed to compare the clinical effects and imaging features of polymethyl methacrylate (PMMA) bone cement with and without mineralized collagen (MC) in percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fractures (OVCFs). SUMMARY OF BACKGROUND DATA: PKP with PMMA is widely performed for OVCF. However, numerous complications have also been reported about the PMMA bone cement. Moreover, PMMA bone cement with and without MC have not been compared with respect to their postoperative efficacy and long-term follow-up. METHODS: From July 2016 to July 2017, 105 OVCF patients were randomly divided into two groups based on their PKP treatment: MC-PMMA group and PMMA group. Clinical operation, cement leakage, Oswestry Disability Index, visual analog scale, height of the fractured vertebrae, Cobb angle, refracture of the adjacent vertebra, recompression, and computed tomography values of the injured vertebra were compared between the two groups postoperatively and after 1-year follow-up. RESULTS: Clinical operation showed no differences between the two groups. Visual analog scale scores, Oswestry Disability Index scores, and Cobb angles showed statistically significant differences between the two groups after 1-year follow-up. The height of the vertebral body showed significant difference at 3 days postoperatively and preoperatively in each group and significant difference after 1 year between the two groups. The rate of refracture and leakage of the MC-PMMA group was lower than that of the PMMA group. The computed tomography value of the MC-PMMA group was obviously higher than that of the PMMA group after 1-year follow-up. CONCLUSION: MC-modified PMMA did not change the beneficial properties of PMMA. This new bone cement has better biocompatibility, can form a stable structure in the vertebral body, and improve the prognosis of patients by reducing pain and reoperation. LEVEL OF EVIDENCE: 3.

Integrating 3D Printing and Biomimetic Mineralization for Personalized Enhanced Osteogenesis, Angiogenesis, and Osteointegration.

Titanium (Ti) alloy implants can repair bone defects at load-bearing sites. However, they mechanically mismatch with the natural bone and lack customized adaption with the irregularly major-sized load-bearing bone defects, resulting in the failure of implant fixation. Mineralized collagen (MC), a building block in bone, can induce angiogenesis and osteogenesis, and 3D printing technology can be employed to prepare scaffolds with an overall shape customized to the bone defect. Hence, we induced the formation of MC, made of hydroxyapatite (HAp) nanocrystals and collagen fibers, in 3D-printed porous Ti6Al4V (PT) scaffolds through in situ biomimetic mineralization. The resultant MC/PT scaffolds exhibited a bone-like Young's modulus and were customized to the anatomical contour of actual bone defects of rabbit model. We found that the biocompatibility and osteogenic differentiation are best when the mass ratio between HAp nanocrystals and collagen fibers is 1 in MC. We then implanted the MC/PT scaffolds into the customized radius defect rabbit model and found that the MC/PT scaffolds significantly improved the vascularized bone tissue formation and integration between new bone and the implants. Therefore, a combination of 3D printing and biomimetic mineralization could lead to customized 3D PT scaffolds for enhanced angiogenesis, osteogenesis, and osteointegration. Such scaffolds represent novel patient-specific implants for precisely repairing irregular major-sized load-bearing bone defects.

A high-strength mineralized collagen bone scaffold for large-sized cranial bone defect repair in sheep.

Large-sized cranial bone defect repair presents a great challenge in the clinic. The ideal cranioplasty materials to realize the functional and cosmetic recovery of the defect must have sufficient mechanical support, excellent biocompatibility, good osseointegration and biodegradability as well. In this study, a high-strength mineralized collagen (MC) bone scaffold was developed with biomimetic composition, microstructure and mechanical properties for the repair of sheep large-sized cranial bone defects in comparison with two traditional cranioplasty materials, polymethyl methacrylate and titanium mesh. The compact MC scaffold showed no distinct pore structure and therefore possessed good mechanical properties. The strength and elastic modulus of the scaffold were much higher than those of natural cancellous bone and slightly lower than those of natural compact bone. In vitro cytocompatibility evaluation revealed that the human bone marrow mesenchymal stem cells (hBMSC) had good viability, attachment and proliferation on the compact MC scaffold indicating its excellent biocompatibility. An adult sheep cranial bone defect model was constructed to evaluate the performances of these cranioplasty materials in repairing the cranial bone defects. The results were investigated by gross observation, computed tomography scanning as well as histological assessments. The in vivo evaluations indicated that compact MC scaffold showed notable osteoconductivity and osseointegration with surrounding cranial bone tissues by promoting bone regeneration. Our results suggested that the compact MC scaffold has a promising potential for large-sized cranial bone defect repair.

Clinical outcome comparison of polymethylmethacrylate bone cement with and without mineralized collagen modification for osteoporotic vertebral compression fractures.

A retrospective study of consecutive patients.The purpose of this study was to compare the clinical effect of biomimetic mineralized collagen (MC) modified polymethylmethacrylate (PMMA) bone cement and traditional PMMA bone cement for the treatment of osteoporotic vertebral compression fractures (OVCF).New fracture on adjacent level is the major postoperative complication of percutaneous vertebroplasty (PVP). The clinical incidence was 12.4% to 27.7%. The increased stiffness of the treated vertebral body caused by filling bone cement is considered as one of the main reasons.A total of 30 patients treated with traditional PMMA bone cement from June 2013 to March 2016 were selected as the traditional group, while 50 patients treated with MC modified PMMA bone cement from July 2014 to March 2016 were selected as the modified group. The 2 groups were compared by injection time of the bone cements, postoperative pain relief effects, vertebral height restoration, CT value changes of the treated vertebral bodies, and postoperative complications in the clinical observations.The surgeries were successfully completed in both groups. In the treatment of OVCF, the MC modified bone cement was able to achieve the same pain relief and vertebral height restoration effects compared to traditional bone cement during the follow-ups, although the injection time of the cement was prolonged in the operation. MC modified bone cement significantly reduced the incidence of postoperative adjacent vertebral fracture from 13.3% to 2%, and significantly increased bone density of the treated vertebral bodies.The MC modified PMMA bone cement showed good clinical outcomes and better mechanical properties than the traditional bone cements.

[Application of biomimetic mineralized collagen bone graft material in rabbits posterolateral spinal fusion].

Objective: To investigate the bone repair and regeneration ability of biomimetic mineralized collagen bone graft material and autologous bone marrow in rabbit posterolateral spinal fusion model. Methods: Twenty-seven 20-week-old male New Zealand white rabbits ï¼»weighing (5.0±0.5) kgï¼½ were used to establish the posterolateral spinal fusion model of L 5 and L 6 segments by stripping the transverse process and exposing cancellous bone with electric burr. The rabbits were randomly divided into 3 groups, 9 in each group. Groups A, B, and C were implanted 1.5 mL autologous iliac bone, 1.5 mL (30 mm×10 mm×5 mm) biomimetic mineralized collagen bone graft material, and 1.5 mL (30 mm×10 mm×5 mm) biomimetic mineralized collagen bone graft material and autologous bone marrow in each bone defect. At 4, 8, and 12 weeks after operation, the apparent hardness of the bone grafting area was observed by manipulation method, in order to evaluate bone graft fusion effects. Three animals were sacrificed in each group at each time point, the vertebral body specimens were excised and the bone defect repair and fusion were observed by X-ray films, and three-dimensional CT examination was performed to evaluate whether new bone was formed in the body. HE staining was performed at each time point to observe the formation of new bone and the repair and fusion of bone defects. Results: The manipulation test showed that bone graft fusion was not found in all groups at 4 weeks after operation; 3 (50.0%), 2 (33.3%), and 4 (66.7%) of groups A, B, and C reached bone graft fusion at 8 weeks after operation; 5 (83.3%), 4 (66.7%), and 5 (83.3%) of groups A, B, and C reached bone graft fusion at 12 weeks after operation; the fusion rate of group C was similar to that of group A, and all higher than that of group B. X-ray film observation showed that the fusion rate of group C at 8 and 12 weeks after operation was higher than that of group B, similar to group A. Three-dimensional CT observation showed that the effect of bone fusion in group C was better than that in group B, which was close to group A. HE staining observation showed that large area of mature lamellar bone coverage appeared in the bone graft area of groups A, B, and C at 12 weeks after operation, the material was completely degraded, and the marginal boundary of the host bone disappeared and tightly combined. Conclusion: Biomimetic mineralized collagen bone graft material mixed with autologous bone marrow has good osteoinduction and osteogenesis guidance. Compared with biomimetic mineralized collagen bone graft material, it has better and faster osteogenesis effect, which is close to autologous bone transplantation.

Histopathological and imageological studies on clinical outcomes of mineralized collagen reconstruction rod for femoral head necrosis with one case report.

In this article, the biodegradation process and bone formation of a mineralized collagen reconstruction rod embedding in necrosis of human femoral head were investigated by imageological and histological methods. Computed radiography (CR) computerized tomography (CT), common pathological section and hard tissue section analysis were used to evaluated the dynamics of imageological and histopathological changes of femoral head, interface between the host bone and implant and the bone reconstruction process. The results showed that the density of rods increased closed to that of host bones after 1 year implanting, and the interface between them turns to blurring. Hard tissue grinding sections analysis showed osteocytes appearing in sparse bone trabecular and bone pit region, as well as a few vessels in the degraded dye powder matrix were noticed, indicating the new bone forming between the implants and host bones. Regular decalcified sections analysis showed scattered osteoclasts, multinucleated giant cells and fibrosis components existing in the degraded rod and the host bone trabecular. Degraded debris was endocytosed by giant cells, and vascular network formed around the boundaries of the implanted rod. The good osteointegration has been expressed by the interface between the implanted rod and the host bone becoming blurred. Histological results indicated that the implanted rod degradation process and new bones regeneration simultaneously occurred around the boundaries of embedding rod. New bone and host bone were hinged and co-existed.

Mineralized Collagen-Based Composite Bone Materials for Cranial Bone Regeneration in Developing Sheep.

Cranial bone defects remain a great challenging problem in clinical settings, the influences of which are serious because of the intricate complications and related social problems, especially for young children with rapidly growing skulls. Currently, an increasing number of bone materials are being developed for cranial bone defects repair. In this study, two different biodegradable composite bone materials based on mineralized collagen (MC), with compact/porous structure, were constructed to promote bone regeneration for large cranial bone defect repair of one-month-old baby sheep. The porous MC (pMC) scaffold had interconnected porous structure with a porosity of about 73% and a 20-150 µm pore size range, and the compact MC (cMC) showed no distinct pore structure. Mechanical tests indicated that the compressive strength and elastic modulus of cMC and pMC were comparable with those of natural compact and cancellous bone, respectively. Both of these two MC scaffolds possessed good biocompatibility and supported osteoblasts adhesion and proliferation in vitro. A one-month-old sheep cranial bone defect model was first established to investigate the cranial bone regeneration behaviors in vivo, which was evaluated by CT imaging, X-rays scans, and histological assessments. It was found that the pMC promoted bone ingrowth from the diploic layer of surrounding cranium and dura mater-derived osteogenesis at three months after surgery, along with gradual biodegradation. In contrast, the cMC had very little biodegradation but could promote bone formation beneath the scaffold through dura mater-derived osteogenesis pathway. Furthermore, Ti-mesh restricted the growth of surrounding cranial bone in the rapidly growing sheep, thereby causing obvious deformation of the skull at six months after surgery, whereas no visible geometric deformation of skull occurred in the cMC and pMC groups. Our findings suggested that the MC-based composite bone materials have great promise for the repair of large cranial bone defects in a developing skull.

Comparison of safety and efficiency of microendoscopic discectomy with automatic nerve retractor and with nerve hook.

This study compares the safety and efficiency of two techniques in microendoscopic discectomy (MED) for lumbar disc herniation. The two techniques are MED with automatic nerve retractor and MED with nerve hook which had been widely used for many years. The former involves a newly developed MED device which contains three parts to protect nerve roots during operation. Four hundred and twenty-eight patients underwent MED treatments between October 2010 and September 2015 were recruited and randomized to either intraoperative utilization of automatic nerve retractor (n = 315, group A) or application of nerve hook during surgery (n = 113, group B). Operation time and intraoperative bleeding volume were evaluated. Simultaneously, Visual Analogue Scales (VAS) and muscle strength grading were performed preoperatively, and 1, 2, 3 days, 1, 2 weeks, 3 and 6 months postoperatively. No dramatic difference of pain intensity was observed between the two groups before surgery and 6 months after surgery (P > 0.05). The operation time was shorter in group A (30.30 ± 1.89 min) than that in group B (59.41 ± 3.25 min). Group A (67.83 ± 13.14 ml) experienced a significant decrease in the amount of blood loss volume when compared with group B (100.04 ± 15.10 ml). There were remarkable differences of VAS score and muscle strength grading after postoperative 1, 2, 3 days, 1, 2 weeks and 3 months between both groups (P ≤ 0.05). MED with automatic nerve retractor effectively shortened operation time, decreased the amount of bleeding, down-regulated the incidence of nerve traction injury.

Clinical evaluations of mineralized collagen in the extraction sites preservation.

The purpose of this study was to explore the different effects between biomimetic mineralized collagen (MC) and ordinary physically blended hydroxyapatite/collagen (HA/Col) composite in evaluating new bone formation and regenerated bone height in human extraction sockets. Thirty-four patients who cannot retain teeth caused by trauma or decay were randomly selected from Department of Stomatology of Dongzhimen Hospital from December 2013 to December 2014. The patients were randomly divided into two groups. After the operation of tooth extraction, 17 patients were implanted with biomimetic MC (MC group), and other 17 patients were implanted with ordinary physically blended nHA/Col composite (nHA/Col group). X-ray positioning projection by auto-photographing was taken to test the distance between the lowest position and the neighboring CEJm-CEJd immediately, 1 month and 3 months after the operation. The height of new bone formation of the MC group was significantly higher than the nHA/Col group. Biomimetic MC showed better clinical outcomes in the bone formation for extraction site preservation and would have broad application prospect in the field of oral and maxillofacial surgeries.

Test in canine extraction site preservations by using mineralized collagen plug with or without membrane.

The aim of this study was to discuss the feasibility of porous mineralized collagen plug and bilayer mineralized collagen-guided bone regeneration membrane in site preservation in extraction sockets. The third mandibular premolars on both sides were extracted from four dogs, thus there were 16 alveolar sockets in all dogs and were randomly assigned into three groups. Group A had six alveolar sockets, and groups B and C had five alveolar sockets, respectively. Each alveolar socket of group A was immediately implanted with a porous mineralized collagen plug and covered with a bilayer mineralized collagen-guided bone regeneration membrane after tooth extraction. Alveolar sockets of group B were implanted with porous mineralized collagen plug only, and group C was set as blank control without any implantation. The healing effects of the extraction sockets were evaluated by gross observation, morphological measurements, and X-ray micro-computed tomography after twelve weeks. Twelve weeks after operation, both groups A and B had more amount of new bone formation compared with group C; in terms of the degree of alveolar bone height, group A was lower than groups B and C with significant differences; the bone mineral density in the region of interest and bone remodeling degree in group A were higher than those of groups B and C. As a result, porous mineralized collagen plug could induce the regeneration of new bone in extraction socket, and combined use of porous mineralized collagen plug and bilayer mineralized collagen guided bone regeneration membrane could further reduce the absorption of alveolar ridge and preserve the socket site.