Bone Regeneration In Cranial Defects Research Articles

Bioactive poly(ethylene glycol)-chondroitin sulfate-triple helical recombinant collagen hydrogel for enhanced cranial defect repair

The reconstruction of critical-size calvarial defects remains a fundamental challenge. Recombinant collagen has gained significant attention in bone tissue engineering owing to its remarkable bioactivity and non-immunogenicity. Herein, we have for the first time developed a bioactive poly(ethylene glycol)-chondroitin sulfate-triple helical recombinant collagen (PEG-ChS-THRC) hydrogel for enhanced bone regeneration in cranial defects. A simple and mild crosslinking reaction of two-arm polyethylene glycol active ester (NHS-PEG-NHS), adipic dihydrazide modified chondroitin sulfate (ChS-ADH) and triple helical recombinant collagen (THRC) leads to the formation of the PEG-ChS-THRC hydrogel. The hydrogel demonstrates interconnected porous structures, enhanced mechanical strength, diminished swelling ratios and adjustable biodegradability. It possesses exceptional biocompatibility and bioactivity, significantly facilitating cell proliferation, adhesion, migration, and osteogenic differentiation of BMSCs. Micro-computed tomography (micro-CT), magnetic resonance imaging (MRI) and histological characterization of rat models with critical-size cranial defects have consistently demonstrated that the PEG-ChS-THRC hydrogel significantly promotes bone tissues regeneration. The innovative bioactive scaffold provides a remarkably improved remedy for critical-size cranial defects, holding greatly promising applications in the fields of bone tissue regeneration.Graphical

Mechanically robust and personalized silk fibroin-magnesium composite scaffolds with water-responsive shape-memory for irregular bone regeneration

The regeneration of critical-size bone defects, especially those with irregular shapes, remains a clinical challenge. Various biomaterials have been developed to enhance bone regeneration, but the limitations on the shape-adaptive capacity, the complexity of clinical operation, and the unsatisfied osteogenic bioactivity have greatly restricted their clinical application. In this work, we construct a mechanically robust, tailorable and water-responsive shape-memory silk fibroin/magnesium (SF/MgO) composite scaffold, which is able to quickly match irregular defects by simple trimming, thus leading to good interface integration. We demonstrate that the SF/MgO scaffold exhibits excellent mechanical stability and structure retention during the degradative process with the potential for supporting ability in defective areas. This scaffold further promotes the proliferation, adhesion and migration of osteoblasts and the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro. With suitable MgO content, the scaffold exhibits good histocompatibility, low foreign-body reactions (FBRs), significant ectopic mineralisation and angiogenesis. Skull defect experiments on male rats demonstrate that the cell-free SF/MgO scaffold markedly enhances bone regeneration of cranial defects. Taken together, the mechanically robust, personalised and bioactive scaffold with water-responsive shape-memory may be a promising biomaterial for clinical-size and irregular bone defect regeneration.

Cross-linking N-succinyl chitosan-oxidated hyaluronic acid-based hydrogel loaded with bone marrow mesenchymal stem cell-derived exosomes induce bone regeneration in cranial defects

BackgroundHydrogel carrying exosomes shows better prospects for bone regeneration. ObjectiveThis work investigated the effect of cross-linking N-succinyl chitosan-oxidated hyaluronic acid-based hydrogel loaded with bone marrow mesenchymal stem cell-derived exosomes on bone regeneration in cranial defects. MethodsCross-linking N-succinyl chitosan-oxidated hyaluronic acid-based hydrogel loaded with bone marrow mesenchymal stem cell-derived exosomes was prepared, and utilized to treat bone marrow mesenchymal stem cells, human umbilical vein endothelial cells, and rats with cranial defects. Logical experiments were implemented to research the effect of the prepared hydrogel on osteogenesis and angiogenesis of cells in vitro, and on bone regeneration in rats with cranial defects. ResultsCross-linking N-succinyl chitosan-oxidated hyaluronic acid-based hydrogel loaded with bone marrow mesenchymal stem cell-derived exosomes showed good biocompatibility and self-healing property. It promoted osteogenic differentiation of bone marrow mesenchymal stem cells and angiogenesis of human umbilical vein endothelial cells, and facilitated osteogenic differentiation, angiogenesis and bone regeneration in rats with cranial defects. ConclusionCross-linking N-succinyl chitosan-oxidated hyaluronic acid-based hydrogel loaded with bone marrow mesenchymal stem cell-derived exosomes facilitated osteogenesis, angiogenesis and bone regeneration in rats with cranial defects. It might be an effective strategy for inducing bone regeneration in individuals with cranial defects.

Bone morphogenetic protein-2 loaded triple helix recombinant collagen-based hydrogels for enhancing bone defect healing

The development of efficacious bone substitute biomaterials remains a major challenge for research and clinical surgical. Herein, we constructed triple helix recombinant collagen (THRC) -based hydrogels loading bone morphogenetic protein-2 (BMP-2) to stimulate bone regeneration in cranial defects. A series of in situ forming hydrogels, denoted as THRC-oxidized carboxymethylcellulose (OCMC)-N-succinyl-chitosan (NSC) hydrogels, was synthesized via a Schiff base reaction involving OCMC, THRC and NSC. The hydrogels underwent rapid formation under physiological pH and temperature conditions. The composite hydrogel exhibits a network structure characterized by uniform pores, the dimensions of which can be tuned by varying THRC concentrations. The THRC-OCMC-NSC and THRC-OCMC-NSC-BMP2 hydrogels display heightened mechanical strength, substantial biodegradability, and lower swelling properties. The THRC-OCMC-NSC hydrogels show exceptional biocompatibility and bioactivity, accelerating cell proliferation, adhesion, and differentiation. Magnetic resonance imaging, computed tomography and histological analysis of rat cranial defects models revealed that the THRC-OCMC-NSC-BMP2 hydrogels substantially promote new bone formation and expedite bone regeneration. The novel THRC-OCMC-NSC-BMP2 hydrogels emerge as promising candidates for bone substitutes, demonstrating substantial potential in bone repair and regeneration applications.

Magnesium-containing bioceramics stimulate exosomal miR-196a-5p secretion to promote senescent osteogenesis through targeting Hoxa7/MAPK signaling axis

Stem cell senescence is characterized by progressive functional dysfunction and secretory phenotypic changes including decreased proliferation, dysfunction of osteogenic and angiogenic differentiation, increased secretion of the senescence-associated secretory phenotype (SASP), which bring difficulties for bone repair. Rescuing or delaying senescence of aged bone marrow mesenchymal stem cells (O-BMSCs) was considered as effective strategy for bone regeneration in aging microenvironment. Magnesium (Mg) ion released from bioceramics was reported to facilitate bone regeneration via enhancing osteogenesis and alleviating senescence. In this study, Akermanite biocreamics (Akt) containing Mg ion as a model was demonstrated to promote osteogenesis and angiogenesis effects of O-BMSCs by activating the MAPK signaling pathway in vitro. Moreover, the enhanced osteogenesis effects might be attributed to enhanced Mg-containing Akt-mediated exosomal miR-196a-5p cargo targeting Hoxa7 and activation of MAPK signaling pathway. Furthermore, the in vivo study confirmed that 3D-printed porous Mg-containing Akt scaffolds effectively increased bone regeneration in cranial defects of aged rats. The current results indicated that the exosomal-miR-196a-5p/Hoxa7/MAPK signaling axis might be the potential mechanism underlying Akt-mediated osteogenesis. The exosome-meditaed therapy stimulated by the released Mg ion contained in Akt biocreamics or other biomaterials might serve as a candidate strategy for bone repair in aged individuals.

Accelerating bone regeneration in cranial defects using an injectable organic-inorganic composite hydrogel.

Bone tissue engineering, as an important and attractive multidisciplinary field, affords a feasible strategy for large bone defects which are difficult to heal without clinical intervention. However, the complicated requirements of bone regeneration result in the imperfect performance of many current materials. Inspired by the composite nature of bone tissues, we proposed an organic-inorganic composite strategy. Specifically, we loaded a bone regeneration drug (simvastatin, SIM) and an inorganic component (strontium hydrogen phosphate (SrHPO4)/beta-tricalcium phosphate (β-TCP)) to a thermogel, constituted by poly(ε-caprolactone-co-D,L-lactide)-poly(ethylene glycol)-poly(ε-caprolactone-co-D,L-lactide) (PCLA-PEG-PCLA), with a thermo-induced sol-gel transition, to prepare an injectable composite for bone regeneration in cranial defects. The SIM/(Sr/β-TCP)/PCLA-PEG-PCLA composite was able to be conveniently injected and it spontaneously filled the defect. The appropriate mechanical strength obtained by thermogelation under the stimuli of the body temperature provided the necessary support while the capacity of loading drugs and bioceramics offered bioactivity and osteoinduction. In vitro drug release experiments demonstrated a gentle and sustained release of SIM for as long as 2 months, benefitting bone regeneration. The excellent capacity of promoting the formation of osteocytes was proved by cell differentiation assays. Furthermore, the enhanced bone regeneration capacity was verified by the micro-CT results of rat cranial defects with implantation time. Based on our results, the organic-inorganic composite integrates the advantages of each component and is far beyond, thus it might serve as a promising material candidate for bone regeneration.

The polycaprolactone/silk fibroin/carbonate hydroxyapatite electrospun scaffold promotes bone reconstruction by regulating the polarization of macrophages.

Macrophages are known to modulate the osteogenic environment of bone regeneration elicited by biological bone grafts. Alteration in certain chemical components tends to affect macrophages polarization. Comparatively to hydroxyapatite (HAp), carbonate hydroxyapatite (CHA) consists of 7.4 (wt%) carbonate ions and more closely resembles the mineral content of bone. It remains unknown whether CHA scaffolds or HA scaffolds have better osteogenic properties. In this study, we fabricated PCL/SF scaffold, PCL/SF/HAp scaffold and PCL/SF/CHA scaffold using the electrospinning technique. Despite comparable mechanical properties, the PCL/SF/CHA scaffold exhibited better osteogenic properties than the PCL/SF/HAp scaffold. Although no significant differences were observed between the two scaffolds for promoting osteoblast differentiation in vitro, the PCL/SF/CHA group appeared to be more effective at promoting bone regeneration in cranial defects in vivo. The PCL/SF/CHA scaffold was found to promote macrophage polarization toward M2 via activating the JAK/STAT5 pathway which caused a pro-osteogenic microenvironment to facilitate osteoblast differentiation. The results of this study indicated a higher potential of CHA to substitute HAp in the production of bone scaffolds for better bone regeneration.

Mineralized collagen-based bone materials for bone regeneration in cranial defect of immaturity

Mineralized collagen-based bone materials for bone regeneration in cranial defect of immaturity

Human embryonic stem cells and macroporous calcium phosphate construct for bone regeneration in cranial defects in rats

Human embryonic stem cells (hESCs) are an exciting cell source as they offer an unlimited supply of cells that can differentiate into all cell types for regenerative medicine applications. To date, there has been no report on hESCs with calcium phosphate cement (CPC) scaffolds for bone regeneration in vivo. The objectives of this study were to: (i) investigate hESCs for bone regeneration in vivo in critical-sized cranial defects in rats; and (ii) determine the effects of cell seeding and platelets in macroporous CPC on new bone and blood vessel formation. hESCs were cultured to yield mesenchymal stem cells (MSCs), which underwent osteogenic differentiation. Four groups were tested in rats: (i) CPC control without cells; (ii) CPC with hESC-derived MSCs (CPC+hESC-MSC); (iii) CPC with hESC-MSCs and 30% human platelet concentrate (hPC) (CPC+hESC-MSC+30% hPC); and (iv) CPC+hESC-MSC+50% hPC. In vitro, MSCs were derived from embryoid bodies of hESCs. Cells on CPC were differentiated into the osteogenic lineage, with highly elevated alkaline phosphatase and osteocalcin expressions, as well as mineralization. At 12weeks in vivo, the groups with hESC-MSCs and hPC had three times as much new bone as, and twice the blood vessel density of, the CPC control. The new bone in the defects contained osteocytes and blood vessels, and the new bone front was lined with osteoblasts. The group with 30% hPC and hESC-MSCs had a blood vessel density that was 49% greater than the hESC-MSC group without hPC, likely due to the various growth factors in the platelets enhancing both new bone and blood vessel formation. In conclusion, hESCs are promising for bone tissue engineering, and hPC can enhance new bone and blood vessel formation. Macroporous CPC with hESC-MSCs and hPC may be useful for bone regeneration in craniofacial and orthopedic applications.

A novel oxysterol promotes bone regeneration in rabbit cranial bone defects

Bone morphogenetic proteins (BMPs) have played a central role in the development of regenerative therapies for bone reconstruction. However, the high cost and side-effect profile of BMPs limits their broad application. Oxysterols, naturally occurring products of cholesterol oxidation, are promising osteogenic agents alternative to BMPs. The osteogenic capacity of these non-toxic and relatively inexpensive molecules has been documented in rodent models. We studied the impact of Oxy49, a novel oxysterol analogue, on the osteogenic differentiation of rabbit bone marrow stromal cells (BMSCs). Moreover, we evaluated the capacity for in vivo bone regeneration with Oxy49 in rabbit cranial bone defects. We found that rabbit BMSCs treated with Oxy49 demonstrated differentiation along osteogenic pathways, and that complete bone regeneration occurred when cranial defects were treated with Oxy49. Collectively, these results demonstrate that Oxy49 has the ability to induce osteogenic differentiation in rabbit BMSCs with an efficacy comparable to that of BMP-2 and to promote significant bone regeneration in cranial defects. Oxysterols may be a viable novel agent in bone tissue engineering. Copyright © 2016 John Wiley & Sons, Ltd.

Slow-Release Human Recombinant Bone Morphogenetic Protein-2 Embedded Within Electrospun Scaffolds for Regeneration of Bone Defect: In Vitro and In Vivo Evaluation

The design of mat-like scaffolds slow-releasing bone morphogenetic protein-2 (BMP-2) retaining bone regeneration functions has been a major challenge in tissue engineering. This study aimed to develop core-shell fiber scaffolds releasing BMP-2 to support bone regeneration. BMP-2 was incorporated in an aqueous core solution of poly(ethylene oxide), whereas the shell solution was made of polycaprolactone blended with poly(ethylene glycol). This blending induced pores in the shell, which pronouncedly affected the movement of proteins out of the fibers. BMP-2 release profiles were monitored. In vitro bioactivity of BMP-2 released from the scaffolds was assessed using human mesenchymal stem cells by measuring alkaline phosphatase activity. Bone regeneration capabilities were demonstrated by implanting the BMP-2-embedded scaffolds in rat cranial defect model followed by micro-computed tomography analysis. The degree of fiber's shell porosity, highly correlative with the slow- and fast-release patterns of BMP-2, were found to be dependent on the relative amount of poly(ethylene glycol) within the shell. In vitro assays of scaffolds manifesting the slow-release pattern have revealed significant (∼9-fold) increase in alkaline phosphatase activity, compared to fast BMP-2 releasing scaffolds. Likewise, in vivo studies have revealed significant bone regeneration in cranial defects of scaffold implants with recombinant human BMP-2 with slow-release pattern.

Bone Regeneration in Cranial Defects Previously Treated with Radiation

Bone reconstruction in the head and neck region is frequently performed in the context of previous radiation treatment. Thus, the effectiveness of tissue engineering approaches for regenerating bone in radiated defects needs to be determined before considering application to patients. Incomplete healing is described when using osteoinductive protein therapy alone for bone defects previously treated with radiation. We hypothesized that a different approach using ex vivo gene therapy can heal these severely compromised defects. Animal study using Fisher rats. Two weeks before surgery, rats received either no radiation or a 12 Gray radiation dose to the calvarium. Syngeneic dermal fibroblasts were transduced ex vivo using an adenoviral vector containing the cDNA for bone morphogenetic protein (BMP)-7. Critical-sized calvarial defects were created, and either a transduced cell-seeded scaffold or an autologous bone graft was placed into the defect. Nonradiated defects were harvested 4 weeks later for both groups. Radiated defects treated with bone grafts were harvested at 4 weeks, and those treated with gene therapy were harvested either at 4 or 8 weeks. Gross inspection and histology were used to evaluate wound healing. None of the bone grafts had gross or histologic evidence of healing at the wound margins. The nonradiated gene therapy treated defects revealed gross and histologic near-100% bone regeneration by 4 weeks after surgery. By gross inspection, the radiated defects had soft tissue admixed with islands of bone at both 4 and 8 weeks. The histologic appearance revealed areas of dense bone in a nonconfluent pattern admixed with adjacent cells having the morphologic appearance of hypertrophic chondrocytes, suggesting continued endochondral ossification. Preoperative radiation significantly impairs the ability of BMP-7 ex vivo gene therapy to heal rat critical-sized cranial defects. This finding has significant implications for translating this tissue engineering approach to patients with cancer-related segmental bone defects.

Evaluation of the potential beneficial effects of ostrich eggshell combined with eggshell membranes in healing of cranial defects in rabbits.

Potential beneficial effects of outer and inner ostrich eggshell membranes alone and in combination with the shell powder on bone regeneration in cranial defects of 18 rabbits were investigated using radiological, clinical and histological methods. Three 6 mm wide, half-thickness defects were made in the calvarial bones of each rabbit. One defect remained empty as a control; prepared eggshell membranes were extended across the other two defects; and prepared eggshell powder was inserted inside the membrane in one case. Either alone or in combination with eggshell powder, the outer and inner ostrich eggshell membranes produced little adjunctive effect under the conditions and duration of this experiment.

Compartmentalized bone regeneration of cranial defects with biodegradable barriers--effects of calcium sodium phosphate surface coatings on LactoSorb.

In bony defects of the cranium, bone healing may be complicated by prolapse of surrounding tissue into the defect. This tissue acts as a potential obstruction to the migration of osteogenic cells, resulting in impaired bone formation. It has been shown in previous studies that when a membrane composed of resorbable polymers (LactoSorb) is placed over a cranial bone defect, it inhibits connective tissue from entering the wound and improves the rate and quality of the bony regenerate. This study is an extension of this work and specifically evaluated the effects of differing calcium-based surface coatings on membrane-covered cranial defects in the rabbit model. In non-critical size, full-thickness defects of the mature rabbit calvarium, four differently treated LactoSorb membranes were evaluated in each animal model over a 1-year postoperative period. The surface coatings (three treated, one untreated) consisted of a base-powdered material of calcium sodium phosphate (Osteostim, EBI, NJ), which were applied by different methods (pressed, brushed, one-sided versus two-sided). Evaluation consisted of cross-sectional histologic assessment of the cranial detects determining the quantitative bony fill and the presence of residual polymer material and calcium sodium phosphate. This study produced the following findings: (1) cranial defect regeneration occurs faster with calcium-coated membranes and is complete by 3 months; (2) no difference could be seen between the different methods of calcium sodium phosphate coating; (3) the calcium sodium phosphate coatings did not inhibit resorption of the biodegradable membranes for those systems that had coatings on one side; however, systems completely covered showed delayed resorption; and (4) the calcium sodium phosphate coatings did not produce any inflammatory reactions. These findings suggest that, in addition to inhibiting connective tissue from entering the wound site, the calcium coatings on resorbable devices may have beneficial effects in selected clinical conditions, especially in conditions where faster bone regeneration is necessary.

Compartmentalized bone regeneration of cranial defects with biodegradable barriers: an animal model.

In bony defects of the cranium, bone healing may be complicated by prolapse of surrounding tissue into the defect. This tissue acts as an impediment to prevent the migration of osteogenic cells, leading to impaired bone formation. It has been previously shown that a membrane placed over the bony defect inhibits the connective tissue cells from entering the wound and theoretically improves bone formation. The use of a proven resorbable material, Lactosorb, is used in this animal model and has shown a significant increase in autogenous bony formation. The majority of previous work was accomplished with nonresorbable material that resulted in foreign body formation. This paper is unique because resorbable material in the animal model is relatively inexpensive and easy to use and has allowed successful autogenous bony regeneration.

Guided bone regeneration of cranial defects using various membranes: An experimental study in rabbits

Guided bone regeneration of cranial defects using various membranes: An experimental study in rabbits

Guided bone regeneration of cranial defects, using biodegradable barriers: an experimental pilot study in the rabbit

The aim of this study was to test if a biodegradable barrier could be used to achieve proper bone healing of full-thickness trephine skull defects, applying the biological principle of guided tissue regeneration (GTR). Two New Zealand white rabbits were used. In each animal, 2 circular through-and-through bone defects with a diameter of 8 mm were created in the midline of the frontal and parietal bones of the calvarium. One defect was covered with the mucoperiosteal flaps without placement of an intervening membrane barrier (control). One test defect (test 1) was covered by a biodegradable, non-porous polylactic acid membrane on the outer (supra-calvarial) side of the defect, and 2 test defects (tests 2 and 3) were covered by similar membranes on both the outer and the inner aspects of the defects, prior to flap closure. 6 weeks postsurgically, the animals were sacrificed and the defect areas including surrounding tissues were harvested for histological preparation. The control defect was essentially occupied by supra-calvarial soft tissue, located in direct contact with the dural tissue. In the test cavities, there was a continuous bridge of regenerated bone extending from one edge of the defect to the other, although in test 1 not attaining the same thickness as the bone bordering the defect. In the 2 other test defects, the regenerated bone had reached a thickness almost corresponding to that of the surrounding bone. The bone regeneration was achieved without recourse to adjunctive bone graft materials.(ABSTRACT TRUNCATED AT 250 WORDS)