Repair Of Calvarial Defects Research Articles

Facile one-step bioinspired mineralization by chitosan functionalized with graphene oxide to activate bone endogenous regeneration

Facilitated endogenous tissue engineering is emerging as a convenient and easy strategy for bone repair. However, the substitution with satisfactory bioactivity and osteoinductivity which can activate endogenous stem cells responds and in situ recruit them homing towards to damaged area remains a challenge. To stimulate the biomineralization process of inorganic nanoparticles in natural bone, bioactive nano hydroxyapatite particles (nHAP) were in situ crystallized into the graphene oxide/chitosan/nHAP (GO/CS/nHAP) scaffold via effective regulation of CS functionalized with GO network matrix and presented a uniform dispersion with nanometer-scale. As-prepared scaffold exhibited better physicochemical properties, such as three-dimensional (3D) porous bone-like hierarchical structure, proper mechanical property, biodegradation as well as suitable water uptake and retention ratio. The biomimetic mineralization and cell culture experiments demonstrated that hybrid scaffold possessed superior bioactivity and cell proliferation ability in vitro. In addition, the rat calvarial defect repair models and tissue pathological characterization further proved that the hybrid scaffold had excellent biocompatibility and capacity of in situ inducing bone regeneration. Herein, the prepared scaffold might be an excellent candidate for endogenous bone repair.

3D Superelastic Scaffolds Constructed from Flexible Inorganic Nanofibers with Self‐Fitting Capability and Tailorable Gradient for Bone Regeneration

AbstractRepair of bone defects with irregular shapes or at soft tissue insertion sites faces a huge challenge. Scaffolds capable of adapting to bone cavities, generating stiffness gradients, and inducing osteogenesis are necessary. Herein, a superelastic 3D ceramic fibrous scaffold is developed by assembly of intrinsically rigid, structurally flexible electrospun SiO2 nanofibers with chitosan as bonding sites (SiO2 NF‐CS) via a lyophilization technique. SiO2 NF‐CS scaffolds exhibit excellent elasticity (full recovery from 80% compression), fast recovery rate (>500 mm min−1), and good fatigue resistance (>10 000 cycles of compression) in an aqueous medium. SiO2 NF‐CS scaffolds induce human mesenchymal stem cell (hMSC) elongation and differentiation into osteoblasts. In vivo self‐fitting capability is demonstrated by implanting compressed SiO2 NF‐CS scaffolds into different shaped mandibular defects in rabbits, with a spontaneous recovery and full filling of defects. Rat calvarial defect repair validates enhanced bone formation and vascularization by cell (hMSC) histomorphology analysis. Further, subchondral bone scaffolds with gradations in SiO2 nanofibers are developed, leading to a stiffness gradient and spatially chondrogenic and osteogenic differentiation of hMSCs. This work presents a type of 3D ceramic fibrous scaffold, which can closely match bone defects with irregular shapes or at different implant sites, and is promising for clinical translation.

P34HB electrospun fibres promote bone regeneration in vivo.

ObjectiveBone tissue engineering was introduced in 1995 and provides a new way to reconstruct bone and repair bone defects. However, the design and fabrication of suitable bionic bone scaffolds are still challenging, and the ideal scaffolds in bone tissue engineering should have a three‐dimensional porous network, good biocompatibility, excellent biodegradability and so on. The purpose of our research was to investigate whether a bioplasticpoly3‐hydroxybutyrate4‐hydroxybutyrate (P34HB) electrospun fibre scaffold is conducive to the repair of bone defects, and whether it is a potential scaffold for bone tissue engineering.Materials and methodsThe P34HB electrospun fibre scaffolds were prepared by electrospinning technology, and the surface morphology, hydrophilicity, mechanical properties and cytological behaviour of the scaffolds were tested. Furthermore, a calvarial defect model was created in rats, and through layer‐by‐layer paper‐stacking technology, the P34HB electrospun fibre scaffolds were implanted into the calvarial defect area and their effect on bone repair was evaluated.ResultsThe results showed that the P34HB electrospun fibre scaffolds are interwoven with several fibres and have good porosity, physical properties and chemical properties and can promote cell adhesion and proliferation with no cytotoxicity in vitro. In addition, the P34HB electrospun fibre scaffolds can promote the repair of calvarial defects in vivo.ConclusionsThese results demonstrated that the P34HB electrospun fibre scaffold has a three‐dimensional porous network with good biocompatibility, excellent biosafety and ability for bone regeneration and repair; thus, the P34HB electrospun fibre scaffold is a potential scaffold for bone tissue engineering.

Delivery vehicle of muscle-derived irisin based on silk/calcium silicate/sodium alginate composite scaffold for bone regeneration.

Irisin is a cytokine produced by skeletal muscle and usually plays a pivotal role in inducing fat browning and regulating energy expenditure. In recent years, it was found that irisin might be the molecular entity responsible for muscle-bone connectivity and is useful in osteogenesis induction. To study its effect on bone regeneration, we developed silk/calcium silicate/sodium alginate (SCS) composite scaffold based on an interpenetrating network hydrogel containing silk fibroin, calcium silicate, sodium alginate. Then we loaded irisin on the SCS before coating it with polyvinyl alcohol (PVA). The SCS/P scaffold was physically characterized and some in vitro and in vivo experiments were carried out to evaluate the scaffold effect on bone regeneration. The SCS/P scaffold was showed a porous sponge structure pursuant to scanning electron microscopy analysis. The release kinetics assay demonstrated that irisin was stably released from the irisin-loaded hybrid system (i/SCS/P system) to 50% within 7 days. Moreover, osteoinductive studies using bone marrow stem cells (BMSCs) in vitro exhibited the i/SCS/P system improved the activity of alkaline phosphatase (ALP) and enhanced the expression levels of a series of osteogenic markers containing Runx-2, ALP, BMP2, Osterix, OCN, and OPN. Alizarin red staining also demonstrated the promotion of osteogenesis induced by i/SCS/P scaffolds. In addition, in vivo studies showed that increased bone regeneration with better mineralization and higher quality was found during the repair of rat calvarial defects through utilizing the i/SCS/P system. These data provided strong evidence that the composite i/SCS/P would be a promising substitute for bone tissue engineering.

Induction of bone repair in rat calvarial defects using a combination of hydroxyapatite with phosphatidylserine liposomes.

Phosphatidylserine (PS)-normally present on the inner leaflet of the plasma membrane-translocates to the outer leaflet at an early stage of apoptosis. PS-containing liposomes (PSLs) can mimic the effect of apoptotic cells in inducing the secretion of prostaglandin E2 from phagocytes and inhibiting the maturation of dendritic cells and osteoclast precursors. The present study attempted to evaluate the effect of calcium phosphate (in the form of hydroxyapatite [HAP]) in the presence or absence of PSLs for repair of rat calvarial bone defects. The defects, each 5 mm in diameter, were created in the calvaria parietal bone of 8-week-old Wistar rats and subjected to one of the following treatments: no augmentation (Sham), HAP alone, or a mixture of HAP and PSL (HAP+PSL). Micro-computed tomography data showed that the HAP+PSL complexes promoted greater bone regeneration in comparison with either the Sham procedure or HAP alone at 4 and 8 weeks after implantation. The regeneration of calvarial bone defects induced by PSLs was mediated partly through upregulation of the osteogenic marker Alkaline Phosphatase, Type I collagen, osteocalcin, Runx2, and Osterix mRNAs. These data are the first to show that PSLs can influence bone regeneration by regulating osteoblast differentiation.

Osteoinductive Agents-Incorporated Three-Dimensional Biphasic Polymer Scaffold for Synergistic Bone Regeneration.

Large-scale bone defects are difficult to be regenerated entirely in the clinical practice. Bone tissue engineering has drawn more attention as an alternative to bone grafting owing to its convenience and flexibility. However, the low bioactivity of scaffolds and adverse effects of growth factors have hindered its practical application. Herein, the properties of poly(lactic-co-glycolic acid) (PLGA) scaffold, including hydrophilicity and mechanical strength, were improved by a gelatin coating incorporated with two small molecules, alendronate (ALD) and naringin (NG). Interestingly, these two drugs demonstrated a synergistic effect for the repair of rat calvarial defect, as ALD had an inhibitory impact on osteoclast activity and NG had an osteogenic effect on mesenchymal stem cells. From the results of histopathological staining and microcomputed tomography, the PLGA scaffold incorporated with gelatin, ALD, and NG (PLGA+Gelatin/ALD/NG) almost completely repaired the rat calvarial defect with physiological integrity at 16 weeks. In all, this biphasic scaffold can be a promising alternative to the conventional scaffold for clinical application.

BMP-IHH-mediated interplay between mesenchymal stem cells and osteoclasts supports calvarial bone homeostasis and repair

Calvarial bones are connected by fibrous sutures. These sutures provide a niche environment that includes mesenchymal stem cells (MSCs), osteoblasts, and osteoclasts, which help maintain calvarial bone homeostasis and repair. Abnormal function of osteogenic cells or diminished MSCs within the cranial suture can lead to skull defects, such as craniosynostosis. Despite the important function of each of these cell types within the cranial suture, we have limited knowledge about the role that crosstalk between them may play in regulating calvarial bone homeostasis and injury repair. Here we show that suture MSCs give rise to osteoprogenitors that show active bone morphogenetic protein (BMP) signalling and depend on BMP-mediated Indian hedgehog (IHH) signalling to balance osteogenesis and osteoclastogenesis activity. IHH signalling and receptor activator of nuclear factor kappa-Β ligand (RANKL) may function synergistically to promote the differentiation and resorption activity of osteoclasts. Loss of Bmpr1a in MSCs leads to downregulation of hedgehog (Hh) signalling and diminished cranial sutures. Significantly, activation of Hh signalling partially restores suture morphology in Bmpr1a mutant mice, suggesting the functional importance of BMP-mediated Hh signalling in regulating suture tissue homeostasis. Furthermore, there is an increased number of CD200+ cells in Bmpr1a mutant mice, which may also contribute to the inhibited osteoclast activity in the sutures of mutant mice. Finally, suture MSCs require BMP-mediated Hh signalling during the repair of calvarial bone defects after injury. Collectively, our studies reveal the molecular and cellular mechanisms governing cell–cell interactions within the cranial suture that regulate calvarial bone homeostasis and repair.

Effects of combined menaquinone-4 and PTH1-34 treatment on osetogenesis and angiogenesis in calvarial defect in osteopenic rats.

The aim of this study was to evaluate the effect of combining human parathyroid hormone (1-34) (PTH1-34; PTH) and menaquinone-4 (MK-4) on calvarial bone defect repair in osteopenic rats. Fourteen week olds were subject to craniotomy for the establishment of osteopenic animal models fed through a chronically low-protein diet. After that, critical calvarial defect model was established and all rats were randomly divided into four groups: sham, MK-4, PTH, and PTH + MK-4. The animals received MK-4 (30 mg/kg/day), PTH1-34 (60 μg/kg, three times a week), or PTH1-34 (60 μg/kg, three times a week) plus MK-4 (30 mg/kg/day) for 8 weeks, respectively. Serum γ-carboxylated osteocalcin (Gla-OC) levels, histological and immunofluorescent labeling were employed to evaluate the bone formation and mineralization in calvarial bone defect. In addition, Microfil perfusion, immunohistochemical, and micro-CT suggested enhanced angiogenesis and bone formation in calvarial bone healing. In this study, treatment with either PTH1-34 or MK-4 promoted bone formation and vascular formation in calvarial bone defects compared with the sham group. In addition, combined treatment of PTH1-34 plus MK-4 increased serum level of Gla-OC, improved vascular number and vascular density, and enhanced bone formation in calvarial bone defect in osteopenic conditions as compared with monotherapy. In summary, this study indicated that PTH1-34 plus MK-4 combination therapy accelerated bone formation and angiogenesis in calvarial bone defects in presence of osteopenia.

Systemic Injection of Substance P Promotes Murine Calvarial Repair Through Mobilizing Endogenous Mesenchymal Stem Cells

Craniofacial defect is a critical problem in dental clinic, which has a tremendous impact on patients’ quality of life. Mesenchymal stem cell-based therapy has emerged as a promising approach for tissue defect repair. However, reduced survival after mesenchymal stem cells (MSCs) transplantation remains as a major problem in this area, which hampers the outcome of regeneration. Recently, the mechanism to mobilize endogenous MSCs for tissue regeneration has received increasing attentions, as it does not require exogenous cell transplantation. The primary goal of this study was to confirm the role of intravenous substance P in mobilizing endogenous CD45−CD11b−CD29+ MSCs in critical-sized bone defect animals and to investigate the effects of substance P on calvarial bone repair. Flow cytometry analyses revealed that intravenous substance P promoted the mobilization of endogenous CD45−CD11b−CD29+ MSCs after bone defect. In addition, Micro-CT showed that intravenous substance P improved the outcomes of calvarial bone repair. Furthermore, we discovered that systemic injection of substance P attenuated inflammation and enhanced the survival of the local-transplanted GFP+ MSCs. Our findings suggested that substance P together with its mobilized CD45−CD11b−CD29+ MSCs helped improve calvarial defect repair through regulating inflammatory conditions and promoting the survival of local-transplanted cells.

Preparation of Bone Marrow Mesenchymal Stem Cells Combined with Hydroxyapatite/Poly(d,l-lactide) Porous Microspheres for Bone Regeneration in Calvarial Defects.

A novel three-dimensional biomimetic porous microsphere was successfully designed in this study, which was composed of PDLLA, bone marrow mesenchymal stem cells (MSCs), and nanohydroxyapatite (nHAp). nHAp/PDLLA/MSC porous microspheres that are supposed to be a significant constituent of bone in vertebrate were prepared to act as biodegradable support materials. In addition, bone MSCs act as seeding cells in bone defect repair. The microstructure of the obtained nHAp/PDLLA/MSC porous microspheres was characterized. Scanning electronic microscopy showed that the composite materials exhibited a cross-linked porous structure. In vivo biocompatibility was studied by the way of implanting the nHAp/PDLLA porous microspheres subcutaneously in rats for 4 and 8 weeks. In addition, the osteogenic capacity of the nHAp/PDLLA/MSC porous microspheres was assessed by implanting the 10 mm × 10 mm × 3 mm cranial defect of New Zealand white rabbits. In vivo studies confirmed that nHAp/PDLLA/MSC porous microspheres had a good biocompatibility and were better in inducing bone regeneration than nHAp/PDLLA porous microspheres and the self-healing process. All of the results suggested that the nHAp/PDLLA/MSC porous microspheres present a remarkable potential in calvarial defect repair and bone tissue engineering.

Treatment of calvarial defects by resorbable and non-resorbable sonic activated polymer pins and mouldable titanium mesh in two dogs: a case report

BackgroundTo date, calvarial defects in dogs have traditionally been addressed with different types of implants including bone allograft, polymethylmethacrylate and titanium mesh secured with conventional metallic fixation methods. This report describes the use of an absorbable and non absorbable novel polymer fixation method, Bonewelding® technology, in combination with titanium mesh for the repair of calvarial defects in two dogs. The clinical outcomes and comparative complication using resorbable and non-resorbable thermoplastic pins were compared.Case presentationThis report of two cases documents the repair of a traumatic calvarial fracture in an adult male Greyhound and a cranioplasty following frontal bone tumor resection in an adult female Cavalier King Charles Spaniel with the use of a commercially available titanium mesh secured with an innovative thermoplastic polymer screw system (Bonewelding®). The treatment combination aimed to restore cranial structure, sinus integrity and cosmetic appearance. A mouldable titanium mesh was cut to fit the bone defect of the frontal bone and secured with either resorbable or non-resorbable polymer pins using Bonewelding® technology. Gentamycin-impregnated collagen sponge was used intraoperatively to assist with sealing of the frontal sinuses. Calvarial fracture and post-operative implant positioning were advised using computed tomography. A satisfactory restoration of skull integrity and cosmetic result was achieved, and long term clinical outcome was deemed clinically adequate with good patient quality of life. Postoperative complications including rostral mesh uplift with minor associated clinical signs were encountered when resorbable pins were used. No postoperative complications were experienced in non-resorbable pins at 7 months follow-up, by contrast mesh uplift was noted 3 weeks post-procedure in the case treated using absorbable pins.ConclusionsThe report demonstrates the innovative use of sonic-activated polymer pins (Bonewelding® technology) alongside titanium mesh is a suitable alternative technique for skull defect repair in dogs. The use of Bonewelding® may offer advantages in reduction of surgical time. Further, ultrasonic pin application may be less invasive than alternative metallic fixation and potentially reduces bone trauma. Polymer systems may offer enhanced mesh-bone integration when compared to traditional metallic implants. The use of polymer pins demonstrates initial potential as a fixation method in cranioplasty. Initial findings in a single case comparison indicate a possible advantage in the use of non-absorbable over the absorbable systems to circumvent complications associated with variable polymer degradation, further long term studies with higher patient numbers are required before reliable conclusions can be made.

Repair of Critical-Sized Rat Calvarial Defects With Three-Dimensional Hydroxyapatite-Gelatin Scaffolds and Bone Marrow Stromal Stem Cells.

IntroductionThe repair of critical-sized defects (CSDs) are one of the most challenging orthopedic problems and the attempts for development of an ideal scaffold for treatment of large bone defect are ongoing.AimThe aim of this study was the effectiveness of hydroxyapatite-gelatin seeded with bone marrow stromal cells construct for healing of critical-sized bone defect in vivo.Material and MethodsIn this experimental study, the bone marrow stromal cells (BMSCs) were isolated by flushing method. For in vitro study, the cells were seeded on the scaffold and the cell viability as well as cytotoxicity were tested by MTT and LDH specific activity. The scaffold-cell construct was implanted into the critical-sized bone defect created in calvaria of Wistar male rats.15 rats were randomly divided into 3 groups (n=5), group 1 (control group): Injury without transplantation, group 2: implanted with hydroxyapatite-gelatin scaffold, group 3: hydroxyapatite-gelatin scaffold seeded with BMSCs. At different days post-implantation, the implanted site was collected and the bone healing was evaluated through H&E and Masson’s Trichrome staining. ANOVA and paired t-test were used for data comparison and P<0.05 was considered significant.ResultsThe results of MTT showed that the scaffold has no toxic effects on stromal cells. The first signs of ossification in hydroxyapatite-gelatin with BMSCs cells group appeared in the first week. However, in the fourth week, ossification was completed and the scaffold remaining was found as embedded islands in the spongy bone tissue. The greatest number of lymphocytes in the experimental group was observed after one week of planting scaffold.ConclusionHydroxyapatite-gelatin scaffold coated with BMSCs cells has a potential role in the healing process of bone and would be a possible new therapeutic strategy to repair extensive bone lesions.

Fabrication of large-pore mesoporous Ca-Si-based bioceramics for bone regeneration.

Our previous study revealed that mesoporous Ca-Si-based materials exhibited excellent osteoconduction because dissolved ions could form a layer of hydroxycarbonate apatite on the surface of the materials. However, the biological mechanisms underlying bone regeneration were largely unknown. The main aim of this study was to evaluate the osteogenic ability of large-pore mesoporous Ca-Si-based bioceramics (LPMSCs) by alkaline phosphatase assay, real-time PCR analysis, von Kossa, and alizarin red assay. Compared with large-pore mesoporous silica (LPMS), LPMSCs had a better effect on the osteogenic differentiation of dental pulp cells. LPMSC-2 and LPMSC-3 with higher calcium possessed better osteogenic abilities than LPMSC-1, which may be related to the calcium-sensing receptor pathway. Furthermore, the loading capacity for recombinant human platelet-derived growth factor-BB was satisfactory in LPMSCs. In vivo, the areas of new bone formation in the calvarial defect repair were increased in the LPMSC-2 and LPMSC-3 groups compared with the LPMSC-1 and LPMS groups. We concluded that LPMSC-2 and LPMSC-3 possessed both excellent osteogenic abilities and satisfactory loading capacities, which may be attributed to their moderate Ca/Si molar ratio. Therefore, LPMSCs with moderate Ca/Si molar ratio might be potential alterative grafts for craniomaxillofacial bone regeneration.

Growth differentiation factor 15 promotes blood vessel growth by stimulating cell cycle progression in repair of critical-sized calvarial defect

Repair of large bone defects remains a challenge for surgeons, tissue engineering represents a promising approach. However, the use of this technique is limited by delayed vascularization in central regions of the scaffold. Growth differentiation factor 15(GDF15) has recently been reported to be a potential angiogenic cytokine and has an ability to promote the proliferation of human umbilical vein endothelial cells(HUVECs). Whether it can be applied for promoting vascularized bone regeneration is still unknown. In this study, we demonstrated that GDF15 augmented the expression of cyclins D1 and E, induced Rb phosphorylation and E2F-1 nuclear translocation, as well as increased HUVECs proliferation. Furthermore, we also observed that GDF15 promoted the formation of functional vessels at an artificially-induced angiogenic site, and remarkably improved the healing in the repair of critical-sized calvarial defects. Our results confirm the essential role of GDF15 in angiogenesis and suggest its potential beneficial use in regenerative medicine.

Repair of the calvarial defect in goat model using magnesium-doped porous hydroxyapatite combined with recombinant human bone morphogenetic protein-2.

Hydroxyapatite (HA) is a representative bone repairing biomaterial for its similar composition to human bones and teeth. However, pure HA is limited in application for some unwanted characteristic, such as it is brickle and weakness in degradation. In this study, we modified HA by doping magnesium (Mg) to the material and studied its property in vitro. Besides, we also evaluated the calvarial defect repair effect using MgHA combined with rhBMP-2 in goat model. According to our outcomes, HA composited Mg made the scaffold smooth and the pore regular. In vitro study, Mg could increase the Ca releasing, which may reflect a faster degradation property modified by Mg. And then, MgHA improved the cell viability and proliferation. Furthermore, MgHA could increase the expression of ALP, Collagen I and VEGF protein compared with pure HA (p<0.5, respectively). In the vivo study, MgHA showed a better bone defect healing effect in computed tomography (CT) evaluation compared with HA (p<0.05), but it was inferior to the MgHA/rhBMP-2 (p<0.05). Besides, in the histological analysis, MgHA/rhBMP-2 showed the most effective bone formation outcome (p<0.05), and the MgHA group was significant better than the pure HA group on osteogenesis (p<0.05). Furthermore, Collagen I and VEGF mRNA expression at 12 week in MgHA/rhBMP-2 group were also significat higher than other two groups. In conclusion, Mg had effects on bone formation and angiogenesis, and MgHA/rhBMP-2 had improved the bone defect repair effect. It is worthy of being recommended to bone tissue engineering.

RETRACTED ARTICLE: Guangxi cobra venom-derived NGF promotes the osteogenic and therapeutic effects of porous BCP ceramic

Neuro-osteological interactions have an important role in the regulation of bone metabolism and regeneration. Neuropeptides combined with porous biphasic calcium phosphates (BCP) using protein adsorption may contribute to the acceleration of bone formation. In the present study, we investigated the effect of BCP combined with nerve growth factor (NGF) on the growth of osteoblasts in vitro and the combinational therapeutic effect on the repair of calvarial defects in vivo. NGF was separated and purified from Chinese cobra venom using a simplified three-step chromatography method. BCP combined with NGF exerted a potent effect on osteoblast differentiation, as evidenced by enhanced cell proliferation, increased ALP activity and the up-regulated expression of osteogenesis-related genes and proteins. Further, combinational therapy with BCP and NGF improved calvarial regeneration, which was superior to treatment with therapy alone, as observed using imageological and morphological examination and histological and immunohistochemical staining. The results confirmed the effect of neuro-osteological interactions through combinatorial treatment with NGF and BCP to promote osteogenesis and bone formation, which may provide an effective and economical strategy for clinical application.

Chitosan/nHAC/PLGA microsphere vehicle for sustained release of rhBMP-2 and its derived synthetic oligopeptide for bone regeneration.

Both of the osteogenic factor and the suitable delivery system in bone tissue engineering are essential for bone regeneration. In this study, we manufactured two kinds of composite vehicles for sustained release of rhBMP-2 and its derived synthetic oligopeptide (Peptide-24, abbreviated as P24) for osteogenesis and bone defect repair. The composite vehicle was based on cross-linked chitosan, nano-hydroxyapatite/collagen (nHAC), and poly (lactide-co-glycolide) acid microsphere. The physicochemical properties of the composite vehicles (abbreviated as CS/nHAC/PLGA-MS) were investigated. The rhBMP-2 and P24 release kinetics from the vehicles were examined and the secondary structure of rhBMP-2 and P24 after 28 days' release process was analyzed. In vitro cell proliferation, osteogenic differentiation and rat calvarial defect repair were evaluated. The results proved that the composite vehicle had favorable compressive strength, elastic modulus, the porosity, and the bulk density. The secondary structures of rhBMP-2 and P24 kept stability during microencapsulation and release process. P24 from the vehicle kept a geared-up release and rhBMP-2 from the vehicle kept a three-stage mode release process. The results of in vitro cell detection showed that the composite vehicle had good biocompatibility and osteoinduction. In vivo rat calvarial defect repair demonstrated that both groups of vehicles with rhBMP2 and P24 exhibited satisfied bone defect repair. This research showed that the composite vehicle could exhibit sustained release of osteogenic factors. CS/nHAC/PLGA-MS loading rhBMP-2 or P24 could be a novel and ideal scaffold for bone regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1593-1606, 2017.

Identification of Bone Marrow-Derived Soluble Factors Regulating Human Mesenchymal Stem Cells for Bone Regeneration.

SummaryMaintaining properties of human bone marrow-derived mesenchymal stem cells (BMSCs) in culture for regenerative applications remains a great challenge. An emerging approach of constructing a culture environment mimicking the bone marrow niche to regulate BMSC activities has been developed. In this study, we have demonstrated a systematic approach to identify soluble factors of interest extracted from human bone marrow and used them in BMSC culture for tissue regeneration. We have found that lipocalin-2 and prolactin are key factors in bone marrow, involved in regulating BMSC activities. Treating the cell with lipocalin-2 and prolactin delays cellular senescence of BMSCs and primes the cell for osteogenesis and chondrogenesis. We have also demonstrated that BMSCs pretreated with lipocalin-2 and prolactin can enhance the repair of calvarial defects in mice. Together, our study provides research evidence of using a viable approach to prime BMSC properties in vitro for improving cell-based tissue regeneration in vivo.

Effects of Sr-HT-Gahnite on osteogenesis and angiogenesis by adipose derived stem cells for critical-sized calvarial defect repair

Tissue engineering strategies to construct vascularized bone grafts are now attracting much attention. Strontium-hardystonite-Gahnite (Sr-HT-Gahnite) is a strong, highly porous, and biocompatible calcium silicate based bio-ceramic that contains strontium and zinc ions. Adipose derived stem cells (ASCs) have been demonstrated to have the ability in promoting osteogenesis and angiogenesis. In this study, the effects of Sr-HT-Gahnite on cell morphology, cell proliferation, and osteogenic differentiation of ASCs were systematically investigated. The cell proliferation, migration and angiogenic differentiation of human umbilical vein endothelial cell (HUVECs) were studied. Beta-tricalcium phosphate/hydroxyapatite (TCP/HA) bioceramic scaffolds were set as the control biomaterial. Both bio-ceramics exhibited no adverse influence on cell viability. The Sr-HT-Gahnite scaffolds promoted cell attachment and alkaline phosphatase (ALP) activity of ASCs. The Sr-HT-Gahnite dissolution products enhanced ALP activity, matrix mineralization, and angiogenic differentiation of ASCs. They could also improve cell proliferation, migration, and angiogenic differentiation of HUVECs. Levels of in vivo bone formation with Sr-HT Gahnite were significantly higher than that for TCP/HA. The combination of Sr-HT-Gahnite and ASCs promoted both osteogenesis and angiogenesis in vivo study, compared to Sr-HT-Gahnite and TCP/HA bio-ceramics when administered alone, suggesting Sr-HT-Gahnite can act as a carrier for ASCs for construction of vascularized tissue-engineered bone.

Effects of HAp and TCP in constructing tissue engineering scaffolds for bone repair.

In recent years, hydroxyapatite (HAp) and β-tricalcium phosphate (TCP) were extensively used to prepare composite scaffolds for bone repair. However, due to a lack of systematical evaluation of HAp and TCP composite scaffolds for bone repair, their distinctions on bone regeneration in vivo have not been clearly clarified to date. In this study, we constructed HAp and TCP composite poly(lactic-co-glycolic acid) (PLGA) scaffolds with the same contents of HAp and TCP and similar structures and porosities, and systematically investigated their performance in the repair of rabbits' calvarial bone defects. The HAp/PLGA scaffold possessed stronger mechanical property and higher cell proliferation than the TCP/PLGA scaffold, endowing it with better performance of bone regeneration at an early stage. Since TCP could greatly neutralize degraded acidic products and be slowly absorbed in vivo to release occupied room for new bone growth compared to HAp, the TCP/PLGA scaffold yielded more intact new bone for long-term repair of the defects. Our results clearly demonstrate that TCP is a superior bioceramic for bone tissue engineering, showing promise for the perfect repair of bone defects via tissue engineering.