Orbital Soft Tissue Displacement After Blow-Out Fracture Repair Using Poly (L-Lactide-Co-Glycolide) Polymer Plates Based on Image Fusion Technique.

PURPOSE: To analyze the displacement of orbital soft tissue after blow-out fracture (BOF) repair with poly (L-lactide-co-glycolide) plates. MATERIALS AND METHODS: In this retrospective study, all patients who had undergone repair operations for orbital BOF from 2017 to 2021 were evaluated. Poly (L-lactide-co-glycolide) plates were used as repair materials. Preoperative and postoperative computed tomography images were integrated into the same coordinate system applying image fusion technique and were compared to determine the maximum displacement of orbital tissue after surgical repair. RESULTS: A total of 15 patients were included. Five were male, and 10 were female. Mean age was 33±16 years. Median waiting period was 18 (12-23) days. Six cases were medial wall fractures, 5 were floor fractures, and 4 were combined fractures. Maxillo-ethmoidal strut was involved in 4. Mean defect area was 176.52±108.48 mm 2 . Median interval between postoperative imaging examinations was 292 (223-600) days. Mean orbital tissue displacement was 2.6±1.8 mm. Using simple and multivariable linear regression analysis, the fracture defect area ( P =0.001) and maxillo-ethmoidal strut involvement ( P =0.013) were found to be significantly associated with orbital tissue displacement. Median orbital volume change was 0.804 (0.647-1.010) cm 3 . Average proptosis variation was 1.2±0.8 mm. CONCLUSIONS: Poly (L-lactide-co-glycolide) plates were more suitable for orbital BOF with small defect size. Those with large defect or maxillo-ethmoidal strut involved might have greater tissue displacements due to decline of supporting strength of poly (L-lactide-co-glycolide) plates.

Surgical repair of large orbital floor and medial wall fractures with destruction of the inferomedial strut: Initial experience with a combined endoscopy navigation technique.

The application of navigation and endoscope is an area of intense interest in the surgical repair of orbital fractures. This study explored the advantages of a combined endoscopy navigation technique (ENT) for repairing large orbital floor and medial wall fractures (OFMWFs) with destruction of the inferomedial strut (IMS). Fifty-two consecutive patients with large OFMWFs with the destruction of the IMS underwent ENT-assisted surgical repair from January 2013 to February 2016. Patient demographics, causes of injury, clinical features, imaging data, and follow-up information (diplopia, ocular dysmotility, enophthalmos, infraorbital hypoesthesia, and other conditions) were collected and analyzed. Orbital volumes and implant positions were also evaluated. The median follow-up duration was 21 (range, 16-29) months. At the end of the follow-up visits, orbital reconstruction was demonstrated by orbital computed tomography. Of the 30 patients with diplopia within the 30-degree visual field of gaze, 27 (90%) reached diplopia remission. Of 40 patients, 34 (85%) achieved complete elimination of ocular dysmotility. Of 47 patients with enophthalmos of >2 mm, 43 (91%) acquired good symmetry with a mean improvement of 3.00 ± 1.00 mm. Of 33 patients, 27 (82%) recovered from infraorbital hypoesthesia. The postoperative orbital volumes of the two sides showed no significant differences (p = 0.087, paired t-test). Early surgical repair showed better outcomes of diplopia, ocular motility, and enophthalmos than late repair (p = 0.001, p = 0.007, and p = 0.000, generalized estimated equations). No patient developed surgery-related complications of visual acuity compromise, strabismus, ectropion, entropion, or lacrimal canaliculus injuries. ENT-assisted surgery appears to be safe, precise, and effective for the repair of large OFMWFs with destruction of the IMS.

Long-term outcomes of a new anatomy-based method for finding the medial cut end during late canalicular repair.

BACKGROUND: Locating the medial cut end during late repair of canalicular lacerations can be challenging. OBJECTIVE: The aim of this study was to evaluate the effectiveness and long-term outcomes of a new anatomy-based method for solving the problem of locating the medial cut end. METHODS: This retrospective interventional study included 85 eyes of 85 consecutive adult patients with unilateral inferior canalicular lacerations who underwent late primary (≥2 days after injury) or secondary (≥6 months after initial treatment) surgery. Before surgery, the lacerations were classified as lateral, central, or medial according to the 'distance from the punctum to the distal end' of the lacerated inferior canaliculus. The time spent to locate the proximal lacerated end (TSL) was recorded. All patients were followed up for ≥1 year to evaluate the lacrimal passage patency and the distance between the superior and inferior punctum (DBSIP, to assess cosmesis). RESULTS: There were 16 (18.82%) lateral-type, 55 (64.71%) central-type, and 14 (16.47%) medial-type canalicular lacerations. The TSL was 3.48 ± 1.05 (range 0.9-6.8) min for all patients and differed significantly among the three types of canalicular lacerations (P < 0.001). Lacrimal irrigation showed patent lacrimal passages in 69 patients (81.18%) at 3 months and a further 4 patients (4.71%) at 6 months, residual stenosis without obstruction in 5 patients (5.88%), and obstruction in 7 patients (8.24%). The postoperative DBSIP on the affected side was shorter than the preoperative DBSIP (2.66 ± 0.66 vs. 3.09 ± 1.72 mm, P = 0.006) and comparable to that on the unaffected side (2.78 ± 0.40 mm). CONCLUSION: Our new anatomy-based method is efficient and achieves good long-term outcomes for all types of late canalicular repair.

Cathelicidin LL37 Promotes Osteogenic Differentiation in vitro and Bone Regeneration in vivo.

Different types of biomaterials have been used to repair the defect of bony orbit. However, exposure and infections are still critical risks in clinical application. Biomaterials with characteristics of osteogenesis and antibiosis are needed for bone regeneration. In this study, we aimed to characterize the antimicrobial effects of cathelicidin-LL37 and to assess any impacts on osteogenic activity. Furthermore, we attempted to demonstrate the feasibility of LL37 as a potential strategy in the reconstruction of clinical bone defects. Human adipose-derived mesenchyme stem cells (hADSCs) were cultured with different concentrations of LL37 and the optimum concentration for osteogenesis was selected for further in vitro studies. We then evaluated the antibiotic properties of LL37 at the optimum osteogenic concentration. Finally, we estimated the efficiency of a PSeD/hADSCs/LL37 combined scaffold on reconstructing bone defects in the rat calvarial defect model. The osteogenic ability on hADSCs in vitro was shown to be dependent on the concentration of LL37 and reached a peak at 4 µg/ml. The optimum concentration of LL37 showed good antimicrobial properties against Escherichia coli and Staphylococcus anurans. The combination scaffold of PSeD/hADSCs/LL37 showed superior osteogenic properties compared to the PSeD/hADSCs, PSeD, and control groups scaffolds, indicating a strong bone reconstruction effect in the rat calvarial bone defect model. In Conclusion, LL37 was shown to promote osteogenic differentiation in vitro as well as antibacterial properties. The combination of PSeD/hADSCs/LL37 was advantageous in the rat calvarial defect reconstruction model, showing high potential in clinical bone regeneration.

Biomimetic nanofibrous hybrid hydrogel membranes with sustained growth factor release for guided bone regeneration.

Bone regeneration, a complex physiological process, remains a challenge due to the susceptibility to the environment and absence of osteogenic growth factors around the defect region. Although autologous bone grafting is regarded as the gold standard for bone defect treatment, guided bone regeneration membranes in combination with multiple functional growth factors show a striking regeneration effect. Here, a biomimetic nanofibrous hybrid hydrogel composed of bacterial cellulose membranes and alginate/CaCl2 for sustained growth factor delivery was developed. The antibacterial peptide beta-defensin 2 served as an antibacterial, osteogenic, and angiogenic growth factor and was loaded into the aforementioned hydrogel. The mechanical and physical properties of the biomimetic nanofibrous hybrid hydrogel were investigated. Then, the in vitro osteogenic and angiogenic differentiation was confirmed by alkaline phosphatase (ALP) activity, Alizarin Red S staining, qPCR, western blot analysis and tube formation assays. After implantation into a rat calvarial defect model for 12 weeks, nanofibrous hybrid hydrogel membranes could adhere to the defect surface and promote new bone and vessel regeneration.

Self-assembled supramolecular dispersive liquid-phase microextraction for concentration and determination of anthraquinone compounds in Rhubarb.

Self-assembled supramolecular dispersive liquid-phase microextraction combined with high-performance liquid chromatography was developed and introduced for simultaneous extraction and determination of the trace level rhein, chrysophanol, and physcion in Rhubarb. Compared with conventional dispersive liquid-phase microextraction, the proposed method used a self-assembled ternary supramolecular consisting of the mixed extraction solvent (heptanol and nonanol) and dispersant (acetone) to achieve high enrichment factors of target analytes. Several factors affecting performance were investigated and optimized, including the mixed extraction solvent, type and volume of the dispersant, the pH of sample phase, salt concentration, shaking time, volume of sample phase, centrifugation time, and rate. Meanwhile, the method mechanism of self-assembled supramolecular dispersive liquid-phase microextraction was analyzed and described. Under the optimized extraction conditions, the enrichment factors of rhein, chrysophanol, and physcion were 116.5, 325.9, and 356.1, respectively. Good linearities (r ≥ 0.9952) for all analytes, low limits of detection (less than 0.04 ng/mL), satisfactory precisions (0.1-8.9%), and accuracies (recoveries, 88.2-104.1%) were achieved. The experimental results showed that the approach was simple, fast, with short extraction time, high enrichment factors, good linearities, and low limits of detection.

Effect of Bifunctional ß Defensin 2-Modified Scaffold on Bone Defect Reconstruction.

Bone tissue engineering has emerged as an effective alternative treatment to the problem of bone defect. To repair a bone defect, antibiosis and osteogenesis are two essential aspects of the repair process. By searching the literature and performing exploratory experiments, we found that ß defensin 2 (BD2), with bifunctional properties of antibiosis and osteogenesis, was a feasible alternative for traditional growth factors. The antimicrobial ability of BD2 against Staphylococcus aureus and Escherichia coli was studied by the spread plate and live/dead staining methods (low effective concentration of 20 ng/mL). BD2 was also demonstrated to enhance osteogenesis, with higher messenger RNA (mRNA) and protein expression of the osteogenic markers collagen I (Col1), runt-related transcription factor 2 (Runx2), osteopontin (Opn), and osteocalcin (Ocn) in vitro (1.5-2.5-fold increase compared with the control group in the most effective concentration group), which was consistent with the alkaline phosphatase (ALP) and alizarin red S (ARS) staining results. We implanted poly(sebacoyl diglyceride) (PSeD) combined with BD2 and rat bone tissue-derived mesenchymal stem cells (rBMSCs) under the back skin of rats and found that the inflammatory response was significantly lower with this combination than with the PSeD/rBMSCs scaffold without BD2 and the pure PSeD group and was similar to the control group. Importantly, when assessed in a critical-sized in vivo rat 8 m diameter calvaria defect model, a scaffold we developed combining bifunctional BD2 with porous organic polymer displayed an osteogenic effect that was 160-200% greater than the control group. The in vivo study results revealed a significant osteogenic response and antimicrobial effect and were consistent with the in vitro results. In summary, BD2 displayed a great potential of simultaneously promoting bone regeneration and preventing infection and could provide a viable alternative to traditional growth factors applied in bone defect repair.

[Practice and exploration of orbital anatomy and orbital imaging courses in dental students].

PURPOSE: To improve the teaching effect of orbital anatomy course for students majoring in stomatology. METHODS: Based on a retrospective analysis of average score of orbital anatomy course for previous dental and medical students, and the problems existing in teaching effect, orbital anatomy and orbital imaging course were designed and carried out in dental students. The course combined imaging with orbital anatomy, and included clinical examples. Medical students were set as control. Examination was carried out after the end of the whole course, and the professional knowledge of orbital anatomy of two groups was compared. A self-designed questionnaire was designed to evaluate the teaching effect of orbital anatomy and orbital imaging courses for dental students and residents over 1 year after graduation. SPSS 22 software package was used for Statistical analysis. RESULTS: The previous average score of dental students was 7.50, and the average score of medical students was 8.67. There was significant difference between the two groups (P=0.004). The average score of dental students after offering the course of orbital anatomy and orbital imaging was 9.67, and the average score of medical students was 9.00. No significant difference was noticed between the two groups(P=0.184). Questionnaire survey showed that the after-class review time of dental students was 20 min, and that of medical students was 30 min. 74.7% of the dental students and 80% of the dental residents did not study orbital anatomy and imaging courses before. 87.4% of the dental students and 100% of dental residents considered that the orbital imaging course was helpful to master the anatomical characteristics of the orbit. 89.7% of the dental students and 100% of dental residents believed that orbital imaging course was helpful to their clinical work. CONCLUSIONS: Orbital anatomy and orbital imaging course were designed for dental students as supplementary teaching programme. It successfully inspired students' interest in learning, cultivated the students' overall and comprehensive thinking, narrowed students to master the knowledge of orbital anatomy, closed the gap of teaching effect between dental and clinical medicine, and laid the foundation to develop dental professional work in the future.

Serial Z-plasty for Correction of Cicatricial Conjunctival Constriction Rings.

BACKGROUND: Cicatricial conjunctival constriction rings caused by trauma seriously influences visual function and causes blepharon deformities. The treatment of cicatricial conjunctival constriction rings is intractable. METHODS: A 45-year-old male presented severe cicatricial conjunctival constriction ring due to traffic accident injury. This 5-mm diameter constriction ring resulted in the patient's eyelid deformities, including eyelid ptosis, ectropion, and visual obstruction. The patient underwent primary surgery of serial conjunctival Z-plasty for correction of the constriction ring. Conjunctival constriction ring was corrected immediately after Z-plasy. Fornix deepening suturing was adopted to promote formation of fornix and correct eyelid ectropion. A secondary surgery of frontalis flap suspension was adopted to correct ptosis 6 months after Z-plasty. RESULTS: The patient achieved a satisfactory and symmetrical appearance with no recurrence of cicatricial conjunctival constriction and no other complications during the 6-month follow-up period. CONCLUSION: In this patient, the authors claimed that serial Z-plasty surgery can effectively be used for correction of cicatricial conjunctival constriction rings. No further material implantation was applied during the operation.

Delayed surgical treatment of orbital trapdoor fracture in paediatric patients.

BACKGROUND: Trapdoor fracture is a special type of orbital blowout fracture. Although early surgery is recommended, there still remain some patients delayed by various reasons. In this study, we analysed the clinical characteristics of delayed paediatric patients, especially those with different levels of ocular motility restriction before surgery. METHODS: Thirty patients (3 to 14 years old) who underwent delayed surgery for trapdoor fractures between January 2008 and September 2016 were enrolled. Their demographics, causes of injury and delay, clinical features, imaging data and follow-up information were collected. RESULTS: Muscular entrapment was found in 17 patients (group A) and soft-tissue entrapment in 13 patients (group B). 12 (7 in group A) presented with severe motility restriction and 18 (10 in group A) with mild restriction before surgery. 41.7% with severe restriction recovered after surgery, compared with 83.3% with mild restriction. Four (23.7%) in group A (all with severe restriction) and six (46.2%) in group B (half with severe restriction) presented with persistent diplopia. CONCLUSIONS: Long recovery time and a high percentage of persistent diplopia are the main problems of delayed trapdoor fracture in children. A prompt surgery within 48 hours is strongly recommended in patients with muscular entrapment even if an urgent treatment is hard to achieve. So are patients with soft-tissue entrapment and significant motility restriction. In the other patients without such indications, even though some recovery might be possible in the long term, a prompt surgery right after diagnosis is still preferable regardless of the entrapped contents.

A biodegradable functional water-responsive shape memory polymer for biomedical applications.

Shape memory polymers (SMPs) have exhibited great potential in biomedical applications. However, the typical triggers of shape recovery such as heat, UV light, and electricity may be harmful to humans. Accordingly, water-responsive SMPs have become significant, especially for in vivo applications, due to the intrinsic biocompatibility and ready availability of water. However, the reported water-responsive SMPs are limited and relatively complicated. Here, we design a new water-responsive SMP, poly(butanetetrol fumarate) (PBF); the properties of PBF could be modulated by curing. The cured PBF scaffolds exhibited high shape recovery and fixity rates (>95%). PBF showed good biodegradability, and it could support the attachment, viability and alkaline phosphatase activity of osteoblasts. Furthermore, PBF could be readily functionalized via pendant hydroxyl groups, which was demonstrated by the immobilization and controlled release of bone morphogenetic protein 2. We expect that PBF will be useful for various biomedical applications including water-responsive scaffolds, sensors or actuators.

Enhanced bioactivity and osteoinductivity of carboxymethyl chitosan/nanohydroxyapatite/graphene oxide nanocomposites.

Tissue engineering approaches combine a bioscaffold with stem cells to provide biological substitutes that can repair bone defects and eventually improve tissue functions. The prospective bioscaffold should have good osteoinductivity. Surface chemical and roughness modifications are regarded as valuable strategies for developing bioscaffolds because of their positive effects on enhancing osteogenic differentiation. However, the synergistic combination of the two strategies is currently poorly studied. In this work, a nanoengineered scaffold with surface chemistry (oxygen-containing groups) and roughness (R q = 74.1 nm) modifications was fabricated by doping nanohydroxyapatite (nHA), chemically crosslinked graphene oxide (GO) and carboxymethyl chitosan (CMC). The biocompatibility and osteoinductivity of the nanoengineered CMC/nHA/GO scaffold was evaluated in vitro and in vivo, and the osteogenic differentiation mechanism of the nanoengineered scaffold was preliminarily investigated. Our data demonstrated that the enhanced osteoinductivity of CMC/nHA/GO may profit from the surface chemistry and roughness, which benefit the ß1 integrin interactions with the extracellular matrix and activate the FAK-ERK signaling pathway to upregulate the expression of osteogenic special proteins. This study indicates that the nanocomposite scaffold with surface chemistry and roughness modifications could serve as a novel and promising bone substitute for tissue engineering.

Poly (fumaroyl bioxirane) maleate: A potential functional scaffold for bone regeneration.

Proper scaffolds combined with mesenchymal stem cells (MSCs) represent a promising strategy for repairing bone defects. In a previous study, poly (fumaroyl bioxirane) maleate (PFM), a newly developed functional polymer with numerous functional groups, exhibited excellent biocompatibility and enhanced the alkaline phosphatase (ALP) activity of osteoblasts in vitro. Here, to provide further and comprehensive insight into the application of PFM in bone tissue engineering, we investigated the osteoinductive potential of PFM cultured with rat adipose-derived mesenchymal stem cells (rADSCs). The results showed that PFM resulted in greater proliferation of rADSCs and that the PFM substrate had stronger osteoinductivity than PLGA and the control, as indicated by the significant upregulation of osteogenesis-related genes, proteins and calcium mineralization in vitro. Next, PFM was combined with rADSCs to repair a critical-sized calvarial defect in rats. Compared to the PLGA scaffold, the PFM scaffold significantly promoted new bone formation and exhibited excellent effects in repairing rat calvarial defects. In conclusion, PFM possesses strong osteoinductivity, which could markedly enhance bone regeneration, suggesting that PFM could serve as a promising and effective optimization method for traditional scaffolds in bone regeneration.

Effects of miR-146a on the osteogenesis of adipose-derived mesenchymal stem cells and bone regeneration.

Increasing evidence has indicated that bone morphogenetic protein 2 (BMP2) coordinates with microRNAs (miRNAs) to form intracellular networks regulating mesenchymal stem cells (MSCs) osteogenesis. This study aimed to identify specific miRNAs in rat adipose-derived mesenchymal stem cells (ADSCs) during BMP2-induced osteogenesis, we selected the most significantly down-regulated miRNA, miR-146a, to systematically investigate its role in regulating osteogenesis and bone regeneration. Overexpressing miR-146a notably repressed ADSC osteogenesis, whereas knocking down miR-146a greatly promoted this process. Drosophila mothers against decapentaplegic protein 4 (SMAD4), an important co-activator in the BMP signaling pathway, was miR-146a's direct target and miR-146a exerted its repressive effect on SMAD4 through interacting with 3'-untranslated region (3'-UTR) of SMAD4 mRNA. Furthermore, knocking down SMAD4 attenuated the ability of miR-146a inhibitor to promote ADSC osteogenesis. Next, transduced ADSCs were incorporated with poly(sebacoyl diglyceride) (PSeD) porous scaffolds for repairing critical-sized cranial defect, the treatment of miR-146a inhibitor greatly enhanced ADSC-mediated bone regeneration with higher expression levels of SMAD4, Runt-related transcription factor 2 (Runx2) and Osterix in newly formed bone. In summary, our study showed that miR-146a negatively regulates the osteogenesis and bone regeneration from ADSCs both in vitro and in vivo.

In vitro osteogenic induction of bone marrow mesenchymal stem cells with a decellularized matrix derived from human adipose stem cells and in vivo implantation for bone regeneration.

Tissue engineering technology that adopts mesenchymal stem cells combined with scaffolds presents a promising strategy for tissue regeneration. Human adipose-derived stem cells (hADSCs) have attracted considerable attention in bone engineering for their osteogenic potential. The extracellular matrix (ECM) is critical for the stem cell niche as a physical support and is known to be able to maintain stem cell properties. In this study, the ECM derived from ADSCs was produced and termed the ADM. The ADM was demonstrated to markedly promote proliferation of bone marrow derived stem cells (BMSCs) and exhibited strongly osteogenic simulative effects in vitro. The results showed that alkaline phosphatase (ALP) activity, Alizarin red S (ARS) staining, osteogenic gene markers and proteins were significantly up-regulated. Next, we developed a poly(sebacoyl diglyceride) (PSeD) mesh scaffold coated with the ADM and evaluated its capacity to create an osteogenic microenvironment. BMSCs were cultured on the composite scaffolds and subjected to osteogenic differentiation in vitro. The results showed that the composite scaffolds facilitated the osteogenesis more than a simple PSeD scaffold. Then the PSeD/ADM scaffold seeded with BMSCs was used to repair critical-sized calvarial defects in rats, which significantly enhanced the reparative effects as confirmed via micro-CT, sequential fluorescent labeling and histological observation. In conclusion, we demonstrated that the ADM could promote both proliferation and osteogenesis of BMSCs, and the combination of ADM and PSeD synergistically stimulated bone formation, which may provide a novel scheme for bone regeneration.

Poly(sebacoyl diglyceride) Cross-Linked by Dynamic Hydrogen Bonds: A Self-Healing and Functionalizable Thermoplastic Bioelastomer.

Biodegradable and biocompatible elastomers (bioelastomers) could resemble the mechanical properties of extracellular matrix and soft tissues and, thus, are very useful for many biomedical applications. Despite significant advances, tunable bioelastomers with easy processing, facile biofunctionalization, and the ability to withstand a mechanically dynamic environment have remained elusive. Here, we reported new dynamic hydrogen-bond cross-linked PSeD-U bioelastomers possessing the aforementioned features by grafting 2-ureido-4[1H]-pyrimidinones (UPy) units with strong self-complementary quadruple hydrogen bonds to poly(sebacoyl diglyceride) (PSeD), a refined version of a widely used bioelastomer poly(glycerol sebacate) (PGS). PSeD-U polymers exhibited stronger mechanical strength than their counterparts of chemically cross-linked PSeD and tunable elasticity by simply varying the content of UPy units. In addition to the good biocompatibility and biodegradability as seen in PSeD, PSeD-U showed fast self-healing (within 30 min) at mild conditions (60 °C) and could be readily processed at moderate temperature (90-100 °C) or with use of solvent casting at room temperature. Furthermore, the free hydroxyl groups of PSeD-U enabled facile functionalization, which was demonstrated by the modification of PSeD-U film with FITC as a model functional molecule.

Electrospun silk fibroin/poly(lactide-co-ε-caprolactone) nanofibrous scaffolds for bone regeneration.

BACKGROUND: Tissue engineering has become a promising therapeutic approach for bone regeneration. Nanofibrous scaffolds have attracted great interest mainly due to their structural similarity to natural extracellular matrix (ECM). Poly(lactide-co-ε-caprolactone) (PLCL) has been successfully used in bone regeneration, but PLCL polymers are inert and lack natural cell recognition sites, and the surface of PLCL scaffold is hydrophobic. Silk fibroin (SF) is a kind of natural polymer with inherent bioactivity, and supports mesenchymal stem cell attachment, osteogenesis, and ECM deposition. Therefore, we fabricated hybrid nanofibrous scaffolds by adding different weight ratios of SF to PLCL in order to find a scaffold with improved properties for bone regeneration. METHODS: Hybrid nanofibrous scaffolds were fabricated by blending different weight ratios of SF with PLCL. Human adipose-derived stem cells (hADSCs) were seeded on SF/PLCL nanofibrous scaffolds of various ratios for a systematic evaluation of cell adhesion, proliferation, cytotoxicity, and osteogenic differentiation; the efficacy of the composite of hADSCs and scaffolds in repairing critical-sized calvarial defects in rats was investigated. RESULTS: The SF/PLCL (50/50) scaffold exhibited favorable tensile strength, surface roughness, and hydrophilicity, which facilitated cell adhesion and proliferation. Moreover, the SF/PLCL (50/50) scaffold promoted the osteogenic differentiation of hADSCs by elevating the expression levels of osteogenic marker genes such as BSP, Ocn, Col1A1, and OPN and enhanced ECM mineralization. In vivo assays showed that SF/PLCL (50/50) scaffold improved the repair of the critical-sized calvarial defect in rats, resulting in increased bone volume, higher trabecular number, enhanced bone mineral density, and increased new bone areas, compared with the pure PLCL scaffold. CONCLUSION: The SF/PLCL (50/50) nanofibrous scaffold facilitated hADSC proliferation and osteogenic differentiation in vitro and further promoted new bone formation in vivo, suggesting that the SF/PLCL (50/50) nanofibrous scaffold holds great potential in bone tissue regeneration.

Phosphorylated poly(sebacoyl diglyceride) - a phosphate functionalized biodegradable polymer for bone tissue engineering.

Phosphorylated polymers are promising for bone regeneration because they may recapitulate the essence of the phosphorylated bone extracellular matrix (ECM) to build an instructive environment for bone formation. However, most of the existing synthetic phosphorylated polymers are not fully biodegradable; thus, they are not ideal for tissue engineering. Here, we designed and synthesized a new phosphorylated polymer, poly(sebacoyl diglyceride) phosphate (PSeD-P), based on the biodegradable osteoconductive backbone PSeD. To our knowledge, PSeD-P is the first polymer to integrate the osteoinductive moiety ß-glycerol phosphate (ß-GP). PSeD-P shows good biodegradability and can be readily fabricated on 3D porous scaffolds. It has a porous structure with interconnected macropores (75-150 µm) and extensive micropores (several microns). PSeD-P promotes the adhesion, proliferation, and maturation of osteoblasts more effectively than poly(lactic-co-glycolic acid) (PLGA). Furthermore, PSeD-P induces a significantly higher expression of osteogenic biomarkers and ALP activity in mesenchymal stem cells (MSCs) compared to its non-phosphorylated precursor, PSeD. The level of improvement is comparable to free ß-GP in culture medium. More importantly, without using ß-GP, the typical mineralization promoter in osteogenic culture media, PSeD-P substantially induces the mineralization of the ECM in MSCs, which is totally absent using PSeD under identical culture conditions. PSeD-P provides a new strategy to integrate bioactive phosphates viaß-GP into biomaterial, and has promise for bone regeneration applications. In addition, the synthetic method is versatile; both the backbone and the side phosphate groups could be readily tailored to generate a family of phosphorylated polymers for a wide range of biomedical applications.

The role of miR-135-modified adipose-derived mesenchymal stem cells in bone regeneration.

Tissue-engineering technology employing genetically-modified mesenchymal stem cells combined with proper scaffolds represents a promising strategy for bone regeneration. Elucidating the underlying mechanisms that govern the osteogenesis of mesenchymal stem cells will give deeper insights into the regulatory patterns, as well as provide more effective methods to enhance bone regeneration. In this study, miR-135 was identified as an osteogenesis-related microRNA that was up-regulated during the osteogenesis of rat adipose-derived stem cells (ADSCs). Gain- and loss-of-function experiments using a lentiviral expression system showed that Homeobox A2 (Hoxa2) was negatively regulated by miR-135, and luciferase reporter assay further indicated that miR-135 repressed Hoxa2 expression through binding to the 3'-untranslated region (3'-UTR) of the Hoxa2 mRNA. In vitro analyses showed that the overexpression of miR-135 significantly enhanced the expression of bone markers and extracellular matrix calcium deposition, whereas the knockdown of miR-135 suppressed these processes. Transduced ADSCs were then combined with poly(sebacoyl diglyceride) (PSeD) scaffold to repair a critical-sized calvarial defects in rats. The results showed that the overexpression of miR-135 significantly promoted new bone formation with higher bone mineral density (BMD) and number of trabeculae (Tb.N), as well as larger areas of newly formed bone and mineralization labeled by tetracycline, calcein and alizarin red. In contrast, the knockdown of miR-135 attenuated these processes. Additionally, immunohistochemical analyses showed that transduced ADSCs participated in new bone formation and a miR-135/Hoxa2/Runx2 pathway might contribute to the regulation of ADSC osteogenesis and bone regeneration. Taken together, our data suggested that miR-135 positively regulated the osteogenesis and bone regeneration of ADSCs both in vitro and in vivo. Thus, the combination of miR-135-modified ADSCs and the PSeD scaffold may serve as a promising and effective method to repair critical-sized bone defects.

A regulatory loop containing miR-26a, GSK3ß and C/EBPα regulates the osteogenesis of human adipose-derived mesenchymal stem cells.

Elucidating the molecular mechanisms responsible for osteogenesis of human adipose-derived mesenchymal stem cells (hADSCs) will provide deeper insights into the regulatory mechanisms of this process and help develop more efficient methods for cell-based therapies. In this study, we analysed the role of miR-26a in the regulation of hADSC osteogenesis. The endogenous expression of miR-26a increased during the osteogenic differentiation. The overexpression of miR-26a promoted hADSC osteogenesis, whereas osteogenesis was repressed by miR-26a knockdown. Additionally, miR-26a directly targeted the 3'UTR of the GSK3ß, suppressing the expression of GSK3ß protein. Similar to the effect of overexpressing miR-26a, the knockdown of GSK3ß promoted osteogenic differentiation, whereas GSK3ß overexpression inhibited this process, suggesting that GSK3ß acted as a negative regulator of hADSC osteogenesis. Furthermore, GSK3ß influences Wnt signalling pathway by regulating ß-catenin, and subsequently altered the expression of its downstream target C/EBPα. In turn, C/EBPα transcriptionally regulated the expression of miR-26a by physically binding to the CTDSPL promoter region. Taken together, our data identified a novel feedback regulatory circuitry composed of miR-26a, GSK3ß and C/EBPα, the function of which might contribute to the regulation of hADSC osteogenesis. Our findings provided new insights into the function of miR-26a and the mechanisms underlying osteogenesis of hADSCs.