Prefabrication of vascularized porous three-dimensional scaffold induced from rhVEGF(165): a preliminary study in rats.

BACKGROUND/AIMS: Several shortcomings have limited the routine use of autogenous vascularized bone graft. The present study investigates the prefabrication of vascularized scaffold with the desired shape and microarchitecture combined with recombinant human vascular endothelial growth factor 165 (rhVEGF(165)) to mimic autogenous vascularized bone graft. METHODS: Eighty-five porous calcium phosphate cement scaffolds constructed by rapid prototyping technology were divided into four groups: group A [rhVEGF(165)-fibrin sealant (FS) scaffold], group B (hVEGF(165) scaffold), group C (FS scaffold), and group D (scaffold alone). The release of rhVEGF(165) from the scaffolds was examined in vitro. The vessel density, relative functionalized vessels, vessel diameter and relative vessel area were also measured. RESULTS: The sustained release of hVEGF(165) lasted 14 days in the absence of plasmin and 12 days in the presence of plasmin in group A and 10 days in group B. There was no statistical difference between groups A and B at 2 or 4 weeks in terms of vessel density, relative functionalized vessels, vessel diameter, and relative vessel area, as between groups C and D. However, the above parameters were greater in groups A and B than groups C and D. CONCLUSION: The scaffolds with the desired shape and microarchitecture combined with rhVEGF(165) could shorten the time needed for the construction of prefabricated vascularized grafts and accelerate the maturation of the vessels.

Slow-release lubrication effect of graphene oxide/poly(ethylene glycol) wrapped in chitosan/sodium glycerophosphate hydrogel applied on artificial joints.

The artificial joints would go through serious wear after implantation surgery due to the poor lubrication of the body fluid, and the biomimetic lubricants directly injected in vitro is easy to be absorbed by human tissues, and after a period of time, it will lose its lubrication effect. However, the composite hydrogel with slow-release lubrication effect provides a new way for the lubrication of artificial joints. In this study, Graphene oxide/Poly(ethylene glycol) (GO/PEG) composites were prepared to improve the artificial joint lubrication, and through wrapped in the Chitosan/Sodium glycerophosphate (CS/GP) hydrogel, the GO/PEG lubricant will be released under the squeezing action, thus to prolong the service time of biomimetic lubricants. The friction experimental results showed that GO/PEG had better lubrication effect, and the average friction coefficient of the slow-release solution was below 0.03, especially with the pressure increasing. GO, PEG and small molecule GP in the slow-release solution through hydrogen-bond interaction might form a particular structure, which led to the good lubricating effect. The experiments of cell and acute toxicity in vivo showed that GO and its composite hydrogel had good biocompatibility.

Carbon dots intensified poly (ethylene glycol)/chitosan/sodium glycerophosphate hydrogel as artificial synovium tissue with slow-release lubricant.

The ultra-high molecular weight polyethylene (UHMWPE) and metal artificial joint pair is limited by wear debris and short service life. Here we report the development of a hydrogel which exhibits lubricant release to intensify the lubrication effect of artificial joints.This study adopted an injectable method to prepare carbon dots/poly (ethylene glycol)/chitosan/sodium glycerophosphate (CDs/PEG/CS/GP) composite hydrogel, and the carbon dots were used to intensify the rheological and mechanical properties. In addition, the composite hydrogel had slow-release properties, and the release solution contained CDs, PEG and GP has excellent lubrication effect. At last, the MTT assay, LIVE/DEAD staining, H&E staining results and safety evaluation in BALC/c mice proved that the hydrogels had good biocompatibilility and were safety for application in vivo.

Pharmacokinetics and antitumor efficacy of DSPE-PEG2000 polymeric liposomes loaded with quercetin and temozolomide: Analysis of their effectiveness in enhancing the chemosensitization of drug-resistant glioma cells.

In the present study, a new type of DSPE-PEG2000 polymeric liposome for the brain-targeted delivery of poorly water-soluble anticancer drugs was successfully prepared and characterized. The nanoparticles were formed by the self-assembly of an amphiphilic polymer consisting of hydrophilic 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE­PEG2000). These nanoliposomes served as a safe delivery platform for the simultaneous delivery of quercetin (QUE) and temozolomide (TMZ) to rat brains. The 2-in-1 PEG2000­DSPE nanoliposomes containing QUE and TMZ (QUE/TMZ-NLs) were rapidly taken up by the U87 glioma cells in vitro, whereas at the same concentrations, the amounts of the free drugs taken up were minimal. The QUE/TMZ-NLs showed an enhanced potency in the U87 cells and the TMZ-resistant U87 cells (U87/TR cells), possibly due to the high intracellular drug concentration and the subsequent drug release. In vivo biodistribution experiments revealed a significant accumulation of QUE/TMZ-NLs in the brain, with significantly increased plasma concentrations of QUE and TMZ, as well as delayed clearance in our rat model of glioma. The results were not so significant for the QUE-loaded nanoliposomes (QUE-NLs) and free TMZ. The findings of our study establish the DSPE­PEG2000 polymeric liposome as a novel and effective nanocarrier for enhancing drug delivery to brain tumors.

Effect of one versus two distal locking bolts on the biomechanics of tibial interlocking nail: a comparative study using a new model.

OBJECTIVE: To investigate the impact of one versus two distal locking bolts on the mechanical properties of tibial interlocking intramedullary nails. METHODS: Twenty 9-mm titanium alloy locking nails were divided into two equal groups in which the nails were fixed with only one and two distal locking bolts, respectively. Each group was further divided into two sub-groups for compression and torsion tests separately using a universal material-testing machine. RESULTS: In the compression tests, the average maximum strength of double bolts was greater than that of the single bolt (P<0.05), but the number of the bolts did not significantly affect the results of the torsion tests in terms of the either the maximum torsion moment or angle (P>0.05). CONCLUSION: One distal bolt is sufficient for fixing stable fractures and double bolts are recommended for management of serious fractures. The model we used is convenient and economic for examining the biomechanics of the tibial nails, especially for comparative purposes.

Preparation and properties of composite MAO/ECD coatings on magnesium alloy.

Magnesium alloys are potential biodegradable implants because of their outstanding biological performance and biodegradability in the bioenvironment. However, the rapid corrosion of magnesium and its alloys in human body fluids or blood plasma limits their clinical application. In the present work, we first fabricated porous micro-arc oxidation (MAO) coatings containing Ca/P on the magnesium alloy substrate by conducting MAO in the electrolyte containing calcium gluconate. Subsequently, hydroxyapatite (HA) coatings were prepared using electrochemical deposition (ECD) on the MAO coatings. Finally, a MAO/ECD composite coating was successfully fabricated on the magnesium alloy. The phase, morphology and composition of the biological coatings were monitored with X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy, and corrosion resistance was evaluated by means of electrochemical methods in a simulated body fluid. The experimental results indicated that the formation of HA-containing composite coatings on magnesium alloy effectively decreases its corrosion rate and more importantly endows it with a potential bioactivity. We believe that the combined use of MAO and ECD to modify magnesium alloys would make them more attractive for clinical applications.

The influence of UV irradiation on the biological properties of MAO-formed ZrO2.

Zirconium and its alloys are thought to be ideal materials for dental and orthopedic implants. However, the surface of native zirconium is bio-inert. It has been reported that micro-arc oxidation (MAO) is a convenient and effective method to improving the biocompatibility and bioactivity of the zirconium surface, and ultraviolet (UV) irradiation can improve the bioactivity of the MAO-formed ZrO(2) without altering its surface morphology, grain size and phase component. The aim of the present study was to evaluate the influence of UV irradiation on the biocompatibility and bioactivity of MAO-formed ZrO(2). Two types of samples were established. Those formed by MAO were labeled as MAO ZrO(2) samples, while those that underwent UV irradiation after MAO treatment were labeled as MAO-UV ZrO(2) samples. In the in vitro study, osteoblasts were seeded on the surfaces of the MAO and MAO-UV samples and were then studied by inverted phase contrast microscopy, scanning electron microscope (SEM) and MTT (3-(4.5-dimethyl-2-thiazolyl)-2.5-diphenayl-2H-tetrazolium bromide) testing. While in the in vivo study, the samples were implanted into calvarias of New Zealand white rabbits and were then evaluated by histology and shear strength analysis. The results indicated that the MAO-UV surfaces showed better biocompatibility, faster new bone formation and firmer bonds with bone than the MAO surfaces. Therefore, UV irradiation may be an optimal second-stage treatment that can improve the properties of MAO-formed ZrO(2).

Osteogenesis of the construct combined BMSCs with beta-TCP in rat.

BACKGROUND: The use of artificial bone graft substitutes has increased as the surgical applications widen and the availability of allograft bone decreases. The present study was to evaluate the construct combined bone marrow stromal cells (BMSCs) with beta-tricalcium phosphate (beta-TCP) as bone substitute implanted in rat dorsal muscles. METHODS: To study the osteogenic capability in vivo, specimens were harvested on 1 week, 4 weeks and 8 weeks after implantation, and were analyzed by hematoxylin and eosin (HE) staining. The percentages of new bone formation for each implant type and implantation period were determined by histomorphometry. RESULTS: After 1 week of implantation, new bone formation for both beta-TCP and BMSCs+beta-TCP group had no formed. After 4 weeks of implantation, the amount of bone formation was increased to 1.32 % in beta-TCP group and 6.35% in BMSCs+beta-TCP group. After 8 weeks of implantation, more bone was found in the BMSCs+beta-TCP group (21.58 %), while in the beta-TCP group bone formation was increased to 4.78%. Significant differences between the two groups have been observed. CONCLUSIONS: Based on these results, we conclude that bone substitutes constructed by porous beta-TCP scaffold loaded with osteogenically induced BMSCs could promote newly formed bone.