BACKGROUND:Silk fibroin, chitosan, and nano hydroxyapatite are natural materials, and they al have good biological activity and physical or chemical properties. As tissue engineering materials, they have been already widely used in clinic or research work, but there are some defects in the application of these three kinds of materials. OBJECTIVE:To discuss the preparation and characteristics of silk fibroin/chitosan/nano hydroxyapatite complicated scaffolds which could be used in bone tissue engineering. METHODS:Silk fibroin, chitosan, and nano hydroxyapatite were separately prepared into 2%solution, and then mixed at the ratio of 1:1:0.5, 1:1:1, 1:1:1.5 respectively. The three-dimensional complicated scaffolds were prepared by those mixed liquids through repeated freeze drying and chemical crosslinking technology. Scanning electron microscope was used to detect the pore size of the scaffolds. Porosity, water absorption rate, and hot-water loss rate were determined. Mechanical tester was used to measure the tensile and compressive modulus of dried three-dimensional scaffolds. RESULTS AND CONCLUSION:The silk fibroin/chitosan/nano hydroxyapatite complicated scaffold in the dry state had no special smel , appeared to be a stabilized solid cylinder, and exhibited clear resiliency and flexibility with a touch. With the increased content of nano hydroxyapatite, the porosity, water absorption rate and average pore size of the scaffolds appeared to be decreased, while the hot-water loss rate and compressive strength were increased. The scaffold prepared at 1:1:1 was better for bone tissue engineering, and the average pore size, water absorption rate and hot-water loss rate were 85.67 μm, (135.65±4.56)%and (22.84±1.06)%, respectively, closer to the needs of the bone tissue engineering. Uniform pores were found within the scaffold at 1:1:1, showing the network structure, developed transport among pores, and the network structure was approximately 10μm.

BACKGROUND:Poly lactic acid as an excellent delivery has good biocompatibility.
OBJECTIVE:To prepare recombinant human bone morphogenetic protein-2 (rhBMP-2)/poly lactic acid (PLA) sustained release microspheres, and to study its physical and chemical properties.
METHODS:The rhBMP-2/PLA sustained release microspheres were prepared using w/o/w solvent evaporation method. Scanning electron microscopy, laser particle size, zeta potential, and swel ing properties were detected. ELISA kit was utilized for measurement of encapsulation efficiency, drug-loading rate and in vitro drug release rate.
RESULTS AND CONCLUSION:Under the scanning electron microscope, rhBMP-2/PLA sustained release microspheres were approximately circle with excellent dispersion. The uniform spheres were visible with a mean particle size of 839.6 nm. The zeta potential were (-32.93±3.74) mV. The swel ing coefficient was 1.157±0.059. The drug-loading rate and encapsulation efficiency of rhBMP-2/PLA sustained release microspheres were (88.943±2.878)%and (0.026±0.001)%respectively. The drug release rate at 1 day was about 10.199%, then the drug release was relatively constant, and til 19 days, the cumulative drug release rate was 54.643%. These findings indicate that the constructed rhBMP-2/PLA sustained release microspheres meet the requirement of the Chinese Pharmacopoeia (10th edition) that the encapsulation efficiency is not less than 80%and the microspheres have a good slow-release function in vitro.

BACKGROUND:Bone morphogenetic protein-2 (BMP-2) is a key to bone formation and repair.However,it has some disadvantages such as easy to lose and degrade and difficult to sustain continuous effect.OBJECTIVE:To study the preparation and properties of silk fibroin/chitosan/nano-hydroxyapatite (SF/CS/nHA) scaffold loading BMP-2.METHODS:After silk degumming,dissolution and purification,2％ SF solution was obtained.BMP-2 was dissolved in 2％ CS solution,and then fully mixed with equal volume of SF solution and proper amount of nHA.At last,the SF/CS/nHA scaffold loading BMP-2 was prepared using freeze-drying method as experimental group.The SF/CS/nHA scaffold was soaked in the BMP-2 solution as control group.The scaffold porosity was measured by Archimedes method,the surface morphology of the scaffold was observed by scanning electron microscope,the compressive strength was measured by universal testing machine.Scaffolds in the two groups were soaked in PBS,and the release of BMP-2 was measured by ELISA method at different time points.RESULTS AND CONCLUSION:(1) The scaffolds in the two groups had irregular porous structure,interconnected pores and uneven pore wall.There was no significant difference between the two groups in mean pore diameter,porosity and maximum compressive strength.(2) On the 1st day,the release rate of BMP-2 was 4.63％ in the experimental group,and the release curve increased slowly.After 28 days,the release curve of BMP-2 was transferred to the plateau stage.But in the control group,the release rate of BMP-2 on the 1stday was 58.84％,and it was a significant initial burst release.The release curve increased rapidly,and was transferred to the platform stage on the 10th day.The release rate of BMP-2 release was significantly different between the two groups at days 1,2,4,10 (P ＜ 0.05).These results show that the SF/CS/nHA scaffold loading BMP-2 could sustainably and slowly release BMP-2.

Objective To investigate the influence of recombinant human bone morphogenetic protein‐2(rhBMP‐2)of poly lactic acid(PLA) release microspheres for compatibility of rabbit bone marrow mesenchymal stem cells(BMSCs) .Methods The rh‐BMP‐2‐PLA release microspheres were prepared by w/o/w multiple emulsion volatilizing method and then cocultured BMSCs .The effects of rhBM P‐2‐PLA release microspheres on the cytotoxicity and relative proliferation rate by MTTassay .Evaluation of mate‐rials biocompatibility by inverted microscope and scanning electron microscope(SEM) .Results The rhBMP‐2‐PLA release micro‐spheres in various concentration of leaching solution and BMSCs training of uninfected cells .Experimental group and control group in 4 different time cell proliferation OD values by analysis of repeated measurement variance between time OD values were statisti‐cally significant(P=0 .000) ,the experimental group and control group OD values are statistically significant(P=0 .025) ,the exper‐imental group higher than the control group ,experimental group OD value time there was a significant interaction effect and the group number ,the change trend are obviously different(P=0 .006) .Inverted microscope to observe materials normal cell prolifera‐tion ,SEM found that vaccination cells surrounding rhBMP‐2‐PLA release microspheres of 7 days later ,the cells grew well and split proliferation activity .Conclusion rhBMP‐2‐PLA release microspheres of BMSCs has non‐toxic and has compatibility .

BACKGROUND:Silk fibroin/chitosan/nano hydroxyapatite (SF/CS/nHA) composite scaffold constructed in preliminary experiments has good physical and chemical properties.
OBJECTIVE:To study the capacity and mechanism of SF/CS/nHA composite scaffold for repair of rabbit radial bone defects.
METHODS:Thirty-six New Zealand white rabbits were selected to make animal models of right radial bone defects, and then randomly divided into SF/CS/nHA group, SF/CS group and blank control group. Blank control group had no treatment after modeling. X-ray radiography, gross observation and histopathological observation were performed at 4, 8, 12, 16 weeks postoperatively.
RESULTS AND CONCLUSION:Sixteen weeks after surgery, bone defects in the SF/CS/nHA group were completed replaced by normal bone tissue on X-ray images, and the bone marrow cavity showed complete recanalization with new bone formation;hematoxylin-eosin staining showed bone trabecula and many fusiform bone cells. In the SF/CS group, the bone mineral density in the defect area was slightly lower than that of the normal bone tissues, the bone marrow cavity was partly rehabilitated, and many chondrocytes were seen around bone cells that arranged irregularly with no bone trabecula or bone lamel a. In the blank control group, the images of bone calcification were consistent with normal bone tissues, and a closed bone ununion was formed at each end;hematoxylin-eosin staining showed that the blank control group was fil ed by fibrous connective tissue and a smal amount of bone-like tissues. SF/CS/nHA composite scaffold is better for repair of rabbit radial bone defects.

Ganoderma lingzhi is widely recognized as a medicinal basidiomycetes. Triterpene acids (TAs) are the key bioactive medicinal components of G. lingzhi. Our previous studies have shown that phospholipid acid (PA) produced by phospholipase D (PLD) plays a regulatory role in TA synthesis. In order to further elucidate the molecular mechanism how PA regulates TA synthesis in G. lingzhi, PA beads enrichment combined with LC-MS/MS technology was used to identify PA interacting proteins in G. lingzhi. A total of 19 PA interacting proteins were identified, including cytochrome P450 monooxygenase (GL22084), specific protein kinase MAPK (GL23765), catalase and cell surface hydrophobicity-associated protein. GST tagged GL22084 and GL23765 proteins were obtained through gene cloning, heterologous expression, and purification. The interactions between GL22084/GL23765 and PA were verified by GST pull down assay. The identification of PA interacting proteins provides a basis for further understanding the molecular mechanism how PLD-mediated PA signaling molecules regulates the TA synthesis in G. lingzhi. Moreover, the PA interacting proteins identified in this study can also provide clues for the research of PLD/PA signaling pathway in other species.
Chromatography, Liquid ; Ganoderma ; Phosphatidic Acids ; Tandem Mass Spectrometry