Influence of post-treatment with 75% (v/v) ethanol vapor on the properties of SF/P(LLA-CL) nanofibrous scaffolds.

In order to improve the water-resistant ability of silk fibroin (SF) and SF/P(LLA-CL) blended nanofibrous scaffolds for tissue engineering applications, 75% (v/v) ethanol vapor was used to post-treat electrospun nanofibers. SEM indicated that the treated SF and SF/P(LLA-CL) nanofibrous scaffolds maintained a nanofibrous structure and possessed good water-resistant ability. Characterization of (13)C CP-MAS NMR clarified that 75% (v/v) ethanol vapor could induce SF conformation from random coil or α-helix to ß-sheet. Although the water contact showed that treated SF/P(LLA-CL) blended nanofibrous scaffolds were hydrophobic, the water uptake demonstrated that their hydrophilicity was greatly superior to those of pure P(LLA-CL) nanofibrous scaffolds. Furthermore, the treated SF/P(LLA-CL) nanofibrous scaffolds, both in dry state and wet state, could retain good mechanical properties. Therefore, 75% (v/v) ethanol vapor treatment might be an ideal method to treat SF and SF/P(LLA-CL) nanofibrous scaffolds for biomedical applications.

Fabrication and intermolecular interactions of silk fibroin/hydroxybutyl chitosan blended nanofibers.

The native extracellular matrix (ECM) is composed of a cross-linked porous network of multifibril collagens and glycosaminoglycans. Nanofibrous scaffolds of silk fibroin (SF) and hydroxybutyl chitosan (HBC) blends were fabricated using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and trifluoroacetic acid (TFA) as solvents to biomimic the native ECM via electrospinning. Scanning electronic microscope (SEM) showed that relatively uniform nanofibers could be obtained when 12% SF was blended with 6% HBC at the weight ratio of 50:50. Meanwhile, the average nanofibrous diameter increased when the content of HBC in SF/HBC blends was raised from 20% to 100%. Fourier transform infrared spectra (FTIR) and (13)C nuclear magnetic resonance (NMR) showed SF and HBC molecules existed in hydrogen bonding interactions but HBC did not induce conformation of SF transforming from random coil form to ß-sheet structure. X-ray diffraction (XRD) confirmed the different structure of SF/HBC blended nanofibers from both SF and HBC. Thermogravimetry-Differential thermogravimetry (TG-DTG) results demonstrated that the thermal stability of SF/HBC blend nanofibrous scaffolds was improved. The results indicated that the rearrangement of HBC and SF molecular chain formed a new structure due to stronger hydrogen bonding between SF and HBC. These electrospun SF/HBC blended nanofibers may provide an ideal tissue engineering scaffold and wound dressing.

Europium-doped amorphous calcium phosphate porous nanospheres: preparation and application as luminescent drug carriers.

Calcium phosphate is the most important inorganic constituent of biological tissues, and synthetic calcium phosphate has been widely used as biomaterials. In this study, a facile method has been developed for the fabrication of amorphous calcium phosphate (ACP)/polylactide-block-monomethoxy(polyethyleneglycol) hybrid nanoparticles and ACP porous nanospheres. Europium-doping is performed to enable photoluminescence (PL) function of ACP porous nanospheres. A high specific surface area of the europium-doped ACP (Eu3+:ACP) porous nanospheres is achieved (126.7 m2/g). PL properties of Eu3+:ACP porous nanospheres are investigated, and the most intense peak at 612 nm is observed at 5 mol% Eu3+ doping. In vitro cytotoxicity experiments indicate that the as-prepared Eu3+:ACP porous nanospheres are biocompatible. In vitro drug release experiments indicate that the ibuprofen-loaded Eu3+:ACP porous nanospheres show a slow and sustained drug release in simulated body fluid. We have found that the cumulative amount of released drug has a linear relationship with the natural logarithm of release time (ln(t)). The Eu3+:ACP porous nanospheres are bioactive, and can transform to hydroxyapatite during drug release. The PL properties of drug-loaded nanocarriers before and after drug release are also investigated.

The role of substance P in the marginal division of the neostriatum in learning and memory is mediated through the neurokinin 1 receptor in rats.

Substance P (SP) is a neuropeptide that plays an important role in inflammation, respiration, pain, aggression, anxiety, and learning and memory mainly through its high affinity neurokinin 1 receptor (NK1R). The marginal division (MrD) is a pan-shaped subdivision in the caudomedial margin of the neostriatum in the mammalian brain and is known to be involved in learning and memory. We studied the expression of SP, NK1R and NK1R mRNA in the rat striatum by immunohistochemistry, immunofluorescence and in situ hybridization, and found that the levels of SP, NK1R protein and NK1R mRNA were high in the cell bodies, fibers and terminals of neurons in the neostriatum, especially in the MrD. Knocking down NK1R activity in the MrD by using an antisense oligonucleotide against NK1R mRNA inhibited learning and memory in a Y-maze behavioral test. Our results show that NK1R mediates the role of SP in the MrD in learning and memory.

Aligned natural-synthetic polyblend nanofibers for peripheral nerve regeneration.

Peripheral nerve regeneration remains a significant clinical challenge to researchers. Progress in the design of tissue engineering scaffolds provides an alternative approach for neural regeneration. In this study aligned silk fibroin (SF) blended poly(L-lactic acid-co-ε-caprolactone) (P(LLA-CL)) nanofibrous scaffolds were fabricated by electrospinning methods and then reeled into aligned nerve guidance conduits (NGC) to promote nerve regeneration. The aligned SF/P(LLA-CL) NGC was used as a bridge implanted across a 10mm defect in the sciatic nerve of rats and the outcome in terms of of regenerated nerve at 4 and 8 weeks was evaluated by a combination of electrophysiological assessment and histological and immunohistological analysis, as well as electron microscopy. The electrophysiological examination showed that functional recovery of the regenerated nerve in the SF/P(LLA-CL) NGC group was superior to that in the P(LLA-CL) NGC group. The morphological analysis also indicated that the regenerated nerve in the SF/P(LLA-CL) NGC was more mature. All the results demonstrated that the aligned SF/P(LLA-CL) NGC promoted peripheral nerve regeneration significantly better in comparison with the aligned P(LLA-CL) NGC, thus suggesting a potential application in nerve regeneration.

Cross-linking of gelatin and chitosan complex nanofibers for tissue-engineering scaffolds.

The aim of this study is to investigate cross-linked gelatin-chitosan nanofibers produced by means of electrospinning. Gelatin and chitosan nanofibers were electrospun and then cross-linked by glutaraldehyde (GTA) vapor at room temperature. Scanning electron microscopy (SEM) images showed that the cross-linked mats could keep their nanofibrous structure after being soaked in deionized water at 37° C. The cross-linking mechanism was discussed based on FT-IR results. The two main mechanisms of cross-linking for chitosan and gelatin-chitosan complex are Schiff base reaction and acetalization reaction. For gelatin, the mechanism of cross-linking was Schiff base reaction. The mechanical properties of nanofibrous mats were improved after cross-linking. The biocompatibility of electrospun nanofibrous mats after cross-linking was investigated by the viability of porcine iliac endothelial cells (PIECs). The morphologies of PIECs on the cross-linked nanofibrous mats were observed by SEM. In addition, proliferation of PIECs was tested with the method of methylthiazol tetrazolium (MTT) assay. The results indicate that gelatin-chitosan nanofibrous mats could be a promising candidate for tissue-engineering scaffolds.

Fabrication of chitosan/silk fibroin composite nanofibers for wound-dressing applications.

Chitosan, a naturally occurring polysaccharide with abundant resources, has been extensively exploited for various biomedical applications, typically as wound dressings owing to its unique biocompatibility, good biodegradability and excellent antibacterial properties. In this work, composite nanofibrous membranes of chitosan (CS) and silk fibroin (SF) were successfully fabricated by electrospinning. The morphology of electrospun blend nanofibers was observed by scanning electron microscopy (SEM) and the fiber diameters decreased with the increasing percentage of chitosan. Further, the mechanical test illustrated that the addition of silk fibroin enhanced the mechanical properties of CS/SF nanofibers. The antibacterial activities against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) were evaluated by the turbidity measurement method; and results suggest that the antibacterial effect of composite nanofibers varied on the type of bacteria. Furthermore, the biocompatibility of murine fibroblast on as-prepared nanofibrous membranes was investigated by hematoxylin and eosin (H&E) staining and MTT assays in vitro, and the membranes were found to promote the cell attachment and proliferation. These results suggest that as-prepared chitosan/silk fibroin (CS/SF) composite nanofibrous membranes could be a promising candidate for wound healing applications.

[Effects of Epimedium on proliferation, function and apoptosis of mouse osteoblasts in vitro].

OBJECTIVE: To investigate the effects of Epimedium on proliferation, function and apoptosis of mouse osteoblasts in vitro. METHODS: Primary osteoblasts were obtained by sequential digestion of mouse calvaria with collagenase and hyaluronidase. The identification of derived cells was done by histochemical staining of alkaline phosphatase (ALPase) and immunohistochemical staining of type I collagen, bone sialoprotein and osteopontin. MTT assay was employed to examine the proliferation of osteoblasts after treatment with Epimedium. The alkaline phosphatase activity level of mouse osteoblasts was also determined through an enzyme dynamical method. Apoptosis of osteoblasts was induced by dexamethasone and flow cytometry was utilized to examine the effects of Epimedium on the dexamethasone-induced apoptosis of osteoblasts. RESULTS: Five populations of bone cells were obtained by sequential digestion. Osteoblasts were purely obtained by discarding the first two populations and identified by the positive staining of ALPase, type I collagen, bone sialoprotein, and osteopontin. The alkaline phosphatase activity level of osteoblasts was significantly increased by the addition of Epimedium at 0.1 - 10 g/L, with the most significant increase at 1 g/L. On the other hand, the proliferation of osteoblasts was not affected after different doses of Epimedium added into the culture medium. Determined by flow cytometry, apoptosis of osteoblasts were induced by treatment with dexamethasone for 72 h. However, simultaneous administration of 1 g/L Epimedium had no effects on dexamethasone-induced apoptosis in osteoblasts. CONCLUSION: Epimedium did not affect the cell proliferation and cell survival of mouse osteoblasts, but could significantly increase alkaline phosphatase activity of the cells. The increase of alkaline phosphatase activity by Epimedium in osteoblasts may be one of the important mechanisms by which Epimedium can effectively prevent osteoporosis.

Relation between nutritional state and postoperative complications in patients with oral and maxillofacial malignancy.

PURPOSE: To evaluate the role of nutrition in the development of postoperative complications in patients with oral and maxillofacial malignancy. PATIENTS AND METHODS: Ninety-six patients treated surgically for oral and maxillofacial malignancy, 27 of whom developed postoperative complications; the remaining 69 recovered uneventfully. Nutritional state and clinical variables in the two groups were compared. RESULTS: The incidence of poor nutrition was greater in the complication group (56%) than in the uncomplicated group (20%) (p<0.001); the values for body weight, triceps skinfold thickness, arm circumference, arm muscle circumference, and creatinine-height index decreased more in the complicated than in the uncomplicated group (p<0.001); nitrogen and calorie intake during the first postoperative week was less in the complicated than in the uncomplicated group (p<0.001). CONCLUSIONS: Poor nutrition plays an important part in the development of postoperative complications, and perioperative nutritional support of patients with oral and maxillofacial cancer must be properly managed.

[Bone formation in vitro and in vivo by human bone marrow-derived mesenchymal stem cells].

OBJECTIVE: To culture and study the osteogenic characteristics of human bone marrow-derived mesenchymal stem cells (hBMMSCs). METHODS: hBMMSCs were separated and cultured from human iliac crest marrow. Growth kinetics of hBMMSCs was studied by growth curve. Under the osteoinductive culture, osteogenic differentiation of hBMMSCs was tested by alkaline phosphatase (ALP). Osteogenic functions of hBMMSCs in vitro and in vivo were also respectively detected by von Kossa stain and by transplanting hydroxyapatite/tricalcium phosphate ceramics (HA/TCP) with hBMMSCs. RESULTS: hBMMSCs were cultured successfully. The growth curve of the second passage of BMMSCs indicated that the time of population doublings was about 3.5 days. The results of ALP stain were evident by the significant increase in ALP activity after hBMMSCs cultured in osteoinductive medium. Some mineralized nodules were detected by von Kossa stain at nineteenth day of osteoinductive culture. In vivo assay, histological evalution showed bone formation in 3 months after grafts of HA/TCP with hBMMSCs. CONCLUSIONS: Osteoinductive solution can induce hBMMSCs to differentiate osteogenetic cell lines. Mineralized nodules and bone formation were found in vitro and in vivo assay. The results demonstrate that hBMMSCs have the potential for osteogenesis.

[Distribution of substance P and its receptor in the marginal division of rat striatum and its association with the function of learning and memory].

OBJECTIVE: To investigate the distribution of the substance P (SP) and its receptor in the marginal division (MrD) of rat striatum and to understand the relationship between SP and the learning and memory function of rats. METHODS: Using immunohistochemistry and in situ hybridization techniques, the distribution of SP and its receptor in the MrD was studied, and the relationship between the SP and learning and memory of the MrD was observed by means of SP receptor gene knockout in combination with Y-maze test. RESULTS: Numerous SP immunopositive fibers and large quantities of SP receptor protein and NK1 mRNA were identified in the MrD of rat striatum. After knockout of the SP receptor gene in the MrD, the ability of learning and memory of the rats was obviously decreased. CONCLUSION: SP and its receptor in the MrD may play important roles in the learning and memory function of rat, possibly through the regulation of the neurotransmitters as 5-HT by SP via NK1 receptor.