Identification of potential SLA-I-specific T-cell epitopes within the structural proteins of porcine deltacoronavirus.

Porcine deltacoronavirus (PDCoV) is an emerging swine enteropathogenic coronavirus that mainly threatens newborn piglets and poses a potential broad cross-species transmission risk. The antigenic epitopes of PDCoV are currently unidentified, and no information about T cell epitopes is available. Here, T-cell epitopes of PDCoV structural proteins were predicted using computational methods. 17 epitope peptides were synthesized and then screened using ELIspot, intracellular cytokine staining (ICS), and RT-qPCR detection of IFN-γ mRNA to evaluate their ability to elicit interferon-gamma (IFN-γ) responses in peripheral blood mononuclear cells (PBMCs) from PDCoV-challenged pigs. Five peptides (M1, M2, M3, N6, and S4) elicited high levels of IFN-γ and were investigated further as potential T-cell epitope candidates. All five peptides were cytotoxic T lymphocyte (CTL) epitopes, and two peptides (M3, N6) were recognized simultaneously by CD8 + and CD4 + T cells. A multi-epitope peptide combining the five epitopes (designated "5T") was synthesized and its immune response and protection efficacy was evaluated in a piglet model. ELISpot assay results indicated that 5T induces robust epitope-specific cellular immune responses. Four epitopes (M1, M2, N6, S4) elicited IFN-γ responses in 5T-vaccinated piglets. No obvious protection efficacy was detected in piglets vaccinated with 5T alone. Our results provide valuable information concerning PDCoV-related antigenic epitopes and will be useful in the design of epitope-based vaccines.

Identification of an immunodominant neutralizing epitope of porcine Deltacoronavirus spike protein.

Porcine deltacoronavirus (PDCoV) is a novel swine enteropathogenic coronavirus that, because of its broad host range, poses a potential threat to public health. Here, to identify the neutralizing B-cell epitopes within the S1-CTD protein, we generated three anti-PDCoV monoclonal antibodies (mAbs). Of these, the antibody designated 4E-3 effectively neutralized PDCoV with an IC50 of 3.155 µg/mL. mAb 4E-3 and one other, mAb 2A-12, recognized different linear B-cell epitopes. The minimal fragment recognized by mAb 4E-3 was mapped to 280FYSDPKSAV288 and designated S280-288, the minimal fragment recognized by mAb 2A-12 was mapped to 506TENNRFTT513, and designated S506-513. Subsequently, alanine (A)-scanning mutagenesis indicated that Asp283, Lys285, and Val288 were the critical residues recognized by mAb 4E-3. The S280-288 epitope induces PDCoV specific neutralizing antibodies in mice, demonstrating that it is a neutralizing epitope. Of note, the S280-288 coupled to Keyhole Limpet Hemocyanin (KLH) produces PDCoV neutralizing antibodies in vitro and in vivo, in challenged piglets it potentiates interferon-γ responses and provides partial protection against disease. This is the first report about the PDCoV S protein neutralizing epitope, which will contribute to research of PDCoV-related pathogenic mechanism, vaccine design and antiviral drug development.

Infant Exposure to PCBs and PBDEs Revealed by Hair and Human Milk Analysis: Evaluation of Hair as an Alternative Biomatrix.

Human hair, as an emerging biological monitoring matrix, has begun to be used in various human exposure studies, but little research has been done on persistent organic pollutants (POPs), especially for the body burden of POPs in infants. In this study, 36 breast-fed infants in Shanghai were recruited for a study to determine their exposure to POPs, including 12 dioxin-like polychlorinated biphenyls (dl-PCBs), 6 indicator PCBs, and 8 polybrominated diphenyl ethers (PBDEs) in the inner layer (internal) and outer layer (external) of infant hair and human milk. The similarity or difference of the POP distribution pattern or concentration among these matrices was investigated, and only weak correlations (r < 0.4) were observed between the POP concentration in human milk and infant hair (internal or external). POPs in human milk have a different profile than those in infant hair, while they have stable concentration ratios (0.58-2.72), similar distribution patterns, fine Spearman's rank correlations, and tangled principal component analysis (PCA) plots in each POP family between external and internal hair samples. The result suggested that POPs in internal hair can be easily affected by those in external hair, but POPs in human milk seem to have little contribution to the POP profile in internal hair. Although infant hair cannot reflect the POPs from diet or from body burden, it can be an ideal biomatrix that estimates infant exposure to POPs from exogenous sources like house dust when considering the similar pattern of POPs and their proper accumulation period in hair.

Porcine Deltacoronavirus (PDCoV) Entry into PK-15 Cells by Caveolae-Mediated Endocytosis.

(1) Background: Porcine deltacoronavirus (PDCoV) is a newly emerged enteric virus affecting pig breeding industries worldwide, and its pathogenic mechanism remains unclear. (2) Methods: In this study, we preliminarily identified the endocytic pathway of PDCoV in PK-15 cells, using six chemical inhibitors (targeting clathrin-mediated endocytosis, caveolae-mediated endocytosis, macropinocytosis pathway and endosomal acidification), overexpression of dominant-negative (DN) mutants to treat PK-15 cells and proteins knockdown. (3) Results: The results revealed that PDCoV entry was not affected after treatment with chlorpromazine (CPZ), 5-(N-ethyl-N-isopropyl) amiloride (EIPA)or ammonium chloride (NH4Cl), indicating that the entry of PDCoV into PK-15 cells were clathrin-, micropinocytosis-, PH-independent endocytosis. Conversely, PDCoV infection was sensitive to nystatin, dynasore and methyl-ß-cyclodextrin (MßCD) with reduced PDCoV internalization, indicating that entry of PDCoV into PK-15 cells was caveolae-mediated endocytosis that required dynamin and cholesterol; indirect immunofluorescence and shRNA interference further validated these results. (4) Conclusions: In conclusion, PDCoV entry into PK-15 cells depends on caveolae-mediated endocytosis, which requires cholesterol and dynamin. Our finding is the first initial identification of the endocytic pathway of PDCoV in PK-15 cells, providing a theoretical basis for an in-depth understanding of the pathogenic mechanism of PDCoV and the design of new antiviral targets.

Study of the inhibitory effect of STAT1 on PDCoV infection.

Porcine deltacoronavirus (PDCoV) is an enteropathogen found in many pig producing countries. It can cause acute diarrhea, vomiting, dehydration, and death in newborn piglets, seriously affecting the development of pig breeding industries. To date, our knowledge of the pathogenesis of PDCoV and its interactions with host cell factors remains incomplete. Using Co-IP coupled with LC/MS-MS, we identified 67 proteins that potentially interact with PDCoV in LLC-PK1 cells; five of the identified proteins were chosen for further evaluation (IMMT, STAT1, XPO5, PIK3AP1, and TMPRSS11E). Five LLC-PK1 cell lines, each with one of the genes of interest knocked down, were constructed using CRISPR/cas9. In these knockdown cells lines, only STAT1KD resulted in a significantly greater virus yield. Knockdown of the remaining four genes resulted, to varying degrees, in a lower virus yield that wild-type LLC-PK1 cells. The absence of STAT1 did not significantly affect the attachment of PDCoV to cells, but did result in increased viral internalization. Additionally, PDCoV infection stimulated expression of interferon stimulated genes (ISGs) downstream of STAT1 (IFIT1, IFIT2, RADS2, ISG15, MX1, and OAS1) while knockdown of STAT1 resulted in a greater than 80 % decrease in the expression of all six ISGs. Our findings show that STAT1 interacts with PDCoV, and plays a negative regulatory role in PDCoV infection.

HSP90 inhibitors 17-AAG and VER-82576 inhibit porcine deltacoronavirus replication in vitro.

Porcine deltacoronavirus (PDCoV) is highly pathogenic to piglets, and no specific drugs or vaccines are available for the prevention and treatment of PDCoV infection, the need for antiviral therapies is pressing. HSP90 inhibitors have potent inhibitory effects against the replication of numerous viruses, hence we evaluated three HSP90 inhibitors, 17-AAG, VER-82576, and KW-2478, for their effects on PDCoV infection in vitro. We evaluated their effectivenesses at suppressing PDCoV by qRT-PCR, western blot, and TCID50 assay, and found that 17-AAG and VER-82576 inhibited PDCoV at the early stage of replication, while KW-2478 showed no significant antiviral activity at any stage of infection. These results indicated that the PDCoV-inhibitory effects of 17-AAG and VER-82576 might be exerted by targeting host cell factor HSP90AB1 but not HSP90AA1. Further study showed that HSP90AB1 mRNA and protein levels were not significantly different in 17-AAG and VER-82576-treated cells versus control cells. 17-AAG and VER-82576 were also evaluated for their effects on the expressions of TNF-α, IL-6, and IL-12, which are PDCoV-induced proinflammatory cytokines. We found that both 17-AAG and VER-82576 inhibited the expressions of TNF-α, IL-6, and IL-12 to varying degrees, but in a dose dependent manner. From our data we can conclude that the HSP90 inhibitors 17-AAG and VER-82576 are promising candidates for the treatment of PDCoV infection.

Exposure and health risk assessment of secondary contaminants closely related to brominated flame retardants (BFRs): Polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in human milk in shanghai.

Polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), as the secondary environmental pollutants of the widely used brominated flame retardants (BFRs), possess the similar physicochemical and toxic properties as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). However, studies on human body exposure to them are extremely limited. In this study, forty human milk samples collected in Shanghai were measured for 13 PBDD/F congeners using gas chromatography-high resolution mass spectrometry (GC-HRMS), to investigate their exposure level and characteristics, potential source and corresponding health risks to breastfed infants. The results showed no PBDDs but three PBDF congeners including 2,3,7,8-TBDF, 1,2,3,4,6,7,8-HpBDF and OBDF (mean concentration (detection rates) are 3.2 pg/g (72.5%), 9.5 pg/g (100%) and 28 pg/g (67.5%), respectively) were detected. The average toxic equivalent quantity (TEQ, 0.42 pg/g lw) presented the highest concentration level compared to other regions reported. The contribution of PBDFs to the total TEQ of PBDD/Fs and PCDD/Fs is 6.8%. The correlation between PBDD/Fs and age or dietary habits was not observed, which normally existed in their chlorinated analogues-PCDD/Fs. Significant correlations were observed between PBDFs and highly brominated polybrominated diphenyl ethers (PBDEs) (especially for BDE 183 and BDE 209). The correlation between PCDD/Fs and PBDFs was not observed except 2,3,7,8-TBDF. The high PBDFs exposure in Shanghai may originate from the emission of PBDEs and/or non-PBDE BFRs in environment, according to the consistency of the environmental data previously reported. The average estimated dietary intakes (EDI) for breastfed infants is 2.0 pg TEQ/kg·bw/day (0.13-13 pg TEQ/kg·bw/day), within the range of the tolerable daily intake (TDI) for TCDD (1-4 pg TEQ/kg·bw/day) suggested by the World Health Organization (WHO). However, given the high toxicity of PBDD/Fs, the potential health risks of these pollutants for breastfed infants should be of concern.

Multi-analyte method development for analysis of brominated flame retardants (BFRs) and PBDE metabolites in human serum.

Commonly, analytical methods measuring brominated flame retardants (BFRs) of different chemical polarities in human serum are labor consuming and tedious. Our study used acidified diatomaceous earth as solid-phase extraction (SPE) adsorbent and defatting material to simultaneously determine the most abundant BFRs and their metabolites with different polarities in human serum samples. The analytes include three types of commercial BFRs, tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD) isomers, and polybrominated biphenyl ethers (PBDEs), and dominant hydroxylated BDE (OH-PBDE) and methoxylated BDE (MeO-PBDE) metabolites of PBDEs. The sample eluents were sequentially analyzed for PBDEs and MeO-BDEs on online gel permeation chromatography/gas chromatography-electron capture-negative ionization mass spectrometry (online GPC GC-ECNI-MS) and for TBBPA, HBCD, and OH-BDEs on liquid chromatography-tandem mass spectrometry (LC-MS/MS). Method recoveries were 67-134% with a relative standard deviation (RSD) of less than 20%. Method detection limits (MDLs) were 0.30-4.20 pg/mL fresh weight (f.w.) for all analytes, except for BDE-209 of 16 pg/mL f.w. The methodology was also applied in a pilot study, which analyzed ten real samples from healthy donors in China, and the majority of target analytes were detected with a detection rate of more than 80%. To our knowledge, it is the first time for us in effectively determining BFRs of most types in one aliquot of human serum samples. This new analytical method is more specific, sensitive, accurate, and time saving for routine biomonitoring of these BFRs and for integrated assessment of health risk of BFR exposure.

Adenosine triphosphate promotes locomotor recovery after spinal cord injury by activating mammalian target of rapamycin pathway in rats.

The mammalian target of rapamycin (mTOR) pathway plays an important role in neuronal growth, proliferation and differentiation. To better understand the role of mTOR pathway involved in the induction of spinal cord injury, rat models of spinal cord injury were established by modified Allen's stall method and interfered for 7 days by intraperitoneal administration of mTOR activator adenosine triphosphate and mTOR kinase inhibitor rapamycin. At 1-4 weeks after spinal cord injury induction, the Basso, Beattie and Bresnahan locomotor rating scale was used to evaluate rat locomotor function, and immunohistochemical staining and western blot analysis were used to detect the expression of nestin (neural stem cell marker), neuronal nuclei (neuronal marker), neuron specific enolase, neurofilament protein 200 (axonal marker), glial fibrillary acidic protein (astrocyte marker), Akt, mTOR and signal transduction and activator of transcription 3 (STAT3). Results showed th+at adenosine triphosphate-mediated Akt/mTOR/STAT3 pathway increased endogenous neural stem cells, induced neurogenesis and axonal growth, inhibited excessive astrogliosis and improved the locomotor function of rats with spinal cord injury.

[Effects of bone marrow mesenchymal stem cells with acellular muscle bioscaffolds on repair of acute hemi-transection spinal cord injury in rats].

OBJECTIVE: To investigate the effects of allogenic transplantation of acellular muscle bioscaffolds (AMBS) seeded with bone marrow mesenchymal stem cells (BMSCs) on the repair of acute hemi-transection spinal cord injury (SCI) in rats. METHODS: AMBS were prepared by reformed chemical approach and sterilized by compound cold sterilization; BMSCs were harvested by density gradient centrifugation and cultured with adherent method. The 3rd generation BMSCs labeled by Hoechst 33342 were injected into AMBS to construct the BMSCs-AMBS composite scaffolds; the biocompatibility was observed under scanning electron microscope (SEM) and fluorescence microscope in vitro at 14 days. Forty-eight adult female Sprague Dawley rats were used to build SCI model by hemi-transecting at T(9-11) level, then randomly divided into 4 groups (n=12). Defects were repaired with BMSCs-AMBS composite scaffolds, BMSCs, and AMBS in groups A, B, and C, respectively; group D was blank control by injecting PBS. At 1, 2, 3, and 4 weeks after surgery, the functional recovery of the hind limbs was evaluated by the Basso-Beattie-Bresnahan (BBB) locomotor rating score. At 4 weeks after surgery, HE staining and immunofluorescent assay were adopted. RESULTS: Masson staining and HE staining showed that AMBS was mainly of the collagen fibers in parallel arrange, without muscle fibers. After 14 days of BMSCs and AMBS co-culture, a large number of survival BMSCs labeled by Hoechst 33342 were seen under fluorescence microscope; SEM showed that BMSCs grew and attached to the inner surfaces of AMBS. At 2-4 weeks, the BBB score in group A was significantly higher than that in groups B, C, and D (P < 0.05), and it was significantly lower in group D than in the other 3 groups (P < 0.05); at 4 weeks, the BBB score in group B was significantly higher than that in group C (t=10.352, P=0.000). HE staining revealed that the area of spinal cord cavity after SCI was markedly smaller in group A than in the other 3 groups; immunofluorescent assay showed that more neurofilament 200 positive fibers and Nestin positive cells were detected in group A than in groups B, C, and D, but glial fibrillary acidic protein (GFAP) positive cells significantly decreased. The integral absorbance (IA) values of GFAP were 733.01 +/- 202.04, 926.42 +/- 59.46, 1 069.37 +/- 33.42, and 1 469.46 +/- 160.53 in groups A, B, C, and D, respectively; the IA value of group A was significantly lower than that of groups B, C, and D (P < 0.05), and it was significantly higher in group D than in groups A, B, and C (P < 0.05). CONCLUSION: With relatively regular internal structures and good biocompatibility, AMBS can inhibit glial scar and enhance the survival, migration, and differentiation of BMSCs, so AMBS is the ideal nature vector for cell transplantation. Co-transplantation of AMBS and BMSCs has synergistic effect in treating SCI, it can promote rat motor function recovery.

[Study on estrogenic effect of genistein and apigenin in vitro].

OBJECTIVE: To detect the estrogenic activity of genistein and apigenin with ER-positive cell line MCF-7 human breast cancer cells. METHOD: MTT method was adopted to study the impact of genistein and apigenin on MCF-7 proliferation in vitro. Real-time RT-PCR method was used to detect their impact on ERalpha, ERbeta, PR and PS2 mRNA expression levels. RESULT: Genistein and apigenin promoted the proliferation of MCF-7. Genistein 1 x 10(-10) mol x L(-1) group showed a significant increase in the expression of ERa mRNA levels or a 17. 76 times more than the control group and a 1.75 times more than the E2 group. Apigenin notably promoted the PR mRNA expression or a 4. 57 times more than the control group and a 1.11 times more than the E2 group. Both of them had different effect in promoting ERalpha, ERbeta, PR or PS2 mRNA. CONCLUSION: Both genistein and apigenin have a strong estrogen-like effect. Although they have different effect in promoting estrogenic response genes (such as ERa, ERbeta, PR and PS2 mRNA), genistein shows a stronger activity than apigenin. It also suggests that the signaling pathways of phytoestrogens showing estrogen-like effect are not completely identical with estrogen pathways. The B-cycle position of flavonoids is one of the key sites to estrogen-like activity, and isoflavones (cycle B on site 3) show stronger estrogen-like activity than flavones (B-cycle lies in site 2).

Simultaneous determination of 45 pesticides in fruit and vegetable using an improved QuEChERS method and on-line gel permeation chromatography-gas chromatography/mass spectrometer.

In this study, a method was developed to determine 45 selected pesticides (of different chemical families) in fruit and vegetable (including apple, spinach and cucumber). Samples were extracted using an improved QuEChERS method with salting out and phase separation in two steps. The target pesticides in concentrated extracts were analyzed by an on-line gel permeation chromatography-gas chromatography/mass spectrometer (online-GPC-GC/MS). Online GPC effectively removed matrix interferences and greatly improved the method sensitivity, recoveries and automation. Method limits of quantification were 10 ng/g for uniconazole and metalaxyl, and 5 ng/g for other 43 target analytes. In three fruit and vegetable matrices each spiked with 45 pesticides (0.01 µg/g), mean recoveries ranged from 80 to 118% for most of the tested pesticides except for profenofos (77% in apple) and chlorpyrifos (68% in apple and 75% in cucumber), with relative standard deviations (RSDs) of less than 14%. The results of the proficiency testing showed that the method is very successful in measuring the certified pesticides with less than 1.3 of the absolute value of Z-score. This method has been applied for routinely monitoring pesticides in fresh fruit and vegetable.

[Effect of salidroside on rat bone marrow mesenchymal stem cells differentiation into cholinergic nerve cells].

OBJECTIVE: To investigate the effect of salidroside on rat bone marrow mesenchymal stem cells (BMSCs) differentiation into the cholinergic nerve cells, so as to provide the theory basis of the combination of salidroside and stem cells for clinical therapy of nervous system diseases. METHODS: BMSCs were isolated from 2 Wistar rats (aged 4-6 weeks,weighing 120 g), which were identified by CD34, CD45, CD90, and CD106 with flow cytometry. According to inducing method, BMSCs at passage 2 were divided into 3 groups: In groups A and B, BMSCs were induced by salidroside (20 microg/mL) and retinoic acid (5 micromol/mL) respectively for 1, 3, 6, and 9 days, in group C, BMSCs were cultured with serum-free DMEM/F12 medium as control. MTT assay was used to detect the cellular proliferation activity. The immunofluorescence chemical technology was used to detect the expressions of nerve growth factor (NGF) and relevant marker molecule of nerve cells, including neuron-specific enolase (NSE), microtubule-associated protein 2 (MAP2), beta-Tubulin III, glial fibrillary acidic protein (GFAP), and the marker of cholinergic neuron, such as Acetylcholine (Ach) and NGF. RT-PCR was used to detect mRNA expressions of NSE, beta-Tubulin III, GFAP,brain derived neurotrophic factor (BDNF),and gamma-aminobutyric acid (GABA). ELISA was used to detect the levels of BDNF and NGF, and the expression level of NGF protein was analyzed by Western blot. RESULTS: The results of the flow cytometry showed that the cultured cells were CD90 and CD106 positive, and CD34 and CD45 negative,which indicated that the cells were BMSCs. The cellular proliferation activity in groups A and B were significantly higher than that in group C at 6 days and 9 days (P < 0.05). RT-PCR results showed that the expression level of NSE,BDNF, beta-Tubulin III,GFAPmRNA were increased in group A at 6 days; In group B, that expression level of NSE mRNA was up-regulated at 6 days, that expression level of BDNF mRNA increased at 1 days and reached the peak at 6 days, and that expression level of beta-Tubulin III mRNA was up-regulated at 3 days, which was significantly higher than that at the other time points, and than that in group C (P < 0.01). But no GABA mRNA expression was detected in each group. Immunofluorescence chemical technology staining showed that the positive rates of NSE, MAP2, beta-Tubulin III, and GFAP were significantly higher in group A than those in group C at 3 days; the positive rates of Ach were significantly higher at 3, 6, and 9 days than those at 1 day in groups A and B, and in groups A and B than in group C (P < 0.01); the positive rates of NGF in groups A and B were significantly higher than those in group C (P < 0.01). The levels of BDNF and NGF in groups A and B were significantly higher than those in group C at 1, 3, 6, and 9 days (P < 0.01), but no significant difference of BDNF was found between groups A and B (P > 0.05). The expression level of NGF protein in groups A and B were significantly higher than that in group C (P < 0.01). The NGF expression reached the peak at 6 days in group A and at 3 days in group B. CONCLUSION: Salidroside could induce rat BMSCs differentiate into cholinergic nerve cells in vitro.

[Adenosine-triphosphate promoting repair of spinal cord injury by activating mammalian target of rapamycin/signal transducers and activators of transcription 3 signal pathway in rats].

OBJECTIVE: To investigate the mechanism of adenosine-triphosphate (ATP) activated mammalian target of rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3) signal pathway in the physiology and pathology of spinal cord injury (SCI). METHODS: Ninety-six adult healthy female Sprague-Dawley rats were randomly divided into 4 groups (groups A, B, C and D, n=24). In groups A, B and C, the rats were made the SCI models at T8-10 levels by using a modified Allen's stall, and in group D, rats were given laminectomy without SCI. The rats were subjected to the administration of ATP (40 mg/kg) for 7 days in group A, to the administration of physiological saline (equal-volume) for 7 days in group B, to the administration of ATP (40 mg/kg) and rapamycin (3 mg/kg) for 7 days in group C, and to the administration of physiological saline (equal-volume) for 7 days in group D. Locomotor activity was evaluated using the Basso-Beattie-Bresnahan rating scale at the postoperative 1st, 2nd, 3rd, and 4th weeks. Then, the expressions of spinal cord cell marker [Nestin, neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP)] and the mTOR/STAT3 pathway factors (mTOR, STAT3) were detected at the postoperative 1st, 2nd, 3rd, and 4th weeks by immunohistochemistry analysis, Western blot assay, and real-time fluorescence PCR analysis. RESULTS: The BBB scores in group A showed a steady increase in the postoperative 1st-4th weeks and were significantly higher than those in groups B and C (P < 0.01), but were lower than that in group D (P < 0.01). Real-time fluorescence PCR results showed that the mRNA expressions of mTOR, STAT3, NSE of group A steadily increased, however, the Nestin mRNA expression gradually decreased in the postoperative 1st-4th weeks, which were all significantly higher than those of groups B, C, and D (P < 0.01). The mRNA expression of GFAP showed a steady increase in group A and was significantly less than those of groups B and C, but was higher than that of group D (P < 0.01). There were significant differences (P < 0.01) in all markers between groups B, C, and group D; there were significant differences in mTOR, P-mTOR, STAT3, and P-STAT3 mRNA between groups B and C at 1st-4th weeks (P < 0.05). The similar changes were found by Western blot assay. CONCLUSION: ATP can activate the mTOR/STAT3 pathway to induce endogenic NSCs to proliferate and differentiate into neurons in rats, it enhances the healing of SCI.

[Transplantation of bone marrow mesenchymal stem cells into spinal cord injury: a comparison of delivery different times].

OBJECTIVE: To investigate the influence of different transplantation times on the survival and immigration of the bone marrow mesenchymal stem cells (BMSCs) in injured spinal cord by subarachnoid administration, and to evaluate the most optimal subarachnoid administration times for BMSCs. METHODS: Eight adult male rats (weighing 120 g) were used to isolate BMSCs that were cultured, purified and labeled with Hoechst 33342 in vitro. Another 75 adult Wistar rats (weighing 220 g) were made the spinal cord injury (SCI) models at T9,10 level according to the improved Allen's method and were randomly divided into 5 groups (groups A, B, C, D, and E, n=15). The labeled BMSCs at 1 x 10(7)/mL 0.1 mL were injected into subarachnoid space of the rats via a catheters under the subarachnoid space in groups A (one time at 1 week), B ( two times at 1 and 3 weeks), C (3 times at 1, 3, and 5 weeks) and D (5 times at 1, 3, 5, 7, and 9 weeks) and 0.2 mL phosphate-buffered saline (PBS) was injected in group E (5 times at 1, 3, 5, 7, and 9 weeks) as blank control. The neurological functions were evaluated using the Basso-Beattie-Bresnahan (BBB) scale 1, 3, 5, 7, 9, and 12 weeks after transplantation. The migration, survival, differentiation, and histomorphological changes of BMSCs were observed by HE, immunohistochemistry, and fluorescence microscopy. RESULTS: At 3 weeks after injury, there were significant differences in the BBB scores between group E and groups A, B, C, D (P < 0.01), and between groups A, B and groups C, D (P < 0.01). At 7, 9, and 12 weeks, the BBB scores were significantly higher in groups C and D than in groups A and B (P < 0.01), and in group B than in group A (P < 0.01). There were no significant differences in the BBB scores between groups C and D (P > 0.05). The fluorescence microscopy showed that the transplanted BMSCs survived and grew in the injured region at 3 weeks after injury and as time went on, the transplanted cells gradually decreased in group A; in groups B, C, and D, BMSCs count reached the peak values at 5 and 7 weeks and then gradually decreased. At 12 weeks, the survival BMSCs were significantly more in groups C and D than in groups A and B (P < 0.01). HE staining showed that the formation of cavity was observed in each group at 3 weeks after injury and the area of cavity gradually decreased in groups A, B, C, and D. At 12 weeks, the area of cavity was the maximal in groups C and D, moderate in groups A and B, and the maximal in group E. The immunohistochemistry staining indicated that the expression of NF-200 was more intense in groups C and D than in groups A and B. The expression of NF-200-positive fibers was more intense in group C. CONCLUSION: Multiple administration of BMSCs promotes the restoration of injured spinal cord and improves neurological functions, and three times for BMSCs transplantation is best.

[Experimental study on bone marrow mesenchymal stem cells seeded in chitosan-alginate scaffolds for repairing spinal cord injury].

OBJECTIVE: To investigate tissue engineered spinal cord which was constructed of bone marrow mesenchymal stem cells (BMSCs) seeded on the chitosan-alginate scaffolds bridging the both stumps of hemi-transection spinal cord injury (SCI) in rats to repair the acute SCI. METHODS: BMSCs were separated and cultured from adult male SD rat. Chitosan-alginate scaffold was produced via freeze drying, of which the structure was observed by scanning electron microscope (SEM) and the toxicity was determined through leaching liquor test. Tissue engineered spinal cord was constructed by seeding second passage BMSCs on the chitosan-alginate scaffolds (1 x 10(6)/mL) in vitro and its biocompatibility was observed under SEM at 1, 3, and 5 days. Moreover, 40 adult female SD rats were made SCI models by hemi-transecting at T9 level, and were randomly divided into 4 groups (each group, n=10). Tissue engineered spinal cord or chitosan-alginate scaffolds or BMSCs were implanted in groups A, B, and C, respectively. Group D was blank control whose spinal dura mater was sutured directly. After 1, 2, 4, and 6 weeks of surgery, the functional recovery of the hindlimbs was evaluated by the Basso-Beattie-Bresnahan (BBB) locomotor rating score. Other indexes were tested by wheat germ agglutinin-horseradish peroxidase (WGA-HRP) retrograde tracing, HE staining and immunofluorescence staining after 6 weeks of surgery. RESULTS: Chitosan-alginate scaffold showed three-dimensional porous sponge structure under SEM. The cells adhered to and grew on the surface of scaffold, arranging in a directional manner after 3 days of co-culture. The cytotoxicity of chitosan-alginate scaffold was in grade 0-1. At 2, 4, and 6 weeks after operation, the BBB score was higher in group A than in other groups and was lower in group D than in other groups; showing significant differences (P < 0.05). At 4 and 6 weeks, the BBB score was higher in group B than in group C (P < 0.05). After 6 weeks of operation, WGA-HRP retrograde tracing indicated that there was no regenerated nerve fiber through the both stumps of SCI in each group. HE and immunofluorescence staining revealed that host spinal cord and tissue engineering spinal cord linked much compactly, no scar tissue grew, and a large number of neurofilament 200 (NF-200) positive fibers and neuron specific enolase (NSE) positive cells were detected in the lesioned area in group A. In group B, a small quantity of scar tissue intruded into non-degradative chitosan-alginate scaffold at the lesion area edge, and a few of NSE fluorescence or NF-200 fluorescence was observed at the junctional zone. The both stumps of SCI in group C or group D were filled with a large number of scar tissue, and NSE positive cells or NF-200 positive cells were not detected. Otherwise, there were obviously porosis at the SCI of group D. CONCLUSION: The tissue engineered spinal cord constructed by multi-channel chitosan-alginate bioscaffolds and BMSCs would repair the acute SCI of rat. It would be widely applied as the matrix material in the future.

[Preliminary study on cryopreservation of tissue engineered bone at -8 degrees C].

OBJECTIVE: To study the effects of various methods of cryopreservation on the bioactivity of tissue engineered bone. METHODS: MSCs were cocultured with partialy deproteinised bone to produce tissue engineered bone. The experiment was divided into A, B, C and D group. Group A: Tissue engineered bone was stored in preservation solution with cryopreservation medium. Group B: Tissue engineered bone was stored in preservation solution without cryopreservation medium. Group C: Tissue engineered bone was stored without cryopreservation. Group D: MSCs were cultured without cryopreservation. The tissue engineered bone of group A and B had been cryopreserved at -80 degrees C for three months and thawed three months later. The electronic scanning microscope was used to evaluate the adhesion and distribution of MSCs, cell viability was measured by MTT, ALP activity was detected by p-nitrophosphate, cell cycle was analysed by flow cytometry. RESULTS: MSCs could adhere to the surface of the material and distribute in the hole of material. The cell viability of MSCs adhered to the material was C > A > B group (P < 0.01, P < 0.05). The ALP activity of MSCs adhered to material was C > A > B group (P < 0.01). The cell cycles of different groups did not change significantly; the abnormal cells were not observed. CONCLUSION: The choice of proper cryopreservative solution could optimize the bioactivity of tissue engineered bone.