Induced migration of dental pulp stem cells for in vivo pulp regeneration

Dental pulp has intrinsic capacity for self-repair. However, it is not clear whether dental pulp cells can be recruited endogenously for regenerating pulp tissues, including mineralizing into dentin. This work is based on a hypothesis that dental pulp stem/progenitor cells can be induced to migrate by chemotactic cytokines and act as endogenous cell sources for regeneration and mineralization. Dental stem cells (DSCs) were isolated from adult human tooth pulp and seeded on the surfaces of 3D collagen gel cylinders that were incubated in chemically defined media with stromal-derived factor-1α (SDF1), basic fibroblast growth factor (bFGF), or bone morphogenetic protein-7 (BMP7). Significantly more cells were recruited into collagen gel by SDF1 or bFGF than without cytokines in 7 days, whereas BMP7 had little effect on cell recruitment. BMP7, however, was highly effective, equally to dexamethasone, in orchestrating mineralization of cultured DSCs. Cell membrane receptors for SDF1, bFGF, and BMP7 were up-regulated in treated DSCs. Upon in vivo delivery, bFGF induced re-cellularization and re-vascularization in endodontically treated human teeth implanted into the dorsum of rats. Thus, endogenous dental pulp cells, including stem/progenitor cells, may be recruited and subsequently differentiated by chemotaxis of selective cytokines in the regeneration of dental pulp.

Sequence analyses of the representative Chinese-prevalent strain of avian nephritis virus in healthy chicken flocks

Avian nephritis virus (ANV), which belongs to the Astroviridae family, has been associated with acute nephritis in chickens. Cases of ANV infection have been recorded in Japan and in several European countries. However, related studies have never been performed in China. Thus, this study isolated ANV in Chinese chicken flocks. ANV RNA was detected by reverse transcription-PCR in stool samples collected from healthy layer chickens in the Sichuan Province of China in 2009. Of the 192 stool specimens collected, 32.3% (62/192) were positive for ANV infection. The whole genome of ANV-Sichuan54, the first representative Chinese strain, was 6941 nucleotides in length, including the 5' untranslated region, three open reading frames (ORFs), a 3' UTR, and a poly-(A) tail. Comparative and phylogenetic analyses based on partial RNA-dependent RNA polymerase (ORF1b) demonstrated that the majority of ANV investigations were more closely related to the U.S. ANV strain (DQ324827-324836) than to the G-4260 (AB033998).

Risk of locoregional recurrence by receptor status in breast cancer patients receiving modern systemic therapy and post-mastectomy radiation

We assessed differences in locoregional outcome based on receptor status combinations in a cohort of stage II-III breast cancer patients treated with modern trimodality therapy. Medical records of 582 consecutively treated patients receiving post-mastectomy radiation (PMRT) between 1/1999 and 12/2009 were reviewed. Rate of local regional recurrence (LRR) was estimated by the method of cumulative incidence allowing for competing risks. The effect of prognostic factors was examined by Gray's test and by Fine and Gray's modeling approach. Median follow-up was 44.7 months. Five-year progression-free survival (PFS) was 73.9% and overall survival (OS) was 84%. The cumulative 5-year incidence of LRR as first site of failure was 6.2% (95% CI 4.2-8.7). Five-year cumulative incidence of LRR was 8.6 versus 4.4% for estrogen receptor (ER) negative versus ER positive (P = 0.017), 8.5 versus 3.4% for progesterone receptor (PR) negative versus PR positive (P = 0.011), and 1.7 versus 7.5% for HER2 positive (86% received trastuzamab) versus HER2 negative (P = 0.032). Five-year cumulative incidence of LRR was 11.8% for the triple negative subtype and 3.9% for other receptor combinations (P < 0.001). Among patients whose disease is ER positive, 5-year LRR rate was 7.8 versus 3.4% for PR negative versus PR positive (P = 0.130). The prognostic value of the triple negative and HER2 negative subtypes was maintained on multivariate analysis. In the era of HER-2 targeted therapy, tumors that are HER-2 over expressing and are treated with trastuzumab have a very low rate of LRR. ER negative, PR negative, and triple negative status are associated with increased risk of LRR.

Characterization of antigen-presenting cells induced by intragastric immunization with recombinant chimeric immunogens constructed from Streptococcus mutans AgI/II and type I or type II heat-labile enterotoxins

Intragastric (i.g.) immunization with recombinant chimeric proteins constructed from the saliva-binding region (SBR) of Streptococcus mutans surface antigen AgI/II and the A2/B subunits of enterobacterial heat-labile enterotoxins has been successfully used to induce salivary and circulating antibodies against S. mutans that have protective potential against dental caries. To investigate the mode of action of these vaccine constructs, mice were immunized i.g. with chimeric proteins constructed from SBR and cholera toxin (CT) or the type II enterotoxins of Escherichia coli, LT-IIa and LT-IIb. Antigen-presenting cells (APC) in Peyer's patches (PP) and mesenteric lymph nodes (MLN) were characterized by flow cytometry. Compared with immunization with SBR alone, chimeric proteins SBR-LTIIaA2/B and SBR-LTIIbA2/B increased the number of B cells and macrophages in PP and diminished B cell numbers in MLN, whereas SBR-CTA2/B diminished the numbers of B cells and macrophages in PP and MLN. Immunization with all three chimeric proteins led to upregulation of MHC class II molecules and co-stimulatory receptors CD40, CD80, and CD86 especially on dendritic cells in PP and also on APC in MLN. The results provide a molecular basis for the enhanced immune responses induced by chimeric proteins compared with uncoupled antigen, and for differential responses to chimeric proteins based on CT or type II enterotoxins.

Distinguishing benign from malignant parotid gland tumours: low-dose multi-phasic CT protocol with 5-minute delay

Objectives

To explore the percentage enhancement wash-out ratio (PEW) and relative PEW (RPEW) of low-dose multi-phasic computed tomography (CT) in distinguishing benign from malignant parotid gland tumours.

Methods

This study was approved by the ethics committee, and informed patient consent was obtained. 51 patients with parotid tumours proven by histopathology received CT, including 18 with pleomorphic adenomas, 14 with Warthin’s tumours and 19 with malignant tumours. Size and attenuation of parotid tumours were measured. Compared with 5-min attenuation, the 30-s and 90-s PEW (PEW_30, PEW₉₀) and RPEW (RPEW₃₀, RPEW₉₀) were calculated.

Results

There was a significant difference in PEW₃₀, RPEW₃₀, PEW₉₀ and RPEW₉₀ in the parotid neoplasms groups (P < 0.01), and statistical significance existed simultaneously in pleomorphic adenomas vs malignant tumours and Warthin’s tumours vs malignant tumours according to SNK-q test. The optimal diagnosis results of malignancy with 100% specificity (32/32) was obtained by using a combination of the following criteria: −70% > PEW₃₀ < 36%, −30% > PEW₃₀ < 19%, PEW₉₀ > 12%, and the sensitivity (74%) for diagnosis of malignancy was yield.

Conclusions

Wash-out ratio may assist in differentiating the benign from malignant parotid gland tumours. Combining the percentage of enhanced wash-out ratios of CT protocols can yield diagnostic results for malignancy.

Molecular characterization of the porcine TIM-3 gene

TIM-3 is a member of the TIM (T-cell immunoglobulin domain and mucin domain) family, which plays an important role in TH1 responses and autoimmune diseases. In this study, we cloned and characterized the porcine TIM-3 gene. Real-time PCR showed little expression of porcine TIM-3 in muscle and stomach, low expression in kidney, brain, stomach and muscle, moderate expression in liver, small intestine and lymph, and high expression in spleen and lung. Transient transfection indicated that porcine TIM-3 fusion protein was found to localize on the cell membranes or cytoplasm. Association analysis indicated that the SNP AccI in exon2 was significantly associated (P < 0.05) with red blood cell count mean corpuscular haemoglobin, packed cell volume, Lymphocyte percentage and Lymphocyte modulus. In conclusion, our results provide some information for conducting further studies on the functions of porcine TIM-3 gene in type I diabetes and suggest that SNP AccI in exon2 may be utilized as a marker for molecular-assisted selection in animal breeding.

Cell surface engineering of mesenchymal stem cells

By leveraging the capacity to promote regeneration, stem cell therapies offer enormous hope for solving some of the most tragic illnesses, diseases, and tissue defects world-wide. However, a significant barrier to the effective implementation of cell therapies is the inability to target a large quantity of viable cells with high efficiency to tissues of interest. Systemic infusion is desired as it minimizes the invasiveness of cell therapy, and maximizes practical aspects of repeated doses. However, cell types such as mesenchymal stem cells exhibit a poor homing capability or lose their capacity to home following culture expansion (i.e. FASEB J 21:3197-3207, 2007; Circulation 108:863-868, 2003; Stroke: A Journal of Cerebral Circulation 32:1005-1011; Blood 104:3581-3587, 2004). To address this challenge, we have developed a simple platform technology to chemically attach cell adhesion molecules to the cell surface to improve the homing efficiency to specific tissues. This chemical approach involves a stepwise process including (1) treatment of cells with sulfonated biotinyl-N-hydroxy-succinimide to introduce biotin groups on the cell surface, (2) addition of streptavidin that binds to the biotin on the cell surface and presents unoccupied binding sites, and (3) attachment of biotinylated targeting ligands that promote adhesive interactions with vascular endothelium. Specifically, in our model system, a biotinylated cell rolling ligand, sialyl Lewisx (SLeX), found on the surface of leukocytes (i.e., the active site of the P-selectin glycoprotein ligand (PSGL-1)), is conjugated on MSC surface. The SLeX engineered MSCs exhibit a rolling response on a P-selectin coated substrate under shear stress conditions. This indicates that this approach can be used to potentially target P-selectin expressing endothelium in the more marrow or at sites of inflammation. Importantly, the surface modification has no adverse impact on MSCs' native phenotype including their multilineage differentiation capacity, viability, proliferation, and adhesion kinetics. We anticipate that the present approach to covalently modify the cell surface and immobilize required ligands is not limited to MSCs or the SLeX ligand. Therefore, this technology should have broad implications on cell therapies that utilize systemic administration and require targeting of cells to specific tissues. The approach may also be useful to promote specific cell-cell interactions. In this protocol, we describe the conjugation of SLeX on MSC surface and methods to study cell rolling behaviors of SLeX-modified MSCs on a P-selectin coated substrate using an in vitro flow chamber assay. We also provide a brief description of cell characterization assays that can be used to examine the impact of the chemical modification regimen.

Abstract PD07-09: Hypoxia (VEGF-S) Signature and CRYAB Predict Response to Neoadjuvant Anthracycline/Taxane Containing Chemotherapy within Triple Negative and Unselected Breast Tumors

Background: Aggressive breast tumors are a clinically challenge to manage. A VEGF-signature (VEGF-s) developed in vivo (Hu et al. BMC Med. 09) and the profile of the anti-apoptotic gene and regulator of tumor angiogenesis, CRYAB (Moyano et al. J Clin Invest 06; Dimberg et al. Blood 08), are both associated with distant metastasis. In this study, we sought to test if these two mechanistically related biomarkers predict pathological complete response(pCR) to anthracyline/taxane-based neoadjuvant chemotherapy.

Methods: Gene expression data of pre-treatment fresh frozen tumors were combined, 149 from the ISPY trial (Agilent 44K) and 225 from MD Anderson Cancer Center(MDACC) (Affymetrix HG U133A). Patients from I-SPY were treated with doxorubicin/cyclophosphamide followed by a taxane. Patients from MDACC were treated with paclitaxel followed by sequential fluorouracil-AC. Tumors were classified into intrinsic subtypes using PAM50(Parker et al. J Clin Oncol 09) and Claudin-low(CL) predictor(Prat et al., Submitted). Odds ratios of biomarkers to pCR were determined using logistic regression. Predictive values of multivariable models were estimated using receiver operating characteristic curve. Results: 319 patients had complete data; the pCR rate was similar between the datasets (ISPY 22%, MDACC 20%). Both the VEGF-s and CRYAB were highly expressed within Basal-like(BL) and CL (P&lt;0.0001); these two biomarkers were positively correlated with each other (r: 0.4, P&lt;0.001). In univariate analysis, both VEGF-s (P&lt;0.001) and CRYAB (P&lt;0.001) were significantly associated with pCR. A multivariable test including tumor size, grade, ER, Her2, intrinsic subtypes, VEGF-s and CRYAB, had an AUC value of 0.86 to predict pCR(Table 1). T stage, Her2, intrinsic subtypes and CRYABwere significant.

82 patients with triple-negative tumors within this combined cohort. In univariate analysis, T stage, grade or classifying tumors into BL vs not did not predict pCR; but VEGF-s (p= 0.04) and CRYAB (p = 0.02) were associated with pCR. Multivariable model, including VEGF-s, CRYAB and the clinical variables, had a predictive value of 0.71 to pCR(Table 1), which identified CRYAB as the most significant factor by likelihood ratio test.

Table 1: Multivariable logistic regression models to predict pCR.

Conclusion: VEGF-s and CRYAB expression are associated with aggressive subtypes and may possibly help to predict response of anthracycline/taxane-based neoadjuvant chemotherapy beyond ER, Her2, and intrinsic subtypes.

A solid-state amorphous selenium avalanche technology for low photon flux imaging applications

PURPOSE

The feasibility of a practical solid-state technology for low photon flux imaging applications was investigated. The technology is based on an amorphous selenium photoreceptor with a voltage-controlled avalanche multiplication gain. If this photoreceptor can provide sufficient internal gain, it will be useful for an extensive range of diagnostic imaging systems.

METHODS

The avalanche photoreceptor under investigation is referred to as HARP-DRL. This is a novel concept in which a high-gain avalanche rushing photoconductor (HARP) is integrated with a distributed resistance layer (DRL) and sandwiched between two electrodes. The avalanche gain and leakage current characteristics of this photoreceptor were measured.

RESULTS

HARP-DRL has been found to sustain very high electric field strengths without electrical breakdown. It has shown avalanche multiplication gains as high as 10(4) and a very low leakage current (< or = 20 pA/mm2).

CONCLUSIONS

This is the first experimental demonstration of a solid-state amorphous photoreceptor which provides sufficient internal avalanche gain for photon counting and photon starved imaging applications.

Renin-angiotensin system blockers and modulation of radiation-induced brain injury

Radiation-induced brain injury remains a major cause of morbidity in cancer patients with primary or metastatic brain tumors. Approximately 200,000 individuals/year are treated with fractionated partial or whole-brain irradiation, and > half will survive long enough (≤6 months) to develop radiation-induced brain injury, including cognitive impairment. Although short-term treatments have shown efficacy, no long-term treatments or preventive approaches are presently available for modulating radiation-induced brain injury. Based on previous preclinical studies clearly demonstrating that renin-angiotensin system (RAS) blockers can modulate radiation-induced late effects in the kidney and lung, we and others hypothesized that RAS blockade would similarly modulate radiation-induced brain injury. Indeed, studies in the last 5 years have shown that both angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor antagonists (AT(1)RAs) can prevent/ameliorate radiation-induced brain injury, including cognitive impairment, in the rat. The mechanistic basis for this RAS blocker-mediated effect remains the subject of ongoing investigations. Putative mechanisms include, i] blockade of Ang II/NADPH oxidase-mediated oxidative stress and neuroinflammation, and ii] a change in the balance of angiotensin (Ang) peptides from the pro-inflammatory and pro-oxidative Ang II to the anti-inflammatory and anti-oxidative Ang-1-7). However, given that both ACEIs and AT(1)RAs are 1] well-tolerated drugs routinely prescribed for hypertension, 2] exhibit some antitumor properties, and 3] can prevent/ameliorate radiation-induced brain injury, they appear to be ideal drugs for future clinical trials, offering the promise of improving the quality of life of brain tumor patients receiving brain irradiation.