Electric pulse exposure reduces AAV8 dosage required to transduce HepG2 cells.

We demonstrate that applying electric field pulses to hepatocytes, in vitro, in the presence of enhanced green fluorescent protein (EGFP)-expressing adeno-associated virus (AAV8) vectors reduces the viral dosage required for a given transduction level by more than 50-fold, compared to hepatocytes exposed to AAV8-EGFP vectors without electric field pulse exposure. We conducted 48 experimental observations across 8 exposure conditions in standard well plates. The electric pulse exposures involved single 80-ms pulses with 375 V/cm field intensity. Our study suggests that electric pulse exposure results in enhanced EGFP expression in cells, indicative of increased transduction efficiency. The enhanced transduction observed in our study, if translated successfully to an in vivo setting, would be a promising indication of potential reduction in the required dose of AAV vectors. Understanding the effects of electric field pulses on AAV transduction in vitro is an important preliminary step.

Multiple clinically relevant immunotherapies prolong the function of microencapsulated porcine islet xenografts in diabetic NOD mice without the use of anti-CD154 mAb.

BACKGROUND: Our goal was to identify clinically relevant immunotherapies that synergize with microencapsulation to protect adult porcine islet (API) xenografts in diabetic NOD mice. We have shown previously that dual costimulatory blockade (CTLA4-Ig plus anti-CD154 mAb) combined with encapsulation protects APIs long-term in NOD mice. Since no anti-CD154 mAbs currently are approved for use in humans, we tested the efficacy of other targeted immunosuppression regimens that might be used for diabetic patients receiving encapsulated islets. METHODS: Microencapsulated APIs were transplanted i.p. in diabetic NOD mice given either no immunosuppression or combinations immunosuppressive reagents. Graft function was monitored by blood glucose levels, i.p. glucose tolerance tests, and histology. Mechanisms of rejection were investigated by phenotyping host peritoneal cells and measuring graft site cytokine and chemokine levels. RESULTS: New immunosuppressive therapies were compared to CTLA4-Ig plus anti-CD154 mAb, used here as a control. The most effective was triple treatment with CTLA4-Ig, anti-CD154 mAb, and intracapsular CXCL12, and the next most effective was a non-depleting anti-CD4 mAb (YTS177.9) plus intracapsular CXCL12. Three additional regimens (CTLA4-Ig plus YTS177.9, YTS177.9 alone, and anti-OX40-Ligand mAb alone) significantly prolonged encapsulated API function. Dual treatment with CTLA4-Ig plus anti-CD40 mAb was as effective as CTLA4-Ig plus anti-CD154 mAb. Five other monotherapies and three combination therapies did not augment encapsulated API survival. Most peritoneal cytokines and chemokines were either absent or minimal. At necropsy, the capsules were intact, not fibrosed, and clean when function was maintained, but were coated with host cells if rejection had occurred. CONCLUSIONS: Multiple different immunotherapies which specifically inhibit CD4+ T cells, modulate T-cell trafficking, or interfere with antigen presentation can substitute for anti-CD154 mAb to prolong encapsulated islet xenograft function in diabetic NOD mice.

Mechanical stimulation increases collagen type I and collagen type III gene expression of stem cell-collagen sponge constructs for patellar tendon repair.

Our group has shown that mechanical stimulation increases the stiffness of stem cell-collagen sponge constructs at 14 days in culture and subsequent rabbit patellar tendon repairs at 12 weeks postsurgery. What remains unclear is which genes might be responsible for this increase in stiffness. Therefore, the objective of this study was to determine how a tensile stimulus affects the gene expression of stem cell-collagen sponge constructs used to repair rabbit central patellar tendon defects. Tissue-engineered constructs were created by seeding mesenchymal stem cells (MSCs) from 10 adult rabbits at 0.14 x 10(6) cells/construct in type I collagen sponges. Half of the constructs were mechanically stimulated once every 5 min for 8 h/d to a peak strain of 2.4% for 2 weeks. The other half remained in an incubator without mechanical stimulation for 2 weeks. After 14 days in culture, half of the stimulated and nonstimulated constructs were prepared to determine the expression of collagen type I, collagen type III, decorin, fibronectin, and glyceraldehyde-3-phosphate dehydrogenase genes using real-time quantitative reverse transcriptase polymerase chain reaction. The remaining constructs were mechanically tested to determine their mechanical properties. Two weeks of in vitro mechanical stimulation significantly increased collagen type I and collagen type III gene expression of the stem cell-collagen sponge constructs. Stimulated constructs showed 3 and 4 times greater collagen type I (p = 0.0001) and collagen type III gene expression (p = 0.001) than nonstimulated controls. Stimulated constructs also had 2.5 times the linear stiffness and 4 times the linear modulus of nonstimulated constructs. However, mechanical stimulation did not significantly increase decorin or fibronectin gene expression (p = 0.2) after 14 days in culture. This study shows that mechanical stimulation of cell-sponge constructs produces similar increases in the expression of 2 structural genes, as well as linear stiffness and linear modulus.

Transcriptional profiles of intestinal tumors in Apc(Min) mice are unique from those of embryonic intestine and identify novel gene targets dysregulated in human colorectal tumors.

The adenomatous polyposis coli (APC) tumor suppressor is a major regulator of the Wnt signaling pathway in normal intestinal epithelium. APC, in conjunction with AXIN and GSK-3beta, forms a complex necessary for the degradation of beta-catenin, thereby preventing beta-catenin/T-cell factor interaction and alteration of growth-controlling genes such as c-MYC and cyclin D1. Inappropriate activation of the Wnt pathway, via Apc/APC mutation, leads to gastrointestinal tumor formation in both the mouse and human. In order to discover novel genes that may contribute to tumor progression in the gastrointestinal tract, we used cDNA microarrays to identify 114 genes with altered levels of expression in Apc(Min) mouse adenomas from the duodenum, jejunum, and colon. Changes in the expression of 24 of these 114 genes were not observed during mouse development at embryonic day 16.5, postnatal day 1, or postnatal day 14 (relative to normal adult intestine). These 24 genes are not previously known Wnt targets. Seven genes were validated by real-time reverse transcription-PCR analysis, whereas four genes were validated by in situ hybridization to mouse adenomas. Real-time reverse transcription-PCR analysis of human colorectal cancer cell lines and adenocarcinomas revealed that altered expression levels were also observed for six of the genes Igfbp5, Lcn2, Ly6d, N4wbp4 (PMEPA1), S100c, and Sox4.