The effect of high intensity focused ultrasound on luciferase activity on two tumor cell lines in vitro, under the control of a CMV promoter

Transcriptional activity of an ovarian-specific promoter from rat in dairy goat granulosa cells

Ovarian-specific promoter 1 (OSP-1) is a retrovirus-like element isolated from the complementary DNA library of rat that has been thought to be specifically expressed in ovary. To exploit this promoter in dairy goat ovary granulosa cells (GCs), OSP-1 from rat was used to construct the reporter vector pOSP-1-EGFP, in which egfp coding for enhanced green fluorescent protein (EGFP) was used as a reporter to examine the activity of OSP-1 in GCs. EGFP was successfully expressed in dairy goat GCs transfected with pOSP-1-EGFP. Reverse transcriptase-polymerase chain reaction analysis confirmed the tissue-specific transcription of EGFP messenger RNA in dairy goat GCs transfected with pOSP-1-EGFP. We concluded that OSP-1 promoter from rat can specifically drive foreign gene expression in dairy goat GCs. Thus, we obtained a tissue-specific regulation element and provided a potential tool for the research of regulation and development of the ovary in dairy goats.

Use of in vivo bioluminescence and MRI to determine hyperthermia-induced changes in luciferase activity under the control of an hsp70 promoter

We investigated the in vivo effect of hyperthermia on the expression of heat shock proteins and MRI changes in three tumor cell lines. Three tumor cell lines (SCCVII, NIH3T3, M21) were transfected with a plasmid containing the heat shock protein 70 gene (hsp70) promoter fragment and the luciferase reporter gene, and injected into mice. Tumors of 1100 mm³ in size were exposed to five different temperatures (38, 40, 42, 44 and 46 °C) in a water bath. Bioluminescence and MRI were performed at set time intervals. The MRI scan protocol was as follows: T₁-weighted spin echo ± contrast medium, T₂-weighted fast spin echo, dynamic contrast-enhanced MRI, diffusion-weighted stimulated echo acquisition mode sequence, T₂ time obtained on a 1.5T General Electric MRI scanner. Immunoblotting was also performed. hsp70 transcription was strongly induced at 42 and 44 °C, reaching values as high as 8531.5 ± 432.1-fold above baseline in NIH3T3 tumors. At these temperatures, significant increases in the uptake of contrast medium, slope of initial enhancement, Ak(ep) values and apparent diffusion coefficient (ADC) were observed in the 8-h scan of the NIH3T3 cell line. In SCCVII tumors, ADC increased by about 23% (p = 0.010) in the scans performed at 8, 24, 48 and 96 h. At 46 °C, luciferase activity was reduced significantly in the three cell lines. In all tumor types, a significant increase in ADC was observed, which was highest in SCCVII tumors (33.8%; p < 0.01). In accordance with the bioluminescence results, significant Hsp70 protein production was shown by immunoblot analysis. The best correlation coefficient between luciferase activity and immunoblotting results was found for M21 tumors (r = 0.93, p < 0.0001). Different tissue types display distinct patterns of hsp70 transcription. MRI can be used, in combination with optical imaging, to provide information on hsp70 transcription and protein production. The major finding of the present study was that heat-related biochemical changes in tumor tissue can be determined by MRI.

Inhibitory function of parathyroid hormone-related protein on chondrocyte hypertrophy: the implication for articular cartilage repair

Cartilage repair tissue is usually accompanied by chondrocyte hypertrophy and osseous overgrowths, and a role for parathyroid hormone-related protein (PTHrP) in inhibiting chondrocytes from hypertrophic differentiation during the process of endochondral ossification has been demonstrated. However, application of PTHrP in cartilage repair has not been extensively considered. This review systemically summarizes for the first time the inhibitory function of PTHrP on chondrocyte hypertrophy in articular cartilage and during the process of endochondral ossification, as well as the process of mesenchymal stem cell chondrogenic differentiation. Based on the literature review, the strategy of using PTHrP for articular cartilage repair is suggested, which is instructive for clinical treatment of cartilage injuries as well as osteoarthritis.

Bioluminescence imaging: looking beyond the light

Bioluminescence imaging (BLI) enables in vivo imaging of molecular and cellular processes. It has gained in popularity over the past decade because of its easy translation from in vitro to in vivo experiments, its sensitivity, and its ease of use. However, experience in applying BLI in living subjects is still limited, and many researchers have encountered unexpected or biased BLI readout and reported important influencing factors. In this review, we summarize both the biological and physical effects that occur at the enzyme level or during light propagation towards the camera. The knowledge and detection of such factors, together with the development of new strategies and better BLI compounds, will improve the accuracy of the technique in the future.

Induction of luciferase activity under the control of an hsp70 promoter using high-intensity focused ultrasound: combination of bioluminescence and MRI imaging in three different tumour models

The in vivo temporal changes of luciferase activity were investigated under the control of an hsp70 promoter in three tumour models after the application of different intensities of high-intensity focused ultrasound (HIFU). Three cell lines, SCCVII, NIH3T3 and M21 were stably transfected with a plasmid containing the hsp70 promoter and luciferase reporter gene, and tumours were subcutaneously initiated into mice. At a size of 1300 ± 234 mm(3), the tumours were exposed to five intensities of continuous HIFU (802-1401-2157-3067-4133 W/cm(2)) for 20 sec. Bioluminescence and MR imaging were performed to assess luciferase activity and signal intensity changes in the tissue. The MRI scan protocol was pre- and post-contrast T1-wt-SE, T2-wt-FSE, DCE-MRI, diffusion-wt STEAM sequence, T2 relaxation time determination obtained on a 1.5-T GE MRI scanner. The NIH3T3 tumours showed the highest luciferase activity of 328.1 ± 7.1 fold at 24 h at a HIFU intensity of 3067 W/cm(2), the M21 tumours of 3.2 ± 0.6 fold 8 hours and the SCCVII tumours 2.9 ± 0.9 fold 4 hours post-HIFU at 2157 W/cm(2). The greatest increase in T2 signal intensity and T2 relaxation time of 20.7 ± 3.4% was seen in the SCCVII tumours. The highest contrast medium uptake of 10.1 ± 1.1% was noted in the M21 tumours, and 14.8 ± 1.9% in the SCCVII tumours. In all tumours, a significant increase in the diffusion coefficient was seen with increased HIFU intensity, the highest of which was 40.3 ± 4.1% in the SCCVII tumours. The three tumour cell lines stably transfected with the hsp70/luciferase gene showed differential luciferase activity, which peaked at different times after the application of HIFU and was dependant on tumour type and HIFU energy deposition.