Subcultured Odontogenic Epithelial Cells in Combination with Dental Mesenchymal Cells Produce Enamel–Dentin-Like Complex Structures

We showed in a previous study that odontogenic epithelial cells can be selectively cultured from the enamel organ in serum-free medium and expanded using feeder layers of 3T3-J2 cells. The subcultured odontogenic epithelial cells retain the capacity for ameloblast-related gene expression, as shown by semiquantitative RT-PCR. The purpose of the present study was to evaluate the potential of subcultured odontogenic epithelial cells to form tooth structures in cell–polymer constructs maintained in vivo. Enamel organs from 6-month-old porcine third molars were dissociated into single odontogenic epithelial cells and subcultured on feeder layers of 3T3-J2 cells. Amelogenin expression was detected in the subcultured odontogenic epithelial cells by immunostaining and Western blotting. The subcultured odontogenic epithelial cells were seeded onto collagen sponge scaffolds in combination with fresh dental mesenchymal cells, and transplanted into athymic rats. After 4 weeks, enamel–dentin-like complex structures were present in the implanted constructs. These results show that our culture system produced differentiating ameloblast-like cells that were able to secrete amelogenin proteins and form enamel-like tissues in vivo. This application of the subculturing technique provides a foundation for further tooth-tissue engineering and for improving our understanding of ameloblast biology.

Effective Bone Engineering with Periosteum-derived Cells

Bone augmentation via tissue engineering has generated significant interest. We hypothesized that periosteum-derived cells could be used in place of bone marrow stromal cells (which are widely used) in bone engineering, but the differences in osteogenic potential between these 2 cell types are unclear. Here, we compared the osteogenic potential of these cells, and investigated the optimal osteoinductive conditions for periosteum-derived cells. Both cell types were induced, via bFGF and BMP-2, to differentiate into osteoblasts. Periosteal cells proliferated faster than marrow stromal cells, and osteogenic markers indicated that bone marrow stromal cells were more osteogenic than periosteal cells. However, pre-treatment with bFGF made periosteal cells more sensitive to BMP-2 and more osteogenic. Transplants of periosteal cells treated with BMP-2 after pre-treatment with bFGF formed more new bone than did marrow stromal cells. Analysis of these data suggests that combined treatment with bFGF and BMP-2 can make periosteum a highly useful source of bone regeneration.

MR imaging of the lingual thyroid: Comparison to other submucosal lesions

Purpose: To study MR findings for clues to the diagnosis of lingual thyroid.

Material and Methods: MR findings and clinical and scintigraphic data of 5 cases of lingual thyroid were reviewed and the MR findings were compared to those of 16 cases of other submucosal lesions in the base of the tongue.

Results: Four of the 5 patients with lingual thyroid were women and all had hypothyroidism. MR imaging depicted lingual thyroid in the midline in the base of the tongue (n=5) and additional ectopic thyroid glands in the floor of the mouth (n=2) or between the right and left sternohyoid muscles (n=1). Ectopic thyroid glands appeared isointense or hyperintense relative to muscle tissue on T1-weighted images and showed slight or fair contrast enhancement. All glands had low to intermediate T2 signal, which was also seen in 1 case of non-Hodgkin's lymphoma and 1 case of adenoid cystic carcinoma. All ectopic thyroid glands had well-defined margins, whereas malignant tumors tended to have ill-defined margins and to invade the surrounding structures. All but the 5 cases of lingual thyroid had an MR-demonstrable thyroid gland in the normal cervical position.

Conclusion: A well-defined mass of low-intermediate T2 signal in the midline base of the tongue, neither with invasive tendency nor with a cervical thyroid gland in the normal site on MR imaging, may strongly indicate lingual thyroid.

Clinical efficacy of dual-phase scanning using (68)Ga-DOTATOC-PET/CT in the detection of neuroendocrine tumours

AIM

To investigate whether delayed scanning at approximately 90 minutes post-injection of (68)Ga-labelled 1,4,7,10-tetraazacyclododecane-N,N',N″,N‴-tetraacetic acid-d-Phe(1)-Tyr(3)-octreotide (DOTATOC) had any clinical benefits regarding the evaluation of neuroendocrine tumours (NETs), relative to conventional combined positron-emission tomography (PET) and computed tomography (CT) at 60 minutes post-injection.

MATERIALS AND METHODS

Fifty-four patients who underwent DOTATOC-PET/CT for suspected or known NETs were retrospectively reviewed. PET/CT was performed twice at approximately 60 and 90 minutes post-injection. For visual analysis, a five-point grading scale (0: definitely normal to 4: definitely abnormal) was used, and grade 3-4 lesions were regarded as positive. For quantitative analysis, the time course of the maximum standardised uptake value (SUVmax) in each lesion and the mean SUV of physiological uptake in the liver were evaluated.

RESULTS

Of the 54 patients, 43 had a total of 132 lesions. In interpreting the early images, there were four grade 3 lesions, and the remaining 128 lesions were grade 4. All 132 lesions were grade 4 in the delayed images. SUVs and tumour-to-liver ratios for hepatic lesions were slightly higher in delayed scanning than in early scanning (SUV, 26.8±21.2 versus 28.2±21.2 [p<0.01]; tumour-to-liver ratio, 5.9±4.5 versus 6.2±4.6 [p<0.01]), which did not affect the detection rate. Additionally, bone and peritoneal metastases had slightly higher SUVs at delayed imaging (p<0.05), but there was no difference in diagnostic performance. No significant difference in the SUVs for pancreatic lesions and primary sites in the bowel were observed between the early and delayed scans.

CONCLUSION

Delayed scanning may be helpful for improving diagnostic confidence in some cases, although it provided no specific merits for diagnostic accuracy in detecting primary or metastatic NETs.