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OBJECTIVE: Cultured human thyroid cells in collagen gel culture were examined on cell morphology and the production of thyroglobulin (Tg), triiodothyronine (T3) and thyroxine (T4) which are components of functional differentiation. METHODS: Thyroid cells obtained from normal human thyroid tissues (four cases), follicular adenoma tissues (three cases), papillary carcinoma tissues (three cases), and follicular carcinoma tissue (one case), were cultured in collagen gel. Then these cultured cells were observed on cellular morphology and production of Tg, T3 and T4. Moreover, changes in morphological characteristics and production of Tg, T3 and T4 induced by addition of thyroid stimulating hormone (TSH) and epidermal growth factor (EGF) to medium in collagen gel culture were determined. RESULTS: Normal and tumor cells in collagen gel culture formed colonies and follicles with Tg production, similar to in vivo-like three-dimensional cellular structures and functions. Normal thyroid cells stimulated TSH induced more Tg and produced morphological changes, i.e. enlarged follicular lumens and increased the height of follicular cells, but did not promote cell proliferation. Reversely, normal thyroid cells stimulated with EGF promoted cell proliferation, but did not change morphological findings and did not increase production of Tg, T3 and T4. CONCLUSIONS: These findings suggest that collagen gel culture is useful for observing the effects of stimulation by cell growth factor on the morphological and functional differentiation of human thyroid cells.

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To improve the ability of an in vitro drug sensitivity test to predict in vivo effects, we applied a drug concentration that was pharmacokinetically equivalent to plasma levels and collagen gel droplet-embedded culture with a high cloning efficiency. We reported that the cell-killing effect of cell cycle phase-nonspecific drugs such as mitomycin C, cisplatin and Adriamycin depends on the area under the drug concentration-time curve (AUC). The plasma AUC values of these drugs were estimated after an injection into nude mice at the maximal tolerated doses (MTD). Tumor cells isolated from human tumor xenografts implanted into nude mice and cultured in collagen gel droplets were exposed to drugs under conditions that can reproduce the plasma AUC in vitro. The in vitro sensitivity to a drug was compared with the in vivo response of the same tumor treated with the MTD of the drug. When the criterion of sensitivity was taken as 50% or less of the growth inhibition (growth rate of treated group/that of control group, T/C), the correlation between the in vitro and in vivo growth inhibition of all 3 drugs tested was relatively high (86% of the true-positive rate, 82% of the true-negative rate and 83% of the correlation rate).

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We developed a new in vitro assay for chemosensitivity test using collagen gel droplet embedded culture and image analysis. In this in vitro assay, we successfully minimized the cancer cell number required for culture to approximately 3-10 x 10(3) cells for each 30 microliters collagen gel droplet, obtained the sufficient growth of cancer cells using serum-free medium while suppressing the growth of fibroblastic cells, and measured the volume of cancer cells by eliminating the contaminating fibroblastic cells by an image processing technique. Anticancer effects of the in vitro assay showed a very good correlation with those of in vivo nude mouse assay using human cancer cell lines. The success rates of the in vitro assay for 141 surgical specimens of primary lung cancers and for 65 of primary breast cancers were 89 and 80%, respectively. The accumulated in vitro assay response rates of MMC, CDDP, VDS and VP-16 for primary lung cancers and of MMC, 5-FU and ADR for primary breast cancers were similar to the respective clinical response rates. These results suggest that this in vitro chemosensitivity test may be practically useful for clinical applications.

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Thyroid cells obtained from 21 normal human thyroid tissue samples and 17 tissue samples from diseased thyroid, including one of Graves disease, 4 with follicular adenoma, 11 with papillary carcinoma, and 1 with follicular carcinoma, were cultured in collagen gel, and ability to produce thyroglobulin (Tg), triiodothyronine (T3) and thyroxine (T4) was determined. Changes in morphological characteristics and production of Tg, T3, and T4 induced by addition of thyroid stimulating hormone (TSH) to medium in collagen gel culture were also determined. Twenty of all cases exhibited positive reaction for Tg. No relationship was found between rate of positivity for Tg and pathologic diagnosis. Three with carcinoma showed positive reaction for T3, and 4 with carcinoma showed positive reaction for T4. Only for normal thyroid cells did addition of TSH to medium induce increase the percentage of colonies producing Tg or T4 and morphological changes including an enlarged follicular lumen and increase in the height of columnar epithelium. These findings suggest that thyroid cells in collagen culture develop in an in vivo-like fashion. In conclusion, collagen has important effects on cellular differentiation when included in extracellular matrix.

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Chemotherapy with CDDP and/or other agents was performed in 15 patients after removal of metastatic brain tumors. A chemosensitivity test using a system of collagen gel-embedded culture and computerized image analysis was performed on the tumors from these patients. The clinical usefulness of the chemosensitivity test was evaluated by comparing chemotherapeutic effects with the results of the test. The rates of correlation of the chemosensitivity test with clinical response on brain MRI was 80%, and that of the chemosensitivity test with clinical response in tumor markers or on primary tumors was 75%. This observation suggests that the chemosensitivity test using collagen gel-embedded culture and computerized image analysis is useful in determining optimal chemotherapy for metastatic brain tumors. In ten multiple metastatic brain tumors, three complete responses, two partial responses, one minor response and four non-responses were observed on MRI. Only one case showed a false negative result on the chemosensitivity test and showed partial response. This result also indicates the effectiveness of chemotherapy based on chemosensitivity testing.

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Using normal human thyroid cells and tumor cells, the reconstruction of various diseased cells in collagen gel as well as the relationship between the morphology of colonies in collagen-embedded culture and the biological behavior (benignity, malignancy, metastasis, and invasion) of the original tumors were studied. In collagen gel culture, normal thyroid cells reorganized follicle-like constructions, and follicular adenoma cells showed in vivo-like constructions. However, two different types of colonies were observed in cultures of cells from papillary carcinomas. One was the branching type with many outgrowths projecting to three dimensions and the other was the spherical type without any outgrowths. These spherical colonies were observed in all cases of papillary carcinoma, but varied from one case to another. Metastasis and invasion were detected during pathological examination in cases with a high ratio of spherical colonies. Our results indicate that cells from highly metastatic and invasive thyroid cancer form spherical colonies in the collagen gel culture, and that this collagen culture is a useful method for studying the heterogeneity of tumor cells as well as the metastasis and invasive ability of tumor cells in vitro.

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Thyroid cells from 14 normal subjects, two patients with Grave's disease, four patients with follicular adenoma and eight patients with papillary carcinoma were cultured in collagen gel. The colonies of these cells were stereoscopically observed and their morphological characteristics were studied with regard to relation with pathological findings of mother tumor, extra-capsular invasion and metastatic potential. For normal thyroid, Grave's disease and follicular adenoma (except for one case), their own characteristic branching type colonies were found. For papillary carcinoma, both branching type and spheroid type of colonies were observed. The ratio of branching type/spheroid type varied individually in the patients with papillary carcinoma. However, the spheroid type was found to trend to be predominant in patients with extra-capsular invasion and/or lymph node metastasis. This means that the observation of spheroid type colonies in collagen gel is suggestive of risk of extra-capsular invasion or lymph node metastasis. From the obtained results, it seemed possible to diagnose poorly-differentiated cells in vitro by morphologically observing colonies of human thyroid papillary carcinoma cells developing in collagen gel.

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A new drug sensitivity assay method using the collagen gel embedded culture and image analysis was developed. Human cancer cells cultured in collagen gels showed extremely high cloning efficiency and in vivo-like drug response. In addition, image analysis was used successfully for the first time to automatically discriminate cancer colonies from contaminating fibroblastic cells by taking advantage of the difference in shape between them after cultivation to determine the drug response of cultured cancer cells accurately and easily. A new approach for the practical use of the drug sensitivity test on human cancer cells is suggested.

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The telopeptide of type I collagen is thought to be responsible for causing immunogenic response when introduced into xenogenic hosts. To eliminate this problem, solubilized bovine skin collagen was filtered through a millipore membrane, digested repeatedly with pepsin to remove telopeptides, and used as a carrier for a water-soluble, partially-purified fraction of bone morphogenetic protein (BMP) in mice. Composite implants of this telopeptide-depleted collagen and the partially-purified BMP fraction consistently elicited ectopic bone formation in mice 3 weeks postimplantation. When implanted alone, collagen or BMP failed to show this response. Collagens, prepared by use of conventional methods (acid-solubilized collagen, or collagen-digested once with pepsin) were also assessed as carriers for BMP, but were found to be inferior in terms of consistency of bone formation and amount of induced bone mass. The results suggest that telopeptide-depleted collagen permitted a gradual release of purified BMP for induction of bone, with minimal immunogenic interference. Consequently, this collagen carrier represents an important development for future clinical application of BMP.

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Human thyroid papillary carcinoma cells (surgical materials) were cultured in a monolayer or a collagen gel system. In the monolayer culture, degeneration and necrosis of cancer cells were observed after 10 days of culture. In the collagen gel culture, degenerative necrosis were observed 14 days culture. In histopathological observation monolayer cells proliferated in pavement-like form without forming any colony. On the contrary, collagen gel culture cells formed branching-type colonies and spheroid-type colonies. Those results suggested that papillary carcinoma cells can be cultured more like in vivo in collagen gel culture than monolayer culture.

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A small amount of partially purified, water-soluble murine osteosarcoma-derived bone morphogenetic protein (BMP) was implanted into the dorsal muscles of mice in combination with calf skin gelatin or collagen as carriers. Changes in the ribs adjacent to the implants were then chronologically observed. On implantation of BMP with gelatin, the gelatin was rapidly absorbed and no ectopic bone formation was observed, but periosteal cellular proliferation with subsequent formation of periosteal cartilage and bone was seen in ribs adjacent to the implant. Implantation of the same amount of BMP fraction or gelatin alone as controls did not result in either any ectopic bone formation in situ or any periosteal bone formation in adjacent ribs. Implantation of BMP with collagen resulted consistently in both ectopic bone formation in situ and periosteal bone formation in adjacent ribs. These results suggest that BMP is diffusible in vivo and is capable of eliciting a response from periosteum to stimulate periosteal bone formation.

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