Culturing of cells from giant cell tumour of bone on natural and synthetic calcified substrata: the effect of leukaemia inhibitory factor and vitamin D3 on the resorbing activity of osteoclast-like cells.

Osteoclastic cells from giant cell tumour of bone (GCT) of bone provide a rich source for investigation of cellular mechanisms leading to formation of multinucleated cells, the resorption process and involvement of hormones and cytokines in these events. In the present study we investigated the effect of 1,25-dihydroxyvitamin D3 (VD3) and leukaemia inhibitory factor (LIF) on the resorbing potential of osteoclast of GCT origin using quantitative image-analysis of resorption lacunae in an in vitro dentine model. While VD3 unsignificantly increased the number of resorption pits and implicated surface after 7 days of GCT cell culturing, the stimulative effect of LIF was statistically significant. In cultures supplemented with LIF (5000 U/ml) the number of lacunae and resorption surface increased by 38% and 55%, respectively, when compared with control cultures. We suggest that both osteotropic agents increased osteoclastic activity, as the number of multinucleated cells was similar in control and experimental cultures. Seeding of GCT cells on biphasic calcium phosphate substratum revealed the relative inability of osteoclastic cells to resorb this synthetic material.

[Induced hematopoietic foci in mice. I. Induction of extraskeletal hematopoietic areas using demineralized tooth matrix]. / Indutsirovannye ochagi krovetvoreniia u myshei. I. Induktsiia vneskeletnykh krovetvornykh territorii demineralizovannym zubnym matriksom.

Conditions of formation of induced osteo-hemopoietic foci in mice, in response to ectopic implantation to them of homologous demineralized tooth matrix, have been studied. It is shown that the hemopoietic tissue of the induced foci is similar to the bone marrow of the skeletal bones by the morphological parameters and cellular composition; differentiation of precursor cells takes place in all three directions of myelopoiesis. Induced foci formation under the capsule of the kidney occurs much later (after 5-8 months) than under the skin of muscular fascia (1-1.5 months). The induced hemopoietic foci functioning continues at least for one year.