H. Arzate et al., Electron microscopy, micro-analysis, and x-ray diffraction characterization of the mineral-like tissue deposited by human cementum tumor-derived cells, J DENT RES, 79(1), 2000, pp. 28-34
The nature and characteristics of the mineralized-like tissue deposited by
cementoblasts are not well-known due to the difficulties in obtaining and c
ulturing cells representing the cementum phenotype. We hypothesized that a
putative cementoblastic cell line derived from a human cementoblastoma coul
d serve as a suitable model to study the physical, chemical, and morphologi
cal features of the cementum-like tissue deposited ill vitro. The cementobl
astoma cell line was studied by transmission electron, high resolution, sca
nning, and atomic force microscopy and compared with human cellular cementu
m, human osteoblasts, and human alveolar bone. The analyses of the crystals
and mineral-like tissue in the cell line were performed by x-ray diffracti
on microscopy and energy-dispersive x-ray micro-analysis. TEM examination o
f cementoblastoma cells revealed the presence of electron-dense intracellul
ar vesicles surrounded by a membrane that contained filaments and needle-li
ke structures. The diffraction patterns obtained from the intracellular mat
erial and human cellular cementum were similar, with D-spacings of 3.36 and
2.8, consistent with those of hydroxyapatite (3.440 and 2.814). The compos
ition of the mineral-like tissue had a Ca/P ratio of 1.60 for cementoblasto
ma cells and 1.97 for human cellular cementum. Na (5.29%) and Cl (1.47%) we
re present in the composition of cementoblastoma cells. Human cellular ceme
ntum additionally contained Mg (4.95%). Osteoblastic cells showed a Ca/P ra
tio of 1.6280. Na represented 4.52% and Cl 1.22% of its composition. Human
alveolar bone had a Ca/P ratio value of 2.01. Na (6.63%), Mg (2.10%), and C
l (0.84%) were also present. All samples examined represented biological-ty
pe hydroxyapatite. Based on the compositional and morphological features, t
hese findings indicate that cementoblastoma-derived cells express the human
cellular cementum phenotype.