On the other hand, cytochemical staining resulted in positive selleck kinase inhibitor staining for alkaline phosphatase in the cytoplasm of differentiated HPB-AML-I cells (Figure 4L). Moreover, the differentiated HPB-AML-I cells also secreted calcium, which constitutes the extracellular matrix of the bone, as shown by von Kossa staining (Figure 4M and 4N). These two findings suggested the acquisition of osteogenic characteristics by HPB-AML-I

cells following the induction of osteogenesis. Inhibition of CD3+ T-cell proliferation in the presence of HPB-AML-I cells CD3+ T-cells obtained from peripheral blood were cultured with or without HPB-AML-I cells. The XTT absorbance levels at 450 nm, which show the viability of CD3+ T-cells, decreased selleck in a dose-dependent manner similar to those of UCBTERT-21 (Figure 5). These findings suggested that HPB-AML-I

cells dose-dependently suppress the antigen-driven proliferation of CD3+ T-cells, which is also characteristic of MSCs. Figure 5 Inhibition of CD3 + T-cell proliferation in the presence of HPB-AML-I cells. Mixed lymphocyte culture was performed in the presence or absence of HPB-AML-I cells (white columns). For control, similar experiments were performed with UCBTERT-21 cells (black columns). Results are presented as the XTT absorbance levels at 450 nm, which were normalized to those of the baseline experiments (cell culture in the absence of HPB-AML-I or UCBTERT-21 cells). Means and standard deviations of four independent experiments are shown. *, P < 0.05; **, P < 0.01 compared to the baseline results Discussion Even though HPB-AML-I was established from the PBMCs of an AML-M1 case [12], this cell line presents distinctive morphological features from AML. In terms of cell-surface second antigen expression, multilineage differentiation, and CD3+ T-cell suppression, the characteristics of HPB-AML-I were found to be similar to those of MSCs. Our findings presented here suggest that HPB-AML-I may be a neoplastic

cell line with MSC properties. Few reports have dealt with the establishment of human neoplastic MSC lines. A previous study established F6, a human neoplastic MSC line, from embryonic bone marrow MSCs. Transplantation of F6 cells into the SCID-nude mice resulted in fibrosarcoma formation and tissue metastasis [21, 24]. To the best of our knowledge, however, HPB-AML-I is the first neoplastic MSC line derived from a leukemic case. The appearance of HPB-AML-I cells in suspension phase with their round-polygonal morphology intrigued us. We observed that an increase in the population of HPB-AML-I cells with such morphological patterns occurs in conjunction with the increased confluence of cultured cells. Morphological changes during culturing have previously been described in the case of bone marrow MSCs. Choi et al.