Fig. 1

Histopathological analysis of the influence of MSC in a glucocorticoid-associated rabbit osteonecrosis model (hematoxylin-eosin staining). MSC(−)/MP(−)/14d (a). MSC(−)/MP(+)/14d (b, c). MSC(+)/MP(+)/14d (d). Osteonecrosis was considered to be present when necrosis of medullary haematopoietic cells and fat cells (black arrow), and/or osteocyte empty lacunae and condensed nuclei (white arrow) were evident. As a control, MSC(−)/MP(−)/14d was showed (a). In MSC(−)/MP(+)/14d, in 6 of 10 rabbits achromatic nuclei and/or empty lacunae characteristic of osteonecrosis were found in osteocytes and bone marrow cells (b). Also, in 1 of 10 rabbits bone marrow necrosis was found (c). Osteonecrosis was found in a total of 7 of 10 rabbits (70%). In MSC(+)/MP(+)/14d, in 7 of 8 rabbits no bone marrow necrosis or osteonecrosis was evident (d), while in only a single specimen (12.5%) were necrotic or degenerated cells found in a part of the bone marrow. In MSC(+)/MP(+)/14d as compared to MSC(−)/MP(+)/14d osteonecrosis was significantly decreased. Magnification: ×100, ×200 (enlarged view)