Introduction: In this work a bioactive glass-ceramic (GC) in the system SiO2-CaO-P2O5 was evaluated as bone substitute biomaterial. In this sense, the capacity of mesenchymal stem cells (MSCs) to adhere, proliferate and differentiate into osteoblast (OBs) with or without GC was investigated. Two types of culture medium, i.e. growth medium (GM) and osteogenic medium (OM), were evaluated.

Materials and Methods: The GC was obtained by heat treatment of a bioactive glass obtained by the sol-gel method. Isolation and culture of MSCs: The adult MSCs were isolated from bone marrow of adult rabbits obtained by direct aspirations of ileac crest. Isolation and culture of OBs: The OBs used as control were obtained by enzymatic digestion. Behavior of MSCs on GC: For the study of the behavior of isolated MSCs on the GC, two series of 96-well plates were seeded, one plate with GM and the other one with OM. The number of cells was evaluated through the XTT assay. OC production and CD90 expression of cells cultured in both media were measured to evaluate the differentiation of MSCs into OBs. Statistical analysis: A variance analysis (ANOVA) was carried out.

Results: The number of cells growing in OM and GM, there were no significant differences between them. The MSCs under the conditions of this study expressed an osteoblastic phenotype (OC production, decrease CD90 expression, mineralized extracell matrix). These two effects took place by either the action of exposing the MSCs to a MO and by the effect of the GC.

The clinical, radiographic and pathological features of eighty-eight cases of histologically verified intra-osseous ganglia in eighty-three patients are described. All were located in the subchondral bone adjacent to a joint and most frequently involved the hip, the ankle (medial malleolus), the knee and the carpal bones. Forty-seven of the eighty-three patients were male and all the patients were between fourteen and seventy-three years of age, with an average age of forty-one years. There are two fundamental types of intra-osseous ganglia, one apparently arising by penetration of juxta-osseous ganglion into the underlying bone, a mechanism proved in fourteen of our eighty-eight cases (16 per cent); in the remaining seventy-four cases, the ganglion cyst was primarily intra-osseous ("idiopathic"). The initial cause of the intramedullary mucoid degeneration is discussed. We believe that mechanical stress and repeated minor trauma near the surface of the bone may lead to intramedullary vascular disturbance with consequent foci of aseptic bone necrosis. The revitalisation of these areas causes fibroblastic proliferation, followed by mucoid degeneration of the connective tissue, possibly due to some unknown local factor. Curettage or excision is usually effective, and recurrence (only four cases) is exceptional.