[Value of in vitro study of osteoclast precursors in the case of severe infantile osteopetrosis treated by bone marrow graft].

BACKGROUND

Pathogenesis of osteopetrosis is still debated. Testing the ability of osteoclastic progenitors to support the proliferation of functional cells may be useful in understanding pathogenesis.

CASE REPORT AND

METHODS

A diagnosis of osteopetrosis was made in a girl 1 month-old, born to consanguuineous parents. Bone marrow transplantation was uneffective at the age of 3 months but a second engraftment was successful at 5 months. Unfortunately, the patient died from severe thrombocytopenia at the age of 8 months. Long-term cultures of mononucleated cells from the patient's blood were performed before and after the bone marrow transplantation, with or without growth factors such as vitamin D3, IL-6 and IL-1. Similar studies were made from the patient's marrow obtained after transplantation; all results were compared with those obtained after culturing control cells from cord blood umbilical.

RESULTS

Production of osteoclastic cells was mild in peripheral blood cultures; it was important in bone marrow cultures in presence of growth factors.

CONCLUSION

These results suggest that osteopetrosis in our patient resulted from an intrinsic defect in progenitors of osteoclasts.