Ectopic osteomyelogenous response to demineralized bone matrix implant in busulphan treated mice

Abstract

Swiss female mice (25-30 g; n = 100) were four times treated i.p. with busulphan (20 mg/kg), with 15 day interval between doses. Blood was collected by retroorbital puncture from treated and non treated control animals (n = 15) for white blood cell count, hematocrit and hemoglobin evaluation, before treatment and on 30th, 60th, 90th days following
the first dose of the drug. On day 60 both treated (60 survived animals) and non treated (n = 15) animals received intermuscular implant of demineralized bone matrix (DBM-10 mg). All of them were killed 30 days after implant (90th day post busulphan initial dose) for histological analysis of esternal bone marrow (EBM) and ectopic osteomyelogenous
response to the DBM implant. Thirty days after the first dose of busulphan, leukopenia and drop in the granulocyte, lymphocyte and monocyte numbers were observed. The hematocrit and hemoglobin rate decreased on 60th day. Histologycal analysis of the EBM of the test group showed hypocellularity, sinusoid capilar distention and reduction in
megakaryocyte numbers. Control animals showed 100% positive response to DBM implant with the formation of metaplastic plaques made of bone trabeculae forming cavities filled with haematopoietic cells. 46.7% of the test animals had positive osteomyelogenous response, similar to that of the control groups, except for hypocellularity and more adipocytes; 25% displayed late and incomplete response with predominance of cartilaginous component, less neoformed bone tissue and absence of haematopoietic cells; the remaining 28.3% did not respond at all.