Repair of critical-size bone defects using bone marrow stromal cells: a histomorphometric study in rabbit calvaria. Part I: Use of fresh bone marrow or bone marrow mononuclear fraction

Abstract

ObjectivesThe aim of this study was to compare the bone healing observed after the use of (1) a scaffold enriched with fresh bone marrow, (2) a scaffold enriched with bone marrow mononuclear fraction, and (3) a scaffold alone.Material and methodsTwenty one rabbits were randomly divided into three groups of six animals and 1 group of 3 animals. Bilateral 12-mm diameter defects were created in the animals' parietal bones. in Control Group, the defects were filled with a xenograft alone (n=6); in Group 1, with a xenograft enriched with fresh bone marrow (n=6); in Group 2, with a xenograft enriched with bone marrow mononuclear fraction (n=6) and in Unfilled Group, nothing was grafted (n=3). in Groups 1, 2, and Control, one of the calvarial defects was randomly covered with a barrier membrane. the rabbits were sacrificed 8weeks after surgery, and their parietal bones were harvested and analyzed histomorphometrically.ResultsThe histomorphometric analysis showed no difference between Group 1 and the Control Group regarding non-vital mineralized tissue area, but Group 2 showed a statistically significant higher percentage than the Control Group (P<0.05) for both situations, with membrane (21.24 +/- 3.78% and 13.52 +/- 3.00%, respectively) and without membrane (20.91 +/- 2.01% and 13.08 +/- 1.72%, respectively). Group 2 showed the highest percentage of vital mineralized tissue area, followed by Group 1 and the Control Group (P<0.05) for both situations, with membrane (28.17 +/- 3.19%; 21.14 +/- 7.38% and 13.06 +/- 5.24%, respectively) and without membrane (21.13 +/- 0.55%; 12.45 +/- 6.34% and 6.56 +/- 1.20%, respectively). Group 2 showed the lowest percentage of non-mineralized tissue area, followed by Group 1 and Control Group (P<0.05) for both situations, with membrane (50.59 +/- 6.64%; 58.75 +/- 7.14% and 73.41 +/- 6.87%, respectively) and without membrane (57.97 +/- 1.91%; 71.74 +/- 6.63% and 80.37 +/- 2.67%, respectively). the sides in which the defects were covered with the barrier membrane showed better bone healing compared with the uncovered sides, in all groups (intragroup comparison, P<0.05). the Unfilled Group specimens showed no bone formation.ConclusionsBoth methods using bone marrow stromal cells contributed to enhancing bone healing, especially that using the bone marrow mononuclear fraction. the use of a barrier membrane seemed to have a synergistic effect.