ANGIOGENESIS AND OSTEOGENESIS IN AN ORTHOPEDICALLY EXPANDED SUTURE

The purpose of this study was to examine the angiogenic and the subseq uent osteogenic responses during a 96-hour time-course after sutural e xpansion. Fifty rats were divided into: (1) a control group that recei ved only angiogenic induction through injection of 5 ng/gm recombinant human endothelial cell growth factor (rhECGF); (2) an experimental gr oup that received orthopedic expansion and rhECGF; (3) a sham group th at received expansion and sodium chloride (NaCl) injection; and (4) a baseline group that received no expansion or injection. All rats were injected with H-3-thymidine (1.0 mu Ci/gm) 1 hour before death to labe l the DNA of S-phase cells. Demineralized sections (4 mu m thick) were stained with hematoxylin and eosin. Angiogenesis and cell migration w ere analyzed with a previously established cell kinetics model. Analys is of variance was used to test the hypothesis that enhancement of ang iogenesis stimulates reestablishment of osteogenic capability. Blood v essel number, area, and endothelial cell-labeled index significantly i ncreased in experimental groups, but no difference was found between c ontrol and baseline groups. Labeled-pericyte index and activated peric yte numbers in the experimental group were also higher than in the sha m groups. These results show that supplemental rhECGF enhances angioge nesis in expanded sutures but not in nonexpanded sutures. Data also su ggest that pericytes are the source of osteoblasts in an orthopedicall y expanded suture.