Search tips
Search criteria

Results 1-4 (4)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
Document Types
1.  Cell lineage in vascularized bone transplantation 
Microsurgery  2013;34(1):37-43.
The biology behind vascularized bone allotransplantation remains largely unknown. We aim to study cell traffic between donor and recipient following bone auto,-and allografting.
Vascularized bone allografts and isografts were analyzed in a rat model at 4 and 18 weeks. Bone remodeling areas were laser capture microdissected. Analysis by RT-PCR measured the relative Expression Ratio (rER) of donor to recipient cells.
The rER was 0.456 (+/−0.266) at 4 weeks in allotransplants and 0.749 (+/−0.387) at 18 weeks, implying donor bone was gradually repopulated with recipient bone forming cells. In isotransplants, rER was 0.412 (+/−0.239) at 4 and 0.467 (+/−0.252) at 18 weeks. Cells in the inner and outer cortical bone remodeling areas were mainly donor derived (rER<0.5) at 18 weeks in isotransplants and mainly recipient derived in allotransplants (rER>0.5).
Applying novel methodology we describe detailed cell traffic in vascularized bone transplants, elaborating our comprehension on bone transplantation.
PMCID: PMC3972888  PMID: 24038399
2.  Surgical Revascularization Induces Angiogenesis in Orthotopic Bone Allograft 
Remodeling of structural bone allografts relies on adequate revascularization, which can theoretically be induced by surgical revascularization. We developed a new orthotopic animal model to determine the technical feasibility of axial arteriovenous bundle implantation and resultant angiogenesis.
We asked whether arteriovenous bundles implanted in segmental allografts would increase cortical blood flow and angiogenesis compared to nonrevascularized frozen bone allografts and contralateral femoral controls.
We performed segmental femoral allotransplantation orthotopically from 10 Brown Norway rats to 20 Lewis rats. Ten rats each received either bone allograft reconstruction alone (Group I) or allograft combined with an intramedullary saphenous arteriovenous flap (Group II). At 16 weeks, we measured cortical blood flow with the hydrogen washout method. We then quantified angiogenesis using capillary density and micro-CT vessel volume measurements.
All arteriovenous bundles were patent. Group II had higher mean blood flow (0.12 mL/minute/100 g versus 0.05 mL/minute/100 g), mean capillary density (23.6% versus 2.8%), and micro-CT vessel volume (0.37 mm3 versus 0.07 mm3) than Group I. Revascularized allografts had higher capillary density than untreated contralateral femora, while vessel volume did not differ and blood flow was lower.
Axial surgical revascularization in orthotopic allotransplants can achieve strong angiogenesis and increases cortical bone blood flow.
Clinical Relevance
Poor allograft revascularization results in frequent complications of nonunion, infection, and late stress fracture. The presented technique of surgical revascularization could therefore offer a beneficial adjunct to clinical segmental bone allografting.
PMCID: PMC3830091  PMID: 22723247
3.  Vascularized Bone Grafting in a Canine Carpal Avascular Necrosis Model 
Limited experimental research has been performed on the treatment of avascular necrosis (AVN) by vascularized bone grafting.
A new model simulating carpal AVN was created to investigate surgical revascularization of necrotic bone.
In seven mongrel dogs, AVN was induced by removal of the radial carpal bones bilaterally, deep-freezing, coating in cyanoacrylate, and reimplantation. A reverse-flow vascularized bone graft from the distal radius was implanted in the avascular radial carpal bone. The contralateral side served as an untreated ischemic control. Bone blood flow, bone volume, radiography, histomorphometry, histology, and MRI were analyzed at 4 weeks.
Blood flow was substantially higher in grafted bones when compared with controls (14.68 ± 15.43 versus 0.27 ± 0.28 mL/minute/100 g). Blood flow correlated with increased osteoid formation and higher levels of bone turnover. T1 and T2 signals on MRI did not correlate with quantitative bone blood flow measurements. Necrotic bones with no blood flow had normal T1 and T2 signals, whereas revascularized bones had signal changes when compared with adjacent carpal bones. No major collapse occurred in any radiocarpal bone.
In a canine experimental model, investigation of carpal AVN shows the ability of vascularized bone grafting to revascularize and remodel avascular bone.
Clinical Relevance
Surgical revascularization of necrotic bone induced by vascularized bone grafting results in increased bone perfusion and bone remodeling as compared with untreated necrotic bone. MRI T1 and T2 signals can be normal in necrotic avascular bone.
PMCID: PMC3171535  PMID: 21533527
4.  Augmentation of Surgical Angiogenesis in Vascularized Bone Allotransplants with Host-Derived AV Bundle Implantation, Fibroblast Growth Factor-2 and Vascular Endothelial Growth Factor Administration 
We have previously shown experimental transplantation of living allogeneic bone to be feasible without long-term immunosuppression by development of a recipient-derived neoangiogenic circulation within bone. In this study we study the role of angiogenic cytokine delivery with biodegradable microspheres to enhance this process. Microsurgical femoral allotransplantation was performed from DA to PVG rats. Poly(D,L-lactide-co-glycolide) microspheres loaded with buffer, basic fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), or both were inserted intramedullarly along with a recipient-derived a/v bundle. FK-506 was administered daily for 14 days, then discontinued. At 28 days, bone blood flow was measured using hydrogen washout. Microangiography, histologic and histomorphometric analysis were performed. Capillary density was greater in the FGF+VEGF group (35.1%) than control (13.9%) (p<0.05), and a linear trend was found from control, FGF, VEGF, to FGF+VEGF (p<0.005). Bone formation rates were greater with VEGF (p<0.01) and FGF+VEGF (p<0.05). VEGF or FGF alone increased blood flow more than when combined. Histology rejection grading was low in all grafts. Local administration of vascular and fibroblast growth factors augments angiogenesis, bone formation and bone blood flow from implanted blood vessels of donor origin in vascularized bone allografts after removal of immunosuppression.
PMCID: PMC2892011  PMID: 20162714
bone; allotransplantation; microspheres; FGF; VEGF

Results 1-4 (4)