DOS 2016

· DOS Abstracts

Investigating time point for stimulation of vascular

endothelial growth factor and mesenchymal stem cell

on bone formation in severe immunodeficiency mice

Chris Dreyer, Kristian Kjærgaard, Nicholas Ditzel, Jørgensen Niklas , Søren

Overgaard, Ming Ding

Department of Orthopaedic Surgery and Traumatology, Odense University Hospital

Institute of Clinical Research, University of Southern Denmark; Department of

Endocrinology, Odense Unversity Hospital; Center for Ageing and Osteoporosis,

Glostrup, Rigshospitalet.

Background:

To get sufficient bone formation, optimal conditions are needed, and in-

sufficient blood supply may be a limitation. VEGF promotes angiogenesis by increasing

endothelial proliferation and migration, vessel permeability, tube formation and survival.

Purpose / Aim of Study:

To evaluate time points for stimulation with VEGF of mes-

enchymal stem cell derived bone formation in severe immunodeficiency (SCID) mice.

Materials and Methods:

Twenty-eight SCID mice were divided into 7 groups. All

groups received hydroxyapatite (HA) granules coated with 5x10^5 MSCs. One group

without VEGF served as the control without. 6 groups had different VEGF stimulation

time points through degradable pellets: Day 1-7 post-operatively; day 1- 14; day 1-

21; day 1-42; day 7-14 and day 21-42. Granules+MSCs+VEGF were placed subcu-

taneously dorsally in 3 pockets of the mice. Each group contained 4 randomly allocated

mice. At sacrifice, the implant samples were stained with haematoxylin eosin (HE) for

histomorphometric analysis. Human vimentin staining (HVIM) was performed to confirm

the origin of sheep stem cell. Serum blood samples were collected for determination

of bone-related markers: Osteoprotegerin (OPG), Receptor activator of nuclear factor

kappa-B ligand (RANKL), osteocalcin, type 1 procollagen (P1NP), sclerostin and C- ter-

minal telopeptide (CTX).

Findings / Results:

The histomorphometric analysis revealed the VEGF stimulation in

the day 1-14, and day 1-21 groups showed more bone formation relative to the control

group and the day 21-42 group (p<.01). Serum biomarkers of the 6 groups with VEGF

stimulation were not significantly different compared to control group. HVIM staining

confirmed bone regenerative effect was caused by MSCs from sheep.

Conclusions:

The most bone formation was shown when stimulating with VEGF in

1-14 or 1-21 days after surgery.

No conflicts of interest reported