Recovery of small-sized blood vessels in ischemic bone under static magnetic field

Abstract

Effects of static magnetic field (SMF) on the vascularization in bone were evaluated using an ischemic bone model, where rat femoral artery was ligated. Magnetized and unmagnetized samarium-cobalt rods were implanted transcortically into the middle diaphysis of the ischemic femurs. Collateral circulation was evaluated by injection of microspheres into the abdominal aorta at the third week after ligation. It was found that the bone implanted with a magnetized rod showed a larger amount of trapped microspheres than that with an unmagnetized rod at the proximal and the distal region (P < 0.05 proximal region). There were no significant differences at the middle and the distal region. This tendency was similar to that of the bone mineral density in the SMF-exposed ischemic bone.

Figure 1.

The magnetic flux density as a function of the distance from the face of the magnetized rod. S, side face of the south pole; S′, lateral side face of the south pole; N, side face of the north pole; N′, lateral side face of the north pole.

Figure 2.

Ischemic bone model indicating ligated and amputated points.

Figure 3.

Schematic representation of implantation and regions of bone for measurement. The rod was implanted at the middle portion of the femurs.

Figure 4.

Slice preparation in the sagittal direction at 0.1 mm interval. The rod was implanted at the middle portion of the femurs.

Figure 5.

Number of microspheres (Ø = 10.0 μ) (A) and the BMD (B) (13) of the rat femur at 3 weeks after operation. L, femoral artery was ligated. CON, no operation (n = 24 for each group). *P < 0.05. **P < 0.01.

Figure 6.

The number of microspheres (A) (n = 24 for each group) and the BMD (B) (L + M: n = 26; L + S: n = 22; L: n = 24) (13) of the rat femur exposed to SMF for 3 weeks. L, femoral artery was ligated. M, a magnetized rod (180 mT) was implanted. S, an unmagnetized rod was implanted. *P < 0.05. **P < 0.01.