Effect of the alternative magnetic stimulation on peripheral circulation for regenerative medicine

Intrinsically superparamagnetic Fe-hydroxyapatite nanoparticles positively influence osteoblast-like cell behaviour

BACKGROUND

Superparamagnetic nanoparticles (MNPs) have been progressively explored for their potential in biomedical applications and in particular as a contrast agent for diagnostic imaging, for magnetic drug delivery and more recently for tissue engineering applications. Considering the importance of having safe MNPs for such applications, and the essential role of iron in bone remodelling, this study developed and analysed novel biocompatible and bioreabsorbable superparamagnetic nanoparticles, that avoid the use of poorly tolerated magnetite based nanoparticles, for bone tissue engineering applications.

RESULTS

MNPs were obtained by doping hydroxyapatite (HA) with Fe ions, by directly substituting Fe2+ and Fe3+ into the HA structure yielding superparamagnetic bioactive phase. In the current study, we have investigated the effects of increasing concentrations (2000 μg/ml; 1000 μg/ml; 500 μg/ml; 200 μg/ml) of FeHA MNPs in vitro using Saos-2 human osteoblast-like cells cultured for 1, 3 and 7 days with and without the exposure to a static magnetic field of 320 mT. Results demonstrated not only a comparable osteoblast viability and morphology, but increased in cell proliferation, when compared to a commercially available Ha nanoparticles, even with the highest dose used. Furthermore, FeHA MNPs exposure to the static magnetic field resulted in a significant increase in cell proliferation throughout the experimental period, and higher osteoblast activity.In vivo preliminary results demonstrated good biocompatibility of FeHA superparamagnetic material four weeks after implantation into a critical size lesion of the rabbit condyle.

CONCLUSIONS

The results of the current study suggest that these novel FeHA MNPs may be particularly relevant for strategies of bone tissue regeneration and open new perspectives for the application of a static magnetic field in a clinical setting of bone replacement, either for diagnostic imaging or magnetic drug delivery.

Effect of magnetic stimulation in spinal cord on limb angiogenesis and implication: a pilot study

OBJECTIVE

To investigate the effect of repetitive magnetic stimulation (rMS) of the spinal cord on limb angiogenesis in healthy rats and explore its implication for the treatment of lymphedema.

METHOD

Twelve adult male Sprague-Dawley rats were divided into four groups as follows: sham rMS followed by tissue harvest 5 minutes later (group 1, n=2), 1 Hz rMS and tissue harvest 5 minutes later (group 2, n=3), 20 Hz rMS and tissue harvest 5 minutes later (group 3, n=3), 20 Hz rMS and tissue harvest 30 minutes later (group 4, n=4). Animals were treated with 20-minute rMS with 120% of the motor threshold on their left side of upper lumbar spinal cord. Expression of angiogenic factors, that is, Akt, phospho-Akt (pAkt), endothelial nitric oxide synthase (eNOS), phospho-eNOS (p-eNOS) were measured by western blot. Bilateral hindlimb muscles (quadriceps and gastrocnemius) were harvested.

RESULTS

Expression of Akt in left quadriceps increased in group 4 compared with group 2 and 3 (3.4 and 5.3-fold each, p=0.026). Expression of eNOS in left plus right quadriceps markedly increased in group 3 and 4 compared with group 1 and 2 (p=0.007). Expressions of eNOS, Akt and p-eNOS, pAkt in gastrocnemius were not comparable between four groups (p>0.05).

CONCLUSION

Repetitive magnetic stimulation of the spinal cord may exert an angiogenic effect closely linked to lymphangiogenesis. It has clinical implication for the possible therapy of lymphedema caused by breast, cervical or endometrial cancer operation. Future studies with the specific lymphatic endothelial cell markers are required to confirm the effect of rMS on lymphangiogenesis.