This paper demonstrates the stability of HoAcAcMS, both in vitro and in vivo. The in
vitro release was approximately 0.5% after six months of incubation in buffer. The
microspheres remained spherical, and a holmium phosphate complex was formed while the surface morphology was retained. No release of holmium was observed after the intratumoral injection of HoAcAcMS in VX2 tumor-bearing rabbits, and the microspheres remained intact in tumor tissue for one month. The results confirm the potential of these microspheres as a novel intratumoral radioablation device.
Acknowledgements
Financial support by the Dutch Technology Foundation STW, under grant 06069 is gratefully acknowledged. Dr. G.C. Krijger and ms. M.J.J. Koster-Ammerlaan are acknowledged for performing the neutron irradiations. Ms. H.M. de Bruin, Mr. N.J.M. Attevelt and Mr. H.W.G. Vosmeer are gratefully acknowledged for biotechnical assistance. The authors would like to thank prof. dr. K.P. de Jong for valuable discussions. Dr. W.H. Müller and Mr. C.T.W.M. Schneijdenberg are acknowledged for their assistance with the SEM measurements.
Figure 6. Light micrograph at 400x magnification of a H&E stained section of liver tissue. The microspheres in
red are clustered amidst necrotic tissue. The bar represents 20 µm.
Holmium acetylacetonate microspheres: an in vitro and in vivo stability study
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