Untitled

Abstract

The aim of our study was to assess the ability of calcium phosphate powders to serve as growth factor carriers. Vascular endothelial growth factor (VEGF), in particular, is locally involved in the bone formation process throughout osteoblast differentiation. Two different apatitic substrates were tested: hydroxyapatite (HA), widely used as biomaterial, and nanocrystalline carbonated apatite (CA), which has a composition similar to bone mineral crystals. These materials have been compared for their VEGF adsorption and release properties. The adsorption of the growth factor was higher on CA than on HA probably due to differences of both the proteins and the powders involved. The specific activity of the VEGF released was also tested to determine the available activity for cells in contact with these materials. Interestingly, the bioactivity of the VEGF released from CA quantified on fetal bovine aortic endothelial cells (FBAE) by evaluating the proliferation activity, exhibited no marked difference compared to native VEGF. Qualitatively, VEGF adsorbed on CA material induced well-defined collagen type I immunostaining on osteoblast cells compared to the staining obtained after VEGF adsorption on HA.

Biomimetic Nanostructured Apatitic Matrices for Drug Delivery

“…They can only be displaced by mineral ions and/or soluble proteins with a stronger affinity for apatite surfaces but in a predicable manner, or by cell activity. This characteristic has been observed for various growth factors such as BMP-2 or VEGF [122,134], antiosteoporisis agents [135,136], and anticancer drugs such as MTX and cisplatin [124,137]. It has been reported that slow release of MTX from calcium phosphate is due to the porosity like in most of the cases but mainly due to the adsorption of MTX [137].…”

“…Zoledronate grafted to HA coating on titanium implants shows a dose-dependent effect on the inhibition of resorption activity according to the amount of zoledronate loaded [133]. Local and slow administration of antineoplasic drugs such as methotrexate (MTX) is also useful to avoid systemic side effects and because its time effect (the sensitivity of cells to this drug increases with time) is greater than the dose effect [134].…”

Silica xerogels and hydroxyapatite nanocrystals for the local delivery of platinum–bisphosphonate complexes in the treatment of bone tumors: A mini-review

“…Zoledronate grafted to apatite coating on titanium implants shows a dose-dependent effect on the inhibition of resorption activity according to the amount of zoledronate loaded [84]. Local and slow administration of the antineoplastic drug methotrexate (MTX) is also useful to avoid systemic side effects, and because its time effect (the sensitivity of cells to this drug increases with time) is greater than dose effect [85]. Adsorption, by contrast, leads to stable association and control of the amount of bioactive molecules contained in the solid implant, and thus of the dose released.…”

“…They can only be displaced by mineral ions and/or soluble proteins with a stronger affinity for apatite surfaces but in a predictable manner, or by cell activity [86]. This characteristic has been observed for various growth factors like bone morphogenetic protein (BMP-2) or vascular endothelial growth factor (VEGF) [79,85], antiosteoporosis agents [87,88] and anticancer drugs as methotrexate and cisplatin [81,89]. It has been reported that slow release of MTX from calcium phosphate is not only due to the porosity of the inorganic matrix but mainly to the adsorption of MTX [81].…”

Modification of Apatite Materials for Bone Tissue Engineering and Drug Delivery Carriers

“…Carriers fabricated from apatite materials that enable the controlled release of functional molecules are currently under investigation. Molecular release from apatite materials, initially incorporating the functional molecule, is achieved in vivo by desorption, depending on the local environment [87][88][89][90]. Therefore, an understanding of the adsorption and desorption kinetics of the functional molecules of HAp is crucial for achieving optimal drug release.…”