Zheng Dong, Neoh Koon Gee, Kang En-Tang
Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 117576, Singapore.
Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 117576, Singapore.
J Colloid Interface Sci. 2017 Feb 1;487:1-11. doi: 10.1016/j.jcis.2016.10.014. Epub 2016 Oct 8.
Immobilization of alendronate on orthopedic implants offers the possibility of enhancing osteogenesis without potentially adverse effects associated with systemic administration of this drug. In this work, alendronate was immobilized on titanium (Ti) via either its phosphate (Method 1) or amino (Method 2) groups, and responses of osteoblasts and human mesenchymal stem cells (hMSCs) on these surfaces were investigated. These modified substrates have similar surface roughness and are negatively charged. With similar amounts of immobilized alendronate, these two types of modified substrates showed comparable osteogenic stimulating effects in enhancing osteoblasts' alkaline phosphatase (ALP) activity and calcium deposition for the first 10days. However, alendronate immobilized via its phosphate groups was less stable, and gradually leached into the medium. As a result, its stimulating effect on osteoblast differentiation diminished with time. On the other hand, alendronate immobilized via its amino group stimulated osteoblast differentiation over 21days, and with 1655ng/cm of immobilized alendronate on the Ti substrate, calcium deposition by osteoblasts and hMSCs increased by 30% and 69%, respectively, compared to pristine Ti after 21days. The expressions of runt-related transcription factor 2, osterix, osteopontin and osteocalcin in hMSCs cultured on this substrate were monitored. The up-regulation of these genes is postulated to play a role in the acceleration of osteogenic differentiation of hMSCs cultured on the alendronate-modified substrate over those on pristine Ti.
将阿仑膦酸盐固定在骨科植入物上为增强骨生成提供了可能性，且不存在与该药物全身给药相关的潜在不良反应。在本研究中，阿仑膦酸盐通过其磷酸基团（方法1）或氨基基团（方法2）固定在钛（Ti）上，并研究了成骨细胞和人间充质干细胞（hMSCs）在这些表面上的反应。这些改性底物具有相似的表面粗糙度且带负电荷。在固定的阿仑膦酸盐量相似的情况下，这两种类型的改性底物在增强成骨细胞碱性磷酸酶（ALP）活性和钙沉积方面，在前10天显示出相当的成骨刺激作用。然而，通过其磷酸基团固定的阿仑膦酸盐稳定性较差，会逐渐渗入培养基中。因此，其对成骨细胞分化的刺激作用随时间减弱。另一方面，通过其氨基基团固定的阿仑膦酸盐在21天内刺激成骨细胞分化，与原始钛相比，在钛底物上固定1655ng/cm的阿仑膦酸盐后，21天后成骨细胞和hMSCs的钙沉积分别增加了30%和69%。监测了在该底物上培养的hMSCs中与矮小相关转录因子2、osterix、骨桥蛋白和骨钙素的表达。推测这些基因的上调在加速阿仑膦酸盐改性底物上培养的hMSCs的成骨分化中发挥作用，相比于原始钛上培养的hMSCs。
