Pareta Rajesh A, Taylor Erik, Webster Thomas J
Division of Engineering and Department of Orthopedics, Brown University, Providence, RI 02912, USA.
Nanotechnology. 2008 Jul 2;19(26):265101. doi: 10.1088/0957-4484/19/26/265101. Epub 2008 May 19.
Bone diseases (including osteoporosis, osteoarthritis and bone cancer) are of great concern to the medical world. Drugs are available to treat such diseases, but often these drugs are not specifically targeted to the site of the disease and, thus, lack an immediate directed therapeutic effect. The optimal drug delivery system should enhance healthy bone growth with high specificity to the site of bone disease. It has been previously shown that magnetic nanoparticles can be directed in the presence of a magnetic field to any part of the body, allowing for site-specific drug delivery and possibly an immediate increase in bone density. The objective of the present study was to build off of this evidence and determine the density of osteoblasts (bone forming cells) in the presence of various uncoated and coated magnetic nanoparticles that could eventually be used in drug delivery applications. Results showed that some magnetic nanoparticles (specifically, γ-Fe(2)O(3)) significantly promoted osteoblast density (that is, cells per well) after 5 and 8 days of culture compared to controls (no particles). These magnetic nanoparticles were further coated with calcium phosphate (CaP; the main inorganic component of bone) to tailor them for treating various bone diseases. The coatings were conducted in the presence of either bovine serum albumin (BSA) or citric acid (CA) to reduce magnetic nanoparticle agglomeration, a common problem resulting from the use of nanoparticles which decreases their effectiveness. Results with these coatings showed that magnetic nanoparticles, specifically (γ-Fe(2)O(3)), coated in the presence of BSA significantly increased osteoblast density compared to controls after 1 day. In this manner, this study provided unexpected evidence that CaP-coated γ-Fe(2)O(3) magnetic nanoparticles increased osteoblast density (compared to no particles) and, thus, should be further studied to treat numerous bone diseases.
骨疾病（包括骨质疏松症、骨关节炎和骨癌）备受医学界关注。有药物可用于治疗此类疾病，但这些药物往往并非特异性地作用于疾病部位，因此缺乏直接的靶向治疗效果。理想的药物递送系统应能高度特异性地作用于骨疾病部位，促进健康骨骼生长。此前已有研究表明，磁性纳米颗粒在磁场作用下可被引导至身体的任何部位，实现药物的靶向递送，并可能使骨密度立即增加。本研究的目的是基于这一证据，确定各种未涂层和涂层磁性纳米颗粒存在时成骨细胞（骨形成细胞）的密度，这些纳米颗粒最终可用于药物递送应用。结果显示，与对照组（无颗粒）相比，某些磁性纳米颗粒（特别是γ-Fe(2)O(3)）在培养5天和8天后显著提高了成骨细胞密度（即每孔细胞数）。这些磁性纳米颗粒进一步用磷酸钙（CaP；骨的主要无机成分）进行涂层，以使其适合治疗各种骨疾病。涂层过程中加入牛血清白蛋白（BSA）或柠檬酸（CA）以减少磁性纳米颗粒的团聚，这是使用纳米颗粒时常见的问题，会降低其有效性。这些涂层的结果表明，与对照组相比，在BSA存在下涂层的磁性纳米颗粒（特别是γ-Fe(2)O(3)）在1天后显著增加了成骨细胞密度。通过这种方式，本研究提供了意外的证据，即CaP涂层的γ-Fe(2)O(3)磁性纳米颗粒增加了成骨细胞密度（与无颗粒相比），因此应进一步研究其用于治疗多种骨疾病的可能性。
