Duarte Ana Rita C, Mano João F, Reis Rui L
University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, Taipas, Guimarães, Portugal.
Acta Biomater. 2009 Jul;5(6):2054-62. doi: 10.1016/j.actbio.2009.01.047. Epub 2009 Feb 7.
The aim of this study was to evaluate the possibility of preparing dexamethasone-loaded starch-based porous matrices in a one-step process. Supercritical phase inversion technique was used to prepare composite scaffolds of dexamethasone and a polymeric blend of starch and poly(l-lactic acid) (SPLA) for tissue engineering purposes. Dexamethasone is used in osteogenic media to direct the differentiation of stem cells towards the osteogenic lineage. Samples with different drug concentrations (5-15 wt.% polymer) were prepared at 200bar and 55 degrees C. The presence of dexamethasone did not affect the porosity or interconnectivity of the polymeric matrices. Water uptake and degradation studies were also performed on SPLA scaffolds. We conclude that SPLA matrices prepared by supercritical phase inversion have a swelling degree of nearly 90% and the material presents a weight loss of approximately 25% after 21days in solution. Furthermore, in vitro drug release studies were carried out and the results show that a sustained release of dexamethasone was achieved over 21days. The fitting of the power law to the experimental data demonstrated that drug release is governed by an anomalous transport, i.e., both the drug diffusion and the swelling of the matrix influence the release of dexamethasone out of the scaffold. The kinetic constant was also determined. This study reports the feasibility of using supercritical fluid technology to process in one step a porous matrix loaded with a pharmaceutical agent for tissue engineering purposes.
本研究的目的是评估一步法制备载地塞米松淀粉基多孔基质的可能性。采用超临界相转化技术制备了地塞米松与淀粉和聚(L-乳酸)(SPLA)聚合物共混物的复合支架,用于组织工程。地塞米松用于成骨培养基中,引导干细胞向成骨谱系分化。在200巴和55摄氏度下制备了不同药物浓度(聚合物重量百分比为5-15%)的样品。地塞米松的存在不影响聚合物基质的孔隙率或连通性。还对SPLA支架进行了吸水性和降解研究。我们得出结论,通过超临界相转化制备的SPLA基质溶胀度接近90%,该材料在溶液中21天后重量损失约25%。此外,进行了体外药物释放研究,结果表明地塞米松在21天内实现了持续释放。将幂律拟合实验数据表明,药物释放受异常传输控制,即药物扩散和基质溶胀均影响地塞米松从支架中的释放。还测定了动力学常数。本研究报道了使用超临界流体技术一步法制备用于组织工程的载药多孔基质的可行性。