Rivera-Delgado Edgardo, Ward Emily, von Recum Horst A
Department of Biomedical Engineering, Case Western Reserve University Cleveland, Ohio.
J Biomed Mater Res A. 2016 May;104(5):1135-42. doi: 10.1002/jbm.a.35643. Epub 2016 Feb 2.
Small molecule drug activators of gene expression have been used in applications ranging from gene therapy, to tissue engineering and regenerative medicine. One concern is that for sustained gene expression, a long-term, controlled delivery system is needed. Insoluble polymers containing a high proportion of cyclodextrin (CD) affinity groups have been shown to prolong drug delivery far beyond that capable of polymers relying on diffusion alone. In this study we evaluate the capacity of such polymers to deliver the transgene inducer doxycycline. Our results show that initial drug loading is proportional to affinity, with ∼8% loading in high-affinity γ-CD polymers; ∼7% loading in moderate-affinity β-CD polymers; and only ∼4.5% loading in the non-affinity control polymer made from linear dextran. When release aliquots from these polymers were incubated with cells genetically modified for inducible transgene expression we observed activation of transgene expression for up to three weeks from samples released by affinity-based polymers. We showed that drug stability is maintained over the course of the study using a bacterial zone of inhibition assay where again affinity-based polymers show sustained availability of drug, weeks longer than non-affinity controls. Lastly we provide theoretical calculations of strength of binding interactions between cyclodextrins and many additional transgene inducers demonstrating the broad utility of this delivery platform.
基因表达的小分子药物激活剂已应用于从基因治疗到组织工程和再生医学等多个领域。一个担忧是，为了实现持续的基因表达，需要一个长期的、可控的递送系统。已证明含有高比例环糊精（CD）亲和基团的不溶性聚合物能够将药物递送时间延长至远远超过仅依靠扩散的聚合物。在本研究中，我们评估了此类聚合物递送转基因诱导剂强力霉素的能力。我们的结果表明，初始药物负载量与亲和力成正比，高亲和力的γ-CD聚合物中的负载量约为8%；中等亲和力的β-CD聚合物中的负载量约为7%；而由线性葡聚糖制成的非亲和性对照聚合物中的负载量仅约为4.5%。当将这些聚合物释放的等分试样与经过基因改造以实现可诱导转基因表达的细胞一起孵育时，我们观察到基于亲和力的聚合物释放的样品在长达三周的时间内都能激活转基因表达。我们使用细菌抑制圈试验表明，在整个研究过程中药物稳定性得以维持，其中基于亲和力的聚合物同样显示出药物的持续可用性，比非亲和性对照长数周。最后，我们提供了环糊精与许多其他转基因诱导剂之间结合相互作用强度的理论计算，证明了该递送平台的广泛实用性。
