Centre for Human Development, Stem Cells and Regeneration, Bioengineering Sciences, University of Southampton Faculty of Medicine, Tremona Road, Southampton SO16 6YD, United Kingdom.
School of Biological Sciences, University of Southampton, B85, University Road, SO17 1BJ, United Kingdom.
Acta Biomater. 2019 Dec;100:378-387. doi: 10.1016/j.actbio.2019.09.023. Epub 2019 Sep 19.
The retention and sustained activity of therapeutic proteins at delivery sites are goals of regenerative medicine. Vascular endothelial growth factor (VEGF) has significant potential in promoting the growth and regeneration of blood vessels but is intrinsically labile. This is exacerbated by the inflammatory microenvironments at sites requiring regeneration. For VEGF to be efficacious, it may require a carrier that stabilises it, protects it from degradation and retains it at the site of interest. In this study, we tested the hypothesis that injectable nanoclay gels comprising Laponite™ XLG (a synthetic hectorite clay) can stabilise VEGF and retain it in the active form for therapeutic delivery. To achieve this, VEGF was incorporated in Laponite gels and its activity tested at a range of concentrations using in vitro cell culture tubulogenesis assays and in vivo angiogenesis assays. We found that VEGF-Laponite gels enhanced tubulogenesis in a dose-dependent manner in vitro. When administered subcutaneously in vivo, Laponite was retained at the injection site for up to a period of three weeks and promoted a 4-fold increase in blood vessel formation compared with that of alginate or vehicle controls as confirmed by CD31 staining. Notably, as compared to alginate, Laponite gels did not release VEGF, indicating a strong interaction between the growth factor and the nanoclay and suggesting that Laponite enhancement of VEGF efficacy is due to its retention at the implantation site for a prolonged period. Our approach provides a robust method for the delivery of bioactive recombinant VEGF without the necessity for complex hydrogel or protein engineering. STATEMENT OF SIGNIFICANCE: In medicine, it is important to deliver drugs to a particular location in the body. Often, however, the drugs are quickly broken down and carried away in the blood before they can exert their effect. In this study, we used a type of synthetic clay, called Laponite™, to preserve a molecule, named VEGF, that stimulates the growth of blood vessels. Previously, we have been able to bind VEGF to the surface of clays, but the clay is not effective when injected or applied as a gel. Herein, we show that we can mix VEGF with the clay and that it strongly stimulates blood vessel growth. We speculate that this would be a useful material for skin wound healing.
治疗性蛋白质在递药部位的保留和持续活性是再生医学的目标。血管内皮生长因子 (VEGF) 在促进血管生长和再生方面具有显著的潜力，但本身不稳定。在需要再生的部位，炎症微环境使情况更加恶化。为了使 VEGF 有效，它可能需要一种载体来稳定它，保护它免受降解，并将其保留在感兴趣的部位。在这项研究中，我们测试了这样一个假设，即包含 Laponite™ XLG（一种合成锂皂石粘土）的可注射纳米粘土凝胶可以稳定 VEGF 并保持其在治疗递送上的活性形式。为了实现这一目标，将 VEGF 掺入 Laponite 凝胶中，并在一系列浓度下使用体外细胞培养管形成测定法和体内血管生成测定法测试其活性。我们发现，VEGF-Laponite 凝胶在体外以剂量依赖性方式增强管形成。当皮下给予体内时，Laponite 在注射部位保留长达三周的时间，并与藻酸盐或载体对照相比促进血管形成增加了 4 倍，如 CD31 染色所证实。值得注意的是，与藻酸盐相比，Laponite 凝胶没有释放 VEGF，表明生长因子与纳米粘土之间存在强烈相互作用，并表明 Laponite 增强 VEGF 疗效是由于其在植入部位的长时间保留。我们的方法为递送生物活性重组 VEGF 提供了一种稳健的方法，而无需复杂的水凝胶或蛋白质工程。 意义声明：在医学中，将药物递送到体内的特定位置非常重要。然而，通常情况下，药物在血液中被迅速分解并带走，在发挥作用之前。在这项研究中，我们使用了一种称为 Laponite™ 的合成粘土来保存一种名为 VEGF 的分子，该分子刺激血管生长。以前，我们已经能够将 VEGF 结合到粘土的表面上，但是当注射或作为凝胶应用时，粘土并不有效。在此，我们表明我们可以将 VEGF 与粘土混合，并且它强烈地刺激血管生长。我们推测这将是一种用于皮肤伤口愈合的有用材料。
