Moores UCSD Cancer Center, University of California San Diego, CA, USA.
J Transl Med. 2011 Mar 31;9:34. doi: 10.1186/1479-5876-9-34.
Many peptide-based cancer vaccines have been tested in clinical trials with a limited success, mostly due to difficulties associated with peptide stability and delivery, resulting in inefficient antigen presentation. Therefore, the development of suitable and efficient vaccine carrier systems remains a major challenge.
To address this issue, we have engineered polylactic-co-glycolic acid (PLGA) nanoparticles incorporating: (i) two MHC class I-restricted clinically-relevant peptides, (ii) a MHC class II-binding peptide, and (iii) a non-classical MHC class I-binding peptide. We formulated the nanoparticles utilizing a double emulsion-solvent evaporation technique and characterized their surface morphology, size, zeta potential and peptide content. We also loaded human and murine dendritic cells (DC) with the peptide-containing nanoparticles and determined their ability to present the encapsulated peptide antigens and to induce tumor-specific cytotoxic T lymphocytes (CTL) in vitro.
We confirmed that the nanoparticles are not toxic to either mouse or human dendritic cells, and do not have any effect on the DC maturation. We also demonstrated a significantly enhanced presentation of the encapsulated peptides upon internalization of the nanoparticles by DC, and confirmed that the improved peptide presentation is actually associated with more efficient generation of peptide-specific CTL and T helper cell responses.
Encapsulating antigens in PLGA nanoparticles offers unique advantages such as higher efficiency of antigen loading, prolonged presentation of the antigens, prevention of peptide degradation, specific targeting of antigens to antigen presenting cells, improved shelf life of the antigens, and easy scale up for pharmaceutical production. Therefore, these findings are highly significant to the development of synthetic vaccines, and the induction of CTL for adoptive immunotherapy.
许多基于肽的癌症疫苗已经在临床试验中进行了测试，但成功率有限，主要是由于肽的稳定性和递送上的困难，导致抗原呈递效率低下。因此，开发合适和有效的疫苗载体系统仍然是一个主要挑战。
为了解决这个问题，我们设计了聚乳酸-共-羟基乙酸（PLGA）纳米粒子，其中包含：（i）两种 MHC I 类限制性临床相关肽，（ii）一种 MHC II 类结合肽，和（iii）一种非经典 MHC I 类结合肽。我们利用双乳液-溶剂蒸发技术制备了纳米粒子，并对其表面形态、粒径、zeta 电位和肽含量进行了表征。我们还将含肽的纳米粒子加载到人源和鼠源树突状细胞（DC）中，并确定了它们在体外呈现包封肽抗原和诱导肿瘤特异性细胞毒性 T 淋巴细胞（CTL）的能力。
我们证实，这些纳米粒子对小鼠和人源 DC 均无毒性，并且对 DC 的成熟没有任何影响。我们还证明，在 DC 内吞纳米粒子后，包封的肽抗原的呈递显著增强，并且证实改善的肽呈递实际上与更有效的肽特异性 CTL 和 T 辅助细胞反应的产生相关。
将抗原包封在 PLGA 纳米粒子中具有独特的优势，例如抗原负载效率更高、抗原呈递时间延长、防止肽降解、抗原特异性靶向抗原呈递细胞、提高抗原的保质期以及便于进行药物生产的规模化。因此，这些发现对于合成疫苗的开发以及诱导 CTL 进行过继免疫治疗具有重要意义。
