The nature of peptide interactions with acid end-group PLGAs and facile aqueous-based microencapsulation of therapeutic peptides.
The nature of peptide interactions with acid end-group PLGAs and facile aqueous-based microencapsulation of therapeutic peptides.
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DOI：
10.1016/j.jconrel.2013.08.295
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发表时间：
2013-12-28
期刊：
影响因子：
--
通讯作者：
Schwendeman SP
中科院分区：
文献类型：
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作者：
Sophocleous AM;Desai KG;Mazzara JM;Tong L;Cheng JX;Olsen KF;Schwendeman SP
控释库中一个重要而鲜为人知的现象是普通阳离子多肽与低分子量自由酸端基聚(乳酸-乙醇酸)(PLGA)之间的强相互作用，用于实现连续的多肽释放动力学。将0.2~4 mM奥曲肽或醋酸亮丙瑞林的多肽溶液置于0.1M HEPES缓冲液(pH 7.4)中，与聚合物颗粒或膜在4~37℃下孵育24 h，研究了PLGA对多肽的吸附动力学，并通过双相萃取和氨基酸分析测定了多肽在PLGA颗粒/膜中的吸附/载量。利用共聚焦拉曼光谱、受激拉曼散射(SRS)和激光扫描共聚焦成像技术研究了多肽在聚合物相中的渗透行为。分别在体外(PBST+0.02%叠氮钠，37℃)和体内(雄性SD大鼠)考察了亮丙瑞林PLGA颗粒的释药特性。我们发现，当PLGA-COOH链被充分动员时，治疗性多肽不仅可以结合在表面，这是迄今为止人们普遍认为的，而且还可以在生理温度下内化并分布在整个聚合物相中，形成具有低分子质量的PLGA-COOH盐。重要的是，低分子量PLGA-COOH微粒对亮丙瑞林的吸收产生了约17wt%的亮丙瑞林负载量(即~70%的PLGA-COOH酸被占据)，并且被吸收的多肽在体外以可控的方式从聚合物中释放2周，雄性SD大鼠的睾酮持续抑制表明。这一新方法绕过了传统的包封法和相关的生产成本，为生产低成本的亮丙瑞林和相关多肽的控释注射库开辟了可能性。
An important poorly understood phenomenon in controlled-release depots involves the strong interaction between common cationic peptides and low Mw free acid end-group poly(lactic-co-glycolic acids) (PLGAs) used to achieve continuous peptide release kinetics. The kinetics of peptide sorption to PLGA was examined by incubating peptide solutions of 0.2-4 mM octreotide or leuprolide acetate salts in 0.1 M HEPES buffer, pH 7.4, with polymer particles or films at 4-37 °C for 24 h. The extent of absorption/loading of peptides in PLGA particles/films was assayed by two-phase extraction and amino acid analysis. Confocal Raman microspectroscopy and stimulated Raman scattering (SRS) and laser scanning confocal imaging techniques were used to examine peptide penetration in the polymer phase. The release of sorbed peptide from leuprolide-PLGA particles was evaluated both in vitro (PBST + 0.02% sodium azide, 37 °C) and in vivo (male Sprague-Dawley rats). We found that when the PLGA-COOH chains are sufficiently mobilized, therapeutic peptides not only bind at the surface, a common belief to date, but can also internalized and distributed throughout the polymer phase at physiological temperature forming a salt with low-molecular weight PLGA-COOH. Importantly, absorption of leuprolide into low MW PLGA-COOH particles yielded ~17 wt% leuprolide loading in the polymer (i.e., ~70% of PLGA-COOH acids occupied), and the absorbed peptide was released from the polymer for > 2 weeks in a controlled fashion in vitro and as indicated by sustained testosterone suppression in male Sprague-Dawley rats. This new approach, which bypasses the traditional encapsulation method and associated production cost, opens up the potential for facile production of low-cost controlled-release injectable depots for leuprolide and related peptides.