MPEG-PLA and PLA-PEG-PLA nanoparticles as new carriers for delivery of recombinant human Growth Hormone (rhGH)

Rohollah Ghasemi,Saman Hosseinkhani,Ali Badeli,Khosrow Khodabakhshi,Hamed Bagheri,Mahdi Abdollahi,Elaheh Emamgholi Zadeh

doi:10.1038/s41598-018-28092-8

Rohollah Ghasemi, Saman Hosseinkhani + Show 5 more

Open Access

https://doi.org/10.1038/s41598-018-28092-8

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Abstract

mPEG-PLA and PLA-PEG-PLA copolymeric nanoparticles with three different PLA to PEG ratios are synthesized and used for encapsulation of recombinant human Growth hormone (rhGH). The structure and composition of the synthesized copolymers were analyzed by 1H NMR and GPC techniques. Moreover, morphology, encapsulation efficiency (EE), cytotoxicity, release profile and stability of the encapsulated rhGH were measured. Structural analysis of the prepared copolymers showed that they were successfully synthesized with approximately expected molecular weight and relatively low size distribution. It was also revealed that by increasing amounts of PLA/PEG ratio, EE content and size of nanoparticles were increased. Release profile evaluation of rhGH from both formulations indicated that copolymeric nanoparticles of Di-B2 and Tri-B2 exhibited the best results among the synthesized nanospheres, by having initial burst release of 17.5% and 28% and then slow and constant release of rhGH up to 65% and 77% of the encapsulated drug, respectively. Furthermore, results of HPLC, SDS-PAGE and CD analyses showed stability of rhGH during encapsulation and release from nanoparticles. Finally, the results showed that these two formulations provided safe and efficient sustained release of rhGH for more than a month and they have the potential to do further studies under in vivo conditions.

Highlights

Structural stability of released recombinant human Growth hormone (rhGH) from the mPEG-Polylactic acid (PLA) and PLA-poly(ethylene glycol) (PEG)-PLA nanospheres was analyzed in terms of the presence of dimer and multimers with higher molecular weights by High-performance liquid chromatography (HPLC) technique
Different studies have revealed that PLA-based drug delivery systems have the property of long-term release of drug in addition to biodegradability and biocompatibility which has made them among the most promising polymers for design of drug delivery systems
These systems suffer from problems such as instability of protein drugs during synthesis of nanoparticles or release process due to protein contact with organic hydrophobic phase and production of acidic environment as the result of polymer degradation

Summary

Introduction

Various formulations have been used for sustained release of rhGH, including crystalline formulation[8], PEGylation[9,10], protein encapsulation into polymeric microspheres[6,7,11,12,13,14], nanospheres[15] and injectable hydrogels[16,17,18,19,20,21], the use of degradable implants[22,23] and oral and transdermal deliveries[15,24]. Nutropin Depot is the first polymeric system for sustained release of rhGH produced in 1999‚ in which rhGH was encapsulated in PLGA microspheres Once injection of this formulation provided hormone for 2 weeks to 1 month. This system had problems such as high initial burst release, inflammation at the injection site and protein denaturation due to acidic environment (because of polymer destruction) which resulted in its exclusion from production and selling cycle in 200419. Their drug release is accompanied with initial burst release which could result in loss of a considerable amount of active drug in a short period of time and increase of concentration-dependent toxicity and decrease of formulation effectiveness time[3] In this regard, numerous studies have been devoted to resolve this problems. By copolymerization of PLA with PEG, diblock copolymers of mPEG-PLA and triblock copolymers of PLA-PEG-PLA and mPEG-PLA-mPEG would be produced which have core-shell structures in aqueous environments

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Conclusion