Engineering of L-Plastin Peptide-Loaded Biodegradable Nanoparticles for Sustained Delivery and Suppression of Osteoclast Function In Vitro.

Sunipa Majumdar,Hanan Aljohani,Mark A Reynolds,Meenakshi Chellaiah,Aniket S Wadajkar,Anthony J Kim

doi:10.1155/2019/6943986

Sunipa Majumdar, Hanan Aljohani + Show 4 more

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https://doi.org/10.1155/2019/6943986

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Abstract

We have recently demonstrated that a small molecular weight amino-terminal peptide of L-plastin (10 amino acids; “MARGSVSDEE”) suppressed the phosphorylation of endogenous L-plastin. Therefore, the formation of nascent sealing zones (NSZs) and bone resorption are reduced. The aim of this study was to develop a biodegradable and biocompatible PLGA nanocarrier that could be loaded with the L-plastin peptide of interest and determine the efficacy in vitro in osteoclast cultures. L-plastin MARGSVSDEE (P1) and scrambled control (P3) peptide-loaded PLGA-PEG nanoparticles (NP1 and NP3, respectively) were synthesized by double emulsion technique. The biological effect of nanoparticles on osteoclasts was evaluated by immunoprecipitation, immunoblotting, rhodamine-phalloidin staining of actin filaments, and pit forming assays. Physical characterization of well-dispersed NP1 and NP3 demonstrated ~130-150 nm size, < 0.07 polydispersity index, ~-3 mV ζ-potential, and a sustained release of the peptide for three weeks. Biological characterization in osteoclast cultures demonstrated the following: NP1 significantly reduced (a) endogenous L-plastin phosphorylation; (b) formation of NSZs and sealing rings; (c) resorption. However, the assembly of podosomes which are critical for cell adhesion was not affected. L-plastin peptide-loaded PLGA-PEG nanocarriers have promising potential for the treatment of diseases associated with bone loss. Future studies will use this sustained release of peptide strategy to systematically suppress osteoclast bone resorption activity in vivo in mouse models demonstrating bone loss.

Highlights

During bone remodeling, mature bone tissue is removed by a process called bone resorption and new bone tissue is formed by a process called ossification or bone formation
We have recently shown that transduction of TAT-fused small molecular weight amino-terminal L-plastin peptides (10 amino acids; “1MARGSVSDEE10” ) containing phosphoSer-5 and Ser-7 has the potential to suppress the phosphorylation of endogenous LPL competitively and nascent sealing zones (NSZs) formation and resorption by osteoclasts [9]
To determine an efficient uptake and release of the peptide of interest, we utilized nanoparticles loaded with small molecular weight amino terminal LPL peptide (sNT-LPL) peptides (NP1 and NP3) of interest in osteoclast derived from RAW 264.7 murine cell line

Summary

Introduction

Mature bone tissue is removed by a process called bone resorption and new bone tissue is formed by a process called ossification or bone formation. Osteoclasts form a tight seal on the bone surface, onto which they secrete acid and proteases to facilitate the resorptive process [3,4,5]. This tight seal on the bone surface is associated with the formation of a ring of actin filaments known as sealing ring [6, 7]. Our previous and recent studies have shown that LPL has a International Journal of Cell Biology regulatory role at the early phase of sealing ring formation in osteoclasts [6, 7, 9]

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