Chlorite oxidized oxyamylose differentially influences the microstructure of fibrin and self assembling peptide hydrogels as well as dental pulp stem cell behavior

Mostafa Ezeldeen,Rafaela Vaz Sousa Pereira,Carmen Bartic,Annelies Bronckaers,Nick Smisdom,Ghislain Opdenakker,Ivo Lambrichts,Reinhilde Jacobs,Olivier Deschaume,Denise Murgia,Hans Van Oosterwyck,Jennifer Patterson,Burak Toprakhisar

doi:10.1038/s41598-021-84405-4

Abstract

Tailored hydrogels mimicking the native extracellular environment could help overcome the high variability in outcomes within regenerative endodontics. This study aimed to evaluate the effect of the chemokine-binding and antimicrobial polymer, chlorite-oxidized oxyamylose (COAM), on the microstructural properties of fibrin and self-assembling peptide (SAP) hydrogels. A further goal was to assess the influence of the microstructural differences between the hydrogels on the in vitro behavior of human dental pulp stem cells (hDPSCs). Structural and mechanical characterization of the hydrogels with and without COAM was performed by atomic force microscopy and scanning electron microscopy to characterize their microstructure (roughness and fiber length, diameter, straightness, and alignment) and by nanoindentation to measure their stiffness (elastic modulus). Then, hDPSCs were encapsulated in hydrogels with and without COAM. Cell viability and circularity were determined using confocal microscopy, and proliferation was determined using DNA quantification. Inclusion of COAM did not alter the microstructure of the fibrin hydrogels at the fiber level while affecting the SAP hydrogel microstructure (homogeneity), leading to fiber aggregation. The stiffness of the SAP hydrogels was sevenfold higher than the fibrin hydrogels. The viability and attachment of hDPSCs were significantly higher in fibrin hydrogels than in SAP hydrogels. The DNA content was significantly affected by the hydrogel type and the presence of COAM. The microstructural stability after COAM inclusion and the favorable hDPSCs' response observed in fibrin hydrogels suggest this system as a promising carrier for COAM and application in endodontic regeneration.

Highlights

Tailored hydrogels mimicking the native extracellular environment could help overcome the high variability in outcomes within regenerative endodontics
While the classical regenerative medicine approach employs a combination of cells with biomaterials to promote tissue regeneration, the economic and regulatory hurdles associated with cell-based therapies have led to the proliferation of cell-free biomaterial approaches, which stimulate the activity of endogenous stem cells
The inclusion of chlorite-oxidized oxyamylose (COAM) did not alter the microstructure of the fibrin hydrogel at the fiber level as demonstrated by atomic force microscopy (AFM) images (Fig. 1A–D) and quantitative analysis (Table 1)

Summary

Introduction

Tailored hydrogels mimicking the native extracellular environment could help overcome the high variability in outcomes within regenerative endodontics. A further goal was to assess the influence of the microstructural differences between the hydrogels on the in vitro behavior of human dental pulp stem cells (hDPSCs). Self-assembling peptide (SAP) hydrogels belong to the synthetic class and are produced using amino acids[28] These peptides self-assemble to form nanofibrous hydrogels in physiological conditions. This self-assembly depends on the specific amino acid sequence of the peptide These scaffolds consist of > 99% water, with fibers thought to be around 10 nm in diameter and 5–200 nm pores, closely mimicking the natural extracellular matrix (ECM)[28]. The SAP (RADA-16) hydrogel has been used in several dental pulp tissue engineering studies with variable degrees of s uccess[17,30,31]

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