Engineering the periodontal ligament in hyaluronan-gelatin-type I collagen constructs: upregulation of apoptosis and alterations in gene expression by cyclic compressive strain

To engineer constructs of the periodontal ligament (PDL), human PDL cells were incorporated into a matrix of hyaluronan, gelatin, and type I collagen (COLI) in sample holders (13×1 mm) of six-well Biopress culture plates. The loading dynamics of the PDL were mimicked by applying a cyclic compressive...

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Bibliographic Details
Published in:	Tissue engineering. Part A Vol. 21; no. 3-4; p. 518
Main Authors:	Saminathan, Aarthi, Sriram, Gopu, Vinoth, Jayasaleen Kumar, Cao, Tong, Meikle, Murray C
Format:	Journal Article
Language:	English
Published:	United States 01-02-2015
Subjects:	Apoptosis - physiology Biocompatible Materials - chemical synthesis Cells, Cultured Collagen Type I - chemistry Compressive Strength - physiology Elastic Modulus - physiology Equipment Design Equipment Failure Analysis Gelatin - chemistry Gene Expression Regulation - physiology Guided Tissue Regeneration, Periodontal - instrumentation Guided Tissue Regeneration, Periodontal - methods Humans Hyaluronic Acid - chemistry Materials Testing Mechanotransduction, Cellular - physiology Periodontal Ligament - cytology Periodontal Ligament - physiology Stress, Mechanical Tissue Engineering - instrumentation Tissue Engineering - methods
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Summary:	To engineer constructs of the periodontal ligament (PDL), human PDL cells were incorporated into a matrix of hyaluronan, gelatin, and type I collagen (COLI) in sample holders (13×1 mm) of six-well Biopress culture plates. The loading dynamics of the PDL were mimicked by applying a cyclic compressive strain of 33.4 kPa (340.6 gm/cm(2)) to the constructs for 1.0 s every 60 s, for 6, 12, and 24 h in a Flexercell FX-4000C Strain Unit. Compression significantly increased the number of nonviable cells and increased the expression of several apoptosis-related genes, including initiator and executioner caspases. Of the 15 extracellular matrix genes screened, most were upregulated at some point after 6-12 h deformation, but all were downregulated at 24 h, except for MMPs1-3 and CTGF. In culture supernatants, matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinases-1 (TIMP-1) protein levels were upregulated at 24 h; receptor activator of nuclear kappa factor B (RANKL), osteoprotegerin (OPG) and fibroblast growth factor-2 (FGF-2) were unchanged; and connective tissue growth factor (CTGF) not detected. The low modulus of elasticity of the constructs was a disadvantage-future mechanobiology studies and tissue engineering applications will require constructs with much higher stiffness. Since the major structural protein of the PDL is COLI, a more rational approach would be to permeabilize preformed COLI scaffolds with PDL-populated matrices.
ISSN:	1937-335X
DOI:	10.1089/ten.tea.2014.0221