The importance of connexin hemichannels during chondroprogenitor cell differentiation in hydrogel versus microtissue culture models

Schrobback, Karsten, Klein, Travis Jacob, & Woodfield, Tim B. F. (2015) The importance of connexin hemichannels during chondroprogenitor cell differentiation in hydrogel versus microtissue culture models. Tissue Engineering Part A, 21(11-12), pp. 1785-1794.

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Abstract

Appropriate selection of scaffold architecture is a key challenge in cartilage tissue engineering. Gap junction-mediated intercellular contacts play important roles in precartilage condensation of mesenchymal cells. However, scaffold architecture could potentially restrict cell-cell communication and differentiation. This is particularly important when choosing the appropriate culture platform as well as scaffold-based strategy for clinical translation, that is, hydrogel or microtissues, for investigating differentiation of chondroprogenitor cells in cartilage tissue engineering. We, therefore, studied the influence of gap junction-mediated cell-cell communication on chondrogenesis of bone marrow-derived mesenchymal stromal cells (BM-MSCs) and articular chondrocytes. Expanded human chondrocytes and BM-MSCs were either (re-) differentiated in micromass cell pellets or encapsulated as isolated cells in alginate hydrogels. Samples were treated with and without the gap junction inhibitor 18-α glycyrrhetinic acid (18αGCA). DNA and glycosaminoglycan (GAG) content and gene expression levels (collagen I/II/X, aggrecan, and connexin 43) were quantified at various time points. Protein localization was determined using immunofluorescence, and adenosine-5'-triphosphate (ATP) was measured in conditioned media. While GAG/DNA was higher in alginate compared with pellets for chondrocytes, there were no differences in chondrogenic gene expression between culture models. Gap junction blocking reduced collagen II and extracellular ATP in all chondrocyte cultures and in BM-MSC hydrogels. However, differentiation capacity was not abolished completely by 18αGCA. Connexin 43 levels were high throughout chondrocyte cultures and peaked only later during BM-MSC differentiation, consistent with the delayed response of BM-MSCs to 18αGCA. Alginate hydrogels and microtissues are equally suited culture platforms for the chondrogenic (re-)differentiation of expanded human articular chondrocytes and BM-MSCs. Therefore, reducing direct cell-cell contacts does not affect in vitro chondrogenesis. However, blocking gap junctions compromises cell differentiation, pointing to a prominent role for hemichannel function in this process. Therefore, scaffold design strategies that promote an increasing distance between single chondroprogenitor cells do not restrict their differentiation potential in tissue-engineered constructs.

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ID Code: 86242
Item Type: Journal Article
Refereed: Yes
Keywords: Chondrocytes, Mesenchymal stromal cells, Connexin 43, Gap junction, Cell Differentiation, Microtissue culture models, Hydrogel, Hemichannel
DOI: 10.1089/ten.TEA.2014.0691
ISSN: 1937-335X
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > BIOCHEMISTRY AND CELL BIOLOGY (060100) > Cell Development Proliferation and Death (060103)
Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > BIOCHEMISTRY AND CELL BIOLOGY (060100) > Receptors and Membrane Biology (060110)
Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > BIOMEDICAL ENGINEERING (090300) > Biomechanical Engineering (090302)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > Institutes > Institute of Health and Biomedical Innovation
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Funding:
  • AO FOUNDATION/S-08-81W
  • EU 7TH FRAMEWORK PRO/318553
  • ROYAL SOCIETY OF NZ/NA
  • NZ LOTTERIES/NA
Copyright Owner: Copyright 2015 Mary Ann Liebert, Inc.
Copyright Statement: Final publication is available from Mary Ann Liebert, Inc., publishers http://dx.doi.org/10.1089/ten.TEA.2014.0691
Deposited On: 06 Aug 2015 02:07
Last Modified: 27 May 2016 14:01

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