TY - JOUR
T1 - A Tunable, Three-Dimensional in Vitro Culture Model of Growth Plate Cartilage Using Alginate Hydrogel Scaffolds
AU - Erickson, Alek G.
AU - Laughlin, Taylor D.
AU - Romereim, Sarah M.
AU - Sargus-Patino, Catherine N.
AU - Pannier, Angela K.
AU - Dudley, Andrew T.
N1 - Funding Information:
The National Science Foundation (CBET-1254415), Center for Nanohybrid Functional Materials (NSF EPS-1004094), UNL ARDU.S. Meat Animal Research Center, UNL-UNMC Bioengineering for Human Health Initiative (Tobacco Settlement Funds), Mary and Dick Holland Regenerative Medicine Program, the National Institute of Arthritis, Musculoskeletal, and Skin Diseases (NIAMS/ AR05485 and AR070242), and USDA CSREES-Nebraska (NEB-21-146 and NEB-26-211) are acknowledged for funding. The authors wish to thank Krishna Sarma for thought-provoking discussions. They also thank Philip Hexley, Victoria Smith, and Samantha Wall of the UNMC Flow Cytometry Core Facility, Janice A. Taylor and James R. Talaska of the UNMC Advanced Microscopy Core Facility, Emily Barber of the UNL Biomedical and Obesity Research Core, and UNMC Comparative Medicine for technical assistance. The authors have no conflict of interest to declare.
Publisher Copyright:
© 2018, Mary Ann Liebert, Inc.
PY - 2018/1
Y1 - 2018/1
N2 - Defining the final size and geometry of engineered tissues through precise control of the scalar and vector components of tissue growth is a necessary benchmark for regenerative medicine, but it has proved to be a significant challenge for tissue engineers. The growth plate cartilage that promotes elongation of the long bones is a good model system for studying morphogenetic mechanisms because cartilage is composed of a single cell type, the chondrocyte; chondrocytes are readily maintained in culture; and growth trajectory is predominately in a single vector. In this cartilage, growth is generated via a differentiation program that is spatially and temporally regulated by an interconnected network composed of long- and short-range signaling mechanisms that together result in the formation of functionally distinct cellular zones. To facilitate investigation of the mechanisms underlying anisotropic growth, we developed an in vitro model of the growth plate cartilage by using neonatal mouse growth plate chondrocytes encapsulated in alginate hydrogel beads. In bead cultures, encapsulated chondrocytes showed high viability, cartilage matrix deposition, low levels of chondrocyte hypertrophy, and a progressive increase in cell proliferation over 7 days in culture. Exogenous factors were used to test functionality of the parathyroid-related protein-Indian hedgehog (PTHrP-IHH) signaling interaction, which is a crucial feedback loop for regulation of growth. Consistent with in vivo observations, exogenous PTHrP stimulated cell proliferation and inhibited hypertrophy, whereas IHH signaling stimulated chondrocyte hypertrophy. Importantly, the treatment of alginate bead cultures with IHH or thyroxine resulted in formation of a discrete domain of hypertrophic cells that mimics tissue architecture of native growth plate cartilage. Together, these studies are the first demonstration of a tunable in vitro system to model the signaling network interactions that are required to induce zonal architecture in growth plate chondrocytes, which could also potentially be used to grow cartilage cultures of specific geometries to meet personalized patient needs.
AB - Defining the final size and geometry of engineered tissues through precise control of the scalar and vector components of tissue growth is a necessary benchmark for regenerative medicine, but it has proved to be a significant challenge for tissue engineers. The growth plate cartilage that promotes elongation of the long bones is a good model system for studying morphogenetic mechanisms because cartilage is composed of a single cell type, the chondrocyte; chondrocytes are readily maintained in culture; and growth trajectory is predominately in a single vector. In this cartilage, growth is generated via a differentiation program that is spatially and temporally regulated by an interconnected network composed of long- and short-range signaling mechanisms that together result in the formation of functionally distinct cellular zones. To facilitate investigation of the mechanisms underlying anisotropic growth, we developed an in vitro model of the growth plate cartilage by using neonatal mouse growth plate chondrocytes encapsulated in alginate hydrogel beads. In bead cultures, encapsulated chondrocytes showed high viability, cartilage matrix deposition, low levels of chondrocyte hypertrophy, and a progressive increase in cell proliferation over 7 days in culture. Exogenous factors were used to test functionality of the parathyroid-related protein-Indian hedgehog (PTHrP-IHH) signaling interaction, which is a crucial feedback loop for regulation of growth. Consistent with in vivo observations, exogenous PTHrP stimulated cell proliferation and inhibited hypertrophy, whereas IHH signaling stimulated chondrocyte hypertrophy. Importantly, the treatment of alginate bead cultures with IHH or thyroxine resulted in formation of a discrete domain of hypertrophic cells that mimics tissue architecture of native growth plate cartilage. Together, these studies are the first demonstration of a tunable in vitro system to model the signaling network interactions that are required to induce zonal architecture in growth plate chondrocytes, which could also potentially be used to grow cartilage cultures of specific geometries to meet personalized patient needs.
KW - 3D culture model
KW - Growth plate cartilage
KW - IHH/PTHrP signaling
KW - alginate hydrogel
KW - tissue architecture
UR - http://www.scopus.com/inward/record.url?scp=85040614534&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85040614534&partnerID=8YFLogxK
U2 - 10.1089/ten.tea.2017.0091
DO - 10.1089/ten.tea.2017.0091
M3 - Article
C2 - 28525313
AN - SCOPUS:85040614534
SN - 1937-3341
VL - 24
SP - 94
EP - 105
JO - Tissue Engineering - Part A
JF - Tissue Engineering - Part A
IS - 1-2
ER -