Hayman Lui1, Janet Denbeigh2, Cedryck Vaquette3, Hoai My Tran3, Allan B Dietz4, Simon M Cool5, Amel Dudakovic6, Sanjeev Kakar2, Andre J van Wijnen7. 1. Griffith University, School of Medicine, Gold Coast, Queensland, Australia; Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States. 2. Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States. 3. The University of Queensland, School of Dentistry, Brisbane, Queensland, Australia. 4. Department of Laboratory Medicine, Mayo Clinic, Rochester, MN, United States. 5. Glycotherapeutics Group, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore. 6. Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States; Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, United States. 7. Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States; Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, United States. Electronic address: vanWijnen.Andre@mayo.edu.
Abstract
INTRODUCTION: Culture conditions and differentiation cocktails may facilitate cell maturation and extracellular matrix (ECM) secretion and support the production of engineered fibroblastic tissues with applications in ligament regeneration. The objective of this study is to investigate the potential of two connective tissue-related ligands (i.e., BMP6 and GDF5) to mediate collagenous ECM synthesis and tissue maturation in vitro under normoxic and hypoxic conditions based on the hypothesis that BMP6 and GDF5 are components of normal paracrine signalling events that support connective tissue homeostasis. METHODS: Human adipose-derived MSCs were seeded on 3D-printed medical-grade polycaprolactone (PCL) scaffolds using a bioreactor and incubated in media containing GDF5 and/or BMP6 for 21 days in either normoxic (5% oxygen) or hypoxic (2% oxygen) conditions. Constructs were harvested on Day 3 and 21 for cell viability analysis by live/dead staining, structural analysis by scanning electron microscopy, mRNA levels by RTqPCR analysis, and in situ deposition of proteins by immunofluorescence microscopy. RESULTS: Pro-fibroblastic gene expression is enhanced by hypoxic culture conditions compared to normoxic conditions. Hypoxia renders cells more responsive to treatment with BMP6 as reflected by increased expression of ECM mRNA levels on Day 3 with sustained expression until Day 21. GDF5 was not particularly effective either in the absence or presence of BMP6. CONCLUSIONS: Fibroblastic differentiation of MSCs is selectively enhanced by BMP6 and not GDF5. Environmental factors (i.e., hypoxia) also influenced the responsiveness of cells to this morphogen.
INTRODUCTION: Culture conditions and differentiation cocktails may facilitate cell maturation and extracellular matrix (ECM) secretion and support the production of engineered fibroblastic tissues with applications in ligament regeneration. The objective of this study is to investigate the potential of two connective tissue-related ligands (i.e., BMP6 and GDF5) to mediate collagenous ECM synthesis and tissue maturation in vitro under normoxic and hypoxic conditions based on the hypothesis that BMP6 and GDF5 are components of normal paracrine signalling events that support connective tissue homeostasis. METHODS:Human adipose-derived MSCs were seeded on 3D-printed medical-grade polycaprolactone (PCL) scaffolds using a bioreactor and incubated in media containing GDF5 and/or BMP6 for 21 days in either normoxic (5% oxygen) or hypoxic (2% oxygen) conditions. Constructs were harvested on Day 3 and 21 for cell viability analysis by live/dead staining, structural analysis by scanning electron microscopy, mRNA levels by RTqPCR analysis, and in situ deposition of proteins by immunofluorescence microscopy. RESULTS: Pro-fibroblastic gene expression is enhanced by hypoxic culture conditions compared to normoxic conditions. Hypoxia renders cells more responsive to treatment with BMP6 as reflected by increased expression of ECM mRNA levels on Day 3 with sustained expression until Day 21. GDF5 was not particularly effective either in the absence or presence of BMP6. CONCLUSIONS: Fibroblastic differentiation of MSCs is selectively enhanced by BMP6 and not GDF5. Environmental factors (i.e., hypoxia) also influenced the responsiveness of cells to this morphogen.