title: Controlling osteogenic stem cell differentiation via soft bioinspired hydrogels.
abstract: Osteogenic differentiation of human mesenchymal stem cells (hMSCs) is guided by various physical and biochemical factors. Among these factors, modulus (i.e., rigidiy) of the ECM has gained significant attention as a physical osteoinductive signal that can contribute to endochondral ossification of a cartilaginous skeletal template. However, MSCs also participate in intramembranous bone formation, which occurs de novo from within or on a more compliant tissue environment. To further understand the role of the matrix interactions in this process, we evaluated osteogenic differentiation of hMSCs cultured on low moduli (102, 390 or 970 Pa) poly(N-isopropylacrylamide) (p(NIPAAm)) based semi-interpenetrating networks (sIPN) modified with the integrin engaging peptide bsp-RGD(15) (0, 105 or 210 µM). Cell adhesion, proliferation, and osteogenic differentiation of hMSCs, as measured by alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX2), bone sialoprotein-2 (iBSP), and osteocalcien (OCN) protein expression, was highest on substrates with the highest modulus and peptide concentrations. However, within this range of substrate stiffness, many osteogenic cellular functions were enhanced by increasing either the modulus or the peptide density. These findings suggest that within a compliant and low modulus substrate, a high affinity adhesive ligand serves as a substitute for a rigid matrix to foster osteogenic differentiation.
authors.affiliation: Department of Bioengineering, University of California, Berkeley, California, United States of America.
authors.forename: Amit K
authors.initials: AK
authors.lastname: Jha
authors.affiliation: Department of Bioengineering, University of California, Berkeley, California, United States of America.
authors.forename: Wesley M
authors.initials: WM
authors.lastname: Jackson
authors.affiliation: Department of Bioengineering, University of California, Berkeley, California, United States of America; Department of Materials Science and Engineering, University of California, Berkeley, California, United States of America.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Healy
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D000469:Alkaline Phosphatase / Q000378:metabolism; D001672:Biocompatible Materials; D002448:Cell Adhesion; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism; D003470:Culture Media; D006801:Humans; D020100:Hydrogels / Q000737:chemistry*; D058574:Integrin-Binding Sialoprotein / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D009842:Oligopeptides / Q000737:chemistry; D010006:Osteoblasts / Q000502:physiology*; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis
chemical_list: D000178:Acrylamides; D001672:Biocompatible Materials; D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; D003470:Culture Media; D020100:Hydrogels; D058574:Integrin-Binding Sialoprotein; D009842:Oligopeptides; C493709:RUNX2 protein, human; D015675:Osteocalcin; C047981:arginyl-glycyl-aspartic acid; C067295:N-isopropylacrylamide; D000469:Alkaline Phosphatase