title: Interplay of Substrate Conductivity, Cellular Microenvironment, and Pulsatile Electrical Stimulation toward Osteogenesis of Human Mesenchymal Stem Cells in Vitro.
abstract: The influences of physical stimuli such as surface elasticity, topography, and chemistry over mesenchymal stem cell proliferation and differentiation are well investigated. In this context, a fundamentally different approach was adopted, and we have demonstrated the interplay of inherent substrate conductivity, defined chemical composition of cellular microenvironment, and intermittent delivery of electric pulses to drive mesenchymal stem cell differentiation toward osteogenesis. For this, conducting polyaniline (PANI) substrates were coated with collagen type 1 (Coll) alone or in association with sulfated hyaluronan (sHya) to form artificial extracellular matrix (aECM), which mimics the native microenvironment of bone tissue. Further, bone marrow derived human mesenchymal stem cells (hMSCs) were cultured on these moderately conductive (10(-4)-10(-3) S/cm) aECM coated PANI substrates and exposed intermittently to pulsed electric field (PEF) generated through transformer-like coupling (TLC) approach over 28 days. On the basis of critical analysis over an array of end points, it was inferred that Coll/sHya coated PANI (PANI/Coll/sHya) substrates had enhanced proliferative capacity of hMSCs up to 28 days in culture, even in the absence of PEF stimulation. On the contrary, the adopted PEF stimulation protocol (7 ms rectangular pulses, 3.6 mV/cm, 10 Hz) is shown to enhance osteogenic differentiation potential of hMSCs. Additionally, PEF stimulated hMSCs had also displayed different morphological characteristics as their nonstimulated counterparts. Concomitantly, earlier onset of ALP activity was also observed on PANI/Coll/sHya substrates and resulted in more calcium deposition. Moreover, real-time polymerase chain reaction results indicated higher mRNA levels of alkaline phosphatase and osteocalcin, whereas the expression of other osteogenic markers such as Runt-related transcription factor 2, Col1A, and osteopontin exhibited a dynamic pattern similar to control cells that are cultured in osteogenic medium. Taken together, our experimental results illustrate the interplay of multiple parameters such as substrate conductivity, electric field stimulation, and aECM coating on the modulation of hMSC proliferation and differentiation in vitro.
authors.affiliation: Max Bergmann Center of Biomaterials, Technische Universität Dresden , Budapester Straße 27, 01069 Dresden, Germany.|Centre for Nano Science and Engineering, Indian Institute of Science , Bangalore 560012, India.
authors.forename: Greeshma
authors.initials: G
authors.lastname: Thrivikraman
authors.affiliation: Max Bergmann Center of Biomaterials, Technische Universität Dresden , Budapester Straße 27, 01069 Dresden, Germany.
authors.forename: Poh S
authors.initials: PS
authors.lastname: Lee
authors.affiliation: Max Bergmann Center of Biomaterials, Technische Universität Dresden , Budapester Straße 27, 01069 Dresden, Germany.
authors.forename: Ricarda
authors.initials: R
authors.lastname: Hess
authors.affiliation: Max Bergmann Center of Biomaterials, Technische Universität Dresden , Budapester Straße 27, 01069 Dresden, Germany.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Haenchen
authors.affiliation: Laboratory for Biomaterials, Materials Research Centre, Indian Institute of Science , Bangalore 560012, India.
authors.forename: Bikramjit
authors.initials: B
authors.lastname: Basu
authors.affiliation: Max Bergmann Center of Biomaterials, Technische Universität Dresden , Budapester Straße 27, 01069 Dresden, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Scharnweber
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000814:Aniline Compounds / Q000494:pharmacology*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D060833:Cellular Microenvironment / Q000187:drug effects*; D020099:Coated Materials, Biocompatible / Q000494:pharmacology; D003094:Collagen / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D004553:Electric Conductivity; D004558:Electric Stimulation; D004602:Elements; D005109:Extracellular Matrix / Q000378:metabolism / Q000648:ultrastructure; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism; D020869:Gene Expression Profiling; D006801:Humans; D006820:Hyaluronic Acid / Q000494:pharmacology; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D010012:Osteogenesis / Q000187:drug effects* / Q000235:genetics; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction; D013052:Spectrometry, X-Ray Emission
chemical_list: D000814:Aniline Compounds; D015415:Biomarkers; D020099:Coated Materials, Biocompatible; D004602:Elements; C416807:polyaniline; D006820:Hyaluronic Acid; D003094:Collagen; D000469:Alkaline Phosphatase; D002118:Calcium
keywords: collagen; electric fields; mesenchymal stem cells; osteogenic differentiation; polyaniline; sulfated hyaluronan; transformer-like coupling