Local deformation in a hydrogel induced by an external magnetic field

The aim of this study is to prove the feasibility of a system able to apply local mechanical loading on cells seeded in a hydrogel for tissue engineering applications. This experimental study is based on a previously developed artificial cartilage model with different concentrations of poly(vinyl alcohol) (PVA) that simulates the cartilage extracellular matrix (ECM). Poly(l-lactic acid) (PLLA) microspheres with dispersed magnetic nanoparticles (MNPs) were produced with an emulsion method. These microspheres were embedded in aqueous PVA solutions with varying concentration to resemble increased viscosity of growing tissue during regeneration. The ability to induce a local deformation in the ECM was assessed by applying a steady or an oscillatory magnetic field gradient to different PVA solutions containing the magnetic microparticles, similarly as in ferrogels. PLLA microparticle motion was recorded, and the images were analyzed. Besides, PVA gels and PLLA microparticles were introduced into the pores of a polycaprolactone scaffold, and the microparticle distribution and the mechanical properties of the construct were evaluated. The results of this experimental model show that the dispersion of PLLA microparticles containing MNPs, together with cells in a supporting gel, will allow applying local mechanical stimuli to cells during tissue regeneration. This local stimulation can have a positive effect on the differentiation of seeded cells and improve tissue regeneration.The authors gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness through the MAT2013-46467-C4-1-R project, including the Feder funds. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. CIBER Actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. The authors thank "Servicio de Microscopia Electronica" of Universitat Politecnica de Valencia for their invaluable help. The translation of this paper was funded by the Universitat Politecnica de Valencia, Spain.Vikingsson, L.; Vinals Guitart, Á.; Valera Martínez, A.; Riera Guasp, J.; Vidaurre Garayo, AJ.; Gallego Ferrer, G.; Gómez Ribelles, JL. (2016). Local deformation in a hydrogel induced by an external magnetic field. Journal of Materials Science. 51(22):9979-9990. https://doi.org/10.1007/s10853-016-0226-8S997999905122Eyre D (2002) Collagen of articular cartilage. Arthritis Res 4:30–35Roughley PJ, Lee ER (1994) Cartilage proteoglycans: structure and potential functions. Microsc Res Tech 28:385–397Gillard GC, Reilly HC, Bell-Booth PG, Flint MH (1979) The influence of mechanical forces on the glycosaminoglycan content of the rabbit flexor digitorum profundus tendon. Connect Tissue Res 7:37–46Quinn TM, Grodzinsky AJ, Buschmann MD, Kim YJ, Hunziker EB (1998) Mechanical compression alters proteoglycan deposition and matrix deformation around individual cells in cartilage explants. J Cell Sci 111:573–583Banes AJ, Tsuzaki M, Yamamoto J, Fischer T, Brigman B, Brown T, Miller L (1995) Mechanoreception at the cellular level: the detection, interpretation, and diversity of responses to mechanical signals. Biochem Cell Biol 73:349–365Appelman T, Mizrahi J, Elisseeff J, Seliktar D (2011) The influence of biological motifs and dynamic mechanical stimulation in hydrogel scaffold systems on the phenotype of chondrocytes. Biomaterials 32:1508–1516Mow VC, Ratcliffe A, Poole AR (1992) Cartilage and diarthrodial joints as paradigms for hierarchical materials and structures. Biomaterials 13:67–97Mow VC, Huiskes R (2005) Basic orthopaedic biomechanics and mechano-biology. Lippincott Williams and Wilkins, PhiladelphiaBrady MA, Waldman SD, Ethier CR (2015) The application of multiple biophysical cues to engineer functional neocartilage for treatment of osteoarthritis. Part I: cellular response. Tissue Eng Part B Rev 21:1–19Valhmu WB, Stazzone EJ, Bachrach NM, Saed-Nejad F, Fischer SG, Mow VC, Ratcliffe A (1998) Load-controlled compression of articular cartilage induces a transient stimulation of aggrecan gene expression. Arch Biochem Biophys 353:29–36Ingber DE (1997) Tensegrity: the architectural basis of cellular mechanotransduction. Ann Rev Physiol 59:575–599Khan S, Sheetz MP (1997) Force effects on biochemical kinetics. Ann Rev Biochem 66:785–805Hutmacher DW (2000) Scaffolds in tissue engineering bone and cartilage. Biomaterials 21:2529–2543Crick FHC, Hughes AFW (1950) The physical properties of cytoplasm: a study by means of the magnetic particle method. Exp Cell Res 1:37–80Valberg PA, Albertini DF (1985) Cytoplasmic motions, rheology, and structure probed by a novel magnetic particle method. J Cell Biol 101:130–140Valberg PA, Feldman HA (1987) Magnetic particle motions within living cells. Measurement of cytoplasmic viscosity and motile activity. Biophys J 52:551–561Wang N, Ingber DE (1995) Probing transmembrane mechanical coupling and cytomechanics using magnetic twisting cytometry. Biochem Cell Biol 73:327–335Pommerenke H, Schreiber E, Durr F, Nebe B, Hahnel C, Moller W, Rychly J (1996) Stimulation of integrin receptors using a magnetic drag force device induces an intracellular free calcium response. Eur J Cell Biol 70:157–164Bausch AR, Hellerer U, Essler M, Aepfelbacher M, Sackmann E (2001) Rapid stiffening of integrin receptor-actin linkages in endothelial cells stimulated with thrombin: a magnetic bead microrheology study. Biophys J 80:2649–2657Li L, Yang G, Li J, Ding S, Zhou S (2014) Cell behaviors on magnetic electrospun poly-d, l-lactide nano fibers. Mater Sci Eng, C 34:252–261Fuhrer R, Hofmann S, Hild N, Vetsch JR, Herrmann IK, Grass RN, Stark WJ (2013) Pressureless mechanical induction of stem cell differentiation is dose and frequency dependent. PLoS One 8:e81362Cezar CA, Roche ET, Vandenburgh HH, Duda GN, Walsh CJ, Mooney DJ (2016) Biologic-free mechanically induced muscle regeneration. Proc Natl Acad Sci USA 113:1534–1539Vikingsson L, Gallego Ferrer G, Gómez-Tejedor JA, Gómez Ribelles JL (2014) An in vitro experimental model to predict the mechanical behaviour of macroporous scaffolds implanted in articular cartilage. J Mech Behav Biomed Mater 32:125–131Vikingsson L, Gomez-Tejedor JA, Gallego Ferrer G, Gomez Ribelles JL (2015) An experimental fatigue study of a porous scaffold for the regeneration of articular cartilage. J Biomech 48:1310–1317Vikingsson L, Claessens B, Gómez-Tejedor JA, Gallego Ferrer G, Gómez Ribelles JL (2015) Relationship between micro-porosity, water permeability and mechanical behavior in scaffolds for cartilage engineering. J Mech Behav Biomed Mater 48:60–69Li F, Su YL, Shi DF, Wang CT (2010) Comparison of human articular cartilage and polyvinyl alcohol hydrogel as artificial cartilage in microstructure analysis and unconfined compression. Adv Mater Res Trans Tech Publ 87:188–193Grant C, Twigg P, Egan A, Moody A, Eagland D, Crowther N, Britland S (2006) Poly(vinyl alcohol) hydrogel as a biocompatible viscoelastic mimetic for articular cartilage. Biotechnol Prog 22:1400–1406Weeber R, Kantorovich S, Holm C (2015) Ferrogels cross-linked by magnetic nanoparticles—Deformation mechanisms in two and three dimensions studied by means of computer simulations. J Magn Magn Mater 383:262–266Lebourg M, Suay Antón J, Gómez Ribelles JL (2008) Porous membranes of PLLA–PCL blend for tissue engineering applications. Eur Polym J 44:2207–2218Santamaría VA, Deplaine H, Mariggió D, Villanueva-Molines AR, García-Aznar JM, Gómez Ribelles JL, Doblaré M, Gallego Ferrer G, Ochoa I (2012) Influence of the macro and micro-porous structure on the mechanical behavior of poly (l-lactic acid) scaffolds. J Non Cryst Solids 358:3141–3149Panadero JA, Vikingsson L, Gomez Ribelles JL, Lanceros-Mendez S, Sencadas V (2015) In vitro mechanical fatigue behaviour of poly-ε-caprolactone macroporous scaffolds for cartilage tissue engineering. Influence of pore filling by a poly(vinyl alcohol) gel. J Biomed Mater Res Part B Appl Biomater 103:1037–1043Hassan CM, Peppas NA (2000) Structure and applications of poly(vinyl alcohol) hydrogels produced by conventional crosslinking or by freezing/thawing methods. Adv Polym Sci 153:37–65Labet M, Thielemans W (2009) Synthesis of polycaprolactone: a review. Chem Soc Rev 38:3484–3504Mano JF, Gómez Ribelles JL, Alves NM, Salmerón Sanchez M (2005) Glass transition dynamics and structural relaxation of PLLA studied by DSC: influence of crystallinity. Polymer 46:8258–8265Eckstein F, Lemberger B, Gratzke C, Hudelmaier M, Glaser C, Englmeier KH, Reiser M (2005) In vivo cartilage deformation after different types of activity and its dependence on physical training status. Ann Rheum Dis 64:291–295Garlotta D (2001) A literature review of poly(lactic acid). J Polym Eng 9:63–84Kovacs AJ, Aklonis JJ, Hutchinson JM, Ramos AR (1979) Isobaric volume and enthalpy recovery of glasses. II. A transparent multiparameter theory. J Polym Sci Polym Phys 17:1097–1162Hernández F, Molina Mateo J, Romero Colomer F, Salmerón Sánchez M, Gómez Ribelles JL, Mano J (2005) Influence of low-temperature nucleation on the crystallization process of poly(l-lactide). Biomacromolecules 6:3291–3299Wang Y, Gómez Ribelles JL, Salmerón Sánchez M, Mano JF (2005) Morphological contribution to glass transition in poly(l-lactic acid). Macromolecules 38:4712–4718Salmerón Sánchez M, Vincent BM, Vanden Poel G, Gómez-Ribelles JL (2007) Effect of the cooling rate on the nucleation kinetics of poly(l-lactic acid) and its influence on morphology. Macromolecules 40:7989–7997Nobuyuki O (1975) A threshold selection method from gray-level histograms. Automatica 11:23–2

Tension-Compression Loading with Chemical Stimulation Results in Additive Increases to Functional Properties of Anatomic Meniscal Constructs

Objective: This study aimed to improve the functional properties of anatomically-shaped meniscus constructs through simultaneous tension and compression mechanical stimulation in conjunction with chemical stimulation. Methods: Scaffoldless meniscal constructs were subjected to simultaneous tension and compressive stimulation and chemical stimulation. The temporal aspect of mechanical loadingwas studied by employing two separate five day stimulation periods. Chemical stimulation consisted of the application of a catabolic GAG-depleting enzyme, chondroitinase ABC (C-ABC), and an anabolic growth factor, TGF-b1. Mechanical and chemical stimulation combinations were studied through a full-factorial experimental design and assessed for histological, biochemical, and biomechanical properties following 4 wks of culture. Results: Mechanical loading applied from days 10–14 resulted in significant increases in compressive, tensile, and biochemical properties of meniscal constructs. When mechanical and chemical stimuliwere combined significant additive increases in collagen per wet weight (4-fold), compressive instantaneous (3-fold) and relaxation (2-fold) moduli, and tensile moduli in the circumferential (4-fold) and radial (6-fold) directions were obtained. Conclusions: This study demonstrates that a stimulation regimen of simultaneous tension and compression mechanical stimulation, C-ABC, and TGF-b1 is able to create anatomic meniscus constructs replicating the compressive mechanica

Cartilage-Specific Cre Recombinase Transgenes/Alleles in the Mouse

Cartilage is a specialized skeletal tissue with a unique extracellular matrix elaborated by its resident cells, chondrocytes. The tissue presents in several forms, including growth plate and articular cartilage, wherein chondrocytes follow a differential differentiation program and have different fates. The induction of gene modifications in cartilage specifically relies on mouse transgenes and knockin alleles taking advantages of transcriptional elements primarily active in chondrocytes at a specific differentiation stage or in a specific cartilage type. These transgenes/alleles have been widely used to study the roles of specific genes in cartilage development, adult homeostasis, and pathology. As cartilage formation is critical for postnatal life, the inactivation or significant alteration of key cartilaginous genes is often neonatally lethal and therefore hampers postnatal studies. Gold standard approaches to induce postnatal chondrocyte-specific gene modifications include the Cre-loxP and Tet-ON/OFF systems. Selecting the appropriate promoter/enhancer sequences to drive Cre expression is of crucial importance and determines the specificity of conditional gain- or loss-of-function models. In this chapter, we discuss a series of transgenes and knockin alleles that have been developed for gene manipulation in cartilage and we compare their expression patterns and efficiencies.</p