title: Laser-structured bacterial nanocellulose hydrogels support ingrowth and differentiation of chondrocytes and show potential as cartilage implants.
abstract: The small size and heterogeneity of the pores in bacterial nanocellulose (BNC) hydrogels limit the ingrowth of cells and their use as tissue-engineered implant materials. The use of placeholders during BNC biosynthesis or post-processing steps such as (touch-free) laser perforation can overcome this limitation. Since three-dimensionally arranged channels may be required for homogeneous and functional seeding, three-dimensional (3-D) laser perforation of never-dried BNC hydrogels was performed. Never-dried BNC hydrogels were produced in different shapes by: (i) the cultivation of Gluconacetobacter xylinus (DSM 14666; synonym Komagataeibacter xylinus) in nutrient medium; (ii) the removal of bacterial residues/media components (0.1M NaOH; 30 min; 100 °C) and repeated washing (deionized water; pH 5.8); (iii) the unidirectional or 3-D laser perforation and cutting (pulsed CO2 Rofin SC × 10 laser; 220 μm channel diameter); and (iv) the final autoclaving (2M NaOH; 121 °C; 20 min) and washing (pyrogen-free water). In comparison to unmodified BNC, unidirectionally perforated--and particularly 3-D-perforated - BNC allowed ingrowth into and movement of vital bovine/human chondrocytes throughout the BNC nanofiber network. Laser perforation caused limited structural modifications (i.e. fiber or globular aggregates), but no chemical modifications, as indicated by Fourier transform infrared spectroscopy, X-ray photoelectron scattering and viability tests. Pre-cultured human chondrocytes seeding the surface/channels of laser-perforated BNC expressed cartilage-specific matrix products, indicating chondrocyte differentiation. 3-D-perforated BNC showed compressive strength comparable to that of unmodified samples. Unidirectionally or 3-D-perforated BNC shows high biocompatibility and provides short diffusion distances for nutrients and extracellular matrix components. Also, the resulting channels support migration into the BNC, matrix production and phenotypic stabilization of chondrocytes. It may thus be suitable for in vivo application, e.g. as a cartilage replacement material.
authors: Jenpolymer Materials Ltd & Co. KG, Wildenbruchstraße 15, 07745 Jena, Germany.
authors: Hannes
authors: H
authors: Ahrem
authors: Experimental Rheumatology Unit, Department of Orthopedics, Jena University Hospital, Jena, Klosterlausnitzer Str. 81, D-07607 Eisenberg, Germany.
authors: David
authors: D
authors: Pretzel
authors: TransTissue Technologies GmbH, Charitéplatz 1/Virchowweg 11, 10117 Berlin, Germany.
authors: Michaela
authors: M
authors: Endres
authors: Günter-Köhler-Institut für Fügetechnik und Werkstoffprüfung GmbH, Otto-Schott-Straße 13, 07745 Jena, Germany.
authors: Daniel
authors: D
authors: Conrad
authors: Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany.
authors: Julien
authors: J
authors: Courseau
authors: Günter-Köhler-Institut für Fügetechnik und Werkstoffprüfung GmbH, Otto-Schott-Straße 13, 07745 Jena, Germany.
authors: Hartmut
authors: H
authors: Müller
authors: Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany.
authors: Raimund
authors: R
authors: Jaeger
authors: TransTissue Technologies GmbH, Charitéplatz 1/Virchowweg 11, 10117 Berlin, Germany.
authors: Christian
authors: C
authors: Kaps
authors: Jenpolymer Materials Ltd & Co. KG, Wildenbruchstraße 15, 07745 Jena, Germany.
authors: Dieter O
authors: DO
authors: Klemm
authors: Experimental Rheumatology Unit, Department of Orthopedics, Jena University Hospital, Jena, Klosterlausnitzer Str. 81, D-07607 Eisenberg, Germany. Electronic address: raimund.w.kinne@med.uni-jena.de.
authors: Raimund W
authors: RW
authors: Kinne
mesh_terms: D000368:Aged; D000818:Animals; D002356:Cartilage / Q000502:physiology*; D002417:Cattle; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002482:Cellulose / Q000494:pharmacology*; D019902:Chondrocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D019245:Compressive Strength / Q000187:drug effects; D055119:Elastic Modulus / Q000187:drug effects; D041822:Gluconacetobacter xylinus / Q000737:chemistry*; D006801:Humans; D020100:Hydrogels; D007834:Lasers; D008297:Male; D008875:Middle Aged; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D056951:Photoelectron Spectroscopy; D019736:Prostheses and Implants; D060888:Real-Time Polymerase Chain Reaction; D012972:Sodium Hydroxide / Q000494:pharmacology; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D020100:Hydrogels; D012972:Sodium Hydroxide; D002482:Cellulose
keywords: Bacterial nanocellulose; Cartilage implant; Chondrocyte ingrowth/differentiation; Laser structuring; Microbial cellulose