@article{HauptsteinForsterNadernezhadetal.2022,
  author    = {Hauptstein, Julia and Forster, Leonard and Nadernezhad, Ali and Horder, Hannes and Stahlhut, Philipp and Groll, J{\"u}rgen and Blunk, Torsten and Teßmar, J{\"o}rg},
  title     = {Bioink Platform Utilizing Dual-Stage Crosslinking of Hyaluronic Acid Tailored for Chondrogenic Differentiation of Mesenchymal Stromal Cells},
  series = {Macromolecular Bioscience},
  volume    = {22},
  journal   = {Macromolecular Bioscience},
  number    = {2},
  doi       = {10.1002/mabi.202100331},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257556},
  pages     = {2100331},
  year      = {2022},
  abstract  = {3D bioprinting often involves application of highly concentrated polymeric bioinks to enable fabrication of stable cell-hydrogel constructs, although poor cell survival, compromised stem cell differentiation, and an inhomogeneous distribution of newly produced extracellular matrix (ECM) are frequently observed. Therefore, this study presents a bioink platform using a new versatile dual-stage crosslinking approach based on thiolated hyaluronic acid (HA-SH), which not only provides stand-alone 3D printability but also facilitates effective chondrogenic differentiation of mesenchymal stromal cells. A range of HA-SH with different molecular weights is synthesized and crosslinked with acrylated (PEG-diacryl) and allylated (PEG-diallyl) polyethylene glycol in a two-step reaction scheme. The initial Michael addition is used to achieve ink printability, followed by UV-mediated thiol-ene reaction to stabilize the printed bioink for long-term cell culture. Bioinks with high molecular weight HA-SH (>200 kDa) require comparably low polymer content to facilitate bioprinting. This leads to superior quality of cartilaginous constructs which possess a coherent ECM and a strongly increased stiffness of long-term cultured constructs. The dual-stage system may serve as an example to design platforms using two independent crosslinking reactions at one functional group, which allows adjusting printability as well as material and biological properties of bioinks.},
  language  = {en}
}
@article{SunStarlyDalyetal.2020,
  author    = {Sun, Wei and Starly, Binil and Daly, Andrew C and Burdick, Jason A and Groll, J{\"u}rgen and Skeldon, Gregor and Shu, Wenmiao and Sakai, Yasuyuki and Shinohara, Marie and Nishikawa, Masaki and Jang, Jinah and Cho, Dong-Woo and Nie, Minghao and Takeuchi, Shoji and Ostrovidov, Serge and Khademhosseini, Ali and Kamm, Roger D and Mironov, Vladimir and Moroni, Lorenzo and Ozbolat, Ibrahim T},
  title     = {The bioprinting roadmap},
  series = {Biofabrication},
  volume    = {12},
  journal   = {Biofabrication},
  number    = {2},
  doi       = {10.1088/1758-5090/ab5158},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-254027},
  year      = {2020},
  abstract  = {This bioprinting roadmap features salient advances in selected applications of the technique and highlights the status of current developments and challenges, as well as envisioned advances in science and technology, to address the challenges to the young and evolving technique. The topics covered in this roadmap encompass the broad spectrum of bioprinting; from cell expansion and novel bioink development to cell/stem cell printing, from organoid-based tissue organization to bioprinting of human-scale tissue structures, and from building cell/tissue/organ-on-a-chip to biomanufacturing of multicellular engineered living systems. The emerging application of printing-in-space and an overview of bioprinting technologies are also included in this roadmap. Due to the rapid pace of methodological advancements in bioprinting techniques and wide-ranging applications, the direction in which the field should advance is not immediately clear. This bioprinting roadmap addresses this unmet need by providing a comprehensive summary and recommendations useful to experienced researchers and newcomers to the field.},
  language  = {en}
}
@article{HauptsteinForsterNadernezhadetal.2022,
  author    = {Hauptstein, Julia and Forster, Leonard and Nadernezhad, Ali and Groll, J{\"u}rgen and Teßmar, J{\"o}rg and Blunk, Torsten},
  title     = {Tethered TGF-β1 in a hyaluronic acid-based bioink for bioprinting cartilaginous tissues},
  series = {International Journal of Molecular Sciences},
  volume    = {23},
  journal   = {International Journal of Molecular Sciences},
  number    = {2},
  issn      = {1422-0067},
  doi       = {10.3390/ijms23020924},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-284239},
  year      = {2022},
  abstract  = {In 3D bioprinting for cartilage regeneration, bioinks that support chondrogenic development are of key importance. Growth factors covalently bound in non-printable hydrogels have been shown to effectively promote chondrogenesis. However, studies that investigate the functionality of tethered growth factors within 3D printable bioinks are still lacking. Therefore, in this study, we established a dual-stage crosslinked hyaluronic acid-based bioink that enabled covalent tethering of transforming growth factor-beta 1 (TGF-β1). Bone marrow-derived mesenchymal stromal cells (MSCs) were cultured over three weeks in vitro, and chondrogenic differentiation of MSCs within bioink constructs with tethered TGF-β1 was markedly enhanced, as compared to constructs with non-covalently incorporated TGF-β1. This was substantiated with regard to early TGF-β1 signaling, chondrogenic gene expression, qualitative and quantitative ECM deposition and distribution, and resulting construct stiffness. Furthermore, it was successfully demonstrated, in a comparative analysis of cast and printed bioinks, that covalently tethered TGF-β1 maintained its functionality after 3D printing. Taken together, the presented ink composition enabled the generation of high-quality cartilaginous tissues without the need for continuous exogenous growth factor supply and, thus, bears great potential for future investigation towards cartilage regeneration. Furthermore, growth factor tethering within bioinks, potentially leading to superior tissue development, may also be explored for other biofabrication applications.},
  language  = {en}
}
@article{RymaTylekLiebscheretal.2021,
  author    = {Ryma, Matthias and Tylek, Tina and Liebscher, Julia and Blum, Carina and Fernandez, Robin and B{\"o}hm, Christoph and Kastenm{\"u}ller, Wolfgang and Gasteiger, Georg and Groll, J{\"u}rgen},
  title     = {Translation of collagen ultrastructure to biomaterial fabrication for material-independent but highly efficient topographic immunomodulation},
  series = {Advanced materials},
  volume    = {33},
  journal   = {Advanced materials},
  number    = {33},
  doi       = {10.1002/adma.202101228},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256381},
  year      = {2021},
  abstract  = {Supplement-free induction of cellular differentiation and polarization solely through the topography of materials is an auspicious strategy but has so far significantly lagged behind the efficiency and intensity of media-supplementation-based protocols. Consistent with the idea that 3D structural motifs in the extracellular matrix possess immunomodulatory capacity as part of the natural healing process, it is found in this study that human-monocyte-derived macrophages show a strong M2a-like prohealing polarization when cultured on type I rat-tail collagen fibers but not on collagen I films. Therefore, it is hypothesized that highly aligned nanofibrils also of synthetic polymers, if packed into larger bundles in 3D topographical biomimetic similarity to native collagen I, would induce a localized macrophage polarization. For the automated fabrication of such bundles in a 3D printing manner, the strategy of "melt electrofibrillation" is pioneered by the integration of flow-directed polymer phase separation into melt electrowriting and subsequent selective dissolution of the matrix polymer postprocessing. This process yields nanofiber bundles with a remarkable structural similarity to native collagen I fibers, particularly for medical-grade poly(ε-caprolactone). These biomimetic fibrillar structures indeed induce a pronounced elongation of human-monocyte-derived macrophages and unprecedentedly trigger their M2-like polarization similar in efficacy as interleukin-4 treatment.},
  language  = {en}
}
@article{WeisShanKuhlmannetal.2018,
  author    = {Weis, Matthias and Shan, Junwen and Kuhlmann, Matthias and Jungst, Tomasz and Tessmar, J{\"o}rg and Groll, J{\"u}rgen},
  title     = {Evaluation of hydrogels based on oxidized hyaluronic acid for bioprinting},
  series = {Gels},
  volume    = {4},
  journal   = {Gels},
  number    = {4},
  issn      = {2310-2861},
  doi       = {10.3390/gels4040082},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197600},
  pages     = {82},
  year      = {2018},
  abstract  = {In this study, we evaluate hydrogels based on oxidized hyaluronic acid, cross-linked with adipic acid dihydrazide, for their suitability as bioinks for 3D bioprinting. Aldehyde containing hyaluronic acid (AHA) is synthesized and cross-linked via Schiff Base chemistry with bifunctional adipic acid dihydrazide (ADH) to form a mechanically stable hydrogel with good printability. Mechanical and rheological properties of the printed and casted hydrogels are tunable depending on the concentrations of AHA and ADH cross-linkers.},
  language  = {en}
}