@article{GrollBurdickChoetal.2019,
  author    = {Groll, J and Burdick, J A and Cho, D-W and Derby, B and Gelinsky, M and Heilshorn, S C and J{\"u}ngst, T and Malda, J and Mironov, V A and Nakayama, K and Ovsianikov, A and Sun, W and Takeuchi, S and Yoo, J J and Woodfield, T B F},
  title     = {A definition of bioinks and their distinction from biomaterial inks},
  series = {Biofabrication},
  volume    = {11},
  journal   = {Biofabrication},
  number    = {1},
  doi       = {10.1088/1758-5090/aaec52},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-253993},
  year      = {2019},
  abstract  = {Biofabrication aims to fabricate biologically functional products through bioprinting or bioassembly (Groll et al 2016 Biofabrication 8 013001). In biofabrication processes, cells are positioned at defined coordinates in three-dimensional space using automated and computer controlled techniques (Moroni et al 2018 Trends Biotechnol. 36 384-402), usually with the aid of biomaterials that are either (i) directly processed with the cells as suspensions/dispersions, (ii) deposited simultaneously in a separate printing process, or (iii) used as a transient support material. Materials that are suited for biofabrication are often referred to as bioinks and have become an important area of research within the field. In view of this special issue on bioinks, we aim herein to briefly summarize the historic evolution of this term within the field of biofabrication. Furthermore, we propose a simple but general definition of bioinks, and clarify its distinction from biomaterial inks.},
  language  = {en}
}
@article{FernandezRobredoSanchoJohnenetal.2014,
  author    = {Fernandez-Robredo, P. and Sancho, A. and Johnen, S. and Recalde, S. and Gama, N. and Thumann, G. and Groll, J. and Garcia-Layana, A.},
  title     = {Current Treatment Limitations in Age-Related Macular Degeneration and Future Approaches Based on Cell Therapy and Tissue Engineering},
  series = {Journal of Ophtamology},
  journal   = {Journal of Ophtamology},
  number    = {510285},
  issn      = {2090-0058},
  doi       = {10.1155/2014/510285},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-118004},
  year      = {2014},
  abstract  = {Age-related macular degeneration (AMD) is the leading cause of blindness in the Western world. With an ageing population, it is anticipated that the number of AMD cases will increase dramatically, making a solution to this debilitating disease an urgent requirement for the socioeconomic future of the European Union and worldwide. The present paper reviews the limitations of the current therapies as well as the socioeconomic impact of the AMD. There is currently no cure available for AMD, and even palliative treatments are rare. Treatment options show several side effects, are of high cost, and only treat the consequence, not the cause of the pathology. For that reason, many options involving cell therapy mainly based on retinal and iris pigment epithelium cells as well as stem cells are being tested. Moreover, tissue engineering strategies to design and manufacture scaffolds to mimic Bruch's membrane are very diverse and under investigation. Both alternative therapies are aimed to prevent and/or cure AMD and are reviewed herein.},
  language  = {en}
}
@article{WeissenbergerWeissenbergerGilbertetal.2020,
  author    = {Weissenberger, M. and Weissenberger, M. H. and Gilbert, F. and Groll, J. and Evans, C. H. and Steinert, A. F.},
  title     = {Reduced hypertrophy in vitro after chondrogenic differentiation of adult human mesenchymal stem cells following adenoviral SOX9 gene delivery},
  series = {BMC Musculoskeletal Disorders},
  volume    = {20},
  journal   = {BMC Musculoskeletal Disorders},
  doi       = {10.1186/s12891-020-3137-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229232},
  year      = {2020},
  abstract  = {Background Mesenchymal stem cell (MSC) based-treatments of cartilage injury are promising but impaired by high levels of hypertrophy after chondrogenic induction with several bone morphogenetic protein superfamily members (BMPs). As an alternative, this study investigates the chondrogenic induction of MSCs via adenoviral gene-delivery of the transcription factor SOX9 alone or in combination with other inducers, and comparatively explores the levels of hypertrophy and end stage differentiation in a pellet culture system in vitro. Methods First generation adenoviral vectors encoding SOX9, TGFB1 or IGF1 were used alone or in combination to transduce human bone marrow-derived MSCs at 5 x 10\(^2\) infectious particles/cell. Thereafter cells were placed in aggregates and maintained for three weeks in chondrogenic medium. Transgene expression was determined at the protein level (ELISA/Western blot), and aggregates were analysed histologically, immunohistochemically, biochemically and by RT-PCR for chondrogenesis and hypertrophy. Results SOX9 cDNA was superior to that encoding TGFB1, the typical gold standard, as an inducer of chondrogenesis in primary MSCs as evidenced by improved lacuna formation, proteoglycan and collagen type II staining, increased levels of GAG synthesis, and expression of mRNAs associated with chondrogenesis. Moreover, SOX9 modified aggregates showed a markedly lower tendency to progress towards hypertrophy, as judged by expression of the hypertrophy markers alkaline phosphatase, and collagen type X at the mRNA and protein levels. Conclusion Adenoviral SOX9 gene transfer induces chondrogenic differentiation of human primary MSCs in pellet culture more effectively than TGFB1 gene transfer with lower levels of chondrocyte hypertrophy after 3 weeks of in vitro culture. Such technology might enable the formation of more stable hyaline cartilage repair tissues in vivo.},
  language  = {en}
}
@article{JungstPenningsSchmitzetal.2019,
  author    = {Jungst, Tomasz and Pennings, Iris and Schmitz, Michael and Rosenberg, Antoine J. W. P. and Groll, J{\"u}rgen and Gawlitta, Debby},
  title     = {Heterotypic Scaffold Design Orchestrates Primary Cell Organization and Phenotypes in Cocultured Small Diameter Vascular Grafts},
  series = {Advanced Functional Materials},
  volume    = {29},
  journal   = {Advanced Functional Materials},
  doi       = {10.1002/adfm.201905987},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-217039},
  year      = {2019},
  abstract  = {To facilitate true regeneration, a vascular graft should direct the evolution of a neovessel to obtain the function of a native vessel. For this, scaffolds have to permit the formation of an intraluminal endothelial cell monolayer, mimicking the tunica intima. In addition, when attempting to mimic a tunica media-like outer layer, the stacking and orientation of vascular smooth muscle cells (vSMCs) should be recapitulated. An integral scaffold design that facilitates this has so far remained a challenge. A hybrid fabrication approach is introduced by combining solution electrospinning and melt electrowriting. This allows a tissue-structure mimetic, hierarchically bilayered tubular scaffold, comprising an inner layer of randomly oriented dense fiber mesh and an outer layer of microfibers with controlled orientation. The scaffold supports the organization of a continuous luminal endothelial monolayer and oriented layers of vSM-like cells in the media, thus facilitating control over specific and tissue-mimetic cellular differentiation and support of the phenotypic morphology in the respective layers. Neither soluble factors nor a surface bioactivation of the scaffold is needed with this approach, demonstrating that heterotypic scaffold design can direct physiological tissue-like cell organization and differentiation.},
  language  = {en}
}