@article{warren_huebner_spang_shirwaiker_fisher_2017, title={Engineering 3D-Bioplotted scaffolds to induce aligned extracellular matrix deposition for musculoskeletal soft tissue replacement}, volume={58}, ISSN={["1607-8438"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85011664862&partnerID=MN8TOARS}, DOI={10.1080/03008207.2016.1276177}, abstractNote={ABSTRACT Purpose: Tissue engineering and regenerative medicine approaches have the potential to overcome the challenges associated with current treatment strategies for meniscus injuries. 3D-Bioplotted scaffolds are promising, but have not demonstrated the ability to guide the formation of aligned collagenous matrix in vivo, which is critical for generating functional meniscus tissue. In this study, we evaluate the ability of 3D-Bioplotted scaffold designs with varying interstrand spacing to induce the deposition of aligned matrix in vivo. Materials and Methods: 3D-Bioplotted polycaprolactone scaffolds with 100, 200, or 400 μm interstrand spacing were implanted subcutaneously in a rat model for 4, 8, or 12 weeks. Scaffolds were harvested, paraffin-embedded, sectioned, and stained to visualize cell nuclei and collagen. Quantitative image analysis was used to evaluate cell density, matrix fill, and collagen fiber alignment within the scaffolds. Results: By 4 weeks, cells had infiltrated the innermost scaffold regions. Similarly, collagenous matrix filled interstrand regions nearly completely by 4 weeks. By 12 weeks, aligned collagen was present in all scaffolds. Generally, alignment along the scaffold strands increased over time for all three interstrand spacing groups. Distribution of collagen fiber alignment angles narrowed as interstrand spacing decreased. Conclusions: 3D-Bioplotted scaffolds allow for complete cell infiltration and collagenous matrix production throughout the scaffold. The ability to use interstrand spacing as a means of controlling the formation of aligned collagen in vivo was demonstrated, which helps establish a design space for scaffold-based meniscus tissue engineering.}, number={3-4}, journal={CONNECTIVE TISSUE RESEARCH}, author={Warren, Paul B. and Huebner, Pedro and Spang, Jeffrey T. and Shirwaiker, Rohan A. and Fisher, Matthew B.}, year={2017}, pages={342–354} }
 @article{mellor_huebner_cai_mohiti-asli_taylor_spang_shirwaiker_loboa_2017, title={Fabrication and Evaluation of Electrospun, 3D-Bioplotted, and Combination of Electrospun/3D-Bioplotted Scaffolds for Tissue Engineering Applications}, volume={2017}, ISSN={["2314-6141"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85018911833&partnerID=MN8TOARS}, DOI={10.1155/2017/6956794}, abstractNote={Electrospun scaffolds provide a dense framework of nanofibers with pore sizes and fiber diameters that closely resemble the architecture of native extracellular matrix. However, it generates limited three-dimensional structures of relevant physiological thicknesses. 3D printing allows digitally controlled fabrication of three-dimensional single/multimaterial constructs with precisely ordered fiber and pore architecture in a single build. However, this approach generally lacks the ability to achieve submicron resolution features to mimic native tissue. The goal of this study was to fabricate and evaluate 3D printed, electrospun, and combination of 3D printed/electrospun scaffolds to mimic the native architecture of heterogeneous tissue. We assessed their ability to support viability and proliferation of human adipose derived stem cells (hASC). Cells had increased proliferation and high viability over 21 days on all scaffolds. We further tested implantation of stacked-electrospun scaffold versus combined electrospun/3D scaffold on a cadaveric pig knee model and found that stacked-electrospun scaffold easily delaminated during implantation while the combined scaffold was easier to implant. Our approach combining these two commonly used scaffold fabrication technologies allows for the creation of a scaffold with more close resemblance to heterogeneous tissue architecture, holding great potential for tissue engineering and regenerative medicine applications of osteochondral tissue and other heterogeneous tissues.}, journal={BIOMED RESEARCH INTERNATIONAL}, author={Mellor, Liliana F. and Huebner, Pedro and Cai, Shaobo and Mohiti-Asli, Mahsa and Taylor, Michael A. and Spang, Jeffrey and Shirwaiker, Rohan A. and Loboa, Elizabeth G.}, year={2017} }
 @article{narayanan_huebner_fisher_spang_starly_shirwaiker_2016, title={3D-Bioprinting of Polylactic Acid (PLA) Nanofiber–Alginate Hydrogel Bioink Containing Human Adipose-Derived Stem Cells}, volume={2}, ISSN={2373-9878 2373-9878}, url={http://dx.doi.org/10.1021/ACSBIOMATERIALS.6B00196}, DOI={10.1021/acsbiomaterials.6b00196}, abstractNote={Bioinks play a central role in 3D-bioprinting by providing the supporting environment within which encapsulated cells can endure the stresses encountered during the digitally driven fabrication process and continue to mature, proliferate, and eventually form extracellular matrix (ECM). In order to be most effective, it is important that bioprinted constructs recapitulate the native tissue milieu as closely as possible. As such, musculoskeletal soft tissue constructs can benefit from bioinks that mimic their nanofibrous matrix constitution, which is also critical to their function. This study focuses on the development and proof-of-concept assessment of a fibrous bioink composed of alginate hydrogel, polylactic acid nanofibers, and human adipose-derived stem cells (hASC) for bioprinting such tissue constructs. First, hASC proliferation and viability were assessed in 3D-bioplotted strands over 16 days in vitro. Then, a human medial knee meniscus digitally modeled using magnetic resonance images was bioprinted and evaluated over 8 weeks in vitro. Results show that the nanofiber-reinforced bioink allowed higher levels of cell proliferation within bioprinted strands, with a peak at day 7, while still maintaining a vast majority of viable cells at day 16. The cell metabolic activity on day 7 was 28.5% higher in this bioink compared to the bioink without nanofibers. Histology of the bioprinted meniscus at both 4 and 8 weeks showed 54% and 147% higher cell density, respectively, in external versus internal regions of the construct. The presence of collagen and proteoglycans was also noted in areas surrounding the hASC, indicating ECM secretion and chondrogenic differentiation.}, number={10}, journal={ACS Biomaterials Science & Engineering}, publisher={American Chemical Society (ACS)}, author={Narayanan, Lokesh Karthik and Huebner, Pedro and Fisher, Matthew B. and Spang, Jeffrey T. and Starly, Binil and Shirwaiker, Rohan A.}, year={2016}, month={Jul}, pages={1732–1742} }