@article{polkoff_gupta_green_murphy_chung_gleason_simpson_walker_collins_piedrahita_2022, title={LGR5 is a conserved marker of hair follicle stem cells in multiple species and is present early and throughout follicle morphogenesis}, volume={12}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-022-13056-w}, abstractNote={Abstract}, number={1}, journal={SCIENTIFIC REPORTS}, author={Polkoff, Kathryn M. and Gupta, Nithin K. and Green, Adrian J. and Murphy, Yanet and Chung, Jaewook and Gleason, Katherine L. and Simpson, Sean G. and Walker, Derek M. and Collins, Bruce and Piedrahita, Jorge A.}, year={2022}, month={Jun} }
 @article{chansoria_asif_polkoff_chung_piedrahita_shirwaiker_2021, title={Characterizing the Effects of Synergistic Thermal and Photo-Cross-Linking during Biofabrication on the Structural and Functional Properties of Gelatin Methacryloyl (GeIMA) Hydrogels}, volume={7}, ISSN={["2373-9878"]}, DOI={10.1021/acsbiomaterials.1c00635}, abstractNote={Gelatin methacryloyl (GelMA) hydrogels have emerged as promising and versatile biomaterial matrices with applications spanning drug delivery, disease modeling, and tissue engineering and regenerative medicine. GelMA exhibits reversible thermal cross-linking at temperatures below 37 °C due to the entanglement of constitutive polymeric chains, and subsequent ultraviolet (UV) photo-cross-linking can covalently bind neighboring chains to create irreversibly cross-linked hydrogels. However, how these cross-linking modalities interact and can be modulated during biofabrication to control the structural and functional characteristics of this versatile biomaterial is not well explored yet. Accordingly, this work characterizes the effects of synergistic thermal and photo-cross-linking as a function of GelMA solution temperature and UV photo-cross-linking duration during biofabrication on the hydrogels' stiffness, microstructure, proteolytic degradation, and responses of NIH 3T3 and human adipose-derived stem cells (hASC). Smaller pore size, lower degradation rate, and increased stiffness are reported in hydrogels processed at lower temperature or prolonged UV exposure. In hydrogels with low stiffness, the cells were found to shear the matrix and cluster into microspheroids, while poor cell attachment was noted in high stiffness hydrogels. In hydrogels with moderate stiffness, ones processed at lower temperature demonstrated better shape fidelity and cell proliferation over time. Analysis of gene expression of hASC encapsulated within the hydrogels showed that, while the GelMA matrix assisted in maintenance of stem cell phenotype (CD44), a higher matrix stiffness resulted in higher pro-inflammatory marker (ICAM1) and markers for cell-matrix interaction (ITGA1 and ITGA10). Analysis of constructs with ultrasonically patterned hASC showed that hydrogels processed at higher temperature possessed lower structural fidelity but resulted in more cell elongation and greater anisotropy over time. These findings demonstrate the significant impact of GelMA material formulation and processing conditions on the structural and functional properties of the hydrogels. The understanding of these material-process-structure-function interactions is critical toward optimizing the functional properties of GelMA hydrogels for different targeted applications.}, number={11}, journal={ACS BIOMATERIALS SCIENCE & ENGINEERING}, author={Chansoria, Parth and Asif, Suleman and Polkoff, Kathryn and Chung, Jaewook and Piedrahita, Jorge A. and Shirwaiker, Rohan A.}, year={2021}, month={Nov}, pages={5175–5188} }
 @article{polkoff_chung_simpson_gleason_piedrahita_2020, title={In Vitro Validation of Transgene Expression in Gene-Edited Pias Using CRISPR Transcriptional Activators}, volume={3}, ISSN={["2573-1602"]}, DOI={10.1089/crispr.2020.0037}, abstractNote={The use of CRISPR-Cas and RNA-guided endonucleases has drastically changed research strategies for understanding and exploiting gene function, particularly for the generation of gene-edited animal models. This has resulted in an explosion in the number of gene-edited species, including highly biomedically relevant pig models. However, even with error-free DNA insertion or deletion, edited genes are occasionally not expressed and/or translated as expected. Therefore, there is a need to validate the expression outcomes gene modifications in vitro before investing in the costly generation of a gene-edited animal. Unfortunately, many gene targets are tissue specific and/or not expressed in cultured primary cells, making validation difficult without generating an animal. In this study, using pigs as a proof of concept, we show that CRISPR-dCas9 transcriptional activators can be used to validate functional transgene insertion in nonexpressing easily cultured cells such as fibroblasts. This is a tool that can be used across disciplines and animal species to save time and resources by verifying expected outcomes of gene edits before generating live animals.}, number={5}, journal={CRISPR JOURNAL}, author={Polkoff, Kathryn M. and Chung, Jaewook and Simpson, Sean G. and Gleason, Katherine and Piedrahita, Jorge A.}, year={2020}, month={Oct}, pages={409–418} }
 @article{chung_zhang_collins_sper_gleason_simpson_koh_sommer_flowers_petters_et al._2018, title={High mobility group A2 (HMGA2) deficiency in pigs leads to dwarfism, abnormal fetal resource allocation, and cryptorchidism}, volume={115}, ISSN={0027-8424 1091-6490}, url={http://dx.doi.org/10.1073/pnas.1721630115}, DOI={10.1073/pnas.1721630115}, abstractNote={Significance}, number={21}, journal={Proceedings of the National Academy of Sciences}, publisher={Proceedings of the National Academy of Sciences}, author={Chung, Jaewook and Zhang, Xia and Collins, Bruce and Sper, Renan B. and Gleason, Katherine and Simpson, Sean and Koh, Sehwon and Sommer, Jeffrey and Flowers, William L. and Petters, Robert M. and et al.}, year={2018}, month={May}, pages={5420–5425} }
 @article{chung_tsai_james_thames_shytle_piedrahita_2012, title={Lack of genomic imprinting of DNA primase, polypeptide 2 (PRIM2) in human term placenta and white blood cells}, volume={7}, ISSN={["1559-2294"]}, DOI={10.4161/epi.19777}, abstractNote={PRIM2, encoding a subunit of primase involved in DNA replication and transcription, is expressed in the placenta and is crucial for mammalian development and growth. Its role in placental function is not well understood. Recently, PRIM2 was reported as imprinted in human white blood cells (WBC). We report here our failure to confirm imprinting of the PRIM2 locus in human placenta or WBC. The discordance between our results and those of others are likely due to an incorrectly annotated PRIM2 pseudogene found in the human genome database.}, number={5}, journal={EPIGENETICS}, author={Chung, Jaewook and Tsai, Shengdar and James, Andra H. and Thames, Betty H. and Shytle, Stephanie and Piedrahita, Jorge A.}, year={2012}, month={May}, pages={429–431} }