@article{sper_proctor_lascina_guo_polkoff_kaeser_simpson_borst_gleason_zhang_et al._2022, title={Allogeneic and xenogeneic lymphoid reconstitution in a RAG2(-/-)IL2RG(y/-) severe combined immunodeficient pig: A preclinical model for intrauterine hematopoietic transplantation}, volume={9}, ISSN={["2297-1769"]}, DOI={10.3389/fvets.2022.965316}, abstractNote={Mice with severe combined immunodeficiency are commonly used as hosts of human cells. Size, longevity, and physiology, however, limit the extent to which immunodeficient mice can model human systems. To address these limitations, we generated RAG2−/−IL2RGy/− immunodeficient pigs and demonstrate successful engraftment of SLA mismatched allogeneic D42 fetal liver cells, tagged with pH2B-eGFP, and human CD34+ hematopoietic stem cells after in utero cell transplantation. Following intrauterine injection at day 42–45 of gestation, fetuses were allowed to gestate to term and analyzed postnatally for the presence of pig (allogeneic) and human (xenogeneic) B cells, T-cells and NK cells in peripheral blood and other lymphoid tissues. Engraftment of allogeneic hematopoietic cells was detected based on co-expression of pH2B-eGFP and various markers of differentiation. Analysis of spleen revealed robust generation and engraftment of pH2B-eGFP mature B cells (and IgH recombination) and mature T-cells (and TCR-β recombination), T helper (CD3+CD4+) and T cytotoxic (CD3+CD8+) cells. The thymus revealed engraftment of pH2B-eGFP double negative precursors (CD4−CD8−) as well as double positive (CD4+, CD8+) precursors and single positive T-cells. After intrauterine administration of human CD34+ hematopoietic stem cells, analysis of peripheral blood and lymphoid tissues revealed the presence of human T-cells (CD3+CD4+ and CD3+CD8+) but no detectable B cells or NK cells. The frequency of human CD45+ cells in the circulation decreased rapidly and were undetectable within 2 weeks of age. The frequency of human CD45+ cells in the spleen also decreased rapidly, becoming undetectable at 3 weeks. In contrast, human CD45+CD3+T-cells comprised >70% of cells in the pig thymus at birth and persisted at the same frequency at 3 weeks. Most human CD3+ cells in the pig's thymus expressed CD4 or CD8, but few cells were double positive (CD4+ CD8+). In addition, human CD3+ cells in the pig thymus contained human T-cell excision circles (TREC), suggesting de novo development. Our data shows that the pig thymus provides a microenvironment conducive to engraftment, survival and development of human T-cells and provide evidence that the developing T-cell compartment can be populated to a significant extent by human cells in large animals.}, journal={FRONTIERS IN VETERINARY SCIENCE}, author={Sper, Renan B. and Proctor, Jessica and Lascina, Odessa and Guo, Ling and Polkoff, Kathryn and Kaeser, Tobias and Simpson, Sean and Borst, Luke and Gleason, Katherine and Zhang, Xia and et al.}, year={2022}, month={Oct} }
 @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={AbstractHair follicle stem cells are key for driving growth and homeostasis of the hair follicle niche, have remarkable regenerative capacity throughout hair cycling, and display fate plasticity during cutaneous wound healing. Due to the need for a transgenic reporter, essentially all observations related to LGR5-expressing hair follicle stem cells have been generated using transgenic mice, which have significant differences in anatomy and physiology from the human. Using a transgenic pig model, a widely accepted model for human skin and human skin repair, we demonstrate that LGR5 is a marker of hair follicle stem cells across species in homeostasis and development. We also report the strong similarities and important differences in expression patterns, gene expression profiles, and developmental processes between species. This information is important for understanding the fundamental differences and similarities across species, and ultimately improving human hair follicle regeneration, cutaneous wound healing, and skin cancer treatment.}, 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{howe_cone_piedrahita_collins_fordham_griffith_spang_fisher_2021, title={Sex-specific biomechanics and morphology of the anterior cruciate ligament during skeletal growth in a porcine model}, volume={11}, ISSN={["1554-527X"]}, DOI={10.1002/jor.25207}, abstractNote={AbstractPediatric anterior cruciate ligament (ACL) injuries are on the rise, and females experience higher ACL injury risk than males during adolescence. Studies in skeletally immature patients indicate differences in ACL size and joint laxity between males and females after the onset of adolescence. However, functional data regarding the ACL and its anteromedial and posterolateral bundles in the pediatric population remain rare. Therefore, this study uses a porcine model to investigate the sex‐specific morphology and biomechanics of the ACL and its bundles throughout skeletal growth. Hind limbs from male and female Yorkshire pigs aged early youth to late adolescence were imaged using magnetic resonance imaging to measure the size and orientation of the ACL and its bundles, then biomechanically tested under anterior‐posterior drawer using a robotic testing system. Joint laxity decreased (p < 0.001) while joint stiffness increased (p < 0.001) throughout skeletal growth in both sexes. The ACL was the primary stabilizer against anterior tibial loading, while the functional role of the anteromedial bundle increased with age (p < 0.001), with an earlier increase in males. ACL and posterolateral bundle cross‐sectional area and ACL and anteromedial bundle length were larger in males than females during adolescence (p < 0.01 for all), while ACL and bundle sagittal angle remained similar between sexes. Additionally, in situ ACL stiffness versus cross‐sectional area regressions were significant across skeletal growth (r2 = 0.75, p < 0.001 in males and r2 = 0.64, p < 0.001 in females), but not within age groups. This study has implications for age and sex‐specific surgical intervention strategies and suggests the need for human studies.}, journal={JOURNAL OF ORTHOPAEDIC RESEARCH}, author={Howe, Danielle and Cone, Stephanie G. and Piedrahita, Jorge A. and Collins, Bruce and Fordham, Lynn A. and Griffith, Emily H. and Spang, Jeffrey T. and Fisher, Matthew B.}, year={2021}, month={Nov} }
 @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
          
            We show that mutations in
            HMGA2
            affect fetal resource allocation, testis descent, and the size of pigs and provides a target for gene modification that can be used to modulate size in other mammalian species. This can have implications in agriculture as well as in the development of new strains of companion animals. In addition, most xenograft pig donors have adult organs larger than those of humans. Recently, it has been shown that regulation of organ growth is donor-controlled, not host-controlled, resulting in organ overgrowth and damage after transplantation. We show here that the
            HMGA2
            gene is a potential target for organ-size regulation in xenotransplantation.
          }, 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} }