Aaron Tze Kai Tan

All Publications

• Secreted Particle Information Transfer (SPIT) - A Cellular Platform forIn VivoGenetic Engineering. bioRxiv : the preprint server for biology Charlesworth, C. T., Homma, S., Suchy, F., Wang, S., Bhadhury, J., Amaya, A. K., Camarena, J., Zhang, J., Tan, T. K., Igarishi, K., Nakauchi, H. 2024

  Abstract

  A multitude of tools now exist that allow us to precisely manipulate the human genome in a myriad of different ways. However, successful delivery of these tools to the cells of human patients remains a major barrier to their clinical implementation. Here we introduce a new cellular approach for in vivo genetic engineering, Secreted Particle Information Transfer (SPIT) that utilizes human cells as delivery vectors for in vivo genetic engineering. We demonstrate the application of SPIT for cell-cell delivery of Cre recombinase and CRISPR-Cas9 enzymes, we show that genetic logic can be incorporated into SPIT and present the first demonstration of human cells as a delivery platform for in vivo genetic engineering in immunocompetent mice. We successfully applied SPIT to genetically modify multiple organs and tissue stem cells in vivo including the liver, spleen, intestines, peripheral blood, and bone marrow. We anticipate that by harnessing the large packaging capacity of a human cell's nucleus, the ability of human cells to engraft into patients' long term and the capacity of human cells for complex genetic programming, that SPIT will become a paradigm shifting approach for in vivo genetic engineering.

  View details for DOI 10.1101/2024.01.11.575257

  View details for PubMedID 38260654

• Physioxia improves the selectivity of hematopoietic stem cell expansion cultures. Blood advances Igarashi, K. J., Kucinski, I., Chan, Y. Y., Tan, T., Khoo, H. M., Kealy, D., Bhadury, J., Hsu, I., Ho, P. Y., Niizuma, K., Hickey, J. W., Nolan, G., Bridge, K. S., Czechowicz, A., Gottgens, B., Nakauchi, H., Wilkinson, A. C. 2023

  Abstract

  Hematopoietic stem cells (HSCs) are a rare hematopoietic cell type that can entirely reconstitute the blood and immune systems following transplantation. Allogeneic HSC transplantation (HSCT) is used clinically as a curative therapy for a range of hematolymphoid diseases, but remains a high-risk therapy due to potential side effects including poor graft function and graft-vs-host disease (GvHD). Ex vivo HSC expansion has been suggested as an approach to improve hematopoietic reconstitution from low-cell dose grafts. Here, we demonstrate that we can improve the selectivity of polyvinyl alcohol (PVA)-based mouse HSC cultures through the use of physioxic culture conditions. Single-cell transcriptomic analysis confirmed inhibition of lineage-committed progenitor cells in physioxic cultures. Long-term physioxic expansion also afforded culture-based ex vivo HSC selection from whole bone marrow, spleen, and embryonic tissues. Furthermore, we provide evidence that HSC-selective ex vivo cultures deplete GvHD-causing T cells and that this approach can be combined with genotoxic-free antibody-based conditioning HSCT approaches. Our results offer a simple approach to improve PVA-based HSC cultures and the underlying molecular phenotype, as well as highlight the potential translational implications of selective HSC expansion systems for allogeneic HSCT.

  View details for DOI 10.1182/bloodadvances.2023009668

  View details for PubMedID 36809781

• Large-Scale Production of Wholly-Cellular Bioinks via the Optimization of Human Induced Pluripotent Stem Cell Aggregate Culture in Automated Bioreactors. Advanced healthcare materials Ho, D. L., Lee, S., Du, J., Weiss, J. D., Tam, T., Sinha, S., Klinger, D., Devine, S., Hamfeldt, A., Leng, H. T., Herrmann, J. E., He, M., Fradkin, L. G., Tan, T. K., Traul, D., Vicard, Q., Katikireddy, K., Skylar-Scott, M. A. 2022: e2201138

  Abstract

  Combining the sustainable culture of billions of human cells and the bioprinting of wholly-cellular bioinks offers a pathway towards organ-scale tissue engineering. Traditional 2D culture methods are not inherently scalable due to cost, space, and handling constraints. Here, we optimize the suspension culture of human induced pluripotent stem cell-derived aggregates using an automated 250 mL stirred tank bioreactor system. Cell yield, aggregate morphology, and pluripotency marker expression are maintained over three serial passages in two distinct cell lines. Furthermore, we demonstrate that the same optimized parameters can be scaled to an automated 1 L stirred tank bioreactor system. Our 4-day culture resulted in a 16.6- to 20.4-fold expansion of cells, we generate approximately 4 billion cells per vessel, while maintaining > 94% expression of pluripotency markers. The pluripotent aggregates can be subsequently differentiated into derivatives of the three germ layers, including cardiac aggregates, and vascular, cortical and intestinal organoids. Finally, the aggregates are compacted into a wholly-cellular bioink for rheological characterization and 3D bioprinting. The printed hAs are subsequently differentiated into neuronal and vascular tissue. This work demonstrates an optimized suspension culture-to-3D bioprinting pipeline that enables a sustainable approach to billion cell-scale organ engineering. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/adhm.202201138

  View details for PubMedID 36314397

• METABOLIC PROFILING OF MOUSE HEMATOPOIETIC STEM CELL SELF-RENEWAL AT SINGLE-CELL RESOLUTION Tan, A., Hartmann, F., Wilkinson, A., Nakauchi, H., Nolan, G. ELSEVIER SCIENCE INC. 2022: S145

  View details for Web of Science ID 000890643400249

• Human Finger-Prick Induced Pluripotent Stem Cells Facilitate the Development of Stem Cell Banking STEM CELLS TRANSLATIONAL MEDICINE Tan, H., Toh, C., Ma, D., Yang, B., Liu, T., Lu, J., Wong, C., Tan, T., Li, H., Syn, C., Tan, E., Lim, B., Lim, Y., Cook, S. A., Loh, Y. 2014; 3 (5): 586–98

  Abstract

  Induced pluripotent stem cells (iPSCs) derived from somatic cells of patients can be a good model for studying human diseases and for future therapeutic regenerative medicine. Current initiatives to establish human iPSC (hiPSC) banking face challenges in recruiting large numbers of donors with diverse diseased, genetic, and phenotypic representations. In this study, we describe the efficient derivation of transgene-free hiPSCs from human finger-prick blood. Finger-prick sample collection can be performed on a "do-it-yourself" basis by donors and sent to the hiPSC facility for reprogramming. We show that single-drop volumes of finger-prick samples are sufficient for performing cellular reprogramming, DNA sequencing, and blood serotyping in parallel. Our novel strategy has the potential to facilitate the development of large-scale hiPSC banking worldwide.

  View details for DOI 10.5966/sctm.2013-0195

  View details for Web of Science ID 000335939000015

  View details for PubMedID 24646489

  View details for PubMedCentralID PMC4006490