Sambathkumar, R. | bioRxiv Science

bioRxiv2024

FAST-STEM: A human pluripotent stem cell engineering toolkit for rapid design-build-test-learn development of human cell-based therapeutic devices

Very recent clinical advances in stem cell derived tissue replacement and gene therapy, in addition to the rise of artificial intelligence-aided scientific discovery, have placed the possibility of sophisticated human cell-based therapies firmly within reach. However, development of such cells and testing of their engineered gene circuit components, has proven highly challenging, due to the need for generating stable cell lines for each design-build-test-learn engineering cycle. Current approaches to generating stable human induced pluripotent stem cell (hiPSC) lines are highly time-consuming and suffer from lack of control, poor integration efficiency, and limited functionality. Validation in clinically relevant stem cell derived tissues is also broadly lacking. Such drawbacks are prohibitive to repeatably conducting cutting-edge stem cell engineering with broad application within a realistic timeframe and will not scale with the future of regenerative medicine. We have developed FAST-STEM (Facile Accelerated Stem-cell Transgene integration with SynBio Tunable Engineering Modes), a hPSC engineering platform that drastically reduces the time to generate differentiation ready stem cell lines from several weeks to 5 days, exhibiting a ~612-fold improvement in transgene integration rate over previous methodologies. Additional FAST-STEM innovations include: (i) rapid and highly efficient transgene integration; (ii) copy number control; (iii) simultaneous or consecutive integration of multiple gene cassettes; (iv) library screen capability. In addition to this unique functional versatility, platform transportability and broad use case for stem cell-engineering was confirmed by differentiation into eight different cell types across nine different laboratories. This platform dramatically lowers the bar for integration of synthetic biology with regenerative medicine, enabling experiments which were previously deemed logistically impossible, thus paving the way for sophisticated human cell device development.

bioengineering↗

bioRxiv2023

Macrophages heterogeneity and significance during human fetal pancreatic development

Organogenesis is a complex process that relies on a dynamic interplay between extrinsic factors originating from the microenvironment and intrinsic factors specific to the tissue. For the endocrine cells of the islet of Langerhans, the local microenvironment consists of various cell types including pancreatic acinar and ductal cells as well as neuronal, immune, endothelial, and stromal cells. Interestingly, hematopoietic cells have been detected in human pancreas as early as 6 post-conception weeks (PCW)1,2, but whether they play a role during islet formation in humans remains largely unknown. To shed light on this question, we performed single nuclei RNA sequencing of the human fetal pancreas during the early weeks of the second trimester, specifically focusing on the molecular interaction between the hematopoietic niche and the pancreatic epithelium. Our analysis identified a wide range of hematopoietic cells as well as two distinct subsets of macrophages that are unique to the fetal pancreas and absent in neonatal or adult pancreatic tissues. Leveraging this discovery, we developed a co-culture system of hESC-derived endocrine-macrophage organoids to model their interaction in vitro. Remarkably, we found that macrophages promoted the differentiation and viability of developing endocrine cells in vitro and enhanced tissue engraftment in immunocompromised mice, supporting a role for these cells in future tissue engineering strategies for diabetes.

developmental biology↗