Bioengineered ipsc-derived models of human bone marrow for studies of systemic injury and disease

The human bone marrow (BM) is one of the most complex and critical tissues in the adult, functioning as the site for hematopoietic stem and progenitor cell (HSPC) maintenance, as well as blood and immune cell production in homeostasis, injury, and disease. As the development of human organs-on-a-chip (OoC) platforms has emerged over the past decade, there has been an increased relevance of using human BM models to study human-specific immune interactions in vitro. Here we report the development of a patient-specific bioengineered model of the BM, derived entirely from induced pluripotent stem cells (iPSCs) and its use in studies of radiation toxicity, cancer, and systemic injury responses. The engineered model of human BM (eBM) is derived from iPSC-derived osteoblasts, mesenchymal stem/stromal cells, and endothelial cells within a decellularized bone scaffold. This model was developed to be modular, with ability to include either healthy cord blood-, iPSC-, or BM-derived HSPCs. We validated the model with histological staining, flow cytometry, colony forming assays, and single-cell RNA sequencing, demonstrating maintenance and differentiation of blood progenitors and progeny, and describe here applications in acute radiation injury, leukemic infiltration, solid tumor metastasis, and systemic, multi-tissue interactions. Notably, eBMs were able to maintain donor acute myeloid and B-/T-lymphoblastic leukemias better than in liquid cultures, as well as recapitulating drug responses seen clinically. Further, we linked the healthy eBM model to engineered cardiac tissues by vascular perfusion to demonstrate the recruitment of monocytes from eBMs in response to an acute cardiac injury, in a multi-OoC setting. We propose that this novel model system can be used to study malignant transformation, systemic immune responses, and the development of personalized therapeutics. The human bone marrow (BM) is one of the most complex and critical tissues in the adult, functioning as the site for hematopoietic stem and progenitor cell (HSPC) maintenance, as well as blood and immune cell production in homeostasis, injury, and disease. As the development of human organs-on-a-chip (OoC) platforms has emerged over the past decade, there has been an increased relevance of using human BM models to study human-specific immune interactions in vitro. Here we report the development of a patient-specific bioengineered model of the BM, derived entirely from induced pluripotent stem cells (iPSCs) and its use in studies of radiation toxicity, cancer, and systemic injury responses. The engineered model of human BM (eBM) is derived from iPSC-derived osteoblasts, mesenchymal stem/stromal cells, and endothelial cells within a decellularized bone scaffold. This model was developed to be modular, with ability to include either healthy cord blood-, iPSC-, or BM-derived HSPCs. We validated the model with histological staining, flow cytometry, colony forming assays, and single-cell RNA sequencing, demonstrating maintenance and differentiation of blood progenitors and progeny, and describe here applications in acute radiation injury, leukemic infiltration, solid tumor metastasis, and systemic, multi-tissue interactions. Notably, eBMs were able to maintain donor acute myeloid and B-/T-lymphoblastic leukemias better than in liquid cultures, as well as recapitulating drug responses seen clinically. Further, we linked the healthy eBM model to engineered cardiac tissues by vascular perfusion to demonstrate the recruitment of monocytes from eBMs in response to an acute cardiac injury, in a multi-OoC setting. We propose that this novel model system can be used to study malignant transformation, systemic immune responses, and the development of personalized therapeutics.