In vitro biomimetic engineering of a human hematopoietic niche with functional properties

Abstract

In adults, human hematopoietic stem and progenitor cells (HSPCs) reside in the bone marrow (BM) microenvironment. Our understanding of human hematopoiesis and the associated niche biology remains limited, due to human material accessibility and limits of existing in vitro culture models. The establishment of an in vitro BM system would offer an experimentally accessible and tunable platform to study human hematopoiesis. Here, we develop a 3D engineered human BM analog by recapitulating some of the hematopoietic niche elements. This includes a bone-like scaffold, functionalized by human stromal and osteoblastic cells and by the extracellular matrix they deposited during perfusion culture in bioreactors. The resulting tissue exhibited compositional and structural features of human BM while supporting the maintenance of HSPCs. This was associated with a compartmentalization of phenotypes in the bioreactor system, where committed blood cells are released into the liquid phase and HSPCs preferentially reside within the engineered BM tissue, establishing physical interactions with the stromal compartment. Finally, we demonstrate the possibility to perturb HSPCs' behavior within our 3D niches by molecular customization or injury simulation. The developed system enables the design of advanced, tunable in vitro BM proxies for the study of human hematopoiesis.

A Human Hematopoietic Niche Model Supporting Hematopoietic Stem and Progenitor Cells In Vitro

“…The model allows further study of interactions between various supportive cell types and HSPCs. Current 3D models are based on MSCs and/or O‐MSCs, mimicking only the endosteal niche . MSCs as well as adipogenic and osteogenic progenitors are known to be an essential component of the HSC niche, required for the quiescence, proliferation, and differentiation of HSPCs .…”

“…Instead, these models applied cell types that are suboptimal for in vitro HSPC culture, such as 2D cultured MSCs and/or O‐MSC . Also cytokine supplemented media was used, with less supportive capacities toward primitive HSPCs over time when compared to feeder cell lines . Other studies focused on optimizing hydrogels or culture conditions did not include controls containing supportive cells or cytokines other than the ones tested in their endosteal models .…”

“…When developing an in vitro HSPC model, it is of importance to optimize both the cellular compartment of the model, as well as the used hydrogel mimicking the ECM of the niche. To mimic the endosteal niche, hydrogels (e.g., Matrigel, collagen, Puramatrix, alginate, or PEG) or bone mimicking materials (e.g., βTCP, hydroxyapatite, or bioderived bone) have been used. In addition to these materials, models used either stromal cell lines or human primary cells as supportive cell sources.…”

“…In addition to these materials, models used either stromal cell lines or human primary cells as supportive cell sources. The primary cell sources are multipotent mesenchymal stromal cells (MSCs) or osteogenic differentiated MSCs (O‐MSCs) . In these primary cell models, the use of additional cytokine supplemented medium is still common practice, to enhance the survival of the cultured HSPCs.…”

Thermoresponsive Inverted Colloidal Crystal Hydrogel Scaffolds for Lymphoid Tissue Engineering

“…This ability opens the door for advanced biomanufacturing of a wide array of hematopoietic‐lymphoid cells. Ex vivo expansion of HSCs, T and B lymphocytes has long been pursued to broaden their therapeutic potential . For example, HSC transplantation is the most advanced and successful stem cell therapy.…”