The hematopoietic niche is a specialized microenvironment that supports the survival, proliferation and differentiation of hematopoietic stem progenitor cells (HSPCs). Three-dimensional (3D) models mimicking hematopoiesis might allow in vitro and in vivo studies of the hematopoietic (HP) process. Here, we investigate the capacity of a 3D construct based on non-adherent murine bone marrow mononuclear cells (NA-BMMNCs), mesenchymal stromal cells (MSCs) and collagen microspheres (CMs), all embedded into plasma clot (PC) to support in vitro and in vivo hematopoiesis. Confocal analysis of the 3D hematopoietic construct (3D-HPC), cultured for 24 h, showed MSC lining the CM and the NA-BMMNCs closely associated with MSC. In vivo hematopoiesis was examined in 3D-HPC subcutaneously implanted in mice and harvested at different intervals. Hematopoiesis in the 3D-HPC was evaluated by histology, cell morphology, flow cytometry, confocal microscopy and hematopoietic colony formation assay. 3D-HPC implants were integrated and vascularized in the host tissue, after 3 months of implantation. Histological studies showed the presence of hematopoietic tissue with the presence of mature blood cells. Cells from 3D-HPC showed viability greater than 90%, expressed HSPCs markers, and formed hematopoietic colonies, in vitro. Confocal microscopy studies showed that MSCs adhered to the CM and NA-BMMNCs were scattered across the 3D-HPC area and in close association with MSC. In conclusion, the 3D-HPC mimics a hematopoietic niche supporting the survival, proliferation and differentiation of HSPCs, in vivo. 3D-HPC may allow evaluation of regulatory mechanisms involved in hematopoiesis.

中文翻译：

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基于间充质基质细胞、胶原微球和血浆凝块的 3D 构建体支持体内造血细胞的存活、增殖和分化

造血生态位是一种特殊的微环境，支持造血干祖细胞 (HSPC) 的存活、增殖和分化。模拟造血的三维 (3D) 模型可能允许对造血 (HP) 过程进行体外和体内研究。在这里，我们研究了基于非贴壁小鼠骨髓单核细胞 (NA-BMMNC)、间充质基质细胞 (MSC) 和胶原微球 (CM) 的 3D 构建体的能力，所有这些构建体都嵌入血浆凝块 (PC) 以支持体外和体内造血。对培养 24 小时的 3D 造血构建体 (3D-HPC) 进行共聚焦分析，显示 MSC 衬在 CM 内，NA-BMMNCs 与 MSC 密切相关。在皮下植入小鼠并在不同时间间隔收获的 3D-HPC 中检查体内造血。3D-HPC 中的造血通过组织学、细胞形态学、流式细胞术、共聚焦显微镜和造血集落形成测定进行评估。植入 3 个月后，3D-HPC 植入物在宿主组织中整合并形成血管。组织学研究表明存在成熟血细胞的造血组织。来自 3D-HPC 的细胞在体外表现出大于 90% 的活力，表达 HSPC 标志物，并形成造血集落。共聚焦显微镜研究表明，粘附在 CM 上的 MSCs 和 NA-BMMNCs 分散在 3D-HPC 区域并与 MSC 密切相关。总之，3D-HPC 模拟了一个造血生态位，支持体内 HSPC 的存活、增殖和分化。3D-HPC 可能允许评估涉及造血的调节机制。