Ex vivo expansion of hematopoietic stem cells (HSCs) is an approach for overcoming cell insufficiency for umbilical cord blood transplantation. It was suggested that in common ex vivo cultures, the stemness specificity of HSCs is rapidly reducing due to DNA hypermethylation. Here, Nicotinamide (NAM), a DNA methyltransferase and histone deacetylase inhibitor, is used with a bioengineered Bone Marrow-like niche (BLN) for HSC ex vivo expansion. The CFSE cell proliferation assay was used for tracking HSCs division. qRT-PCR was conducted to assay the HOXB4 mRNA expression levels. The morphology of BLN-cultured cells was analyzed using scanning electron microscopy (SEM). NAM boosted the induction of HSC proliferation in the BLN group compared to the control group. In addition, the ability of HSCs to colonize was more significant in the BLN group than in the control group. Our data suggest that the presence of NAM in bioengineered niches promotes HSC proliferation. The presented approach showed that small molecules could be used in the clinical setting to overcome the limited number of CD34⁺ cells in cord blood units.

造血干细胞（HSC）的离体扩增是克服脐带血移植细胞不足的一种方法。有人提出，在常见的离体培养物中，由于 DNA 高甲基化，HSC 的干细胞特异性迅速降低。在此，烟酰胺 (NAM)（一种 DNA 甲基转移酶和组蛋白脱乙酰酶抑制剂）与生物工程骨髓样利基 (BLN) 一起用于 HSC 离体扩增。CFSE细胞增殖测定用于追踪HSC分裂。进行 qRT-PCR 测定 HOXB4 mRNA 表达水平。使用扫描电子显微镜 (SEM) 分析 BLN 培养细胞的形态。与对照组相比，NAM 增强了 BLN 组 HSC 增殖的诱导作用。此外，BLN 组的 HSC 定植能力比对照组更显着。我们的数据表明，生物工程利基中 NAM 的存在可促进 HSC 增殖。所提出的方法表明，小分子可用于临床环境，以克服脐带血单位中CD34 ^{+细胞数量有限的问题。}