Maintenance and expansion of hematopoietic stem/progenitor cells in biomimetic osteoblast niche

In this study, we employed bio-derived bone scaffold and composited with the marrow mesenchymal stem cell induced into osteoblast to replicate a “biomimetic niche.” The CD34+ cells or mononuclear cells (MNC) from umbilical cord blood were cultured for 2–5 weeks in the biomimetic niche (3D system) was compared with conventional two dimensional cultures (2D system) without adding cytokine supplement. After 2 weeks in culture, the CD34+ cells from umbilical cord blood in the 3D system increased 3.3–4.8 folds when compared with the initial CD34+ cells. CD34+/CD38− cells accounted for 82–90% of CD34+ cells. After 5 weeks, CD34+/CD38− cells in the 3D system increased when compared with initial (1.3 ± 0.3 × 103 vs. 1.0 ± 0.5 × 104, p < 0.05), but were decreased in the 2D system (1.3 ± 0.3 × 103 vs. 2.5 ± 0.7 × 102, p < 0.05). The CFU progenitors were produced more in the 3D system than in the 2D system (4.6–9.3 folds vs. 1.0–1.5 folds) after 2 weeks in culture, and the colony distribution in the 3D system manifested higher percentage of BFU-E and CFU-GEMM, but in the 2D system was mainly CFU-GM. The LTC-ICs in the 3D system showed 5.2–7.2 folds increase over input at 2 weeks in culture, and maintain the immaturation of hematopoietic progenitor cells (HPCs) over 5 weeks. In conclusion, this new 3D hematopoietic progenitor cell culture system is the first to utilize natural cancellous bone as scaffold with osteoblasts as supporting cells; it is mimicry of natural bone marrow HSC niche. Our primary work has demonstrated it could maintain and expand HSC/HPC in vitro.