Stem Cell Factor is Essential for Preserving NOD/SCID Reconstitution Capacity of Ex vivo Expanded Cord Blood CD34(+) Cells

Objectives: Stem cell factor (SCF) is essential in the haematopoietic stem cells (HSCs) niche, and is therefore used extensively in haematopoietic stem and progenitor cells (HSPCs) ex vivo expansion. However, in the literature, dose and schedule of SCF feeding varies widely. We previously proposed a novel SCF feeding regimen with proven effectiveness for HSPCs expansion; however, physiological function of expanded cells with this SCF feeding regimen required further research.

Materials And Methods: CD34(+) cells were cultured with or without SCF supplementation in serum-free medium for 10 days. Expanded cells were transplanted into sublethally irradiated non-obese diabetic/severe combined immune-deficient (NOD/SCID) mice. Engraftment and multilineage reconstitution of transplanted cells were determined. Also, clonogenic potential of engrafted cells was analysed.

Results: Cells, both cultured with and without SCF supplementation, successfully engrafted and reconstituted blood cell lineages in NOD/SCID mice. However, level of engraftment and multilineage reconstitution reduced when cells were expanded without SCF supplementation. Meanwhile, frequencies of colony-forming cells (CFCs) amongst bone marrow cells were higher in mice transplanted with CD34(+) cells expanded with SCF supplementation.

Conclusions: Reconstitution capacity reduced when CD34(+) cells were expanded without SCF supplementation, though this feeding regimen did not have any effect on cell expansion. This finding suggested that SCF was essential for preserving NOD/SCID reconstitution capacity of ex vivo expanded CD34(+) cells.