In vitro expansion of CD 133+ cells derived from umbilical cord blood in poly-L-lactic acid (PLLA) scaffold coated with fibronectin and collagen

Context: Due to their renewal and potency, umbilical cord blood (UCB) stem cells have the ability to proliferate and serve as an attractive alternative source for bone marrow transplantation. However, insufficient number of haematopoietic stem cells (HSCs) in UCB is still a major constraint in clinical applications.

Objective: In vitro expansion of stem cells on fibronectin (Fn)-coated poly-L-lactic acid (PLLA) scaffold can be a proper way to overcome this limitation.

Materials and method: UCB CD133 + cells were isolated by magnetic cell sorting (MACS), and then the flowcytometry method was used for analysing CD133 + cells. Confirmed cells were seeded on the Fn-coated PLLA scaffold; also, collagen-coated PLLA scaffold, PLLA scaffold and two-dimensional (2D) culture system were expanded for 7 days. During this time, we used the flowcytometric method for analysing CD133 + cells and real-time PCR for the expression level of CXCR4 gene. The number of total cells and CD133 + cells, as well as MTT assay and colony-forming unit (CFU) assay were evaluated.

Results: Flowcytometry data indicated that the purity of CD133 + before expansion was 93%. After 7 days, there was higher number of CD133 + cells on the Fn-coated PLLA scaffold compared to other groups. Moreover, results of MTT and colony assays showed higher viability and proliferation of CD133 + on the Fn-coated PLLA scaffold. Also, the quantity of CXCR4 gene expression increased compared to other groups.

Discussion: The Fn-coated scaffold was the most effective scaffold for proliferation and improved the adhesiveness to the scaffold.

Conclusion: The Fn-coated PLLA scaffold could be a suitable in vitro mimicry niche over a 2D system.