L-carnitine cause to increase cell proliferation of C-Kit+ hematopoietic progenitor cells via decreasing the PI3K and FOXO-1 protein expression

Abstract

Background: Stem cell-based therapy has emerged as an attractive approach for regenerative medicine. Poor survival and maintenance of the cells used in regenerative medicine are considered as serious barriers to enhance the efficacy of the cell therapy. Using some antioxidants has been reported to prevent the aging of stem cells, and finding effective factors to reduce the senescence of these cells has impressive potential in cell therapy. The PI3K pathway adversely regulates the transcription factors known as FOXO, which are thought to have an inhibitory influence on cell proliferation. By downregulating FOXO and other targets, PI3K signaling controls the growth of cells. For this reason, the aim of the present study is to investigate the effect of L-carnitine (LC) as antioxidant on the cell proliferation and the protein expression of PI3K and FOXO.

Methods: For understanding the in vitro effect of LC on the PI3K and FOXO-1 expression of C-kit⁺ hematopoietic progenitor cells, the bone marrow mononuclear cells were isolated, and C-kit⁺ cells was enriched by the magnetic-activated cell sorting (MACS). Next, the identification of enriched C-kit⁺ cells were done by flowcytometry and immunocytochemistry. Then, C-kit⁺ cells were treated with 0.2 mM LC, the cells were collected at the end of the treatment period (48 h), and the proteins were extracted. In the following, the protein expression of PI3K and FOXO-1 was measured by western blotting. In addition, flowcytometry was done to assess the Ki-67 expression as a key marker for cell proliferation investigation.

Results: 0.2 mM LC cause to significantly decrease in the protein expression of PI3K and FOXO-1 (*P<0.05 and **P<0.01, respectively). Also, the expression of Ki-67 was significantly increased in the presence of 0.2 mM LC (***P<0.001).

Conclusion: Briefly, LC can be considered an effective factor in increasing the proliferation of C-kit⁺ cells via some signaling pathways.

Keywords: Aging; C-kit(+) hematopoietic progenitor cells; Clinical agent; Regenerative medicine.