Over expression of HIF-1α in human mesenchymal stem cells increases their supportive functions for hematopoietic stem cells in an experimental co-culture model.

INTRODUCTION: Bone marrow transplantation is a critical approach for the treatment of many hematological disorders. Success of this approach is dependent on many factors the most important of which is the number of hematopoietic stem cells along with an efficient stroma. Co-transplantation of efficient mesenchymal stem cells can greatly improve the outcome of transplantations. Current researches assign a critical role for hypoxia inducible factor (HIF)-1α in protection of various cells and tissues probably through induction of cytokines. To make this feature applicable to human bone marrow-derived mesenchymal stem cells, we manipulated these cells to over express HIF-1α gene. MATERIALS AND METHODS: Full-length cDNA of human HIF-1α was inserted into human bone marrow mesenchymal stem cells by pcDNA.3.1 non-viral plasmid vector, and the effect of this over expression on production of some hematopoietic growth factors was explored. Moreover, using a co-culture system, the interactive impact of HIF-1α-overexpressed mesenchymal stem cells on hematopoietic stem cells was evaluated. Results Over expression of HIF-1α in mesenchymal stem cells in normoxia increased production of one of the most important hematopoietic growth factors, Stem cell factor (also known as Steel factor or c-kit ligand). HIF-1α overexpression had no effect on production of other hematopoietic growth factors. In co-culture of mesenchymal stem cells-HIF-1α with hematopoietic stem cells, enhancement of colony formation and reduced differentiation of hematopoietic stem cells were observed. Conclusion Over expression of HIF-1α in human bone marrow-derived mesenchymal stem cells can augment the production of some hematopoietic growth factors, and we suggest this response of mesenchymal stem cells could help to improve the outcome of bone marrow transplantation.

HIF-1α confers resistance to induced stress in bone marrow-derived mesenchymal stem cells.

BACKGROUND AND AIMS: The major limiting factor in therapeutic application of mesenchymal stem cells (MSCs) is their high vulnerability during the early days of transplantation. Hence, researchers have been encouraged to find various strategies to make the cells resistant to different stresses before and after transplantation. Overexpression of HIF-1α in MSCs to confer resistance against harmful conditions was the aim of this study. METHODS: Using an in vitro approach, we engineered MSCs to overexpress HIF-1α and then evaluated their viability following exposure to hypoxic and oxidative stresses. The inherent expression of HIF-1α was downregulated by siRNA. Viability and apoptosis of the MSCs were then evaluated in vitro following their exposure to hypoxic and oxidative stress conditions. RESULTS: Whereas overexpression of HIF-1α in MSCs was protective against cell death and apoptosis triggered by hypoxic and oxidative stress conditions, its downregulation increased apoptosis and death rate. CONCLUSIONS: Our study is the first to demonstrate how human MSCs can be manipulated to gain protection against stresses that potentially limit their clinical application.