Reconstruction of Hematopoietic Inductive Microenvironment after Transplantation of VCAM-1-Modified Human Umbilical Cord Blood Stromal Cells

Yao Liu,Xing-Hua Chen,Li Gao,Ying-Jian Si,Xi Zhang,Cheng Zhang,Zhong-Jun Li,Lei Gao,Dimas Tadeu Covas

doi:10.1371/journal.pone.0031741

Abstract

The hematopoietic inductive microenvironment (HIM) is where hematopoietic stem/progenitor cells grow and develop. Hematopoietic stromal cells were the key components of the HIM. In our previous study, we had successfully cultured and isolated human cord blood–derived stromal cells (HUCBSCs) and demonstrated that they could secret hemopoietic growth factors such as GM-CSF, TPO, and SCF. However, it is still controversial whether HUCBSCs can be used for reconstruction of HIM. In this study, we first established a co-culture system of HUCBSCs and cord blood CD34+ cells and then determined that using HUCBSCs as the adherent layer had significantly more newly formed colonies of each hematopoietic lineage than the control group, indicating that HUCBSCs had the ability to promote the proliferation of hematopoietic stem cells/progenitor cells. Furthermore, the number of colonies was significantly higher in vascular cell adhesion molecule-1 (VCAM-1)-modified HUCBSCs, suggesting that the ability of HUCBSCs in promoting the proliferation of hematopoietic stem cells/progenitor cells was further enhanced after having been modified with VCAM-1. Next, HUCBSCs were infused into a radiation-damaged animal model, in which the recovery of hematopoiesis was observed. The results demonstrate that the transplanted HUCBSCs were “homed in” to bone marrow and played roles in promoting the recovery of irradiation-induced hematopoietic damage and repairing HIM. Compared with the control group, the HUCBSC group had significantly superior effectiveness in terms of the recovery time for hemogram and myelogram, CFU-F, CFU-GM, BFU-E, and CFU-Meg. Such differences were even more significant in VCAM-1-modified HUCBSCs group. We suggest that HUCBSCs are able to restore the functions of HIM and promote the recovery of radiation-induced hematopoietic damage. VCAM-1 plays an important role in supporting the repair of HIM damage.

Highlights

The hematopoietic inductive microenvironment (HIM) is where hematopoietic stem/progenitor cells (HSCs/HPCs) grow and develop [1]
The results of co-culture of human cord blood–derived stromal cells (HUCBSCs) and cord blood CD34+ cells in this study showed that when using HUCBSCs as the adherent layer, the formation of colonies of each hematopoietic lineage significantly increased; erythroid, myeloid, and megakaryocytic lineages all formed more colonies than those in the control groups without HUCBSCs as feeder layers 12 d after co-culture
The exact mechanism of the interaction between the HIM formed by stromal cells and hematopoietic parenchymal cells is still unclear; the current consensus is that it is due to the direct contact between stromal cells in the HIM and HSCs or the important function of secreted cytokines in the regulation of hematopoiesis

Summary

Introduction

The hematopoietic inductive microenvironment (HIM) is where hematopoietic stem/progenitor cells (HSCs/HPCs) grow and develop [1]. The ability of adherent bone marrow stromal cells of patients pre-treated with radiotherapy and chemotherapy have reduced ability to support the growth of HSCs/HPCs [5]. Some biological factors, such as cytomegalovirus, hepatitis B virus, and human immunodeficiency virus as well as physical and chemical factors, such as radiation and chemotherapeutic drugs, can cause hematopoietic dysfunction through the damage of stromal cells. In some disease states such as aplastic anemia, acute and chronic myeloid leukemia, and myelodysplastic syndrome, the abnormal hematopoietic function is associated with dysfunction of HSCs/HPCs as well as the number of stromal cells or dysfunction of stromal cells in the bone marrow HIM [5,6,7,8,9]

Methods

Results

Conclusion