Placental mesenchymal stem cells of fetal and maternal origins demonstrate different therapeutic potentials

Abstract

Introduction: Therapeutic potentials of mesenchymal stem cells (MSCs) from different sources have been evaluated in pre-clinical and clinical settings. Although MSCs from different sources share MSC-specific characteristics and functions, inconsistent or controversial results of pre-clinical and clinical applications of such cells are frequently reported. This may be partially due to the fact that MSCs isolated from different origins may differentially express some functions not typical for MSCs, and hence have different therapeutic potentials. The aim of this study is to investigate the differences in human placental MSCs (P-MSCs) of fetal and maternal origins in the aspects of clinical importance.

Methods: P-MSCs of fetal and maternal origins isolated from normal term placentas were characterized for their typical phenotype as well as their expression of receptors and growth factors of clinic interests. P-MSCs that preferentially express hepatocyte growth factor (HGF) and CD200 were evaluated for their therapeutic potentials in models of angiogenesis and allogeneic skin transplantation, in comparison with their HGF and CD200 negative partners.

Results: Although all P-MSCs express typical MSC phenotype, fetal but not maternal P-MSCs express high levels of CD200 and HGF. Compared with HGF and CD200 negative P-MSCs, HGF and CD200 positive cells demonstrated significantly high potentials in promoting angiogenesis in vitro and increasing immunosuppressive function in vivo. These therapeutic potentials were at least in part due to their differences in HGF and CD200 expression, respectively.

Conclusions: We conclude that MSC origins may have significant impact on the therapeutic potentials of such cells, and should be taken into consideration in clinical applications.

Figure 1

Fetal and maternal P-MSCs commonly express a MSC-specific phenotype, but differentially express CD200. A: The morphology of maternal and fetal P-MSCs. B: Flow cytometry analysis for PMS-specific phenotype expression by fetal and maternal P-MSCs. Both populations expressed typical MSC phenotype. C and D: Comparison in CD200 expression in transcript (C) and protein (D) levels between fetal and maternal P-MSCs. Shown are representatives of three random donors. **: P <0.01. MSC, mesenchymal stem cells; P-MSCs, placental mesenchymal stem cells.

Figure 2

Differential cytokine expression by fetal and maternal P-MSCs. A: P-MSC cells from fetal and maternal P-MSCs were seeded in equal numbers and re-counted at the end of culture. Cytokine levels in cell culture supernatants were quantified by ELISA and normalized by cell numbers at the end of the study. B: qPCR quantification for HGF expression by fetal and maternal P-MSCs. n = 3. **: P <0.01. HGF, hepatocyte growth factor; P-MSCs, placental mesenchymal stem cells.

Figure 3

Cytokine expression by fetal and maternal P-MSCs in response to IFN-γ and Poly (I:C) stimulations. Equal numbers of cells from fetal and maternal P-MSCs were seeded and stimulated with IFN-γ (A) and Poly (I:C) (B). Cytokine levels in cell culture supernatants were quantified by ELISA and normalized by cell numbers at the end of the study. n = 3. *: P <0.05, **: P <0.01. IFN-γ, interferon gamma; P-MSCs, placental mesenchymal stem cells.

Figure 4

Fetal P-MSCs (fPMSCs) stimulated angiogenesis in vitro in HGF-dependent manner. (A) Tube formation by HUVECs cultured in P-MSCs medium, P-MSCs medium supplemented with 20 ng/mL rhHGF, maternal P-MSCs conditioned medium (mPMSCs cM), fetal P-MSCs conditioned medium (fPMSCs cM) and fPMSCs cM plus100 ng/mL anti-HGF antibody, respectively. Images are representatives of nine randomly chosen images for each culture condition (100x magnification). (B) The average number of tube structures formed in each group as counted from nine randomly chosen images under 40x magnification. **: P <0.01. HGF, hepatocyte growth factor; HUVECs, human umbilical vein endothelial cells; P-MSCs, placental mesenchymal stem cells; rhHGF, recombinant human growth factor.

Figure 5

Fetal P-MSCs (fPMSCs) prolonged skin allograft survival. (A) Representative images of skin allograft survival in different time points post-transplantation. Different groups show mice treated with PBS, maternal P-MSCs (mPMSCs), fPMSCs and fPMSCs plus anti-CD200 antibodies, respectively. Images are representative of 10 mice for each group. (B) Skin allograft survival and average survival times among different mouse groups. n = 10. **: P <0.01. PMSCs, placental mesenchymal stem cells.