Isolation and characterization of mesenchymal progenitor cells from chorionic villi of human placenta

Background

BM-derived mesenchymal stem cells (MSC) are attractive sources for autotransplantation with no risk of rejection, but the use of these cells has problems, including the necessity of harvesting BM from donors, the donors’ age-dependency, limitation to autologous use and difficulty of use for patients with hereditary diseases. We report a method of isolating placenta-derived mesenchymal progenitor cells (PDMPC) that can be used as an alternative source of MSC.

Methods

We isolated PDMPC from human fetal chorionic villi using the explant culture method, from placentas collected after neonatal delivery (38–40 weeks of gestation). The PDMPC were characterized by morphologic and immunophenotypic analysis. The differentiation ability of mesenchymal and neural lineages was detected using specific culture conditions and determined by morphology, reverse transcription (RT)-PCR, histochemical staining and immunocytostaining.

Results

The PDMPC all originated from fetal chorionic villi, as confirmed by fluorescence in situ hybridization analysis. The PDMPC population consisted of spindle-shaped cells and large flat cells. The PDMPC expressed CD13, CD44, CD73, CD90, CD105 and HLA class I as surface epitopes, but not CD31, CD34, CD45 and HLA-DR. These cells differentiated into osteocytes, chondrocytes and adipocytes under specific culture conditions, and were also induced to form neural-like cells.

Discussion

Our study shows that PDMPC can differentiate into mesenchymal lineages and be induced to form neural-like cells. Thus, PDMPC isolated from chorionic villi of placenta may provide a novel source for the research of stem and progenitor cells in placenta, cell therapy and regenerative medicine, particularly as a source of allogenic mesenchymal stem and progenitor cells with little ethical conflict and various advantages.

Introduction

Stem cells are commonly defined as undifferentiated cells that can proliferate and have the capacity for both selfrenewal and differentiation into one or more types of specialized cells. Two types of stem cells have been identified: embryonic stem (ES) cells, found in the inner cell mass of the early embryo, and organ-specific cells, including adult stem cells. Adult or somatic stem cells have been reported to be located in BM [1], blood [2], cornea and retina [3], brain [4], skeletal muscle [5], dental pulp [6], liver [7], skin [8] and adipose tissues [9., 10., 11.]. Among these reports, the pluripotency of ES cells and mesenchymal stem cells (MSC) from adult marrow has been characterized extensively. Although the potential of ES cells is enormous, ethical and technical problems impede their practical use. Therefore, it is hoped that MSC can be an alternative source for cell therapy and regenerative medicine.

MSC are defined as cells capable of expansion, selfrenewal and differentiation into at least osteocytic, chondrocytic and adipocytic lineages when stimulated under specific conditions [1,12,13]. Recently, the potential of BM or adipose stromal cells to develop into neural lineages, such as those for neurons, astrocytes and oligodendrocytes, has been reported both in vivo [14,15] and in vitro [11,16., 17., 18., 19., 20., 21.]. Even some attempts to use MSC for the treatment of central nervous system disorders have been reported [21., 22., 23.]. However, the use of these cells has problems, including the necessity of harvesting BM from donors, the donors’ age-dependency, limitation to autologous use and of no use for hereditary disease patients. This has led many researchers to investigate alternate new sources for MSC that can be used in practice.

UC blood has been used successfully for the treatment of several hematologic, inherent diseases and solid tumors [24., 25., 26.], whereas the human placenta has been treated as medical waste. Recently, several reports have shown that multipotent cells obtained from UC blood, the subendothelial layer, the amniotic epithelial layer, Warton's jelly and the matrix of UC, have the ability to differentiate into mesenchymal, neural and endodermal lineages, such as hepatic progenitor cells, under specific conditions [27., 28., 29., 30., 31., 32.]. The existence of mesenchymal cells in chorionic villi of human placenta has been investigated [33., 34., 35., 36.]. It has also been reported that human placenta-derived mesenchymal cells could be a valuable and practical source for fetal tissue engineering [37]. However, these studies did not show the existence of multipotent cells in the mesenchymal cell population from the human placenta.

We report the first established method to isolate placenta-derived mesenchymal progenitor cells (PDMPC) from the fetal part of chorionic villi without maternal cells, blood cells and endothelial cells. We also show that these cells can differentiate into osteocytes, chondrocytes and adipocytes and be induced to form neural-like cells.