Cells were isolated from placentas of donor women immediately after elective Caesarean section in the absence of labor, preterm rupture of membranes, chorioamnionitis, or chromosomal abnormalities. Cells express mesenchymal stem cell markers and have adipogenic, osteogenic and chondrogenic differentiation potential. Cells were cultured for 6 passages prior to gene expression analysis.
After removal of decidua and fetal membranes, placental tissue was minced and washed in physiologic saline. Blood vessels and clots were mechanically removed. The minced tissue was subjected to sequential digests with trypsin and collagenase I and then transferred through cell strainers. After collecting the cells by centrifugation, they were transferred into hypotonic red blood lysis buffer. After a few minutes, cells were collected by centrifugation, resuspended in nonhematopoietic stem cell expansion medium and plated into tissue culture flasks.