Role of fetal stem cells in maternal tissue regeneration

Abstract

Microchimerism refers to the status of harboring cells from another individual at low levels. It is well known that cells traffic bidirectionally between fetus and mother during pregnancy. This situation resembles a naturally occurring long lasting fetal stem cell transplantation. The fetus acts as the donor and the mother acts as the recipient. To study the role of microchimerism in tissue regeneration, we constructed a murine microchimerism model with wild type C57BL/6J female mice carrying progenies which expressed green fluorescent proteins (GFP). Our data indicated that skin injuries in the female mice during pregnancy increased microchimerism of GFP expressing cells from the GFP transgenic progenies. The GFP positive cells also appeared at the site of spinal cord where injury occurred during pregnancy. Our study suggests that the amount of fetal cells in maternal mice significantly increased if injuries occurred during pregnancy. Fetal stem cells appear to respond to maternal injury signals and may play a role in maternal tissue regeneration during pregnancy.

Keywords: Fetal stem cells; Injury introduction; Microchimerism.

Figure 1

Experimental design for testing the role of injury in microchimerism. Wild type virgin female C57BL/6J mice (8 to 12 weeks old, Jackson Laboratory, ME) were crossed with heterozygous transgenic eGFP male mice. Approximately half of the pups carried the eGFP genes. This is expected for autosomal dominant inheritance of the eGFP gene.

Figure 2

Fetal eGFP cells in injured skin and spinal cord. Both bright field and fluorescent images are taken at 200 × magnification. A. scar tissues were formed after skin injury. Massive new blood vessels were visible around the injury site. B. Fluorescent image of the scar tissue indicate that patches of fetal eGFP cells are presented close to the blood vessels. C. Fluorescent image of the skin next to the skin injury site. There is only one eGFP cells detected (inside the white circle). D. The light microscopic image of C. No angiogenesis signs appeared. E. Fluorescent image of skin from the control mouse without injury. There is no GFP positive cells detected. F. The light microscopic image of a section of the injured spinal cord. G. Patches of fetal eGFP cells were shown at the scar tissue around the spinal cord.