Amniotic Fluid Cells for Future Tissue Engineering

Julie G. Allickson, PhD, MS,
MT (ASCP) is the Director of
Translational Research
at Wake Forest Institute for
Regenerative Medicine.

Amniotic fluid has been used for more than 70 years for prenatal diagnosis (1). It is extracted, by a procedure called "amniocentesis", generally between the 14th and 20th weeks of pregnancy, to assess for genetic birth defects. In addition to the fluid required for testing, the doctor will also withdraw a small amount (a few milliliters) of additional fluid, in case any further testing is required. That extra fluid could be used to isolate fetal stem cells from the baby, as it contains a varied population of cells that originate from the tissues of the baby's skin, respiratory, digestive and urinary tracts.

Stem cells may be one important component of "tissue engineering" to maintain or repair a functional tissue or organ. Tissue engineering has the potential to revolutionize the way we deliver healthcare and may improve the quality of life for millions in the future. One of the most important applications would be to grow life-saving organs in the laboratory to replace living or cadaveric donors used in organ transplantation. There is an extreme shortage of organs available for donation, which does not allow for treatment for a large portion of patients. The need for organs far outpaces the supply.

Stem cells from many different sources are being assessed therapeutically across over 4000 trials listed on ClinicalTrials.gov. Amniotic fluid may provide an important source of immature cells discarded by the developing baby. The primitive nature of the cell may lend itself to a large number of applications due to its plasticity. There is no need to force the cells to become pluripotent, no potential to grow tumors, and no ethical considerations associated with the cell. Furthermore the cells have demonstrated that they are capable of suppressing or altering an immune response (2).

Amniotic fluid cells can differentiate into the three embryonic germ cell layers, and thus harbor the potential to become every cell type in the human body. Here is a list of cell types that scientists have grown from amniotic fluid cells: adipogenic, osteogenic, myogenic, endothelial, neuronal and hepatic lineages (3); epithelial lung (4), cardiomyogenic (5, 6), smooth muscle in a cryo-injured bladder (7), hematopoietic (8), hepatocyte (9) renal (10), and tendon (11), to name a few. A subpopulation of the cells in the amniotic fluid, referred to as c-kit+, can be expanded to more than 250 population doublings while maintaining normal chromosones and long telomeres.

What is even more exciting for the future of tissue engineering, is that some amniotic fluid cells seem to function as specific organ precursor cells (12). For example, one cell line seems to be progenitors of kidney cells. In pre-clinical studies they were able to protect kidneys from tubular necrosis (13).

In the future, amniotic fluid cells may be a useful reservoir of stem cells for in-utero treatment of congenital conditions that carry a heavy burden on the patient and society (12). A case in point would be spina bifida, which is currently under investigation. The amniotic fluid cells surrounding a sick baby can be harvested and grown to treat that baby. This can be done during the course of the pregnancy, and without fear of the cells being rejected since they are native to the patient.

Anthony Atala, M.D., Director of the Wake Forest Institute for Regenerative Medicine, has stated that 99% of the U.S. population could conceivably find genetic matches for tissue regeneration or engineered organs from just 100,000 unique amniotic fluid samples. The amniotic fluid cell source may be revolutionary in the field of healthcare as highly proliferative, immature cells capable of immune modulation.

Julie Allickson has 22 years of experience in Cellular Therapy, Cellular Processing and Regenerative Medicine. She has a Doctorate in Health Sciences along with a Master's Degree in Medical Laboratory Sciences. She is currently an inspector for both NetCord FACT and for AABB, the vice-chair of the AABB Standards Committee for Cell Therapy Product Services, technical advisor for Tissue Engineered Products under ICCBBA, and a founding member of the International Society of Cellular Therapy. Up until recently, Dr. Allickson was Vice President of Laboratory Operations and R & D at Cryo-Cell International, Inc. Since May 2012, Dr. Allickson is the Director of Translational Research at Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, where she is focused on translation of adult and fetal stem cells.

References

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