Stem cell research

New studies threaten to undermine everything you've been told about embryonic stem cell research. The following is a must read for anyone interested in the whole story on stem cell research.

by Dawn Vargo

 

The debate over stem cell research is raging across the nation and echoing through chambers of Congress and state legislatures. Most people have heard just enough to offer an opinion to friends and neighbors; yet, the information they receive is incomplete and often inaccurate.

 

Every new study on embryonic stem cells produces an onslaught of optimistic articles confidently proclaiming that with just a little more time and a lot more public money embryonic stem cells will provide cures for dozens of diseases and hope for millions of sick patients. Meanwhile, stories highlighting adult stem cell successes seem less optimistic and much less prominent. Casual observers might reasonably conclude that embryonic stem cells hold the most promise while adult stem cells are of secondary interest. They would be wrong.

 

Embryonic stem cells are often touted as the most promising research option because they are a "blank slate" capable of differentiating (changing and specializing) into all the cells of the body. Less well known is that adult stem cells have the same ability to change into every kind of cell, tissue, and organ in the body. Yes, you read that correctly: one of the main reasons embryonic stem cells are flaunted as the gold standard in research is their ability to change into every cell type. Yet, adult stem cells have the same capacity.

 

In other words, adult stem cells can do everything embryonic stem cells can do:

 

  • Adult stem cells are flexible: Like embryonic ones, they can change into every cell type of the body. Rsearchers often refer to this ability to specialize into every cell type as pluripotency.
  • Adult stem cells' flexibility show new potential to treat disease: Studies demonstrate that in addition to diseases already being treated with adult stem cells, the recently discovered and often ignored flexibility of adult stem cells offer additional possibilities to cure disease.

 

Contrary to the exclusive claims of embryonic stem cell proponents, the following compilation of research demonstrates the flexibility of adult stem cells to transform into a wide range of specialized cells – just like embryonic ones.

 

Terms to Know

 

Differentiate – A scientific word to describe how something changes and specializes. Normally used to describe how "young" cells change into mature cells with special functions.

 

Germ layer – Within a developing embryo, there are three germ layers that provide the ability for the embryo to change into all the cells of the body. Embryonic stem cells have the ability to change into cells from all three germ layers – this means they can differentiate into every part of the body. There are three distinct germ layers in humans: endoderm (internal layer), mesoderm (middle layer), and ectoderm (external layer).

 

Conventional knowledge says that adult stem cells are not as promising as embryonic stem cells because they lack these embryonic germ layers that can form all of the body's 200+ cells (skin cells, muscle tissue, internal organs, etc). However, a growing body of research shows that adult stem cells have an "embryonic" ability to differentiate.

 

Adult stem cells – There is a wide variety of adult stem cells, including bone marrow stem cells, nasal stem cells, mesenchymal stem cells, etc. These types of adult stem cells are normally identified by where they are located (bone marrow stem cells are found in bone marrow, blood stem cells in the blood, etc).

 

Flexible Stem Cells

 

The following summaries document the ability of adult stem cells to develop into cells outside of their original cell family.1

 

Baby Teeth

 

  • Baby teeth are a rich source of stem cells. Stem cells from dental pulp can differentiate into neural, fat, and tooth-forming cells. 2

     

Blood

 

  • Adult stem cells taken from the blood can differentiate into liver and nerve cells.3
  • White blood cells taken from patients can produce other types of stem cells; newly formed cells included red and white blood cells, nerve cells and heart muscle.4

     

Bone Marrow

  • Bone marrow stem cells can make significant amounts of new lung tissue.5
  • Bone marrow stem cells can change into epithelial cells when transplanted into the lung.6
  • Bone marrow stem cells can be put into various tissues and organs. This research could provide a model for future lung stem cell work.7
  • Bone marrow stem cells from men were implanted into women. They found that the women had brain cells with the Y chromosome. This shows that bone marrow stem cells can turn into brain cells.8
  • A specific type of cells (multipotent adult progenitor cells – MAPCs) has been found in bone marrow. These can specialize into cells from all three germ layers. This study found that these cells can be isolated not only from bone marrow but also from brain and muscle tissue.9
  • Stem cells from bone marrow have the capacity to develop into all cell types in the human body including those that make up the glands, digestive tract, hair, skin, nails, brain, nervous system, and muscle.10
  • Bone marrow stem cells can turn into nerve cells; contrary to previous belief, these bone marrow stem cells did not merely fuse with nerve cells, they changed into nerve cells without any cell fusion.11
  • Pluripotent (able to change into all cell types) bone marrow stem cells can change into insulin-secreting cells.12
  • Researchers in Miami once again found that bone marrow stem cells can change into all cells of the body.13
  • A single bone marrow stem cell can turn into marrow, blood, liver, lung, gastrointestinal tract, skin, heart, and skeletal muscle.14
  • Cells taken from the bone marrow are able to generate new egg production in the ovaries. This finding has significant implications for the long-held belief that females are born with a limited number of eggs that declines throughout life.15

     

Cord Blood

  • Cord blood cells, a type of adult (also known as non-embryonic) stem cells that come from the umbilical cords of newborns, contain mesenchymal stem cells. These mesenchymal stem cells can change into skeletal muscle cells.16 Research Institute of Biotechnology, Histostem Co. Kangdong-gu, Seoul, Korea
  • A special type of umbilical cord blood stem cells (called unrestricted somatic stem cells – USSCs) can change into all cells from all three germ layers. This means they can specialize into all of the cells in the body including brain, bone, cartilage, liver, heart, and blood cells.17
  • A recently discovered type of cord blood stem cells, cord-blood-derived embryonic-like stem cells or CBEs, have the capability of turning into any kind of body tissue 18
  • Stem cells found in the outer lining of the umbilical cord have been successfully differentiated into specific cells such as skin, bone and fat.19

     

Ear

 

  • Stem cells from the inner ear were able to change into the three major cell types of the body (all three germ layers).20

 

Liver

 

  • Liver stem cells can specialize into pancreatic cells. This demonstrates that stem cells from one part of the body (liver) can change into cells from a completely different part of the body (pancreas).21

 

Mesenchymal

 

  • A specific type of adult stem cells, human mesenchymal stem cells, have the ability to self-renew on a long-term basis. They also have the flexibility to specialize into cells from all three germ layers.22

Muscle

 

  • Muscle stem cells have the capacity to change into blood stem cells.23

Nasal

 

  • Nasal stem cells can develop into heart, liver, kidney, muscle, brain, and nerve cells.24

Neural Crest

 

  • A specific type of early embryonic stem cells (epidermal neural crest cells – eNCSC) are found in adult hair follicles and show a high degree of flexibility.25

Neural

 

  • Neural stem cells can change into a broad array of cells within and without the central nervous system. Two types of cells that can be formed from neural stem cells are skeletal muscle and blood cells.26
  • Neural stem cells were isolated from the cerebellum region of the brain and showed the ability to renew and differentiate into several types of neural cells in the brain 27

Pancreas

 

  • Pancreatic stem cells can specialize into muscle cells, neurons, and insulin-producing cells.28

Placenta

 

  • A type of stem cells found in the placenta (amniotic epithelial cells) has the potential to change into all three germ layers.29

Uterus

 

  • Stem cells in the uterus can be grown into bone, muscle, fat, and cartilage.30

Scalp

 

  • Cells from human scalp tissue are able to change into a wide variety of cells – including cells in different cell families like neural, bone, and cartilage cells.31

     

Dawn Vargo is a research assistant in the Public Policy Division of Focus on the Family.

  1. Lead researchers: A. Gritti and R. Galli, Institute for Cell Research, PubMed 2002;171(1):64-76, PMID: 12021492 [PubMed - indexed for MEDLINE], "Adult Neural Stem Cells: Plasticity and Developmental Potential" http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieveanddb=PubMedandlist_uids=12021492anddopt=Abstract
  2. Lead researchers: A. Gritti and R. Galli, Institute for Cell Research, PubMed 2002;171(1):64-76, PMID: 12021492 [PubMed - indexed for MEDLINE], "Adult Neural Stem Cells: Plasticity and Developmental Potential" http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieveanddb=PubMedandlist_uids=12021492anddopt=Abstract
  3. Lead researcher: Eliezer Huberman, Argonne National Laboratory, PNAS | March 4, 2003 | vol. 100 | no. 5 | 2426-2431, "A Human Peripheral Blood Monocyte-derived Subset Acts as Pluripotent Stem Cells," http://www.pnas.org/cgi/content/abstract/100/5/2426?view=abstract
  4. Lead researcher: Dr. Saleh Abuljadayel, TriStem Corporation, London, Current Medical Research and Opinion, 2003; 19(5): 355-375, "Induction of Stem Cell-like Plasticity in Mononuclear Cells Derived from Unmobilised Adult Human Peripheral Blood." Research conducted with human stem cells.
  5. Lead researcher: Benjamin Suratt, University of Vermont College of Medicine, American Journal of Respiratory and Critical Care Medicine Vol 168. pp. 318-322, (2003). http://ajrccm.atsjournals.org/cgi/content/abstract/168/3/318, "Human Pulmonary Chimerism after Hematopoietic Stem Cell Transplantation." Research conducted with mice.
  6. Lead researcher: Diane S. Krause, Yale University School of Medicine, American Journal of Respiratory Cell and Molecular Biology. vol. 27 (2002): 645-651, "Marrow-Derived Cells as Vehicles for Delivery of Gene Therapy to Pulmonary Epithelium," doi: 10.1165/rcmb.2002-0056RC, http://ajrcmb.atsjournals.org/cgi/content/abstract/27/6/645. Research conducted with mice.
  7. Lead researcher: D.N. Kotton, Boston University School of Medicine, Experimental Hematology April 2004 vol 32, issue 4: 340-342, "Lung stem cells: new paradigms."
  8. Mezey E et al, Prceedings of the National Academy of Sciences, Transplanted Bone Marrow Generates New Neurons in Human Brains, February 2003.
  9. Jiang Y, Vaessen B, Lenvik T, Blackstad M, Reyes M, Verfaillie CM. Multipotent progenitor cells can be isolated from postnatal murine bone marrow, muscle, and brain. Exp Hematol. 2002 Aug;30(8):896-904. Stem Cell Institute, Department of Medicine, University of Minnesota Medical School, Minneapolis 55455, USA. Research conducted with mice.
  10. Young-sup Yoon, Doug Losordo, Biotech Week, Caritas St. Elizabeth's: Unique Stem Cell Identified, Feb 23, 2005; Yoon Y-s et al, Clonally Expanded Novel Multipotent Stem Cells from Human Bone Marrow Regenerate Myocardium after Myocardial Infarcation, Journal of Clinical Investigation, February 2005.
  11. Crain BJ, Tran SD, Mezey E, Transplanted Human Bone Marrow Cells Generate New Brain Cells, Journal of Neural Science, June 15 2005.
  12. Moriscot C et al, Stem Cells, Human Bone Marrow Mesnchymal Stem Cells can Express Insulin and key Transcription Factors of the endocrine Pancreas Developmental Pathway upon Genetic and.or Microenvrionmental Manipualation In Vitro, 2005.
  13. D'Ippolito G et al, Journal of Cell Science, Marrow-isolated Adult Multilineage Inducible (MIAMI) Cells, A Unique Population of Postnatal Young and Old Human Cells with Extensive Expansion and Differentation Potential, July 15, 2004.
  14. Krause DS et al, Cell, Multi-Organ, Multi-Lineage Engraftment by a Single Bone Marrow-derived Stem Cell, May 2001.
  15. Johnson, Joshua et al., Oocyte generation in Adult Mammalian Ovaries by Putative Germ Cells in Bone Marrow and Peripheral Blood, Cell Vol 122, 1-13, July 29, 2005; Stem Cells in Bone Marrow Replenish Mouse Ovaries, EurakAlert!, July 27, 2005.
  16. Eun Ji Gang, Ju Ah Jeong, Seung Hyun Hong, Soo Han Hwang, Seong Whan Kim, Il Ho Yang, Chiyoung Ahn, Hoon Han, Hoeon Kim, "Skeletal Myogenic Differentiation of Mesenchymal Stem Cells Isolated from Human Umbilical Cord Blood"
  17. Kogler G et al., Journal of Experimental Medicine, A New Human Somatic Stem Cell from Placental Cord Blood with Intrincis Pluripotent Differentiation Potential, July 2004.
  18. Price, Joyce Howard, Advance made in Stem-Cell Debate, The Washington Times, August 20, 2005; Coghlan, Andy, Cord Blood Yields 'Ethical' Embryonic Stem Cells, New Scientist, August 18, 2005; Olsen, Stefanie, Microgravity Tech Could Sway Stem Cell Debate, The New York Times, August 18, 2005.
  19. ”Biotech Firm Discovers New Source of Stem Cells,” Medical News Service, July 12, 2005.
  20. Li H et al, Nature Medicine, Pluripotent Stem Cells from the Adult Mouse Inner Ear, October 2003.
  21. Lijun Yang, Shiwu Li, Heather Hatch, Kim Ahrens, Janet G. Cornelius, Bryon E. Petersen, and Ammon B. Peck In vitro trans-differentiation of adult hepatic [liver] stem cells into pancreatic endocrine hormone-producing cells Proc. Natl. Acad. Sci. USA, Vol. 99, Issue 12, 8078-8083, June 11, 2002. Research conducted with rats.
  22. Hong SH, et.al., In vitro differentiation of human umbilical cord blood-derived mesenchymal stem cells into hepatocyte-like cells. Biochem Biophys Res Commun. 2005 May 20;330(4):1153-61. Research Institute of Biotechnology, Histostem Co., Seoul, Republic of Korea. (The specialized into mesenchyme-related multipotency, neuroectodermal, endodermal cells.)
  23. Goodell MA, Jackson KA, Majka SM, Mi T, Wang H, Pocius J, Hartley CJ, Majesky MW, Entman ML, Michael LH, Hirschi KK. Stem cell plasticity in muscle and bone marrow. Ann N Y Acad Sci. 2001 Jun;938:208-18; discussion 218-20. Center for Cell and Gene Therapy, Baylor College of Medicine, One Baylor Plaza, N1030, Houston, Texas 77030, USA. Research conducted with adult mice.
  24. Murrell W et al., Multipotent Stem Cells from Adult Olfactory Mucosa, Developmental Dynamics, June 2005.
  25. Sieber-Blum M, Grim M, Hu YF, Szeder V. Pluripotent neural crest stem cells in the adult hair follicle. Dev Dyn. 2004 Oct;231(2):258-69. Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
  26. Lead researchers: A. Gritti and R. Galli, Institute for Cell Research, PubMed 2002;171(1):64-76, PMID: 12021492 [PubMed - indexed for MEDLINE], "Adult Neural Stem Cells: Plasticity and Developmental Potential" http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieveanddb=PubMedandlist_uids=12021492anddopt=Abstract. Research conducted with mice.
  27. Lee, Audra, Jessica D Kessler, Tracy-Ann Read, Constanze Kaiser (Department of Pharmacology & Cancer Biology, Duke University Medical Center), Denis Corbeil, Wieland B Huttner (Max Planck Institute of Molecular Cell Biology and Genetics), Jane E Johnson, Robert J Wchsler-Reyal (Center for Basic Neuroscience, University of Texas Southwestern Medical Center), Isolation Neural Stem Cells from the Postnatal Cerebellum, Nature Neuroscience, 723-729, 2005.
  28. Kruse C et al, Applied Physics, Pluripotency of Adult Stem Cells Derived from Human and Rat Pancreas, November 2004.
  29. Miki, Toshio, Lehmann, Thomas, Cai, Hongbo, Stolz, Donna B, Strom, Stephen, Stem Cell Characteristics of Amniotic Epithelial Cells, Stem Cells, published online August 4, 2005; Spice, Byron, Option to Stem Cells Found, Pittsburgh Post-Gazette, August 5, 2005.
  30. Australian Discovery of Adult Stem Cells in the Uterus, Medical Research News, July 19, 2005.
  31. Tzu-bi Shih, Daniel, et al., Isolation and Characterization of Neurogenic Mesenchymal Stem Cells in Human Scalp Tissue, Stem Cells, Vol. 23 No 7, pp. 1012-1020. August 2005.