Stem Cells 101

What are stem cells?

Today, most biologists agree that stem cells are defined by two key characteristics:

  • Self renewal — Stem cells are capable of dividing and renewing themselves over long periods of time.
  • Differentiation — Stem cells are unspecialized. When stem cells divide, each new cell has the potential to either remain a stem cell or to differentiate into a specialized cell.

Why do we study stem cells?

Studying stem cells can help us understand the complex processes involved in cell division and differentiation. Many debilitating or fatal medical conditions are due to abnormalities in these processes. Whether these anomalies arise from congenital disorders, acquired diseases or trauma, we believe that a better understanding of stem cell biology will ultimately yield better medical intervention, from more accurate and timely diagnosis through more effective and economical treatments.

What is the state of stem cell science today?

Since its first successful use in 1968, bone marrow transplantation has been applied to a variety of indications ranging from leukemia to lymphoma to immune deficiency disorders, as well as to treat damage resulting from radiation treatment or chemotherapy. Patients appear to benefit from the infusion of blood stem cells found in the bone marrow, and today umbilical cord blood, rich in blood stem cells, is being used experimentally as an alternative to bone marrow transplantation. When tissues and organs such as skin, blood and liver are transplanted, stem cells within these tissues are believed to contribute to long-term regeneration.

According to the International Society for Stem Cell Research (ISSCR), “Other stem cell treatments are still at very early experimental stages and have not yet been shown to have a clear-cut advantage over existing therapies, are not considered a standard of care for any condition and do not have regulatory approval for the routine treatment of any disease.”1 Despite wide-ranging claims made by stem cell clinics on the Internet, the successful portrayal of stem cell medicine is not yet substantiated by scientific studies documented in peer-reviewed literature.2

According to the US National Institutes of Health (NIH)3 for stem cells to be made useful for transplant purposes, they must be reproducibly made to:

  • Proliferate extensively and generate sufficient quantities of tissue
  • Differentiate into the desired cell type(s)
  • Survive in the recipient after transplant
  • Integrate into the surrounding tissue after transplant
  • Avoid harming the recipient in any way
  • Function appropriately for the duration of the recipient’s life

StemCells, Inc. has already achieved the first five imperatives on the NIH list above. Data from our pioneering clinical trials have shown the safety of stem cell transplantation, as well as preliminary signs of efficacy. We are now running clinical studies with the goal of demonstrating the potential these cells have to treat spinal cord injury (SCI) and age-related macular degeneration (AMD). Only continued research and time will tell whether the sixth item on the list above comes to fruition, thereby fulfilling our mission to realize the potential of stem cells to transform medicine.

Visit the NIH website to learn more about stem cells…











Types of Stem Cells

  • Adult stem cells (also referred to as tissue-derived stem cells or somatic stem cells) are termed “multipotent” — they can produce all the functional cell types found within the tissue from which they are derived. For example, in mammals, hematopoietic (blood) stem cells are responsible for the constant renewal of the various types of blood and immune system cells; neural (brain) stem cells are capable of becoming the neurons or glial cells comprising the central nervous system; mesenchymal (skeletal) stem cells are able to form bone, cartilage and the stromal cells found in bone marrow.
  • Embryonic stem (ES) cells are derived from the earliest stages of embryonic development and give rise to all the different types of cells found throughout the organism as it grows and matures. They are therefore characterized as “pluripotent.” Pluripotent stem cells have the advantage that they can make any cell type. The downside is they can form tumors of mature cells types (teratomas) unless they are forced to become other specific stem or progenitor cells.
  • Induced pluripotent stem (iPS) cells are differentiated cells that have been genetically reprogrammed to a pluripotent state resembling embryonic stem cells. While these cells meet the defining criteria for pluripotent stem cells, it is not yet fully known if or how iPS cells might behave differently from embryonic or tissue-derived stem cells when used as therapeutics.

Progenitor Cells

In addition to stem cells, scientists at StemCells, Inc. also study progenitor cells, which are sometimes confused with stem cells. Progenitor cells are more specialized than stem cells. They are early descendants of stem cells and, like stem cells, they can differentiate into more specialized cells comprising a specific organ; unlike stem cells, progenitor cells cannot self renew.