Stem Cells

Stem cells are a class of undifferentiated cells with the potential to develop into a diverse range of specialized cell types in the body.

Stem cells have two important characteristics that distinguish them from other cells. First, they are not specialized to do specific jobs. Instead, they are “pluripotent” and, under certain conditions, can be “differentiated” to assume the various functions needed in the body. Second, they can reproduce in large numbers while still remaining undifferentiated. It is the combination of these two characteristics that provide stem cells with their tremendous therapeutic promise for a wide range of degenerative diseases.

The four most commonly used and described classes of stem cells are “embryonic stem cells” (embryonic SCs), “induced pluripotent stem cells” (iPS), “adult stem cells” (adult SCs) and “parthenogenetic stem cells” (hpSCs).

Embryonic stem cells are derived from fertilized eggs (“oocytes”) in the very early stages of development. They are truly pluripotent but do require use of a fertilized egg that, under the right circumstances, has potential to develop into a human.

In contrast, induced pluripotent stem cells are differentiated cells that are chemically or otherwise driven back to earlier developmental stages. While creation of such cells does not involve the use or destruction of a fertilized egg, it requires dramatic changes in gene expression that may have unknown biological impact and likely will be subject to substantial scrutiny by regulatory authorities before any approval for therapeutic use. Also, autologous induced pluripotent stem cells cannot be used for hereditary diseases therapy because of bearing the same genetic defects.

Adult stem cells are rare cells in a person that have a limited ability to differentiate into cells with specific functions. While these stem cells do not require use or destruction of a fertilized egg or extensive manipulation of gene expression, they are rare and hard to identify and they generally proliferate poorly, thus making it hard to produce therapeutic amounts.

Parthenogenetic stem cells are derived from parthenogenetically activated human oocytes. Parthenogenesis is a form of asexual reproduction in which females produce eggs that develop without fertilization, in other words - without spermatozoon. The beginning of the process of parthenogenesis in oocytes can be induced, or “activated” by different electrical or chemical stimuli that simulate spermatozoon penetration. Activated oocytes have the ability to develop into parthenogenetic embryos that are capable of reaching the blastocyst stage. The ICM of such a parthenogenetic blastocyst can give rise to a parthenogenetic stem cell line. These hpSCs are as pluripotent and proliferate as embryonic and induced pluripotent stem cells. Moreover hpSCs avoid the entire ethical consideration around the use of fertilized oocytes for creation of embryonic stem cells. Furthermore, since there is no forced change of gene expression patterns, hpSCs are not likely to face the same safety and regulatory hurdle as induced pluripotent stem cells.