Stem Cells

Stem cell biology has emerged as one of the most significant fields in contemporary science. Stem cells give rise to every other cell in the body and possess the ability to both self-renew and differentiate. In addition, scientists have been able to reprogram or induce the creation of pluripotent stem cells to further expand the possibilities in translational medicine. BioLegend offers stem cell-focused reagents for flow cytometry, cell screening, western blotting, ELISAs, cell differentiation, and more.

Embryonic Stem Cells

Typically derived from in vitro fertilized eggs destined for medical waste, ESCs are obtained from the inner cell mass(ICM) of the blastocyst. These cells are isolated before a portion of the ICM differentiates (post fertilization: 3.5 days in mice, 5 days in humans). With the proper signals, the cells can proliferate indefinitely without differentiating, even in vitro. These pluripotent cells can differentiate into ectoderm, mesoderm, or endoderm. Because of the ethical ramifications of their derivation, there is some controversy over the use of ESCs. However, they represent the most flexible and potent cells compared to stem cells obtained by other means. Given their unlimited potential, ESCs are a favorite among scientists in clinical and research settings.

References:

  1. Nishikawa, S.I. et al. 2007. Nat. Rev. Mol. Cell Biol. 8:502.
  2. Stojkovic, M. et al. 2004. Stem Cells. 22:790.

Adult Somatic Stem Cells

References:

  1. Gavrilov, S. et al. 2009. Curr. Stem Cell. Res. and Ther.. 4:81.
  2. Weaver, C.H. et al. 2001. Bone Marrow Transplant.. 27: S23.

Induced Pluripotent Stem Cells


Image of frozen, human induced pluripotent stem cells provided courtesy of Dr. Deepak Srivastava’s lab.

Induced Pluripotent Stem Cells (iPSCs) are adult cells forced back into an embryonic cell-like state. This is typically done through genetic reprogramming. Mouse iPSCs were first made in 2006, while human iPSCs were not discovered until late 2007. Both human and mouse iPSCs expressed stem cell markers and demonstrated pluripotent characteristics, producing cells for all three germ layers. iPSCs are used in several applications, including drug development, disease modeling, and transplantation medicine. Currently, viruses are used to transfect non-pluripotent cells. Transfected genes are involved with pluripotency and include Oct 3/4, SOX-2, c-Myc, and Klf4. Cells are then typically selected for the expression of Nanog, a transcription factor associated with self renewal. While the use of viruses in this method must be confirmed to be safe for humans, this process provides a form of “devolution,” producing new uses for cells thought to be terminally differentiated.

References:

  1. Takahashi, K. and Yamanaka, S. 2006. Cell 126:663.
  2. Takahashi, K. et al. 2007. Cell 131:861.

Additional Stem Cell Fields

Given the natural ability of stem cells to generate almost any cell type in the human body, scientists have focused on the use of stem cells in therapeutic applications. Degenerative diseases like Parkinson’s and Multiple Sclerosis are associated with defective neural cells and the loss of myelin . Following a heart attack or stroke, myocardial cells can be weakened or killed. Type 1 Diabetes, an autoimmune disease, targets insulin producing cells in the pancreas for destruction. Stem cells could have applications in all of these diseases, where they could be developed into replacement neural, heart, or beta cells. These treatments may even be able to avoid graft versus host disease problems, as the stem cells could be raised by the host, for the host. While these new fields of research must determine optimal methods for delivery and differentiation of the proper cell type, the results are encouraging and opening new avenues of thinking.

References:

  1. Boyle, A.J. et al. 2006. Circulation 114:339.
  2. Lipsett, M. and Finegood, D.T. 2001. Diabetes 51:1834.
  3. Perrier, A.L. et al. 2004. Proc. Natl. Acad. Sci. USA. 101:12543.

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