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Potential of Stem Cells to Cure HIV

March 1st, 2009

Recently, a patient with leukemia and human immunodeficiency virus (HIV) had apparent remission of both after stem cell transplants (Hütter et al., 2009). As discussed earlier, hematopoietic stem cells have been used in transplants to rescue patients with leukemia, but this method has not previously been as successful for treating HIV, the virus that causes acquired immunodeficiency syndrome (AIDS).

Once in the body, HIV primarily attacks the immune system, such as T cells, though some individuals have T cells that are naturally resistant to HIV infection. Over a decade ago, this resistance was found to be due to a mutation in a receptor that is normally on the cell surface of T cells, called chemokine receptor 5 (CCR5) (Liu et al., 1996). CCR5 is a chemokine receptor, meaning it normally binds and receives signals from chemokines, which are molecules cells can release and receive to cause an immune system response. CCR5 is thought to normally be involved in causing a response to infection, though its exact function is not fully understood. HIV normally interacts with CCR5 to gain entry into the target T cell, but some individuals have a mutation in the CCR5 gene, specifically a 32 base-pair deletion, that renders the resultant receptor completely nonfunctional and consequently prevents HIV from being taken into these cells (Liu et al., 1996).

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The T cell membrane (shown as the purple, semicircle double line) allows entry of HIV (in pink) into the cell through multiple cell receptors anchored on the membrane, including CCR5.

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Dental Pulp Stem Cells: Noninvasively Obtained Stem Cells

February 15th, 2009
Tooth Structure

The tooth is made up of four primary components: dental pulp, dentin, enamel, and cementum (Cate, 1998)

A relatively recent addition to the stem cell family and holding promise as an easily obtained source of adult stem cells, dental pulp stem cells (DPSCs) were discovered at the beginning of this decade (Gronthos et al., 2000). DPSCs, also known as SHED cells (stem cells harvested from exfoliated deciduous teeth (Miura et al., 2003)), are one of the few discovered stem cells available from a naturally molted human tissue.

Dental pulp, which is living tissue at the center of the tooth made up of cells called “odontoblasts,” contains the aptly-named DPSCs. DPSCs were originally identified as being able to produce odontoblast-like cells as well as a tissue similar to dentin, which normally surrounds and protects the dental pulp (Gronthos et al., 2000; 2002). Although these studies found DPSCs able to produce two of the primary components of teeth, pulp and dentin, studies have not reported that DPSCs are able to create the other two factors, which are enamel and cementum (Cate, 1998).

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