Modifying stem cells via micro/macro enviroment.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3684257/

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One fundamental issue of stem cell biology is how stem cells are regulated by both the micro-environment immediately adjacent to stem cells, and by the general macro-environment that reflects the body’s physiological status. While the stem cell niche plays an important role, work from different approaches imply that multiple hierarchical layers control stem cell activity. These multi-layer controls ensure all intrinsic and extrinsic clues are taken into consideration and allow hair stem cells to sum the total regulators (activators / inhibitors) in making the decision to either activate or inhibit stem cells (Fig. 4). There is evidence that similar multi-layer controls also exist that regulate other adult stem cells. For example, the release of HSCs can also be affected by adipose tissue [30] and circadian rhythms [68]. Thus the principles discussed here are likely to be shared commonly by adult stem cell in different organs.

Stem cells bring great hope for tissue regeneration, treating degenerative disorders and even for slowing or reversing the aging process. In order to fulfill this dream, scientists have tried their best to identify and harvest stem cells in various tissues. The wish is to obtain therapeutic applications by manipulating the functions and abilities of stem cells. However, the number of stem cells in tissues is very small and it is difficult to definitively identify them or isolate them or expand their population for applicational usage. This hurdle makes using stem cells in a treatment strategy tenuous at present. We have learned that the niche, extra-niche macro-environment, and systemic factors as well as external environment are all key regulators for the homeostasis of stem cells. The more we know about how the homeostasis of stem cells is regulated, the closer we will be to overcome diseases associated with tissue degeneration or wounding. Developing a better understanding of the mechanisms through which multiple layers of the environment can modulate stem cell activities will enable us to target some or multiple layers of these environments as a new direction to regulate stem cells for therapeutic applications

This guy is working with Sung-Jan Lin. Just thought this was an interesting approach to male pattern baldness. We have the androgen approach, the dermal papilla approach and the stem cell approach to fighting pattern hair loss. Which way will give us results the quickest?

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Another great read:





http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3620027/


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excerpt:

Connecting with adjacent tissues.

A feather follicle does not exist independently. It has to be integrated to adjacent tissues.

During development, feather germs first form by epidermal and dermal tissue interactions. The early feather follicle starts to attract muscle, blood vessels, adipose tissues and nerves to come to the feather follicle. This allows the specific dermal muscle network to be connected (Lucas and Stettenheim 1972). Blood vessels originally travel parallel to the skin surface. Now they send out periodically spaced sprouts toward the base of each feather follicle. Eventually blood vessels enter the pulp vial the dermal papilla. Nerve fibers originally are randomly distributed in the dermis. Now the peripheral neurites go around the follicle and eventually enter the follicle via the dermal papilla into the pulp. With these connections, nutrition can be provided to the growing feather follicles. Feather follicles also can be moved with proper muscle control and connected with proper neurites. There is also an adipose layer surrounding the feather follicle, providing cushion and other functions.

During regeneration, muscles remain connected to the follicle sheath which does not degenerate. However, nerve and blood vessels that enter the pulp have to undergo degeneration. They will also have to regenerate, together with the regenerating feathers, to re-establish their function.

Thus feather work as an ideal model for its regeneration and the connection with surrounding tissues, so it is well integrated to the host.