Regeneration

[science_spot]

I am fascinated by the starfish.  This simple creature is able to regenerate its body from a single leg as long as part of the central region is attached.  Most of us have probablly heard how fisherman used to try to kill starfish that invaded their traps and eat their catch - by cutting them up and throwing them back.  According to the story, they stopped this practice when they learned this practice actually increased their numbers.

The starfish is not the only creature who can regenerate a large portion of its body. 

Planarians are flatworms that can regenerate quickly because they maintain a population of stem cells in their bodies at all times.  These cells quickly divide in order to make more cells with can then differentiate into other cell types (such as skin) that will make up the regenerated portion of the body.  The cool thing about planarian regeneration is that an organism cut in half will regenerate from both cuts - giving you two new organisms.  This is a form of asexual reproduction.

The newt can regenerate severed limbs, but the process is slower than planarian regeneration.  Newt limb generation is a well-studied process.  Regeneration begins immediately after the limb is severed, as an "endcap" of skin tissue migrates to cover the wound.  Under the endcap, earby cells will de-differentiate, which means they are inducing themselves to become stem cells again.  After de-differentiation, the cells can then differentiate into all the different cell types needed in the new limb:  bone, muscle, skin, etc.  As these new cells are formed, they also form three dimension structures and regenerate the connects to existing structures, such as neurons and vasculature.  This is necessary in order for the new limb to be functional.

In general, the ability to regenerate large body sections is only available to simple organisms.  Complex organisms such as humans are not normally able to regenerate large body sections, but we can regenrate some smaller pieces, such as fingertips, kidney and liver.  For many years, this ability could not be explained but it was well-documented.  it is now generally accepted that circulating populations of adult stem cells are responsible for human organ regeneration.   I have general stem cell information available in my Cafemom group Stem Cells if you would like to know more.

Many people look forward to the future of human regenerative medicine, some of which depends on the use of stem cells.  A few groups are working to develop whole organs from stem cells (both adult and embryonic) as well as cells from adult tissues.  These new organs are being pursued both in artificial systems (life tissue culture dishes), as well as cell injections that use cues from the body to grow new organs.  Examples such as regrowth of new heart tissue, new neurons and myelinating cells are plentiful, to treat conditions such as myocardial infarction (heart muscle death), spinal cord injury and MS, respectively.

Some wonderful research institutes participating in regenerative medicine studies include the Wake Forest Institute for Regenerative Medicine, California Institute of Regenerative Medicine, the McGowan Institute, and Texas Heart Institute.  The NIH also has a fact sheet that provides more information about regenerative medicine.

Tonya

The Science Spot

It's not Just the Science (a blog about science at my house)

 

[Nonoluna]

Jan. 29, 2010 at 11:56 AM

That's just so cool. :)

[mtnmama111]

Jan. 29, 2010 at 1:15 PM

[arthistmom]

Jan. 30, 2010 at 11:57 AM

What, no pictures?!! :) Good stuff, Tonya!

[science_spot]

Jan. 31, 2010 at 6:37 AM

I know, I want to use more pictures. 

(Original Poster)