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| Background |
For mammals, such as humans, the situation is unfortunately
very different. In most instances, mammals are capable only of
incomplete regeneration: the function of an organ may be
recovered, but the structure will not be restored after tissue
damage, and wounded tissue is most often replaced by scarring.
A key mechanism of endogenous regeneration in amphibians is
known as epimorphosis. This process involves naturally induced,
wound mediated participation of stem cells and (or) other types
of tissue specific progenitor cells. Local cells, via complex
signaling mechanisms, de-differentiate to progenitors, and then
proliferate, re-differentiate, and replace damaged cells.
very different. In most instances, mammals are capable only of
incomplete regeneration: the function of an organ may be
recovered, but the structure will not be restored after tissue
damage, and wounded tissue is most often replaced by scarring.
A key mechanism of endogenous regeneration in amphibians is
known as epimorphosis. This process involves naturally induced,
wound mediated participation of stem cells and (or) other types
of tissue specific progenitor cells. Local cells, via complex
signaling mechanisms, de-differentiate to progenitors, and then
proliferate, re-differentiate, and replace damaged cells.
Repair and regeneration are widespread phenomena in the
biological kingdom, but the capacity for regeneration varies
among species.
Both invertebrates and amphibians can replace lost or damaged
organs and tissues that are identical in structure or function to
the original, in a process called complete regeneration.
biological kingdom, but the capacity for regeneration varies
among species.
Both invertebrates and amphibians can replace lost or damaged
organs and tissues that are identical in structure or function to
the original, in a process called complete regeneration.
In humans, over millions of years of evolution, epimorphosis
has been lost, and most tissues are terminally differentiated
with very limited capability for de-differentiation and
regeneration. While some regeneration is observed in the
human liver, as well as in the kidney following acute injury, the
rest of the human body's critical systems reveal extremely low
capability to regenerate damaged tissues and functions
associated with them.
On a very important parallel note: throughout the animal
kingdom, cancer is very rare in organs or tissues displaying
an efficient regenerative mechanism, even under the action
of carcinogens. When cancer does occur, it is mainly in aged
and (or) injured tissues that have exhausted their regenerative
ability.
has been lost, and most tissues are terminally differentiated
with very limited capability for de-differentiation and
regeneration. While some regeneration is observed in the
human liver, as well as in the kidney following acute injury, the
rest of the human body's critical systems reveal extremely low
capability to regenerate damaged tissues and functions
associated with them.
On a very important parallel note: throughout the animal
kingdom, cancer is very rare in organs or tissues displaying
an efficient regenerative mechanism, even under the action
of carcinogens. When cancer does occur, it is mainly in aged
and (or) injured tissues that have exhausted their regenerative
ability.
