Biomedical Engineering Reference
In-Depth Information
Submucosa is a mucosa supporting layer. Muscular mediates mixing and pro-
pulsion. Many organs are covered by a serosal layer providing support.
A rich vascular, lymphatic (including parietal structures) and neuronal networks
provide the incoming and outgoing communication for the homeostasis. Embry-
ologically, the vast majority of the structures is of endodermal origin but there are
also mesodermal contributions in muscular layers, nervous, lymphatics, and blood
supply.
12.1.2 Gastrointestinal Tract Functions
There are two main functions: assimilation of nutrients and elimination of waste.
All tract segments and solid contiguous viscera secretions are implicated in
nutrients assimilation. Liver also filters and detoxifies substances absorbed in gut
prior the passage into the bloodstream and detoxifies circulating toxins and
metabolic waste elements eliminated by gut or in urine.
12.1.3 Other Considerations
Mucosal epithelial cells and hepatocytes show a hypersensitivity to some injuries
and probably this explains their high renewal rate. In some tract segments,
architecture is organized for this purpose in such way that differentiation and
apoptosis occur in an ordered fashion along the crypt-villus axis.
12.2 Stem Cell Sourcing and Way of Application
These issues are analyzed in detail in another chapters so we are going to make
only some comments.
Stem cells (SCs) can be obtained directly from different adult tissues as Adult
Stem Cells (ASs, with variable differentiation potential), as pluripotent SCs
derived from adult tissue samples (either by therapeutic cloning or through the
creation of Induced Pluripotent cells —iPS), from embryos or from other minor
sources (umbilical cord…).
They can be applied for therapy autologously (to avoid possible immunological
rejection) or in an allogeneic way. For autologous application, cells could be
obtained from adult directly as ASs, by therapeutic cloning or through iPS creation.
SCs can be applied directly (undifferentiated) or after prior differentiation
according to therapeutic goals.
