الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 127 |  |  |
| | | from | 127 | | |
Abstract
Mesenchymal stem cells (MSCs) are heterogenous population
of stem/ progenitor cells with the capacity to differentiate into
mesodermal and non-mesodermal cell lineages. MSCs can self renew,
have multi-potent differentiation potential and represent an attractive
cell source for regeneration of damaged tissues in tissue engineering.
They can be isolated from different tissue sources such as bone
marrow, adipose tissue, umbilical cord, synovium, periosteum and
placenta.
Using specific media, MSC can be induced to differentiate in
vitro into different cell lineages such as adipogenic, osteogenic,
chondrogenic, and myogenic lineages.
For many years, bone marrow has been considered the ―gold
standard‖ for the derivation of MSCs for human stem cell engineering.
However, extraction comes with ethical constraint and problems
associated with painful harvesting and donor site morbidity. Umbilicalcords appear to show potential as a source of MSCs for a number of
reasons; easy isolation, they are considered medical waste, and
therefore their use in research has little ethical concern, they
proliferate rapidly in culture and are thought to be immune privileged.
The aim of this study is to investigate isolation and in vitro
differentiation of umbilical cord mesenchymal stem cells into different
cell lineages such as osteocytes, adipocytes and chondrocytes.
The present study included 35 UC samples, 10 of them
excluded due to use of FBS and contamination. All samples were
subjected to the followings: isolation of UC-MSCs was done using
explants method. The cells then were identified by their morphology (fibroblastic like cells) and flowcytometric analysis of cell surface
markers (CD34-, CD44+ and CD73+). Moreover, osteogenic,
adipogenic and chondrogenic differentiation were induced using
osteogenic, adipogenic and chondrogenic differentiation supplement
respectively and were identified by morphology and ICC.
The results revealed that:
As regards UC-MSCs morphological changes:
In the first five days, the adherent cells grew in a round shape
with few morphological changes.
After 7 days of primary culture, UC-MSCs adhered to the
plastic surface of the culture flasks and presented as a small
population of single cells with spindle-like shape.
On day 10 after initial culture, the cells exhibited long spindleshapedfibroblastic cells; they had begun to form colonies and
were confluent.
By day 14, UC-MSCs were duplicating rapidly and the cell
morphology was mainly spindle-shaped with triangular
appearance.
As regards flowcytometric detection of UC-MSCs:
Isolated MSCs showed positive CD44 (R= 55.0 – 90.0%) with
mean value (71.2±11.1), CD73 (R=60.0–85.0%) with mean
value (73.8± 8.7) and negative CD34 (R=0.3 –3.5%) with mean
value (2.3 ± 0.9).
As regards post-induction morphological changes:
Cells induced with the osteogenic differentiation medium
acquired stellate- shape with cellular processes seen.
Cells induced with the adipogenic differentiation medium
developed lipid droplets that accumulated in the cells. Cells induced with the chondrogenic differentiation medium
changed from differentiated round and polygonal cells at day 7
to reach elongated fibroblastic-like phenotype at day 14.
As regards post-induction ICC analysis:
Immunocytochemical analysis of differentiated osteocytes,
adipocytes and chondrocytes shows that cells were stained red
and the nuclei were counterstained blue.