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Dr. Mohammed Alruby
Stem cell
Prepared by:
Dr. Mohammed Alruby
Stem cell

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Dr. Mohammed Alruby
Definition: are undifferentiated biological cell that can differentiate into specialized cells and can
divide through mitosis to produce more stem cells.
This cells found in multicellular organisms as mammals
Types of stem cells:
1- Embryonic stem cells: which are isolated from the inner cell mass of blastocyst
2- Adult stem cells: which found in various tissue cell and somatic cell.
3- Fetal stem cell: located in the organs of the fetuses
Properties of stem cells:
1- Self-renew: ability to go through numerous cycles of cell division while maintaining the
undifferentiated state.
2- Potency: capacity to differentiate into specialized cell types.
There is an attempts to restore facial defects with the patient’s own stem cells that minimize the
deficiency such as; 1- donor site morbidity, 2- immune-rejection, 3- pathogen transition, 4- sub-
potential repair.
Frontal process----------- middle and upper region of the face
2 maxillary process -------2 maxillary process ------- checks and upper portion of the jaws
Mandibular process ------- lower aspect of the jaws
All these processes are populated from mesenchymal cells that are multipotent and capable of
differentiating into: fibroblast, osteoblast, chondrocyte, lipocyte (from fat tissue).
Differences between the mesenchymal cells and mesenchymal stem cells (MScs)
MScs; is likely the product of a symmetrical division of mesenchymal cell
In adults: MScs maintain necessary tissue turn over and with injury or disease differentiate to
enable tissue regeneration
In many cases: MScs: used to regenerate craniofacial structure in vivo that their prenatal
predecessor mesenchymal cells are capable of generating during development.
Bio-engineering replacement of TMJ:
= to regenerate mandibular condyle, rat or human MScs were first isolated from bone marrow and
exposed separately to chondrogenic or osteogenic supplemented culture media.
= poly-ethylene glycol diacrylate (PEGDA) was dissolved in phosphate buffered saline (PBS) with
biocompatible ultra-violet photo initiator.
=MScs derived cell were encapsulated in (PEGDA) hydrogel into a negative mold of an adult
human cadaver mandibular condyle in two stratified but integrated layers.
NB: type X collagen: non fibrillary collagen found primarily differentiated hypertrophic
chondrocyte.
Type II collagen: basis of articular cartilage and hyaline cartilage forms fibrils which provide
tensile strength to the tissues
Dental tissue engineering:
1- Dentine regeneration: cells with properties of adult stem cells have been isolated
From dental pulp, exfoliated deciduous teeth and periodontal ligament (PDL). After confirming
that dental pulp stem cells differentiate into multiple line ages. Stem cells from human exfoliated

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Dr. Mohammed Alruby
deciduous teeth have also been differentiated into odontoblast like cells which in turn produce
small dentine like structure.
2- PDL regeneration: isolated stem cells from human PDL have been shown to regenerate
cementum / PDL like structure that resemble native PDL as this layer of cementum and
interfaced with dense collagen fibers similar to sharpy’s fibers.
Bone marrow derived MScs transplanted into periodontal osseous defect are capable of
regenerating periodontal tissue in function defect
= by repairing periodontal defect, orthodontist and oral surgeon can place temporary
anchorage for orthodontic movement and restore missing teeth respectively, also improve
bony defect in the mouth will allow orthodontist to position the teeth into sites which it was
impossible without regeneration.
Cranio-facial bone engineering
= stem cell based strategies for craniofacial bone reconstruction may over-come more
differences. Adipose derived mesenchymal cells AMcs (that are obtained from abundant
adipose tissue) are multipotent and capable of differentiation into muscle, bone, cartilage
cells.
= AMcs were seeded in apatite-coated poly-acrylic acid and implanted in the surgically
created calvarial defect to induce new bone formation similar to bone marrow MScs or
osteoblast.
= in patient with radiation therapy the irradiation affects bone remodeling and fracture
healing
Increased apoptosis and xerostomia, so to promote bone formation and this sites,
recombinant human bone morphogenetic protein-2 (BMP2) treated hydroxyapatite disks
were effective in regenerating bone.
= bone formation by transplanted bone marrow stromal cells in enhanced by the concurrent
administration of anaerobic doses of parathyroid hormone
= salivary gland regeneration has been reported using primary human salivary gland cell
to form acinar gland like structure that express amylase.
= for the field of orthodontics, possible change may include biologically derived
periodontium including single or multiple elements such as: PDL, cementum, alveolar bone,
tissue engineered TMJ, cell based bone graft----- used for ---- cleft palate.