الفهرس 
Basics of Stem Cells
Causes of Non-union of fracturesOnly 14 pages are availabe for public view
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Abstract
Stem cells are unspecialized cells in the human body that are capable of becoming specialized cells and are capable of dividing and renewing themselves for long periods. They may be totipotent, pleuripotent, mulipotent or unipotent depending on the type of stem cells.
Sources of stem cells include embryo, umbilical cord, and adult stem cells. Embryonic stem cells are Flexible, immortal and easily available, but difficult to be controlled, may be rejected by immune system and are ethically controversial. While adult stem cells are already somewhat specialized, immune hardy and flexible, but finite, of minimal quantity and genetically unsuitable.
Non union of a fracture is, the failure to unite in whatever time expected for healing to occur and being backed up with radiological changes which indicate that this situation will be permanent.
Causes of nonunion include severe Injury, poor blood supply at the fracture site, infection, inter position of soft tissues, inadequate immobilization, systemic disease, pathological fractures, and distraction of the fracture, non-compliance and neuropathy.
The strategy of use stem cells and gene therapy in bone repair includes: Stem cells and inductive scaffold, direct in vivo gene delivery, stem cell-based gene therapy.
In vivo gene transfer occurs within the host, with direct administration of the vector at a specific anatomic site. It is easy of use, one step procedure and less expensive than ex vivo gene therapy, but has lower transduction efficiency, lack of control over the target cell population and has risks associated with direct viral inoculation.
In stem cell-based gene therapy, cell is genetically engineered ex vivo and transduced to express the gene of interest, and then reimplanted at the fracture site, where they produce the desired protein. It is more specific, has higher transduction efficiency and patient is not exposed to the risks of a direct viral inoculation, but it is two stage procedure and more expensive.
With the progress that has been achieved recently, the promise of stem cells in fracture-healing comes closer to being realized.