الفهرس 
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Abstract
Research on stem cells is advancing knowledge about how an organism develops from a single cell and how healthy cells replace damaged cells in adult organisms. This promising area of science is also leading scientists to investigate the possibility of cell-based therapies to treat disease, which is often referred to as regenerative or reparative medicine (Sabrina et al, 2009).
Stem cells exhibit multilineage differentiation capacity, and are able to generate progenitors with restricted developmental potential, including fibroblast, osteoblast, adipocyte and chondrocyte progenitors. These cells are unique cells possessing two main features. The first is self-renewal ability, and the second is the ability to give rise to differentiating cells (Bacigalupo, 2004).
The source of adult stem cells remains a controversy. They can be harvested from aborted fetuses, umbilical cord blood, or adult tissues. During development, stem cells progress towards cell specific lineages through progenitors, mature into differentiated cell types, and assemble to form tissues. The most accepted hypothesis suggests that the stem cells are somehow set-aside during the fetal development and restrained from differentiating (Schuldiner et al, 2002).
Biomaterials are frequently used in regenerative medicine. They act as artificial extracellular matrix (scaffolds) with distinct mechanical and biological properties or as carriers for drugs and bioactive molecules (Sabrina et al, 2009).
Many organic biomaterials have been investigated for scaffold formation. These are either naturally derived as collagen, fibrin, agarose, alginate, gelatin, silk or hyaluronic acid, or synthetically produced. Synthetically produced organic biomaterials are mainly polyhydroxyacids as polyglycolide or polylactide (Sabrina et al, 2009).
The usefulness of MSCs for cartilage repair has been demonstrated in studies with animal models. The disorder in osteoarthritis seems to affect not only bone and cartilage but muscle as well. The locally present MSCs in osteoarthritic joints are malfunctioning, so It is possible that cells recruited from autologous bone marrow and cultured in vitro could be selected to express a more chondrogenic phenotype and to attach into cartilage defects to allow better repair of joint surfaces without osteophyte formation (Wakitani et al, 1994).
Rheumatoid arthritis (RA) is an autoimmune syndrome that is assumed to be caused by the recognition of arthritogenic antigens in the synovium. The use of peripheral blood stem cells and better supportive care had combined to make HSCT a more realistic option for those with non-malignant conditions such as autoimmune diseases (Bingham and Moor, 2004).
Juvenil chronic arthritis (JCA) is the most frequent autoimmune disease of childhood and is not a benign disease. Functional disability occurs in 20-30% of patients with JCA and 5-10% develop a serious handicap (Petty, 1999).
Case reports of adult patients with autoimmune disease treated with autologous or allogenic stem cells transplantation showed that patients may be cured of their original autoimmune disease. This success motivated the use of autologous stem cell transplantation (ASCT) for the treatment of autoimmune disease and there is a rapid expanding experience with ASCT (Tyndall, 1999).
ASCT is still considered an experimental treatment and is therefore reserved for those patients who have severe disease. The risk of death is significant, and the pre-transplantation conditioning regimen has significant potential toxicity. Patients with chronic inflammatory diseases are at risk of opportunistic infections after ASCT because of previous long term and ongoing immune-suppression. Therefore appropriate screening for infections and meticulous surveillance is critical (Wedderburn et al, 2003).
Systemic lupus erythematosus (SLE) is a multisystem disease of unknown cause that is characterized by the presence of multiple auto-antibodies. The primary rationale for HSCT in SLE is the depletion of auto-reactive T and B-cells which are thought to be responsible for driving the disease (David, 2004).
Systemic sclerosis (scleroderma, SSc) is a heterogeneous autoimmune connective tissue disorder with an often progressive and fatal course. Hematopoietic stem cell transplantation (HSCT) for the treatment of severe, progressive diffuse SSc has been increasingly employed (Dominique et al, 2008).
Systemic vasculitis are a heterogeneous group of potentially fatal inflammatory diseases. There is limited experience of stem cell transplantation in vasculitis (Kotter et al, 2005).
Degeneration of IVDs is characterized by changes involving disc morphology, composition of extracellular matrix, as well as loss of disc cells, proteoglycan and water content. Cell therapy is an alternative approach, and the regenerative effects of transplantation of autologous cells, such as nucleus pulposus cells, cartilaginous chondrocytes, and mesenchymal stem cells into the IVD, have been demonstrated (Sakai et al, 2005).
Inflammatory muscle disease form a heterogeneous group of neuromuscular disorders, characterized by a progressive muscle weakness resulting in ambulatory deficiency that leads to death by respiratory insufficiency in some cases. Primary myoblasts can provide a ready source of cells for cell therapy and tissue engineering applications because they are numerous and easily obtained from a small biopsy (Grenier and Rudnicki, 2006).