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Stem Cells (ASCs) depending Stem cell therapy involves various routes for on their source (Figure-1). The plasticity is the ability transplantation of cells into patients like local delivery of stem cells to differentiate which may form one cell or systemic infusion. Stem cells can be derived from type or multiple types of cells (Figure-2). Totipotent same animal (autologous), same species (allogeneic) means ability to differentiate into all three germ layers or from different species (xenogenic) for transplanincluding placenta similarly pluripotent stem cells can tation. Recent studies report many interesting form all three germ layers except placenta. The examples of the therapeutic use of MSCs and ESCs multipotent stem cells can differentiate into multiple [47-49]. Stem cells address a broad spectrum of cell types of particular tissue type whereas unipotent indications, including spinal cord injury, bone, can form only one cell type [9]. The first successful cartilage and cardiovascular repair. In 1968, first report of mouse embryonic stem cells (ESCs) [10,11] successful allogenic stem cell graft in humans using was followed by isolation and characterization of ES donor bone marrow was undertaken in the United cells in other species like hamster, mink, rabbit, rat, States of America [50,51]. Currently, there are many monkey, marmoset, chicken, human, baboon, dog, cat, research groups studying in vitro expansion of these horse, pig, cow, sheep, goat and buffalo [12-23]. Adult and other stem cells for direct clinical applications stem cells are of various types, hemopoeitic stem cells, [52]. Stem cells must be characterized according to mesenchymal stem cells, neural stem cells, skin stem criteria decided by International Society for Cell cells, retinal stem cells etc. [24]. Mesenchymal Stem Therapy (ISCT) before they are utilization for therapy Cells (MSCs) can be isolated from bone marrow, fat, [53]. In animals, MSCs derived either from bone umbilical cord blood (UCB), amniotic fluid, placenta, marrow or adipose tissues for their routine use in dental pulp, tendons, synovial membrane and skeletal experimental studies and clinical cases [54,47]. MSCs muscle [25-33]. They have the potential to differen- are beneficial in handling various chronic and tiate into cells of various tissues like fibroblasts, debilitating clinical conditions of canines, equines and muscle, bone, tendon, ligament, and adipose tissue caprines though there are very limited reports in large [34,35,36,37]. Friedenstein and co-workers [25] ruminants on therapeutic application of stem cells isolated these cells as colony-forming unit fibroblasts research is still going. Many private companies like from murine bone marrow. Further, Caplan (1991) for Vetstem (U.S.A., http://www.vet-stem.com/), Medistem the first time named these cells as mesenchymal stem Inc. (U.S.A., http://medisteminc.com/), Histostem cells. MSCs have been isolated from a number of (South Korea, http://www.histostem.co.kr) provide species like human, rat, mice, dog, cat, pig, horse, stem cell therapy for animals and claims cure for sheep, goat, cattle [11,38-46]. MSCs can be isolated orthopedic and other injuries (for websites see www.veterinaryworld.org Veterinary World, Vol.5 No.8 August 2012 500 Source: Spencer et al., 2011 [102] Source: Boiani et al., 2005, [103] reference). Recently, some institutions like North Cardiac defects Carolina state university, Cambridge university were Laflamme and co-workers [64] injected diff- in news for treatment of canine spinal injuries. erentiated cardiac-enriched hESC progeny into the left Spinal injuries ventricular wall of athymic rats and found that grafts consisted predominantly of cardiomyocytes by 4 The remarkable developmental potential and weeks. hESCs can form human myocardium in the rat replicative capacity of human embryonic stem (ES) heart, permitting studies of human myocardial cells were utilized by transplanting neural precursors development and physiology and supporting the into the brain of immunosuppressed neonatal mice and feasibility of their use in myocardial repair. Mouse ES no teratomas emerged within 8 weeks after implan- derived cardiomyocytes were engrafted in injured tation [55]. In similar way neural progenitor population myocardium of rat this resulted in an angiogenetic of cells was used in the successful treatment of a effect, and subsequently improved cardiac function Parkinson's rat model for 12 weeks with no teratoma during the 32-week observation period [65]. Menard formation [56]. hESC derived neurons were injected and associates [66] transplanted murine ES derived in primate and rodent models for treatment of neuronal cardiomyocytes in 18 sheep in which myocardial injuries without tumor formation [57]. Acute spinal infarction was induced they found that ESCs were injuries are common in canines and felines that lead to colonized in the scar area and accompanied by a loss of tissue, including myelinated fibre tracts functional bene? t of the damaged myocardium. The responsible for carrying nerve impulses. The nervous findings obtained in a clinically relevant large-animal tissue has limited regeneration capacity and complete model of heart failure strengthen the potential restoration of locomotor activity is challenge to therapeutic use of ESC to regenerate the severely modern
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