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Published: 2017

Total Pages: 478

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Because of recent advances in stem cell research, cell therapies have gained increasing attention. Stem cells have shown promise to treat degenerative diseases and disorders such as Parkinson's disease, Alzheimer's disease, multiple sclerosis and degenerative disc disease. They are also being investigated to repair and regenerate skeletal tissues and structures. Pluripotent embryonic stem cells (ESCs) have the ability to differentiate into all of 200 types of cell in human body and have greatest potential for cell therapy. However, they face ethical and moral concerns. Whereas, adult stem cells (ASCs) such as bone marrow stromal cells (MSCs), hematopoietic stem cells (HSCs) are more acceptable for cell but they display limited proliferation and differentiation potential. Furthermore, ASCs may undergo genetic changes due to aging and environmental stress. Therefore, others and we have searched for alternative sources of cells for therapeutic usage. These efforts have led to discover stem cells (SCs) from perinatal tissues such as human umbilical blood and cord (UC). Not only, the SCs isolated from perinatal sources can be isolated non-invasively but also they are more primitive than ASCs. Current methods to isolate SCs from UC yield low amounts of cells with variable proliferation potential. Since, UC is an anatomically complex organ; we hypothesized that the variation in the SCs could be due to the difference in the various niches the UC harboring the SCs. In this study, we dissected the UC into its discrete parts, cord lining (CL), Wharton's jelly (WJ) and cord placenta junction (CPJ) and isolated SCs from each of these segments using explant culture technique. The isolated cells from all three sources displayed adherent fibroblastoid morphology, and not only expressed MSCs markers, CD29, CD44, CD73, CD90, and CD105 but also pluripotency genes, OCT4, NANOG, SOX2 and KLF4. They differentiated into multiple lineages such as adipogenic, chondrogenic and osteogenic cells. However, these cells displayed variations in their clonal capacity, ability to self-renew and differentiate depending upon the source of their isolation. SCs isolated from CPJ had highest rate of proliferation and greater capacity to self-renew and differentiate as compared to the SCs derived from CT and WJ. Microarray analysis confirmed the differences in these SCs based on the findings of differentially expressed genes between CPJ-, CL- and WJ-MSCs. We also found variation in the expression of IncRNA genes. Our studies demonstrated CJP as the sources of SCs with superior properties. These cells were then used for cell therapy and toxicological studies. Cell therapy feasability studies were conducted using CPJ-SCs and their chondrogenic derivatives, chondroprogenitor cells (CPCs) and nucleus pulposus (NP) like cells (NPCs) to regenerate damaged intervertebral disc (IVD) in a rabbit model. Degeneration of IVD results due to the loss of NP and is a common cause of lower back pain. Animal studies performed by transplanting CPJ-SCs and their derivatives showed significant improvement in the histology, cellularity, extracellular matrix proteins, and water and glycosaminoglycan contents of IVDs. Furthermore, the transplanted cells survived, engrafted and displayed homing into NP in situ. In addition, IVDs receiving CPJ-SCs derivatives exhibited higher expression of NP specific human markers, SOX9, ACAN, COL2, FOXF1, and KRT19. The regulation of the regeneration process and the NP biosynthesis was determined to be via TGF[beta]1/Smad pathway. Overall, the animal study showed that NPCs were is more efficacious than the CPCs and SCs. Our results provide basis and impetus for clinical studies to treat DDD as well as other degenerative diseases and disorders. Furthermore, these cells could be used for tissue engineering, regenerative medicine and pharmaceutical applications.