The ability to artificially simulate the ‘mechanical’ niche, broadly termed as Extracellular Matrix (ECM), of the bone marrow determines success for stem cell growth, architectural organization and differentiation viz. tissue engineering. The advent of various natural and synthetic polymers has greatly influenced tissue engineering. The focus of the review is on various artificial niche simulations, ECM, scaffolds such as hydrogels, electrospun nano and micro fibers, bone-strengthening scaffolds and tissue infills. The utility of the ECMs in the treatment of various medical conditions including bone and cartilage tissues, nervous tissues, spinal cord and tendon tissues as well as wound healing, along with the ability of some ECMs in entrapment of elusive cell secretomes will be discussed. The future of tissue engineering has indeed got a new lease of life with polymer scaffolds and it is feasible that certain goals, thought of impossible so far, may become possible.

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Neonatal tissues, cord and placenta, are explored as alternate sources of mesenchymal stem cells (MSCs) for their therapeutic applications. Conventionally, MSCs isolated from cord tissues are maintained and propagated in FBS containing medium for promotion of growth and survival of cells. However, for therapeutic use, FBS use is not encouraged as it is of animal origin. Thus, there is a need for replacement of FBS by equally potent and clinically acceptable cost effective sources. The current study is designed to compare the effect of cord blood plasma (CBP) with MSC qualified FBS (M FBS) during culture and cryopreservation of MSCs. MSCs were isolated from cord and placenta and propagated in either M FBS or CBP. The efficiency of the cultures was analyzed by growth curve, morphology, phenotype and functionality. The cryo-protective role of the CBP was evaluated by using it in freezing medium of MSCs. Our data showed that CBP is equivalent to M FBS for culturing placental MSCs with respect to the phenotype, proliferation rate and differentiation to various lineages. However, cord MSCs displayed slow growth rate and reduction in surface expression of CD105 marker in CBP, whereas, the other parameters were comparable. Freezing of MSCs with CBP resulted in reduction of the late apoptotic and necrotic population. Thus, CBP imparts superior protection against cryogenic insults, and appears to be a valuable substitute to M FBS for cultivation and freezing of MSCs.

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Induced pluripotent stem cells (iPSCs) have opened up a new avenue for customized regenerative medicine. iPSCs can be generated by forced expression of transcription factors, Oct4, Sox2, c-Myc and KIf4. Although reprogramming techniques are well documented, one of the major concerns has been the poor efficiency of reprogramming. The reprogramming efficiency can be enhanced using various chemical compounds and vector systems. However, low reprogramming efficiencies and use of viral based vector systems limit clinical application of iPSCs. microRNAs (miRNAs) are extensively studied due to their critical role in numerous biological activities like cell cycle regulation, growth control and apoptosis. Discovery of embryonic stem cell (ESC) specific unique miRNAs, encouraged researchers to study contribution of miRNAs towards embryonic stem cell development, differentiation and somatic cell reprogramming (SCR). Depletion of mouse embryonic fibroblast (MEF) enriched miRNAs like miR-29a, miR-21 and let-7, are necessary to enhance reprogramming. Furthermore, up regulation of miR-200, miR-106a/b miR-120, miR-93 miR-301, miR-17, miR-721, miR-29b is required for mesenchymal-to-epithelial transition (MET), a critical initial event during the generation of iPSCs from fibroblasts. The expression of embryonic stem cell specific miRNAs like miR-290/miR-302 cluster, miR-367/miR372 is crucial to maintain pluripotent status of iPSCs. In this review, we discuss contribution of miRNAs to generation of iPSCs, their defined role in maintenance of pluripotent state, transcriptional regulatory networks and epigenetic factors to modulate reprogramming.

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Majority of human cancers are caused, mediated and modified by environmental and lifestyle factors; and the multi-factorial, multi-step and multi-path process of carcinogenesis involves a series of genetic and epigenetic events. In spite of tremendous advancement in understanding of the molecular basis of cancer and identification of several environmental carcinogens, avoidance of exposure to carcinogens and early detection and/or successful treatment for most cancers have met with limited success. Based on the susceptibility to modulations of the multi-step process of carcinogenesis by a multitude of environmental compounds, lifestyle changes and host factors, and the demonstrated success of prevention of certain infectious diseases and cardiovascular events, cancer preventive interventions are receiving increasing attention. Several cancer preventive interventions such as vaccination, chemoprevention, weight control and lifestyle changes have been implemented. The current review focuses on several approaches and agents that have been scrutinized by way of randomized clinical trials in humans for their cancer prevention potential. Successful chemopreventive agents include selective oestrogen receptor modulators and aromatase inhibitors for breast cancer, the 5-α-reductase inhibitors for prostate cancer, non-steroidal antiinflammatory drugs (NSAIDs) for colorectal lesions and vaccines for viruses that are associated with cervical and liver cancers. Several experimentally proven chemopreventive agents have been observed to lack efficacy with and without toxicity. In spite of numerous chemoprevention trials, the number of successful agents is rather small. Identifying novel approaches and chemopreventives holds tremendous potential for reducing the burden of cancer.

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Many theories were put forward about origin of cancer and immense research was carried out to understand the mechanisms involved in the origin and progression of the disease. The gain in scientific knowledge about cancer biology and technical advancement in treatment modalities resulted in improvement of clinical outcome in cancer therapy. However, recurrence and metastasis after therapy poses a major concern to clinicians. Resistant nature against therapeutic modalities and metastatic potential of cancer stem cells (CSCs), which even though form a fraction of tumor mass, result in failure of existing modalities of cancer treatment. The current article reviews the historical background of CSCs, involvement of various signaling pathways in the mechanism(s) of radioresistance and potential targets to be exploited in radiotherapy.

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