D.Tech. (Biomedical Technology) / Stem cells are defined as undifferentiated cells that can proliferate and have the capacity of both self-renewal and differentiation to one or more types of specialised cells (Bishop et al., 2002). The two types of stem cells are embryonic and adult stem cells. Adult stem cells have been isolated from adipose tissue in abundance and with ease (Mvula et al., 2010) and these cells have been differentiated into smooth muscle cells (SMCs) with the enhancement of low intensity laser irradiation and the growth factors (de Villiers et al., 2011). Smooth muscles play an important role in diseases like cancer, hypertension, asthma and others (Rodriguez et al., 2006). Studies have shown that low intensity laser irradiation (LILI) can increase proliferation of cells, cellular attachment, differentiation and production of transforming growth factor-beta 1 (TGF-β1) in cells indicating that in vitro LILI can modulate the activity of cells and tissues (Khadra et al., 2005). Further studies have also discovered that LILI enhances wound healing (Fiszerman and Markmann, 2000). LILI has been successfully used for pain attenuation and to induce wound healing in non-healing defects (Hawkins and Abrahamse, 2005). LILI has been shown to increase viability and proliferation of adipose derived stem cells (ADSCs) (Mvula et al., 2008 and Mvula et al., 2010). Growth factors such as retinoic acids (RA) have been shown to have major influences on cells. They are involved specifically in apoptosis, cell proliferation, differentiation and maturation (Duong and Rochette, 2011; Gudas and Wagner, 2011). Co-culturing is used to achieve several cellular processes including proliferation, differentiation and migration (Kim et al., 2012). When two types of cells are cultured together, they are exposed to a number of complex environmental factors such as cytokines, extracellular matrix components, cell interactions, mechanical stimuli, signalling transcriptional pathways and transcriptional factors such as growth factors. v These factors are able to affect migration, proliferation and differentiation of one cell type into another (Zhang et al., 2012). The aim of this study was to investigate the differentiation potential of ADSCs when co-cultured with (SMCs) and to determine the role of LILI on the co-cultured cells. Short and long term biological effects were monitored on these cells following exposure to LILI and addition of growth factors. The study used commercial and isolated human ADSCs and SMCs (SKUT-1) cells. After growing cells to semiconfluency for ADSCs and confluency for SMCs, they were co-cultured in a ratio of 1:1 using the established methods supplemented with and without growth factors (TGF-β1and RA) and then exposed to LILI. The cellular morphology, viability and proliferation activities of the irradiated cells were then assessed using direct inverted and differential interference contrast microscopy (DIC), trypan blue test, adenosine triphosphate luminescence, optical density analysis, and carboxyfluorescein diacetate succinimdyl ester (CFSE) methods. In particular the expression of the specific markers of both ADSCs, β1 Integrin (CD29) and Thy-1 (CD90) and SMCs, Myosin Heavy Chain (MHC) were investigated through immunoflourescent microscopy and flow cytometric analysis. Up and down regulation of genes involved in the human mesenchymal stem cell array were analysed through Reverse Transcriptase Polymerase Chain Reaction (RTPCR)...

Indiana University-Purdue University Indianapolis (IUPUI) / The hematopoietic system is highly proliferative, making hematopoietic stem and progenitor cells (HSPC) sensitive to radiation damage. Total body irradiation and chemotherapy, as well as the risk of radiation accident, create a need for countermeasures that promote recovery of hematopoiesis. Substantive damage to the bone marrow from radiation exposure results in the hematopoietic syndrome of the acute radiation syndrome (HS-ARS), which includes life-threatening neutropenia, lymphocytopenia, thrombocytopenia, and possible death due to infection and/or hemorrhage. Given adequate time to recover, expand, and appropriately differentiate, bone marrow HSPC may overcome HS-ARS and restore homeostasis of the hematopoietic system. Prostaglandin E2 (PGE2) is known to have pleiotropic effects on hematopoiesis, inhibiting apoptosis and promoting self-renewal of hematopoietic stem cells (HSC), while inhibiting hematopoietic progenitor cell (HPC) proliferation. We assessed the radiomitigation potential of modulating PGE2 signaling in a mouse model of HS-ARS. Treatment with the PGE2 analog 16,16 dimethyl PGE2 (dmPGE2) at 24 hours post-irradiation resulted in increased survival of irradiated mice compared to vehicle control, with greater recovery in HPC number and colony-forming potential measured at 30 days post-irradiation. In a sublethal mouse model of irradiation, dmPGE2-treatment at 24 hours post-irradiation is associated with enhanced recovery of HSPC populations compared to vehicle-treated mice. Furthermore, dmPGE2-treatment may also act to promote recovery of the HSC niche through enhancement of osteoblast-supporting megakaryocyte (MK) migration to the endosteal surface of bone. A 2-fold increase in MKs within 40 um of the endosteum of cortical bone was seen at 48 hours post-irradiation in mice treated with dmPGE2 compared to mice treated with vehicle control. Treatment with the non-steroidal anti-inflammatory drug (NSAID) meloxicam abrogated this effect, suggesting an important role for PGE2 signaling in MK migration. In vitro assays support this data, showing that treatment with dmPGE2 increases MK expression of the chemokine receptor CXCR4 and enhances migration to its ligand SDF-1, which is produced by osteoblasts. Our results demonstrate the ability of dmPGE2 to act as an effective radiomitigative agent, promoting recovery of HSPC number and enhancing migration of MKs to the endosteum where they play a valuable role in niche restoration.