Papers by Keyword: Cell Differentiation

Abstract: By observing the process of hatch chickens, then combined with the modern biological knowledge and computer programming technology the paper proposed a hypothesis--coding sequence of DNA in cell is a set of program code sequence which includes instructions and data. And by making some program model, the paper simulated the two key procedures in life phenomena, namely cell division and cell differentiation. Then we can get some interesting ideas: If we look DNA coding sequence as program code sequence, the life phenomena is fully consistent with the principle of computer process . It is a macroscopic presentation of the life program in running status and whose code sequences were stored in DNA molecule chain. Combined with reflection calculation technology in the computer program model we also can come into an inference that Reflection technology is essential in the life process.

Abstract: The formula that life process follows is a major scientific mystery during centuries. Some people put programming thoughts into this field like Gates brought the idea that “Human DNA is like a computer program but far, far more advanced than any software we’ve ever created”[1]. Here we proposed a more specific hypothesis on this topic as that DNA is a set of p-code[2] and the enzymes which control chemical reactions and transport processes in cell metabolism are the basic instructions. Based on this hypothesis, some program models were developed successfully in this work to simulate the key processes of life phenomena: gene expression, cell division and differentiation, and life evolution. The results of these simulations show that there is a high level of similarity between life phenomena and computer programs; the process of cell differentiation and evolution of life can be explained in a programming way. These models also suggest that reflection technology[3, 4] is essential to life process. Besides, C-value paradox, N-value paradox[5] and pseudogene as well as some other biological problems could be also explained by these programming models. These conclusions imply that life phenomena are consistent with the concept of “process” in computer fields.

Abstract: Osteogenic differentiation of mesenchymal stem cells (MSC) is important in the field of bone tissue engineering. The identification of biological factors that influence osteogenesis is vital for developing a broader understanding of how complex microenvironments play a role in differentiation. The aim of this study was to demonstrate that adipose-derived stem cell (ADSC) osteogenesis is enhanced through interaction with extracellular matrices (ECM) secreted by ADSC undergoing osteogenesis. ADSC were obtained from human patients following elective abdominoplasty. Cells were selected for plastic adherence, characterized, and induced to differentiate using osteogenic supplements (OS; dexamethasone, ascorbic acid, and beta-glycerol phosphate). Cells were removed at several time points during osteogenesis and the secreted ECM was isolated. Undifferentiated cells were re-seeded onto the cell secreted ECMs and induced to differentiate with OS. At several time points, cells cultured on ECMs or tissue culture plastic controls (i.e. uncoated surface) were collected and RNA isolated. QPCR and gene array analysis revealed enrichment of osteogenic markers and more rapid progression through osteogenic maturational phases in cells seeded onto ECM secreted at the midpoint in differentiation (ca. 15 days). Our results demonstrate that the cumulative deposition of ECM reaches a critical point at approximately 15 days, before which there appear to be no definitive osteogenic cues from the matrix, and after which, strong drivers of osteogenesis are present. The creation of microenvironments that contain essential morphogenic matrix signals is an important step towards methods of growing and differentiating MSC in a rapid effective manner, particularly for bone-related clinical applications.

Abstract: Electrospinning technique is an efficient processing method to manufacture micro-and nanosized fibrous structures by electrostatic force for different applications. In biomaterial field, electrospinning technique has been successfully utilized to prepare new drug delivery materials and tissue engineering scaffolds. Fiber mats of biodegradable polymers having a diameter in the nanoto submicro-scale can be considered to mimic the nanofibrous structure of native extracellular matrix (ECM). Native extracellular matrix, constituted of proteins and polysaccharides improving cells growth in its nanofibrous porous structure, controls not only the cell phenotype, but the whole structure of the biological tissues. In the present study we investigated the effect of electrospun reconstituted collagen fibers onto metals for oral implants devices manufacturing as far as the osteoblastic differentiation potential of stem cells and cytofunctionality of osteoblasts in-vitro. The cells cultured onto titanium samples coated with ECM constituents showed faster osteoblastic differentiation and more efficient deposition of mineralized matrix in comparison with those onto uncoated substrates.

Abstract: A major technological barrier to large-scale propagation of human embryonic stem (HES) cells is the persistence of spontaneous differentiation in culture. Our laboratory and others have previously reported that substrate topography, independent of surface chemistry, profoundly modulates fundamental cell behaviors. We hypothesized that topographic cues would also play a role in modulating HES cell behaviors. This hypothesis was tested on substrates containing nanoscale through micron scale grooves and ridges that were generated by soft lithography. Topographically patterned substrates improved maintenance of the self-renewing phenotype (p = 6.7x10-6) under culture conditions that promote stem cell self-renewal. Topographic cues were found to promote differentiation, however, under culture conditions that promote differentiation. To our knowledge these are the first experiments documenting that the physical topography of culture surfaces influences HES cell differentiation and self-renewal. Topographic cues should be considered a fundamental environmental factor that has relevance to emerging strategies of stem cell engineering.

Abstract: We have used zinc aluminate nanostructured films deposited by spray pyrolysis to determine its biocompatibility assessed by cells attachment and cell differentiation. Cell attachment onto zinc aluminate showed an increase of 53, 81 and 86% at 180, 300 and 420 minutes (p<0.05) when compared to controls. Mineralization was analyzed at 5 and 14 days of culture by scanning electron microscopy, microanalysis and atomic force microscopy. Our results showed in experimental culture a higher density of mineral-like tissue with small needle-shaped crystal and granular nanoparticles with preferential orientation when compared to controls. The composition of the mineral-like tissue deposited in zinc aluminate nanostructured material had a Ca/P ratio of 1.6, whereas control culture had a Ca/P ratio of 1.50. Our finding revealed that ZnAl2O4 promoted higher expression of type I collagen, bone sialoprotein, osteocalcin and alkaline phosphatase, suggesting that zinc aluminate provides a microenvironment that favors mineral formation and cell differentiation. Our results point to the potential use of ZnAl2O4 for the osteoinductive process in biomedical implants.

Abstract: Bone marrow cells are a potential source to induce different lineage cells which can be used to rebuild or replace damaged tissues using a Tissue Engineering (TE) approach. However, TE strategies usually require the use of a material to support the development of a biological tissue. Beta-polyvinylidene fluoride (β-PVDF) is a biocompatible, thermoplastic with piezo-electrical properties that has been shown to provide a good cellular attachment and therefore might present advantageous properties as a scaffold material for cell seeding/culturing. The present study describes the characterization of β-PVDF membranes as a support material for growth and differentiation of goat marrow cells (GMCs) into osteoblasts, leading to the formation of substitutes for tissue regeneration. The obtained results suggest that β-PVDF piezoelectric properties influence cellular behavior. β- PVDF membranes not only enhance GMCs adherence and proliferation but also improve differentiation towards the osteogenic phenotype both in static and dynamic culture conditions. Furthermore, β-PVDF membranes exhibit very promising properties, suggesting that this material provides adequate support for the seeding and the development of undifferentiated cells towards a desired phenotype.

Abstract: Appropriate culture conditions cause bone marrow stem cells to differentiate into multilineage cells such as adipocytes, chondrocytes, and osteoblasts. One key factor that regulates intercellular signaling and cell differentiation is the extracellular matrix microenvironment. The composition of the extracellular matrix influences cellular functions. In the present study, we investigated the effects of a microenvironment comprising a three-dimensional apatite-fiber scaffold (AFS) that has two kinds of pores (micro- and macro pores) on proliferation and subsequent differentiation of bone marrow stem cells. Morphologic observation revealed that osteoblastic cells in the AFS were distributed primarily in the same location on the fibrous scaffold and formed bridges within micro- and macro pores. We used molecular approaches to evaluate cell proliferation and differentiation in detail. Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that culturing bone marrow cells on AFS increases expression of osteocalcin (OC) mRNA compared with culture in a dish. Furthermore, cells cultured in AFS expressed type X collagen (Col X), which is a marker of hypertrophic cartilage. These data suggest that the three-dimensional microenvironment of AFS facilitates cell proliferation and differentiation, and promotes endochondral ossification of bone marrow cells.