Tissue formation techniques

Raman spectroscopy can offer a number of advantages over traditional cell or tissue analysis techniques used in the field of TE (Table 18.1). Commonly used analytical techniques in TE include the determination of a specific enzyme activity (e.g. lactate dehydrogenase, alkaline phosphatase), the expression of genes (e.g. real-time reverse transcriptase polymerase chain reaction) or proteins (e.g. immunohistochemistry, immunocytochemistry, flow cytometry) relevant to cell behaviour and tissue formation. These techniques require invasive processing steps (enzyme treatment, chemical fixation and/or the use of colorimetric or fluorescent labels) which consequently render these techniques unsuitable for studying live cell culture systems in vitro. Raman spectroscopy can, however, be performed directly on cells/tissue constructs without labels, contrast agents or other sample preparation techniques. 

Triplet detection. Time-resolved techniques (absorption spectroscopy or diffuse reflectance) allow for detection of the triplet state of the excited chromophore even in intact tissues. This technique has been used to determine the absence (Dillon and Atherton, 1990) of triplet formation by the endogenous 3-hydroxy-kynurenine, as well as the presence of triplets from sensitizing drugs in intact lenses (Roberts et al., 1991b). 

Ref. 6) established that potato-cell suspension cultures synthesize and accumulate sesqulterpenold phytoalexins. This ability to elicit terpenoid phytoalexin formation In cell suspension culture should speed the exploitation of tissue culture techniques In the studies of terpenoid phytoalexin biosynthesis. 

Another level of biosynthetic control must derive directly from available genetic information. The genes may exert control in supplying the appropriate information for formation of both structural protein (the proteoglycan protein) and catalytic protein (the specific enzymes responsible for the biosynthetic steps). Tissue culture techniques have also been useful in the examinations of some factors that influence phenotypic characteristics of cells (see S46), and it has been considered (Nl) that proteoglycan and DNA biosynthesis are mutually antagonistic. Such a phenomenon would affect cell differentiation. With the technique of somatic cell hybridization, it has been possible to combine the genomes of two strains of fibroblasts that differ in the rate of production of hyal-... 

Cell transplantation involves the removal of healthy cells from a biopsy or donor tissue and then injecting the healthy cells directly into the diseased or damaged tissue. However, this technique does not guarantee tissue formation and generally has less than 10% efficiency. 

Yoshikawa and Myoui (2005) reported interconnected porous HA fabricated via a process called form-jel, a technique which creates a scaffold with an excellent vascular network ample for blood supply, an aspect of bone regeneration. It serves as a good scaffold for the delivery of cytokines, which enhance bone tissue formation in defect sites. The use of poly(L-lactic acid)/HA composite scaffold for bone tissue engineering synthesized via a thermally induced phase separation technique records a... 

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