Improve Tissue Quality Research Articles

A tissue quality index: an intrinsic control for measurement of effects of preanalytical variables on FFPE tissue

While efforts are made to improve tissue quality and control preanalytical variables, pathologists are often confronted with the challenge of molecular analysis of patient samples of unknown quality. Here we describe a first attempt to construct a tissue quality index (TQI) or an intrinsic control that would allow a global assessment of protein status based on quantitative measurement of a small number of selected, informative epitopes. Quantitative immunofluorescence (QIF) of a number of proteins was performed on a series of 93 breast cancer cases where levels of expression were assessed as a function of delayed time to formalin fixation. A TQI was constructed based on the combination of proteins that most accurately reflect increased and decreased levels of expression in proportion to delay time. The TQI, defined by combinations of measurements of cytokeratin, ERK1/2 and pHSP-27 and their relationship to cold ischemic time were validated on a second build of the training series and on two independent breast tissue cohorts with recorded time to formalin fixation. We show an association of negative TQI values (an indicator for loss of tissue quality) with increasing cold ischemic time on both validation cohorts and an association with loss of ER expression levels on all three breast cohorts. Using expression levels of three epitopes, we can begin to assess the likelihood of delayed time to fixation or decreased tissue quality. This TQI represents a proof of concept for the use of epitope expression to provide a mechanism for monitoring tissue quality.

Gingival biotype and its clinical significance – A review

Abstract Gingival biotype has a significant impact on the outcome of restorative and regenerative therapy. The disparity in treatment outcome is possibly because of the difference in tissue response to trauma. Hence in clinical practice identification of the periodontal biotype is significant. Gingival thickness can be assessed by various invasive and non invasive methods. Thick and thin tissues often respond differently to inflammation and trauma. Periodontal surgical technique can improve the tissue quality and treatment outcome. This review paper highlights the general aspects of gingival biotype, methods to assess gingival thickness, response to treatment, techniques to improve tissue quality and its clinical significance.

A multiscale approach in the computational modeling of the biophysical environment in artificial cartilage tissue regeneration

Tissue Engineering is a strongly interdisciplinary scientific area aimed at understanding the principles of tissue growth to produce biologically functional replacements for clinical use. To achieve such an ambitious goal, complex biophysical phenomena must be understood in order to provide the appropriate environment to cells (nutrient delivery, fluid-mechanical loading and structural support) in the bioengineered device. Such a problem has an inherent multiphysics/multiscale nature, as it is characterized by material heterogeneities and interplaying processes occurring within a wide range of temporal and spatial scales. In this context, computational models are useful to gain a quantitative and comprehensive understanding of phenomena often difficult to be accessed experimentally. In this paper, we propose a mathematical and computational model that represents, to our knowledge, the first example of a self-consistent multiscale description of coupled nutrient mass transport, fluid-dynamics and biomass production in bioengineered constructs. We specifically focus on articular cartilage regeneration based on dynamically perfused bioreactors, and we investigate by numerical simulations three issues critical in this application. First, we study oxygen distribution in the construct, since achieving an optimal level throughout the construct is a main control variable to improve tissue quality. Second, we provide a quantitative evaluation of how interstitial perfusion can enhance nutrient delivery and, ultimately, biomass production, compared with static culture. Third, we perform a sensitivity analysis with respect to biophysical parameters related to matrix production, assessing their role in tissue regeneration.

Postmastectomy Breast Reconstruction in the Irradiated Breast

Autologous tissue transfer is often indicated to achieve improved tissue quality during breast reconstruction after radiotherapy. The authors evaluated satisfaction with postmastectomy breast reconstruction among irradiated patients. The aim was to compare deep inferior epigastric perforator (DIEP) and latissimus dorsi flaps regarding satisfaction with aesthetic outcome between patients and plastic surgeons. Patients who underwent reconstruction with 24 consecutive DIEP flaps and 21 consecutive latissimus dorsi flaps in combination with prostheses were reviewed retrospectively. They received the Michigan Outcomes Study 36-Item Short Form Health Survey and a complementary form regarding patient satisfaction. They were photographed, and aesthetic results were evaluated by an independent board of plastic surgeons. There was no significant difference between the groups regarding demographic data or 36-Item Short Form Health Survey results. Plastic surgeons found the DIEP flap superior regarding size (p = 0.024) and shape (p = 0.039), whereas patients were more satisfied with the size (p = 0.046) and shape (p = 0.017) of the latissimus dorsi flap when patients' and surgeons' opinions were compared. Discrepancy between patients' and surgeons' opinions was verified with weighted kappa analysis. Regarding the donor scar, the latissimus dorsi flap was favored compared with DIEP flap reconstruction by both patients (p = 0.036) and surgeons (p = 0.001). There is a difference between patients' and plastic surgeons' opinions regarding breast reconstruction outcomes in the irradiated breast. The patients were more satisfied with latissimus dorsi flap reconstruction, which may relate to the donor-site scar. Surgeons favored DIEP flap reconstruction with regard to the size and shape of the breast. Therapeutic, III.

Histological Assessment of PAXgene Tissue Fixation and Stabilization Reagents

Within SPIDIA, an EC FP7 project aimed to improve pre analytic procedures, the PAXgene Tissue System (PAXgene), was designed to improve tissue quality for parallel molecular and morphological analysis. Within the SPIDIA project promising results were found in both genomic and proteomic experiments with PAXgene-fixed and paraffin embedded tissue derived biomolecules. But, for this technology to be accepted for use in both clinical and basic research, it is essential that its adequacy for preserving morphology and antigenicity is validated relative to formalin fixation. It is our aim to assess the suitability of PAXgene tissue fixation for (immuno)histological methods. Normal human tissue specimens (n = 70) were collected and divided into equal parts for fixation either with formalin or PAXgene. Sections of the obtained paraffin-embedded tissue were cut and stained. Morphological aspects of PAXgene-fixed tissue were described and also scored relative to formalin-fixed tissue. Performance of PAXgene-fixed tissue in immunohistochemical and in situ hybridization assays was also assessed relative to the corresponding formalin-fixed tissues. Morphology of PAXgene-fixed paraffin embedded tissue was well preserved and deemed adequate for diagnostics in most cases. Some antigens in PAXgene-fixed and paraffin embedded sections were detectable without the need for antigen retrieval, while others were detected using standard, formalin fixation based, immunohistochemistry protocols. Comparable results were obtained with in situ hybridization and histochemical stains. Basically all assessed histological techniques were found to be applicable to PAXgene-fixed and paraffin embedded tissue. In general results obtained with PAXgene-fixed tissue are comparable to those of formalin-fixed tissue. Compromises made in morphology can be called minor compared to the advantages in the molecular pathology possibilities.

Low Oxygen Concentrations Impair Tissue Development in Tissue-Engineered Cardiovascular Constructs

Cardiovascular tissue engineering has shown considerable progress, but in vitro tissue conditioning to stimulate the development of a functional extracellular matrix still needs improvement. We investigated the environmental factor oxygen concentration for its potential to increase the amount of collagen and collagen cross-links, and therefore improve tissue quality. Cardiovascular tissue engineered (TE) constructs, made of rapidly degrading PGA/P4HB scaffold seeded with human vascular-derived cells, were cultured at 7%, 4%, 2%, 0.5% O(2) for 4 weeks and compared to control cultures at 21% O(2). Tissue properties were evaluated by measuring the extracellular matrix production and mechanical behavior. The culture environment was monitored closely and the oxygen gradient throughout the constructs was simulated with a theoretical model. TE constructs cultured at 21%, 7% and 4% O(2) showed dense and homogeneous tissue formation with comparable strength, stiffness, collagen and collagen cross-link content. At 2% O(2), collagen content and stiffness decreased, whereas at 0.5% O(2), hardly any tissue was formed. Overall, tissue properties deteriorated at the lowest oxygen concentrations, opposing our hypothesis that was based on previous culture at low oxygen concentrations. Further research will focus on establishing the balance between applied oxygen conditions (concentration and exposure time) and optimal tissue outcome.

Corneal diagnostic imaging in the eye banking: how to improve tissue quality?

AbstractAbstract not provided

Functional Base of Tongue Fat Injection in a Patient with Severe Postradiation Dysphagia

Lipofilling is a well-established technique in reconstructive plastic surgery. It is used primarily in recontouring of the body and face to correct post-traumatic and congenital defects. The regenerative properties of adipose tissue have allowed the use of the lipofilling technique for the treatment of burn sequelae and irradiated breast to improve tissue quality and elasticity. We report on the case of a patient treated with radiation therapy for a nasopharyngeal carcinoma who presented with severe postradiation dysphagia. The lipofilling technique was successfully used to improve abnormal swallowing. The technical details and functional outcomes are discussed.

Effects of paraformaldehyde fixation on nicotinic acetylcholine receptor binding in adult and developing rat brain sections

In vitro receptor autoradiography requires unfixed tissue sections, but incubation and washing procedures often result in substantial tissue damage in sections from developing brain, hindering quantitative and qualitative analysis. Formaldehyde fixation greatly preserves morphology. However, fixation can interfere with pharmacological properties of receptors, increase in non-specific background labeling, or even destroy ligand binding sites. Two mild fixation protocols, 0.2% paraformaldehyde (pFA) and pFA vapor fixation, were compared for their ability to improve tissue morphology in postnatal day 7 (P7) brain slices and maintain binding of [ 125I]-epibatidine and [ 125I]-α-bungarotoxin to heteromeric and homomeric nicotinic acetylcholine receptors, respectively. Fixation greatly improved the ability of P7 brain slices to withstand incubation and washing procedures during binding, resulting in minimal or no loss of tissue after prior 0.2% pFA or vapor fixation, respectively. In adults, distribution pattern of [ 125I]-epibatidine was identical in fixed and unfixed slices, with no difference in total and non-specific labeling. Distribution of [ 125I]-αBTX labeling was similarly unaffected by 0.2% pFA fixation, but vapor fixation increased total and non-specific binding signal. Thus, mild fixations greatly improve tissue quality during receptor binding procedures and can preserve pharmacological properties of nicotinic acetylcholine receptors. However, different receptors or ligands might exhibit differential sensitivity to fixation protocols.

Effect of a silicone-containing dressing on exuberant granulation tissue formation and wound repair in horses

To determine the effect of a silicone dressing on the rate and quality of repair of limb wounds and compare microvascular occlusion and apoptosis in wounds treated with the silicone dressing and those treated with a conventional dressing in horses. 5 horses. Horses received two 6.25-cm2 wounds on each metacarpus. Ten wounds were treated with a silicone dressing; the other 10 were treated with a control dressing. Quality of repair and wound size were evaluated at each bandage change. Time to healing and the number of excisions of exuberant granulation tissue were recorded. Biopsy specimens taken from healed wounds were evaluated semiquantitatively via histologic examination, p53 immunohistochemical analysis, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) to quantify apoptosis, and electron microscopic examination to measure microvessel luminal diameters. The silicone dressing surpassed the conventional dressing in preventing formation of exuberant granulation tissue and improving tissue quality. Microvessels were occluded significantly more often in wounds dressed with the silicone gel, which also diminished the expression of mutant p53, an indirect inhibitor of apoptosis, although greater apoptosis was not confirmed quantitatively by use of TUNEL. Because the silicone dressing inhibited the formation of exuberant granulation tissue, it may be integrated in a management strategy designed to improve the repair of limb wounds in horses.

PEGylation does not impair insulin efficacy in three-dimensional cartilage culture: an investigation toward biomimetic polymers.

A major goal in tissue engineering is the controlled application of growth factors. As a novel application system, we are currently developing biomimetic polymers that are processed into three-dimensional scaffolds. Bioactive proteins will be covalently bound to the polymers via a poly(ethylene glycol) (PEG) linker. Of paramount importance is the maintenance of the biological activity of the protein after PEGylation and covalent binding to the polymer. Therefore, within this study, insulin used as a model protein was PEGylated with an active succinimidyl ester of poly(ethylene glycol) (SS-NH-PEG) (MW ~2000) and biological effects of the protein-PEG conjugate were monitored in comparison with unmodified insulin. No significant differences in chondrocyte proliferation were observed in a conventional proliferation assay after treatment with insulin or PEGylated insulin. In a complex three-dimensional cartilage-engineering model the effects of insulin and PEGylated insulin were investigated over a wide concentration range (0.025-25 microg/mL). Insulin and PEGylated insulin at equivalent concentrations resulted in cartilaginous tissue constructs exhibiting identical wet weight, cell number, biochemical composition of the extracellular matrix, and histological appearance, both compounds significantly improving tissue quality as compared with control constructs. In conclusion, the presented study demonstrates that PEGylation of insulin using SS-NH-PEG did not change the activity of the protein in a complex biological environment and is regarded as a step toward the development of biomimetic polymers.

Long pulse biphasic electrical stimulation of denervated muscle.

In recent years a number of studies have employed long pulse biphasic stimulation as a treatment for denervated muscle to improve tissue quality and in some cases to improve contractile capability sufficient to restore function. However, in the U.K., this treatment is yet to be widely adopted clinically. A 5 subject, case based pilot study of long pulse biphasic direct stimulation of peripheral limb denervated muscle is being conducted and its effect on the tissue evaluated by measurement of muscle bulk, limb blood flow, and skin temperature. In cases of partial denervation. trapezoidal shaped pulses are used to minimize sensory and motor nerve fiber recruitment.

Soft-Tissue Modifications of Surgical Techniques for Placement and Uncovering of Osseointegrated Implants

The recommended modifications of soft-tissue management for two-stage implant surgeries have resulted in improved access for implant placement, accommodation of surgical stents, less formation of cicatrix in the vestibules, better control of flap extensions resulting in improved esthetics, and improved tissue quality for long-term peri-implant maintenance and success. The implication of periodontal guidelines to the uncovering procedure of dental implants result in decreased thickness of peri-implant tissues and less pocket formation around the transmucosal sleeves. These modifications contribute significantly to the long-term periodontal maintenance of peri-implant tissues.