Porcine skin tissue for wound closure
Document Type:Thesis
Subject Area:Engineering
In this proposal writing, the aim is to describe physiochemical, biochemical and mechanical considerations that form the basis for the design of the membrane useful as an experiment for wound closure. Regenerative medicine aims to engineer materials to replace or restore damaged or diseased organs. The mechanical properties of such materials should mimic the human tissues they are aiming to replace; to provide the required anatomical shape, the materials must be able to sustain the mechanical forces they will experience when implanted at the defect site. Although the mechanical properties of tissue-engineered scaffolds are of great importance, many human tissues that undergo restoration with engineered materials have not been fully biomechanically characterized. Several compressive and tensile protocols are reported for evaluating materials, but with large variability it is difficult to compare results between studies.
The skin graft also is important for improvement of the external appearance and contour of the skin as well as the texture and the colour of the exterior skin. Patients are increasingly waiting for various organ transplantations to treat failing or injured organs. However, with the shortage of suitable donor organs, regenerative medicine is aiming to create alternative solutions for patients with end-stage organ failure. Regenerative medicine aims to meet this clinical need by engineering materials to act as tissue substitutes, including soft tissues, such as cartilage and skin. To create a successful material to restore damaged tissues, the replacement material should mimic the properties of the native tissue it is going to replace. Preparation of Skin 1. Prepare specimens by manually dissecting off the adipose tissue and the thin layer of deep dermis using a scalpel blade and forceps.
This step is important to ensure consistency between samples14. Cut the resulting sheet of split-thickness skin into a standardized sample size (e. g. Immobilize the sample between two clamps (a commercial jig), one affixed to a 98. N load cell and the other to an immovable base plate14. The resulting area between the clamps tested in uniaxial tension should be 1 cm x 4 cm (Figure 2). A commercial jig was utilized to avoid non-uniform gripping and damage to the sample before testing. The sample is fixed to finger tight tightness. The displacement is held constant during the relaxation phase, not the load. Calculate elastic and viscoelastic properties as per the analysis section guidelines. The mechanical properties investigated will represent the average properties of the split-thickness skin constituents (epidermis and dermis). There is no defined tare load, as it is clear from the raw data when deformation is occurring and thus, only these data points are included.
Preparation of Cartilage 1. Cover the cartilage sample with phosphate-buffered saline (PBS) prior to and during compression testing to ensure that the sample is hydrated. PBS does not exactly match the physiological environment, but it allows both the materials and the tissues to be compared equally. Orientate the cartilage sample so the surface is perpendicular to the indenter. This allows the compression to be uniaxial and limits any shear loading. Program the compressive loading and relaxation testing regime into the software as a list of actions, as follows: Zero Load | Zero Position | Find Contact (Compressive loading) Wait (Relaxation). Thus, it is important to increase the sample size to allow for the testing of cartilage in different directions. As biomechanical properties of tissue also vary with age and gender, studies should be performed with a representative patient cohort to maintain validity to the clinical setting.
Furthermore, some mechanical protocols advocate preconditioning, where the tissue undergoes cyclic loading to ensure that the tissue is in a steady state for subsequent mechanical testing. However, the exact mechanism of preconditioning is unclear and the exact number of cycles needed to produce a consistent and repeatable response varies in different studies. The researcher should consider whether or not to include preconditioning after evaluating the reason for performing the specific biomechanical test. Jacobi, Ute, et al. Porcine ear skin: an in vitro model for human skin. Skin Research and Technology 13. Wu, Jianhong, et al. Toxicity and penetration of TiO2 nanoparticles in hairless mice and porcine skin after subchronic dermal exposure. Murtha, Amy P. et al. Evaluation of a novel technique for wound closure using a barbed suture. Plastic and reconstructive surgery 117.
Parrett, Brian M. Langenbeck's archives of surgery392. Dedmond, Barnaby T. et al. Subatmospheric pressure dressings in the temporary treatment of soft tissue injuries associated with type III open tibial shaft fractures in children. Journal of Pediatric Orthopaedics 26. Journal of orthopaedic trauma 20. MacNeil, Sheila. Progress and opportunities for tissue-engineered skin. Nature 445. Gurtner, Geoffrey C.
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