1,721,018 research outputs found
The progress in ureter tissue engineering
Get PDFThe reconstruction of ureteral in men and women may require tissue engineering to ensure the clear transfer of urine from the kidneys to the urethra. Although most of the existing literature is focused on ureteral, urinary bladder and urinary diversion reconstruction, including stenting, Ureter Tissue Engineering through local tissue or bio-gradable substances is a viable, noninvasive procedure that has been proven to work. The complexities associated with tissue transplant failure are quite varied like tissue rejection, scaffolding procedure, in-body regeneration, species bias, and stem cells protein use. Recent data on ureteral tissue engineering will be thoroughly examined in this book chapter, cell grafting sources will be studied, procedures will be discussed, and seating scaffolding strategies and materials will be rigorously evaluated.</p
Adult stem cells in regenerative medicine of urinary system
No full textThe urinary system, an intricately designed network of kidneys, ureters, bladder, and urethra, orchestrates the symphony of functions such as waste elimination, electrolyte, and homeostasis balance to maintain the physiological equilibrium in the body. Like any other system of the body, the urinary system is not immune to defects and disruptions as it is affected by various urinary system diseases and disorders, which alter its function and architecture. The ineffectiveness of the current treatment methods for urinary diseases and their severity leads to an alternative treatment approach using tissue engineering (TE) to regenerate and reconstruct the urinary system components. The urinary TE approach combines specific cell sources with different scaffolds to develop engineered urinary tissue in vitro and in vivo for urinary reconstruction. Due to the inadequacy of native cells, the focus has been cast on using stem cells. Among stem cells, the use of adult stem cells has been prioritized over embryonic stem cells due to ethical and risk of malignancy considerations. Several studies have shown promising outcomes for TE of the urinary system using adult stem cells such as bone marrow-derived stem cells, adipose-derived stem cells, urinary-derived stem cells, endometrial stem cells, and dental pulp stem cells seeded on acellular matrix scaffolds such as bladder and intestinal submucosa and synthetic scaffold such as polylactic acid (PLA). However, some challenges, such as vascularizing engineered tissue, and selecting ideal scaffolds and cells, must be resolved before interposing into human trials. This chapter focuses on the various urinary diseases and disorders demanding TE for their treatment, provides an overview of types of adult stem cells and scaffolds used in research studies for TE of urinary tissues, and casts light upon the promising outcomes from studies conducted and challenges needed to be addressed for successful implementation of urinary TE applications on human.</p
Fabrication, Characterisation and Optimisation of Biodegradable Scaffolds for Vascular Tissue Engineering Application of PCL and PLGA Electrospun Polymers for Vascular Tissue Engineering
No full textAnnually, about 80,000 people die in the United Kingdom due to myocardial
infarction, congestive heart failure, stroke, or from other diseases related to
blood vessels. The current gold standard treatment for replacing the damaged
blood vessel is by autograft procedure, during which the internal mammary
artery (IMA) graft or saphenous vein graft (SVG) are usually employed.
However, some limitations are associated with this type of treatment, such as
lack of donor site and post-surgery problems that could negatively affect the
patient’s health. Therefore, this present work aims to fabricate a synthetic
blood vessel that mimics the natural arteries and to be used as an alternative
method for blood vessel replacement. Polymeric materials intended to be used
for this purpose must possess several characteristics including: (1) Polymers
must be biocompatible; (2) Biodegradable with adequate degradation rate; (3)
Must maintain its structural integrity throughout intended use; (4) Must have
ideal mechanical properties; and (5) Must encourage and enhance the
proliferation of the cells.
The feasibility of using synthetic biodegradable polymers such as poly (ε-
caprolactone) (PCL) and poly (lactide-co-glycolic acid) (PLGA) for fabricating
tubular vascular grafts was extensively investigated in this work. Many
fundamental experiments were performed to develop porous tissue-
engineered polymeric membranes for vascular graft purposes through
electrospinning technique to achieve the main aim. Electrospinning was
selected since the scaffolds produced by this method usually resemble
structural morphology similar to the extracellular matrix (ECM). Hence, four
6mm in diameter tubular shape vascular grafts PCL only, PLGA only, coaxial
(core-PCL and shell-PLGA), and bilayer (inner layer-PCL and outer layer-PLGA) was designed and fabricated successfully. The structure and properties
of each scaffold membrane were observed by scanning electron microscopy
(SEM), and these scaffolds were fully characterized by Fourier-transform
infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric
analysis (TGA), water contact angle measurements, mechanical tensile test,
as well as cell culture studies were carried out by seeding human umbilical
vein cells (HUVEC) and human vascular Fibroblast cells (HVF). Moreover, all
polymeric grafts underwent degradation process, and the change in their
morphological structure properties was studied over 12 weeks at room
temperature. All scaffolds were also exposed to a controlled temperature of
37°C for four weeks, in phosphate-buffered saline solution (pH, 7.3).
It was found that all scaffolds displayed exceptional fibre structure and
excellent degradability with adequate steady weight-loss confirming the
suitability of the fabricated scaffolds for tissue engineering applications. The
coaxial and bilayer scaffolds degraded at a much slower (and steadier) rate
than the singular PCL and PLGA tubular scaffolds. Coaxial grafts fabricated
via coaxial needle showed an increase in their fibre diameter and pore size
volume than other membranes, but also showed to have significant tensile
strength, elongation at fracture, and Young’s modulus. To conclude, all
scaffolds have demonstrated to be reliable to adhere and proliferate HUVEC,
and HVF cells, but these cells were attracted to the PLGA membrane more
than other fabricated membranes
Coaxial Electrospinning of Synthetic/Natural Polymer Combinations for Controlled Release of Active Components in Biomedical Applications
Get PDFThe project aims to advance coaxial electrospinning techniques for polymer/protein systems, targeting tissue engineering and drug delivery applications. While electrospinning is increasingly utilised in tissue engineering, challenges arise when incorporating active pharmaceutical ingredients due to solubility and release rate limitations. Coaxial spinning addresses these challenges by enabling precise control over release rates and properties. This research focuses on developing coaxial electrospinning processes, with a particular emphasis on incorporating extracellular matrix proteins and biologically active components.
By systematically investigating process parameters, this study elucidates the structural and functional properties of coaxial fibres and their implications for biological response. Extensive characterisation techniques, including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), UV-visible spectroscopy, and transmission electron microscopy (TEM), are employed to analyse fibre morphology, chemical composition, and structural properties.
Specifically, polycaprolactone (PCL) as a shell layer demonstrates sustained prolonged release of active components while gelatin as the shell layer facilitates instant release. These findings underscore the versatility and efficacy of coaxial electrospinning in tailoring scaffold properties for diverse biomedical applications.
The novelty of this work lies in its extensive exploration of coaxial electrospinning techniques and their application in tissue engineering and drug delivery. By controlling release and scaffold properties, this research contributes valuable insights to the field, paving the way for the development of advanced biomaterials with enhanced therapeutic efficacy
Fabrication Characterisation and Optimisation of Electrospun Scaffolds for Ligament Tissue Reconstruction. The Development of an Anterior Cruciate Ligament (ACL) Analogue using Electrospun PCL, PVA Hydrogel and Polyester Sutures
No full textYear 2019, football, rugby, netball and skiing had most occurring ACL injuries, listed by United Kingdom National Ligament Report (NLR). The standard procedure treatment of complete laceration of the ACL, is performed by tissue autograft implantation designed from a patellar tendon, for replacement of damaged tissue using orthopaedic surgery. The aim of this thesis is to design and fabricate an ACL graft, attempting to mimic the natural ACL, for the purpose of tissue reconstruction. The desired graft analogues exhibited properties imitating native connective tissue, reducing pain through drug delivery with great biocompatibility and enhance suture mechanical strength. Various biomaterials were implemented into this study, utilising strategies; polymer solution fabrication, electrospinning, hydrogel synthesis, mechanical braiding and graft assembly to fabricate an ACL graft. The polymeric material poly (E- caprolactone) (PCL) was researched, utilising its ability to fabricate scaffolds. Results showed, three analogue ACL grafts (Braided PCL-BP, Braided PCL + Hydrogel-BPH & Braided PCL + Sutures-BPS) created utilising the properties of braiding, hydrogels and sutures, ultimately improving the versatility of electrospinning for tissue engineering and reconstruction. Graft analogues were tested and compared against patellar tendons producing similar tensile properties. Poly vinyl alcohol (PVA) hydrogels successfully held ibuprofen, revealing drug delivery characteristics, polyester threads improved mechanical properties of electrospun grafts and dry degradation showed that PCL did not lose significant mass over two months. Conclusion, tensile strength of patella tendon was 395x, 790x & 56x of analogue grafts (BP, BPH & BPS) respectively, having potential for improvement of tensile parameters for ligament reconstruction
Surface engineering, characterisation and applications of synthetic polymers for tissue engineering and regenerative medicine. Investigation of the response of MG63 osteosarcoma cell line to modified surface topographies, mechanical properties and cell-surface interactions using different synthetic polymers fabricated in house with various topographical features
No full textAt present there is an extraordinary need to overcome barriers in regards to
discovering novel and enhanced biomaterials for various tissue engineering
applications. The need for durable orthopaedic implants is on the rise to limit
issues such as revision surgery. A promising pathway to enhance fixation is to
accelerate the onset and rate of early cellular adhesion and bone growth
through nanoscale surface topography at the implant surface. The main aim of
this research project was to investigate cellular response to altered physical
and mechanical characteristics of materials suitable for orthopaedic
applications.
Four injection moulded polymeric substrates were produced, each with varied
compositional and topographical characteristics. The four materials fabricated
are Polyether-ether-ketone (PEEK), PEEK with 30% glass fibre (GL/PEEK)
composite, PEEK and GL/PEEK with grooved topography. SEM and AFM
analysis was used to investigate the groove dimensions and surface
roughness of all samples followed by mechanical testing using a nano indenter
to detect the Young’s modulus, stiffness and hardness of all four substrates.
These tests were performed to determine which material has similar
characteristics to cortical bone. These tests were followed by wettability and
surface energy testing. Cell-substrate adhesion was examined using a cell
viability assay to identify if there is a significant difference (p<0.05) between
the percentage of viable cells on all four PEEK based materials. Imaging of
MG-63 osteosarcoma cells using immunohistochemistry staining kits was
conducted to observe the relationship between cell length and surface
topography followed by a comparison between HaCaT (skin) cells and MG-63
(bone) cells.
Following experimental testing mechanical variations between PEEK and
GL/PEEK were identified alongside physical characterization differences. The
grooved topography increased the surface roughness of PEEK and GL/PEEK
in comparison to the planar surface. After 72 hours a correlation between the
increased surface roughness and the percentage of viable MG-63 cells could
be identified. When assessing the effect surface topography has on the water
contact angles and surface energy, all four substrates showed no correlation.
However, the grooved topography did increase the water contact angle and
reduced the surface energy of PEEK in comparison to planar PEEK. Images
of the four substrates after cell culture observed the grooved topography to
affect the cellular orientation of both MG-63 and HaCaT cells.
Polycaprolactone (PCL) scaffolds with a concentration of 1, 3, and 5%
triclosan (an antimicrobial and antifungal agent) were fabricated using
electrospinning. In addition to PCL + Triclosan scaffolds PCL with a
concentration of 1% silver (an antimicrobial agent that can reduce the risk of
infection) and 1, 3, and 5% triclosan were also electrospun. The pore size and
fibre diameters of the scaffolds were investigated using SEM and Image J
software followed by wettability and surface energy testing. MG-63 cells were
cultured on all PCL scaffolds to study cellular viability percentage after 24 and
72 hours. The findings obtained showed the physical characteristics of PCL
scaffolds to affect cellular viability of MG-63 cells.
The output from these findings aim to provide data at a proof of concept level
in understanding the relationship between the mechanical and physical
characteristics of biomaterials and cellular behaviour
Transforming Growth Factor Beta (TGF-β): Natural Curing Agents for Repair
Get PDFyesThere are various techniques to enhance tissue regeneration
via the application of growth factors to the site of regeneration to
induce cells to proliferate, differentiate and regenerate. Generally,
direct application of growth factors has little effect [1] because
the growth factor diffuses out from the site of regeneration very
quickly. This is a problem that can be solved by a controlled
release of growth factor at the site of action over a long period
of time by use of a bioabsorbable scaffold. Growth factors are
protein based molecules in the body which are produced by cells
and attach to the cell surface. Growth factors bind to membrane
receptors, which in turn activate an intracellular signalling
pathway. This will activate or inhibit a gene causing either an
up regulation or down regulation of a gene product, which then
alters the cells behaviour
Cell engineering of human bone monolayers and the effect of growth factors and microcontact printed ECM proteins on wound healing. The role of ECM proteins, TGF¿-1, 2 and 3 and HCl/BSA in cellular adhesion, wound healing and imaging of the cell surface interface with the widefield surface plasmon microscope.
No full textBone repair is modulated by different stimuli. There is evidence that the Transforming Growth Factor-beta (TGF-¿) super-family of cytokines have significant effects on bone structure by regulating the replication and differentiation of chondrocytes, osteoblasts and osteoclasts. There is also significant evidence that interactions with extracellular matrix molecules also influence cell behaviour.
This study aimed at determining the role of the TGF-¿s, Collagen type I, Fibronectin and Laminin in bone cell behaviour. To do this MG63 bone cells were used to examine cell adhesion and alignment to different micro-contact printed ECM protein patterns of different widths. The study also aimed at examining how TGF-¿1, 2 and 3 and their solvent and carrier (HCl and BSA, respectively) effected cell surface interactions, cell morphology, cell proliferation and integrin expression. Finally, this study also aimed at examining how the TGF-¿s and their solvent and carrier influenced wound closure in an in vitro wound closure model and how TGF-¿s influence ECM secretion and integrin expression.
5, 10, 25, 50 and 100¿m wide repeat gratings of Collagen type I, Fibronectin and Laminin patterns were stamp patterned onto glass slides and plated with MG63 cells at 50,000 cells per coverslip. Cells on the fibronectin pattern attached and elongated soon after seeding, but did not adhere readily to collagen and laminin and appeared more rounded until 18hrs after seeding. Cells aligned significantly well on the 50¿m and 100¿m wide fibronectin patterned coverslips with mean angles of alignment ~7.87¿ ¿ 3.06SD and 6.45¿ ¿ 5.08SD, respectively, compared to those with smaller width (p<0.001). In comparison, cells aligned less readily to the other two ECM proteins, showing optimal alignments of 9.66¿ ¿ 4.18SD and 14.36¿ ¿ 1.57SD to the 50¿m wide collagen and laminin patterns, respectively. Differences in cell length mirrored those of alignment, with cells acquiring the greatest length when showing the greatest degree of alignment. The results indicate that MG63 cells responded significantly better to 50 and 100¿m wide fibronectin patterns compared to those with smaller width (p<0.001) indicating that the cells may attach mostly via fibronectin specific integrins.
Cell surface attachment was examined via a trypsinisation assay in which the time taken to trypsinise cells from the surface provided a means of assessing the strength of attachment. The results indicated that treatment with the solvent (HCl), TGF-¿1, 2 and 3 all decreased cell attachment, but this effect was significantly greater in the case of HCl and TGF-¿3 (p<0.001). However, there were significant differences in trypsinisation rates between HCl and TGF-¿3 (p<0.001). The wound healing response to the TGF-¿s and their solvent/carrier was also investigated in 300¿m ± 10-30¿m SD wide model wounds induced in fully confluent monolayers of MG63 bone cells. The results indicated that TGF-¿3 and HCl significantly enhance wound closure when compared against negative controls, TGF-¿1 and TGF-¿2 treatment (p<0.001). It was also found that TGF-¿1 and TGF-¿2 treatment significantly improved wound closure rate in comparison to the controls (p<0.001).
Experiments were performed to determine if the HCl effects on wound closure were dose dependent. Cells were incubated with 20¿M, 40¿M, 80¿M and 160¿M concentrations of HCl prior to wounding and wound closure rates were recorded. Wound closure was dependent on HCl dose with the 80¿M and 160¿M concentrations inducing increases in wound closure rates that were both significantly greater than those induced by 20¿M, 40¿M and control treatments (p<0.001). However, there were significant differences in wound closure between the 80¿M and 160¿M treatment groups after 30hrs of treatment (p<0.001).
The effect of different TGF-¿ isomers and their combinations on proliferation rate and cell length of human bone cells were also assessed. The results suggest that cell morphology changes were observed significantly more in cells treated with TGF-¿(2+3) and TGF-¿(1+3) (p<0.001). Any cell treated with TGF-¿1, TGF-¿(1+2) and TGF-¿(1+2+3) showed significantly less elongation compared to the control and other TGF-¿ isomers. In terms of proliferation rate, TGF-¿3 and TGF-¿(2+3) increased cell numbers more than TGF-¿1, TGF-¿2 and other combinations. TGF-¿1 and its combinations did not show significant proliferation and attachment compared to the control due to perhaps its inhibitory effect in contact with human bone cells.
Immunostaining indicated that treatment with TGF-¿3 significantly promoted the secretion of collagen type I and anti-human fibronectin in addition to integrin (¿3 and ¿1) expression. Statistically TGF-¿3 and their combinations showed significant differences in number of cells stained for collagen type I, anti-human fibronectin, ¿3 and ¿1integrin. Any cell treated with TGF-¿1 or any combination with TGF-¿1 showed significantly lower cell number stained with the same proteins and integrins (p<0.001). Imaging with WSPR allowed observation of the focal contacts without the need for immunostaining. WSPR images revealed guided cells with high contrast band like structures at the border of cells distal to the edge of guidance cue to which they aligned and with less concentrically formed band like features across the cell body. It is believed that the high contrast features are associated with the formation of focal contacts on the edge of the cells distal to the edge of fibronectin patterns, which suggests that cell guidance is aided by a decrease in cell attachment along a guidance feature. The WSPR experiments also indicated that TGF-¿s influenced the distribution of focal contacts. In the case of TGF-¿1 treated cells the bright high contrast regions were intense but only arranged around the periphery of the cell. In TGF-¿2 and TGF-¿3 cells the bright contrast regions were weaker but again mostly localised around the periphery. These findings supported the earlier trypsinisation results
Electrocardiography, ECG Interpretation and Applications
Get PDFYesThe aim of this book is to be able to interpret Electrocardiograms avoiding all possible errors. The accuracy of the interpretation is of great importance but a true diagnosis is far more significant.
This book focuses on the recognition and interpretation of arrhythmias, one of the most important clinical tools in medicine. The greatest degree of accuracy is achieved by familiarising with the normal ECG that enables the recognition of abnormal patterns to be made immediately. Firstly, it is necessary to acquaint the function of the heart and the electrical activity in order to broaden our understanding of how the ECG detects this electrical activity. It is essential to know the characteristic patterns of a normal ECG and to categorise a wide array of morphologic patterns along with determining abnormal ECG patterns to be diagnostic of particular pathological entities.
A series of practical experiments have been carried out on various subjects using the BIOPAC system to record electrical signals of the heart. Subjects were asked to perform various tasks such as lying down, sitting, deep breathing and exercising to detect electrical signals in different conditions and eventually interpret the data. The ethical issue toward each subject is also too important, so it was necessary to let the subject know about any risk factors during experiment. For this purpose, a Volunteer Information Sheet was designed during this work for each subject to read and be aware of all the ethical issues. Also, another Patient Consent Form was designed to make sure that each volunteer fully understands the procedures. Volunteer Questionnaire is necessary to make sure volunteer that there is no problem, which can affect the experimental results.
Finally, ECG results were interpreted using a systematic approach and the precise findings were correlated with the pathophysiology and clinical status of the patient. This book concludes with a thorough investigation into the essential techniques and skills required to accurately interpret an ECG, eliminating as many errors as possible
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