| 1. |
- Ajalloueian, Fatemeh, et al.
(författare)
-
A bedside collagen-PLGA nanofibrous construct for autologous transplantation of minced bladder mucosal
- 2012
-
Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : Hindawi Limited. - 1932-6254. ; 6:suppl 1, s. 128-128
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Bladder regeneration using minced bladder mucosa is an alternative to costly and time-consuming conventional in vitro culturing of urothelial cells. In this method, the uroepithelium expands in vivo and the patient body appears as an incubator. With our preliminary successes, designing an appropriate scaffold that supports in vivo cell expansion and surgical handling in a clinical setting was our aim. This study, investigates cell expansion in a hybrid construct of collagen/poly (lactic-co-glycolide)(PLGA).Materials and methods: An electrospun PLGA mat was placed on a semi-gel collagen inside a mold and covered with a second collagen layer. After gel formation, minced particles of pig bladder mucosa were seeded on the hybrid construct and then processed by plastic compression (PC). The scaffolds were incubated for 2, 4 and 6 weeks in vitro for further studies.Results: Tensile tests show an increase in tensile strength of 0.6 ± 0.1 MPa in PC collagen to 3.6 ± 1.1 MPa in hybrid construct. Morphological studies, histological staining and SEM show that the construct has kept its integrity during the time and proliferated urothelial cells have reached confluence after 4 weeks and a multi-layered urothelium after 6 weeks.Conclusion: We have designed a mechanically robust scaffold that permits surgical handling and tissue expansion in vivo. The construct is easy-to-use for clinical application in an ordinary surgical operating theater for bladder regeneration.
|
|
| 2. |
- Ajalloueian, Fatemeh, et al.
(författare)
-
Bladder biomechanics and the use of scaffolds for regenerative medicine in the urinary bladder
- 2018
-
Ingår i: Nature reviews. Urology. - : Springer Science and Business Media LLC. - 1759-4812 .- 1759-4820. ; 15:3, s. 155-174
-
Forskningsöversikt (refereegranskat)abstract
- The urinary bladder is a complex organ with the primary functions of storing urine under low and stable pressure and micturition. Many clinical conditions can cause poor bladder compliance, reduced capacity, and incontinence, requiring bladder augmentation or use of regenerative techniques and scaffolds. To replicate an organ that is under frequent mechanical loading and unloading, special attention towards fulfilling its biomechanical requirements is necessary. Several biological and synthetic scaffolds are available, with various characteristics that qualify them for use in bladder regeneration in vitro and in vivo, including in the treatment of clinical conditions. The biomechanical properties of the native bladder can be investigated using a range of mechanical tests for standardized assessments, as well as mathematical and computational bladder biomechanics. Despite a large body of research into tissue engineering of the bladder wall, some features of the native bladder and the scaffolds used to mimic it need further elucidation. Collection of comparable reference data from different animal models would be a helpful tool for researchers and will enable comparison of different scaffolds in order to optimize characteristics before entering preclinical and clinical trials.
|
|
| 3. |
|
|
| 4. |
- Ajalloueian, Fatemeh, et al.
(författare)
-
Constructs of electrospun PLGA, compressed collagen and minced urothelium for minimally manipulated autologous bladder tissue expansion
- 2014
-
Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 35:22, s. 5741-5748
-
Tidskriftsartikel (refereegranskat)abstract
- Bladder regeneration based on minced bladder mucosa in vivo expansion is an alternative to in vitro culturing of urothelial cells. Here, we present the design of a hybrid, electrospun poly(lactic-co-glycolide) (PLGA) - plastically compressed (PC) collagen scaffold that could allow in vivo bladder mucosa expansion. Optimisation of electrospinning was performed in order to obtain increased pore sizes and porosity to consolidate the construct and to support neovascularisation and tissue ingrowth. Tensile tests showed an increase in average tensile strength from 0.6 MPa for PC collagen to 3.57 MPa for the hybrid construct. The optimised PLGA support scaffold was placed between two collagen gels, and the minced tissue was distributed either on top or both on top and inside the construct prior to PC; this was then cultured for up to four weeks. Morphology, histology and SEM demonstrated that the construct maintained its integrity throughout cell culture. Cells from minced tissue migrated, expanded and re-organised to a confluent cell layer on the top of the construct after two weeks and formed a multilayered urothelium after four weeks. Cell morphology and phenotype was typical for urothelial mucosa during tissue culture. (C) 2014 Elsevier Ltd. All rights reserved.
|
|
| 5. |
|
|
| 6. |
- Ajalloueian, Fatemeh, et al.
(författare)
-
Investigation of Human Mesenchymal Stromal Cells Cultured on PLGA orPLGA/Chitosan Electrospun Nanofibers
- 2015
-
Ingår i: Journal of Bioprocessing & Biotechniques. - : OMICS Publishing Group. - 2155-9821. ; 5:6
-
Tidskriftsartikel (refereegranskat)abstract
- We compared the viability, proliferation, and differentiation of human Mesenchymal Stromal Cells (MSC)after culture on poly(lactic-co-glycolic acid) (PLGA) and PLGA/chitosan (PLGA/CH) hybrid scaffolds. We appliedconventional and emulsion electrospinning techniques, respectively, for the fabrication of the PLGA and PLGA/CH scaffolds. Electrospinning under optimum conditions resulted in an average fiber diameter of 166 ± 33 nmfor the PLGA/CH and 680 ± 175 nm for the PLGA scaffold. The difference between the tensile strength of thePLGA and PLGA/CH nanofibers was not significant, but PLGA/CH showed a significantly lower tensile modulusand elongation at break. However, it should be noted that the extensibility of the PLGA/CH was higher than thatof the nanofibrous scaffolds of pure chitosan. As expected, a higher degree of hydrophilicity was seen with PLGA/CH, as compared to PLGA alone. The biocompatibility of the PLGA and PLGA/CH scaffolds was compared usingMTS assay as well as analysis by scanning electron microscopy and confocal microscopy. The results showed thatboth scaffold types supported the viability and proliferation of human MSC, with significantly higher rates on PLGA/CH nanofibers. Nonetheless, an analysis of gene expression of MSC grown on either PLGA or PLGA/CH showed asimilar differentiation pattern towards bone, nerve and adipose tissues.
|
|
| 7. |
- Ajalloueian, Fatemeh, et al.
(författare)
-
One-Stage Tissue Engineering of Bladder Wall Patches for an Easy-To-Use Approach at the Surgical Table
- 2013
-
Ingår i: Tissue Engineering. Part C, Methods. - : Mary Ann Liebert Inc. - 1937-3384 .- 1937-3392. ; 19:9, s. 688-696
-
Tidskriftsartikel (refereegranskat)abstract
- We present a method for producing a cell-scaffold hybrid construct at the bedside. The construct is composed of plastic-compressed collagen together with a poly(e-caprolactone) (PCL)-knitted mesh that yields an integrated, natural-synthetic scaffold. This construct was evaluated by seeding of minced bladder mucosa, followed by proliferation in vitro. High mechanical strength in combination with a biological environment suitable for tissue growth was achieved through the creation of a hybrid construct that showed an increased tensile strength (17.9 +/- 2.6 MPa) when compared to plastic-compressed collagen (0.6 +/- 0.12 MPa). Intimate contact between the collagen and the PCL fabric was required to ensure integrity without delamination of the construct. This contact was achieved by surface alkaline hydrolysis of the PCL, followed by adsorption of poly(vinyl) alcohol. The improvement in hydrophilicity of the PCL-knitted mesh was confirmed through water contact angle measurements, and penetration of the collagen into the mesh was evaluated by scanning electron microscopy (SEM). Particles of minced bladder mucosa tissue were seeded onto this scaffold, and the proliferation was followed for 6 weeks in vitro. Results obtained from phase contrast microscopy, SEM, and histological staining indicated that cells migrated from the minced tissue particles and reorganized on the scaffold. Cells were viable and proliferative, with morphological features characteristic of urothelial cells. Proliferation reached the point at which a multilayer with a resemblance to stratified urothelium was achieved. This successful method could potentially be used for in vivo applications in reconstructive urology as an engineered autologous tissue transplant without the requirement for in vitro culture before transplantation.
|
|
| 8. |
- Akhtar, Sultan
(författare)
-
Transmission Electron Microscopy of Graphene and Hydrated Biomaterial Nanostructures : Novel Techniques and Analysis
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Transmission Electron Microscopy (TEM) on light element materials and soft matters is problematic due to electron irradiation damage and low contrast. In this doctoral thesis techniques were developed to address some of those issues and successfully characterize these materials at high resolution. These techniques were demonstrated on graphene flakes, DNA/magnetic beads and a number of water containing biomaterials. The details of these studies are given below.A TEM based method was presented for thickness characterization of graphene flakes. For the thickness characterization, the dynamical theory of electron diffraction is used to obtain an analytical expression for the intensity of the transmitted electron beam as a function of thickness. From JEMS simulations (experiments) the absorption constant λ in a low symmetry orientation was found to be ~ 208 nm (225 ± 9 nm). When compared to standard techniques for thickness determination of graphene/graphite, the method has the advantage of being relatively simple, fast and requiring only the acquisition of bright-field (BF) images. Using the proposed method, it is possible to measure the thickness change due to one monolayer of graphene if the flake has uniform thickness over a larger area.A real-space TEM study on magnetic bead-DNA coil interaction was conducted and a statistical analysis of the number of beads attached to the DNA-coils was performed. The average number of beads per DNA coil was calculated around 6 and slightly above 2 for samples with 40 nm and 130 nm beads, respectively. These results are in good agreement with magnetic measurements. In addition, the TEM analysis supported an earlier hypothesis that 40 nm beads are preferably attached interior of the DNA-coils while 130 nm beads closer to the exterior of the coils.A focused ion-beam in-situ lift-out technique for hydrated biological specimens was developed for cryo-TEM. The technique was demonstrated on frozen Aspergillus niger spores which were frozen with liquid nitrogen to preserve their cellular structures. A thin lamella was prepared, lifted out and welded to a TEM grid. Once the lamella was thinned to electron transparency, the grid was cryogenically transferred to the TEM using a cryo-transfer bath. The structure of the cells was revealed by BF imaging. Also, a series of energy filtered images was acquired and C, N and Mn elemental maps were produced. Furthermore, 3 Å lattice fringes of the underlying Al support were successfully resolved by high resolution imaging, confirming that the technique has the potential to extract structural information down to the atomic scale. The experimental protocol is ready now to be employed on a large variety of samples e.g. soft/hard matter interfaces.
|
|
| 9. |
- Ananta, M., et al.
(författare)
-
A Novel Poly(L-Lactide-co-e-Caprolactone)-Collagen Hybrid Construct for Application in Tissue Engineering
- 2007
-
Ingår i: Termis-EU Meeting Abstracts, London, UK September 4-7 2007. - : Mary Ann Liebert Inc.. ; , s. 1637-1637
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A biodegradable hybrid construct consisting of a slow degrading poly(L-lactide-co-e-caprolactone) (PLA-e-CL) knitted mesh, plastically compressed (1) between two collagen gels was fabricated and tested in vitro for tissue engineering applications. The polymer mesh was incorporated to give greater mechanical stability to the compressed collagen scaffolds. The hybrid construct was characterized for fluid (weight) loss and cell viability during compression and mechanical properties. Hybrid constructs embedded and surface layered with human dermal fibroblasts (2, Eþ5 per 5 ml) were cultured for up to one week in static culture. Quantitative and qualitative data on cell viability and proliferation were obtained. It was found that the fluid (weight) loss in plastic compression of the hybrid construct was time dependent and not weight dependent at an applied load of 240 grams. No significant cell death was observed during the plastic compression process and a homogenous cell distribution was achieved. One week of static culture showed that the cultivated hybrid construct retained its mechanical properties with no evidence of degradation, and cells inside the constructs as well as layered on top of the constructs proliferated. We found the PLA-e-CL-Collagen hybrid construct a useful three-dimensional scaffold for tissue engineering of stratified tissues and potential applications in bladder wall, blood vessels and skin are currently being explored.
|
|
| 10. |
- Ananta, M, et al.
(författare)
-
A Poly(Lactic Acid-Co-Caprolactone)–Collagen Hybrid for Tissue Engineering Applications
- 2009
-
Ingår i: Tissue engineering Part A. - : Mary Ann Liebert, Inc.. - 1937-3341 .- 1937-335X. ; 15:7, s. 1667-1675
-
Tidskriftsartikel (refereegranskat)abstract
- A biodegradable hybrid scaffold consisting of a synthetic polymer, poly(lactic acid-co-caprolactone) (PLACL), and a naturally derived polymer, collagen, was constructed by plastic compressing hyperhydrated collagen gels onto a flat warp-knitted PLACL mesh. The collagen compaction process was characterized, and it was found that the duration, rather than the applied load under the test conditions in the plastic compression, was the determining factor of the collagen and cell density in the cell-carrying component. Cells were spatially distributed in three different setups and statically cultured for a period of 7 days. Short-term biocompatibility of the hybrid construct was quantitatively assessed with AlamarBlue and qualitatively with fluorescence staining and confocal microscopy. No significant cell death was observed after the plastic compression of the interstitial equivalents, confirming previous reports of good cell viability retention. The interstitial, epithelial, and composite tissue equivalents showed no macroscopic signs of contraction and good cell proliferation with a two- to threefold increase in cell number over 7 days. Quantitative analysis showed a homogenous cell distribution and good biocompatibility. The results indicate that viable and proliferating multilayered tissue equivalents can be engineered using the PLACL-collagen hybrid construct in the space of several hours.
|
|
