Fatemeh Ajalloueian
Technical University of Denmark,
Fatemeh Ajalloueian is a Post-doc researcher in Technical University of Denmark (DTU). Her research interests include biomaterials, biomechanics, and tissue engineering. She has had experience of working in different countries including Sweden, Iran, and Denmark. In 2012, she received a 2-year fellowship from Harvard Bioscience Inc. (USA) to continue her research in KI (Sweden). In 2015, she was awarded two Post-doctoral grants from Danish Council for Independent research (DFF) and HC Ørsted COFUND. She was further awarded the Research Talent grant (Sapere Aude) from DFF. She has around 30 publications in high-ranked journals and is member of different scientific societies.
Introduction
Tissue engineering of the urinary bladder has evolved as an attractive alternative method (compared to applying vascularized intestinal grafts) for treating bladder anomalies 1–3. Scaffold, one of the key aspects of tissue engineering, has recently attracted more attention. 3D scaffolds mimicking the natural extracellular matrix of the native tissue, are considered as a structural template to support cell adhesion, migration, proliferation and differentiation. Right selection of biopolymers and fabrication methods are expected to improve regeneration of a target tissue4. In this study, we have tried to look at morphology of main layers of bladder to mimic their structure for a functional bladder wall regeneration.
Materials and methids
To look at the morphology of bladder main layers in a porcine sample, the bladder was opened, fixed on a plate, and urothelium was separated manually from detrusor. Both layers were examined by scanning electron microscopy (SEM). Specimens were fixed in 10% formalin, washed with distilled water, and passed through a graded ethanol series to remove water, and immersed in hexa- methyldisilazane. Samples were then air-dried, mounted on stubs, sputter-coated with gold, and examined on a digital scanning electron microscope. Two different biopolyemrs and fabrication techniques were selected based on the SEM observations to make the final scaffold for tissue engineering studies.
Results and discussions
According to macroscopic and SEM observations, urothelium was found as a thin layer with nanofibrous structure, compared to detrusor with higher thickness and containing combination of microfilaments and nanoscale fibers. In this regard, we applied silk fibroin knitted fabric as a microfilament substrate replicating the detrusor. Collagen was selected as the optimum biomaterial for regeneration of urothelium, and the fabrication technique was compression of collagen hydrogel into the knitted fabric. Consequently, an integrated layered structure resembling the native bladder wall was fabricated. Our tissue-seeding studies into this construct have shown successful regeneration of multilayerd urothelium, and 3D regeneration of smooth muscle cells in a silk-collagen micro-nanostructured substrate similar to detrusor.
1. Atala, A. Br. Med. Bull. (2011)
2. Atala, A., et al Lancet (2006)
3. Atala, A. BJU Int. (2001)
4. Ajalloueian, F., et al. Biomaterials (2014)
Polymer nanocomposites , Tissue engineering and regenerative nanomedicine
