Tissue Engineering

Regeneration and orthotopic transplantation of a bioartificial lung

by Laertis Ikonomou

The Complementarity of the Technical Tools of Tissue Engineering and the Concepts of Artificial Organs for the Design of Functional Bioartificial Tissues

by Laertis Ikonomou

Non-linear microscopy of smooth muscle cells in artificial extracellular matrices made of cellulose

by Nihal Engin Vrana

Authors: Christian Brackmann, Jan-Olof Dahlberg, Nihal Engin Vrana, Caitriona Lally , Paul Gatenholm, Annika Enejder,
Published in Journal of Biophotonics

Non-linear microscopy has been used to characterize bovine smooth muscle cells and their proliferation, migration, and... more Non-linear microscopy has been used to characterize bovine smooth muscle cells and their proliferation, migration, and differentiation in hydrogel cellulose scaffolds, toward the development of fully functional blood vessel implants. The extracellular matrix (ECM) composed of cellulose and endogenous collagen fibers was imaged using Second Harmonic Generation (SHG) microscopy and the cell morphology by Coherent Anti-Stokes Raman Scattering (CARS) microscopy. Images prove that cells adhere on the cellulose scaffold without additional surface modification and that both contractile and proliferating phenotypes are developed. This work shows that non-linear microscopy contributes with unique insights in cell interactions with (artificial) ECM components and has the potential to become an established characterization method in tissue engineering.

Evaluation of porcine aortic valve interstitial cell activity using different serum types in two-and three-dimensional culture

by Wesley Bond

Development of a novel model for the investigation of implant-soft tissue interface

by Chai Wen Lin

Background: In dental implant treatment, the long-term prognosis is dependent on the biologic seal formed by the soft... more Background: In dental implant treatment, the long-term prognosis is dependent on the biologic seal formed by the soft tissue around the implant. The in vitro investigation of the implant-soft tissue interface is usually carried out using a monolayer cell-culture model that lacks a polarized-cell phenotype. This study developed a tissue-engineered threedimensional oral mucosal model (3D OMM) to investigate the implant-soft tissue interface. Methods: A 3D OMM was constructed using primary human oral keratinocytes and fibroblasts cultured on a skin-derived scaffold at an air-liquid interface. A titanium implant was inserted into the engineered oral mucosa and further cultured to establish epithelial attachment. The 3D OMM was characterized using basic histology and immunostaining for cytokeratin (CK) 10 and CK13. Histomorphometric analyses of the implant-soft tissue interface were carried out using a light-microscopy (LM) examination of ground sections and semi-thin sections as well as scanning electron microscopy (SEM). Results: Immunohistochemistry analyses suggests that the engineered oral mucosa closely resembles the normal oral mucosa. The LM and SEM examinations reveal that the 3D OMM forms an epithelial attachment on the titanium surface. Conclusion: The 3D OMM provided mimicking peri-implant features as seen in an in vivo model and has the potential to be used as a relevant alternative model to assess implant-soft tissue interactions.

Tissue-engineered Oral Mucosa

by Chai Wen Lin

Advances in tissue engineering have permitted the three-dimensional (3D) reconstruction of human oral mucosa for... more Advances in tissue engineering have permitted the three-dimensional (3D) reconstruction of human oral mucosa for various in vivo and in vitro applications. Tissue-engineered oral mucosa have been further optimized in recent years for clinical applications as a suitable graft material for intra-oral and extra-oral repair and treatment of soft-tissue defects. Novel 3D in vitro models of oral diseases such as cancer, Candida, and bacterial invasion have been developed as alternatives to animal models for investigation of disease phenomena, their progression, and treatment, including evaluation of drug delivery systems. The introduction of 3D oral mucosal reconstructs has had a significant impact on the approaches to biocompatibility evaluation of dental materials and oral healthcare products as well as the study of implant-soft tissue interfaces. This review article discusses the recent advances in tissue engineering and applications of tissue-engineered human oral mucosa.

Enhanced healing of diabetic wounds by topical administration of adipose tissue-derived stromal cells overexpressing stromal-derived factor-1: biodistribution and engraftment analysis by bioluminescent imaging

by Gabriele Toietta

Giuliana Di Rocco, Antonietta Gentile, Annalisa Antonini, Silvia Truffa, Giulia Piaggio, Maurizio C Capogrossi, Gabriele Toietta
Stem Cells Int. (2010) 2011:304562.

The use of polyhydroxyalkanoates as biodegradable polymer scaffolds for nerve tissue engineering.

by Lani Elisabeth Ackerman

Regenerative Nanomedicine: Ethical, Legal, and Social Issues

by Linda MacDonald Glenn

Co-authored with Dr. Jeannann S. Boyce, published in Methods in Molecular Biology, 2012

Advances in regenerative nanomedicine raise a host of ethical, legal, and social questions that healthcare providers... more Advances in regenerative nanomedicine raise a host of ethical, legal, and social questions that healthcare providers and scientists will need to consider. These questions and concerns include definitions, appropriate applications, dual use, potential risks, regulations, and access. In this chapter, we provide an overview of the questions and concerns and recommend proactive consideration and solutions.

A Hybrid Silk/RADA-based Fibrous Scaffold with Triple Hierarchy for Ligament Regeneration.

by Sambit Sahoo

Chen K, Sahoo S, He PF, Ng KS, Toh SL, Goh JCH. Tissue Eng Part A. 2012

Bio-hybrid tactile sensor and experimental set-up for investigating and mimicking the human sense of touch

by David Cheneler

Cheneler, D., Buselli, E, Oddo, C. M., Kaklamani, G., Beccai, L, Carrozza, M. C., Grover, L., Anthony, C., Ward, M. C. L. and Adams, M., (2012), Bio-hybrid tactile sensor and experimental set-up for investigating and mimicking the human sense of touch, Proceedings of HRI2012, Boston, USA, 3rd March 2012

In this paper, we describe the design and fabrication of a bio-hybrid tactile sensor and experimental platform. The... more In this paper, we describe the design and fabrication of a bio-hybrid tactile sensor and experimental platform. The system uses tissue engineered alginate encapsulated fibroblasts and a conductivity sensor as a transduction system to monitor applied normal and tangential loads in a manner comparable to mechanotransduction in the human haptic system in nonglabrous skin. The tissue is integrated into a microfluidic system interfaced with a nanoporous membrane capable of sustaining the viability of the cells for extended times. The efficacy of the bio-hybrid tactile sensor is validated using a 2 DoF Cartesian manipulator, capable of indenting and sliding textured stimuli over the device. Also, the platform includes a two-cell Peltier-based temperature controlled control module. This allows the evaluation of the effect of temperature variation on the bio-hybrid sensor response, and to decouple the effect of temperature from mechanical stimulation.

Ethology of Art and Science Collaborations: Research Ethics Boards in the Context of Contemporary Art Practice (Bridges II)

by Garnet Hertz

Lecture notes from Bridges II Consortium, October 4-6, 2002. Banff Centre, Canada.

Frameworks for ethical review of scientific research are well established and documented; however, many... more Frameworks for ethical review of scientific research are well established and documented; however, many interdisciplinary artists and art institutions are unfamiliar with these policies and procedures, as well as the potential benefits this process offers within emergent areas of collaborative research. In this paper, we will examine currently established models for ethical review of scientific research as they would apply to interdisciplinary fields. Using the Canadian system as a basis for discussion, a practical overview of its guiding principles, conducts, application processes, terms of approval and liabilities will be presented. Issues covered will include tissue culture, animal use, genetic modification and transgenics. Relavant highlights will be presented from the Interagency Advisory Panel on Research Ethics (PRE), the Canadian Institutes of Health Research (CIHR), the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canada Council of Animal Care (CCAC) and the Social Sciences and Humanities Research Council of Canada (SSHRC). Examples of contemporary artworks will be explored as specific case studies in relation to the ethics review process. Proper navigation of these processes may offer guidance to artists and institutions that engage controversial subjects, use scientific facilities, or attempt to gain access to funding traditionally oriented to scientific research.

Complex microstructured 3D surfaces using chitosan biopolymer.

by Javier G. Fernandez

Co-authored with Christopher A. Mills and Josep Samitier, Published in "Small"

A technique for producing micrometer-scale structures over large, nonplanar chitosan surfaces is described. The... more A technique for producing micrometer-scale structures over large, nonplanar chitosan surfaces is described. The technique makes use of the rheological characteristics (deformability) of the chitosan to create freestanding, three-dimensional scaffolds with controlled shapes, incorporating defined microtopography. The results of an investigation into the technical limits of molding different combinations of shapes and microtopographies are presented, highlighting the versatility of the technique when used irrespectively with inorganic or delicate organic moulds. The final, replicated scaffolds presented here are patterned with arrays of one-micrometer-tall microstructures over large areas. Structural integrity is characterized by the measurement of structural degradation. Human umbilical vein endothelial cells cultured on a tubular scaffold show that early cell growth is conditioned by the microtopography and indicate possible uses for the structures in biomedical applications. For those applications requiring improved chemical and mechanical resistance, the structures can be replicated in poly(dimethyl siloxane).

Mechanical vibrations increase the proliferation of articular chondrocytes in high-density culture

by Jake Kaupp

Published in Journal of Engineering in Medicine 2008

Tissue engineering is a promising approach for articular cartilage repair; however, it still has proven a challenge to... more Tissue engineering is a promising approach for articular cartilage repair; however, it still has proven a challenge to produce tissue from the limited number of cells that can be extracted from a single individual. Relatively few cell expansion methods exist without the problems of dedifferentiation and/or loss of potency. Previously, it has been shown that mechanical vibrations can enhance chondrocyte proliferation in monolayer culture. Thus, it was hypothesized that chondrocytes grown in high-density culture would respond in a similar fashion while maintaining phenotypic stability. Isolated bovine articular chondrocytes were seeded in high-density culture on MillicellTM filters and subjected to mechanical vibrations 48 h after seeding. Mechanical vibrations enhanced chondrocyte proliferation at frequencies above 350Hz, with the peak response occurring at a 1g amplitude for a duration of 30min. Under these conditions, the gene expression of cartilage-specific and dedifferentiation markers (collagen II, collagen I, and aggrecan) were unchanged by the imposed stimulus. To determine the effect of accumulated extracellular matrix (ECM) on this proliferative response, selected cultures were stimulated under the same conditions after varying lengths of preculture. The amount of accumulated ECM (collagen and proteoglycans) decreased this proliferative response, with the cultures becoming insensitive to the stimulus after 1 week of preculture. Thus, mechanical vibration can serve as an effective means preferentially to stimulate the proliferation of chondrocytes during culture, but its effects appear to be limited to the early stages where ECM accumulation is at a minimum.

Mesenchymal Stem Cell Fate is Regulated by the Composition and Mechanical Properties of Collagen-Glycosaminoglycan Scaffolds

by Matthew Haugh

Published in the Journal of the Mechanical Behavior of Biomedical Materials

In stem cell biology, focus has recently turned to the influence of the intrinsic properties of the extracellular... more In stem cell biology, focus has recently turned to the influence of the intrinsic properties of the extracellular matrix (ECM), such as structural, composition and elasticity, on stem cell differentiation. Utilising collagen-glycosaminoglycan (CG) scaffolds as an analogue of the ECM, this study set out to determine the effect of scaffold stiffness and composition on naive mesenchymal stem cell (MSC) differentiation in the absence of differentiation supplements. Dehydrothermal (DHT) and 1-ethyl-3-3-dimethyl aminopropyl carbodiimide (EDAC) crosslinking treatments were used to produce three homogenous CG scaffolds with the same composition but different stiffness values: 0.5, 1 and 1.5 kPa. In addition, the effect of scaffold composition on MSC differentiation was investigated by utilising two glycosaminoglycan (GAG) types: chondroitin sulphate (CS) and hyaluronic acid (HyA). Results demonstrated that scaffolds with the lowest stiffness (0.5 kPa) facilitated a significant up-regulation in SOX9 expression indicating that MSCs are directed towards a chondrogenic lineage in more compliant scaffolds. In contrast, the greatest level of RUNX2 expression was found in the stiffest scaffolds (1.5 kPa) indicating that MSCs are directed towards an osteogenic lineage in stiffer scaffolds. Furthermore, results demonstrated that the level of up-regulation of SOX9 was higher within the CHyA scaffolds in comparison to the CCS scaffolds indicating that hyaluronic acid further influences chondrogenic differentiation. In contrast, enhanced RUNX2 expression was observed in the CCS scaffolds in comparison to the CHyA scaffolds suggesting an osteogenic influence of chondroitin sulphate on MSC differentiation. In summary, this study demonstrates that, even in the absence of differentiation supplements, scaffold stiffness can direct the fate of MSCs, an effect that is further enhanced by the GAG type used within the CG scaffolds. These results have significant implications for the therapeutic uses of stem cells and enhance our understanding of the physical effects of the in vivo microenvironment on stem cell behaviour.

Premixed monetite-­‐forming calcium phosphate cement as a carrier for bone morphogenetic protein 2. A biphasic release profile.

by Nick Walters

Masters research project conducted at Uppsala University, Sweden.

Osseous tissue continuously degrades and remodels itself throughout life, maintaining regenerative potential... more Osseous tissue continuously degrades and remodels itself throughout life, maintaining regenerative potential throughout adulthood. Bone defects caused by trauma, tumour removal or birth defects are common, with grafting of transplanted tissue currently the preferred method for bone replacement. However, there are many issues inherent with autograft and allograft, including donor site morbidity, supply of tissue, immune rejection, infection and expense. In order to overcome these drawbacks, a diverse array of synthetic biomaterials that attempt to structurally mimic bone is under development. Primarily, these materials must be osteoconductive by providing physical properties that support bone growth. Additionally, they may include extra components such as growth factors or stem cells that lend them osteoinductive or osteogenic potential and stimulate more complete graft integration.

Calcium phosphate cements (CPC) are a group of injectable calcium orthophosphates (CaP) whose formulation can be designed to lend them, amongst other characteristics, similar mineral content and porosity to native bone. The composition of a material that forms mineral is crucial, in order for resorption to occur. Upon setting, CPCs form mineral phases such as hydroxyapatite, which is similar to the carbonate hydroxyapatite that constitutes bone, and brushite, which is more readily resorbed. Interconnected macroporosity is also important, allowing cell migration into the material and leading to bone ingrowth and vascularisation of newly formed tissue. CPCs are particularly advantageous due to their low setting temperature and ease of administration by syringe, which allow for minimally invasive surgery. Their physiological setting temperature also makes them convenient carriers for drugs such as bone morphogenetic protein 2 (BMP-2), which some surgeons use routinely during surgery for its ability to promote differentiation of mesenchymal stem cells to osteoblasts.

In recent years attempts have been made to improve the handling properties of CPCs by making them available as off-the-shelf, sterile, premixed cements (PCPC), which remove the mixing step during surgery. Additional advantages include minimal risk of contamination, absence of mixing error, reduced operating time, increased setting time and prolonged storage. This study investigated the release profile of BMP-2 from a PCPC over a one week period. The cement, composed of equimolar quantities of beta-tricalcium phosphate and monocalcium phosphate monohydrate, forms a monetite mineral phase upon setting and has a setting time of 35-40 minutes. BMP-2 was incorporated at 0.00, 0.05 and 0.50 mg of BMP-2 per mL of cement and extracted into cell culture medium in a periodic manner. BMP-2 concentration in the extracts was determined by ELISA.

The release of BMP-2 from the PCPC was shown to be biphasic, with a burst release resulting from precipitation of particles during the setting reaction, followed by a prolonged, minimal release until day four. Release thereafter is negligible and the total amount released after one week amounts to under 1.6% of the total BMP-2 incorporated into the material. The low quantity of BMP-2 detected in cement extracts may be attributed to various factors, including technical limitations of the ELISA and physical properties of BMP-2. In vivo resorption of the material would also likely promote additional BMP-2 release relative to time due to more cement degradation and resorption by osteoclasts. Furthermore, since the protein is effective in the nanogram range, PCPC containing a “high” dose such as 0.50 mg/mL should provide sufficient BMP-2 to the surrounding tissue. The initial burst release upon setting could trigger chemotaxis of mesenchymal stem cells to the site, followed by differentiation to osteoblasts, as well as stimulation of osteoclast activity. The prolonged gradual release of BMP-2 should aid sustained resorption of the material by osteoclasts, combined with new bone formation via promotion of osteoblastic differentiation.

Application of high power quantum dot superluminescent diodes: skin imaging with optical coherence tomography.

by Louise Smith

N. Krstajić, L.E. Smith, S.J. Matcher D. T. D. Childs, M. Bonesi, P.D.L. Greenwood, M. Hugues, K. Kennedy, M. Hopkinson, K.M. Groom, S. MacNeil, R. A. Hogg, R. Smallwood.
IEEE Journal on Selected Topics in Quantum Electronics
Volume 16 Issue 4 Pages 748-754 July 2010

We present a high-power (18 mW continuous wave exiting a single-mode fiber and 35 mW exiting the facet), broadband (85... more We present a high-power (18 mW continuous wave exiting a single-mode fiber and 35 mW exiting the facet), broadband (85 nm full-width at half-maximum) quantum dot-based superluminescent diode, and apply it to a time-domain optical coherence tomography (OCT) setup. First, we test its performance with increasing optical feedback. Then we demonstrate its imaging properties on tissue-engineered (TE) skin and in vivo skin. OCT allows the tracking of epidermal development in TE skin, while the higher power source allows better sensitivity and depth penetration for imaging of in vivo skin layers.

Using swept‐source optical coherence tomography to monitor the formation of neo‐epidermis in tissue‐engineered skin

by Louise Smith

Louise E. Smith, Marco Bonesi, Rod Smallwood, Stephen J. Matcher, Sheila MacNeil.
Journal of Tissue Engineering and Regenerative Medicine
Volume 4, Issue 8, pages 652–658, December 2010

There is an increasing need for a robust, simple to use, non-invasive imaging technology to follow tissue-engineered... more There is an increasing need for a robust, simple to use, non-invasive imaging technology to follow tissue-engineered constructs as they develop. Our aim was to evaluate the use of swept-source optical coherence tomography (SS-OCT) to image tissue-engineered skin as it developed over several weeks. Tissue-engineered skin was produced using both de-epithelialized acellular dermis (DED) and amorphous collagen gels. In both cases the epidermis could be readily distinguished from the neodermis, based on a comparison with standard destructive histology of samples. Constructs produced with DED showed more epidermal/dermal maturation than those produced using collagen. The development of tissue-engineered skin based on DED was accurately monitored with SS-OCT over 3 weeks and confirmed with conventional histology.

An algorithm-based topographical biomaterials library to instruct cell fate

by Hemant Unadkat

It is increasingly recognized that material surface topography is able to evoke specific cellular responses, endowing... more It is increasingly recognized that material surface topography is able to evoke specific cellular responses, endowing materials with instructive properties that were formerly reserved for growth factors. This opens the window to improve upon, in a cost-effective manner, biological performance of any surface used in the human body. Unfortunately, the interplay between surface topographies and cell behavior is complex and still incompletely understood. Rational approaches to search for bioactive surfaces will therefore omit previously unperceived interactions. Hence, in the present study, we use mathematical algorithms to design nonbiased, random surface features and produce chips of poly(lactic acid) with 2,176 different topographies. With human mesenchymal stromal cells (hMSCs) grown on the chips and using high-content imaging, we reveal unique, formerly unknown, surface topographies that are able to induce MSC proliferation or osteogenic differentiation. Moreover, we correlate parameters of the mathematical algorithms to cellular responses, which yield novel design criteria for these particular parameters. In conclusion, we demonstrate that randomized libraries of surface topographies can be broadly applied to unravel the interplay between cells and surface topography and to find improved material surfaces.

(2011) An improved kidney dissociation and re-aggregation culture system results in nephrons arranged organotypically around a single collecting duct system.

by Jamie Davies

Ganeva V, Unbekandt M, Davies JA (2011) Organogenesis 7: 83-87

Methods for constructing engineered ‘tissues’ from simple suspensions of cells are valuable for investigations into... more Methods for constructing engineered ‘tissues’ from simple suspensions of cells are valuable for investigations into basic developmental biology and for tissue engineering. We recently published a method for producing embryonic renal tissues from suspensions of embryonic mouse renal cells. This method reproduced the anatomies and differentiation states of nephrons and stroma very well; it had the limitation, however, that what would in normal development be a single, highly-branched collecting duct tree leading to a ureter developed, in the engineered system, as a multitude of very small, collecting duct trees. These were isolated from each other and therefore would not be effective for draining urine to a common exit, were the tissue to be supplied with blood and physiologically active. Here, we report an improvement on the original method; it results in the formation of nephrons arranged around one single collecting duct tree as would happen in a normal kidney.