Development and Characterization of a Porcine Liver Scaffold.

The growing number of patients requiring liver transplantation for chronic liver disease cannot be currently met due to a shortage in donor tissue. As such, alternative tissue engineering approaches combining the use of acellular biological scaffolds and different cell populations (hepatic or progenitor) are being explored to augment the demand for functional organs. Our goal was to produce a clinically relevant sized scaffold from a sustainable source within 24 h, while preserving the extracellular matrix (ECM) to facilitate cell repopulation at a later stage. Whole porcine livers underwent perfusion decellularization via the hepatic artery and hepatic portal vein using a combination of saponin, sodium deoxycholate, and deionized water washes resulting in an acellular scaffold with an intact vasculature and preserved ECM. Molecular and immunohistochemical analysis (collagen I and IV and laminin) showed complete removal of any DNA material, together with excellent retention of glycosaminoglycans and collagen. Fourier-transform infrared spectroscopy (FTIR) analysis showed both absence of nuclear material and removal of any detergent residue, which was successfully achieved after additional ethanol gradient washes. Samples of the decellularized scaffold were assessed for cytotoxicity by seeding with porcine adipose-derived mesenchymal stem cells in vitro, these cells over a 10-day period showed attachment and proliferation. Perfusion of the vascular tree with contrast media followed by computed tomography (CT) imaging showed an intact vascular network. In vivo implantation of whole intact nonseeded livers, into a porcine model (as auxiliary graft) showed uniform perfusion macroscopically and histologically. Using this method, it is possible to create an acellular, clinically sized, liver scaffold with intact vasculature in less than 24 h.

Ex vivo culture of keratinocytes on papillary and reticular dermal layers remodels skin explants differently: towards improved wound care.

In this study, we characterised the effect that seeding keratinocytes on the papillary and reticular dermis had on the extracellular matrix and tissue integrity ex vivo. Human skin explants from consented patients (n = 6) undergoing routine surgery were cultured at a liquid-air interface, dermal-side up, and autologous keratinocytes seeded on the exposed papillary or reticular layer. After 7-21 days, histological and immunohistochemical evaluation of the morphology and extracellular matrix was performed. While the dermis remained robust in all explants cultures, keratinocytes seeded on the papillary layer showed less tissue infiltration and remodelling and formed clusters across the tissue. In contrast, keratinocytes seeded on the reticular layer infiltrated the tissue homogenously with an intact single-cell-layer surface coverage and structural changes characterised by increased deposition of ground substance, glycosaminoglycans, and collagen VII in 14 days. In addition, while the papillary section showed more new laminin deposition by 14 days than the reticular section, the latter expressed more connexin 43. These differences in re-epithelialisation and extracellular matrix characteristics suggest that wound depth and graft thickness may play a key role in wound healing and indicate that ECM characteristics should be factored in when designing biomaterials for wound applications and in the selection of recipient sites when using cells for grafting.

Gadolinium Tagged Osteoprotegerin-Mimicking Peptide: A Novel Magnetic Resonance Imaging Biospecific Contrast Agent for the Inhibition of Osteoclastogenesis and Osteoclast Activity.

The control of osteoblast/osteoclast cross-talk is crucial in the bone remodelling process and provides a target mechanism in the development of drugs for bone metabolic diseases. Osteoprotegerin is a key molecule in this biosignalling pathway as it inhibits osteoclastogenesis and osteoclast activation to prevent run-away bone resorption. This work reports the synthesis of a known osteoprotegerin peptide analogue, YCEIEFCYLIR (OP3-4), and its tagging with a gadolinium chelate, a standard contrast agent for magnetic resonance imaging. The resulting contrast agent allows the simultaneous imaging and treatment of metabolic bone diseases. The gadolinium-tagged peptide was successfully synthesised, showing unaltered magnetic resonance imaging contrast agent properties, a lack of cytotoxicity, and dose-dependent inhibition of osteoclastogenesis in vitro. These findings pave the way toward the development of biospecific and bioactive contrast agents for the early diagnosis, treatment, and follow up of metabolic bone diseases such as osteoporosis and osteosarcoma.

Carbon-cryogel hierarchical composites as effective and scalable filters for removal of trace organic pollutants from water.

Effective technologies are required to remove organic micropollutants from large fluid volumes to overcome present and future challenges in water and effluent treatment. A novel hierarchical composite filter material for rapid and effective removal of polar organic contaminants from water was developed. The composite is fabricated from phenolic resin-derived carbon microbeads with controllable porous structure and specific surface area embedded in a monolithic, flow permeable, poly(vinyl alcohol) cryogel. The bead-embedded monolithic composite filter retains the bulk of the high adsorptive capacity of the carbon microbeads while improving pore diffusion rates of organic pollutants. Water spiked with organic contaminants, both at environmentally relevant concentrations and at high levels of contamination, was used to determine the purification limits of the filter. Flow through tests using water spiked with the pesticides atrazine (32 mg/L) and malathion (16 mg/L) indicated maximum adsorptive capacities of 641 and 591 mg pollutant/g carbon, respectively. Over 400 bed volumes of water contaminated with 32 mg atrazine/L, and over 27,400 bed volumes of water contaminated with 2 µg atrazine/L, were treated before pesticide guideline values of 0.1 µg/L were exceeded. High adsorptive capacity was maintained when using water with high total organic carbon (TOC) levels and high salinity. The toxicity of water filtrates was tested in vitro with human epithelial cells with no evidence of cytotoxicity after initial washing.

Γ-Al2O3-based nanocomposite adsorbents for arsenic(V) removal: assessing performance, toxicity and particle leakage.

The generation and development of effective adsorption materials for arsenic removal are urgently needed due to acute arsenic contamination of water sources in many regions around the world. In the search for these new adsorbents, the application of nanomaterials or nanocomposites, and especially the use of nanoparticles (NPs), has proven increasingly attractive. While the adsorptive performance of a range of nanocomposite and nanomaterial-based systems has been extensively reviewed in previously-published literature, the stability of these systems in terms of NP release, i.e. the ability of the nanomaterial or nanocomposite to retain incorporated NPs, is less well understood. Here we examine the performance of nanocomposites comprised of aluminium oxide nanoparticles (AluNPs) incorporated in macroporous polyacrylamide-based cryogels (n-Alu-cryo, where n indicates the percentage of AluNPs in the polymer material (n=0-6%, w/v)) for As(V) adsorption, and evaluate AluNP leakage before and after the use of these materials. A range of techniques is utilised and assessed (SEM, TEM, mass weight change, PIXE and in vitro toxicity studies). The 4-Alu-cryo nanocomposite was shown to be optimal for minimising AluNP losses while maximising As(V) removal. From the same nanocomposite we were further able to show that NP losses were not detectable at the AluNP concentrations used in the study. Toxicity tests revealed that no cytotoxic effects could be observed. The cryogel-AluNPs composites were not only effective in As(V) removal but also in immobilising the AluNPs. More challenging flow-through conditions for the evaluation of NP leakage could be included as a next step in a continued study assessing particle loss and subsequent toxicity.